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SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY • NUMBER 310

Principal Sunflower Bees of North America with Emphasis on the Southwestern United States (Hymenoptera: Apoidea)

Paul D. Hurd, Jr., Wallace E. LaBerge, and E. Gorton Linsley

SMITHSONIAN INSTITUTION PRESS

City of Washington

1980

ABSTRACT

Hurd, Paul D., Jr., Wallace E. LaBerge, and E. Gorton Linsley. Principal Sunflower Bees of North America with Emphasis on the Southwestern United States (Hymenoptera: Apoidea). Smithsonian Contributions to Zoology, number 310, 158 pages, 1 frontispiece, 11 figures, 5 plates, 17 tables, 1980.—This investigation focuses primarily on those ecological and evolutionary aspects involved in the natural history of the bees that utilize the pollen, nectar, or both, of sunflowers (Helianthus) in North America either for their survival as species or for their maintenance in viable populations. This bee-flower association is examined principally by analyses of the intrafloral, geographic, diurnal, and seasonal interrelationships that exist between this fauna of bees and the various species of Helianthus present in North America. On the basis of this study it is established that more than 400 species of native bees visit the flowers of Helianthus in America north of Mexico. Of these it is those species that have evolved a specialized intrafloral relationship with these flowers that serve as the principal pollinators of these plants.

OFFICIAL PUBLICATION DATE is handstamped in a limited number of initial copies and is recorded in the Institution's annual report, Smithsonian Year. SERIES COVER DESIGN: The coral Montastrea cavernosa (Linnaeus).

Library of Congress Cataloging in Publication Data

Hurd, Paul David, 1921-

Principal sunflower bees of North America with emphasis on the Southwestern United States

(Hymenoptera, Apoidea)

(Smithsonian contributions to zoology ; no. 310)

Bibliography: p.

1. Bees—Southwest, New. 2. Bees—North America. 3. Helianthus. 4. Insect-plant relationships. 5. Insects—Southwest, New. 6. Insects—North America., I. LaBerge, Wallace E., joint author. II. Linsley, E. Gorton, joint author. III. Title. IV. Series: Smithsonian Institution. Smithsonian contributions to zoology ; no. 310.

QL1.S54   no.310   [QL567.1.S68]   591′.08s   [595.7′99′0979]   79-18794

Contents

Introduction

Methods of Study

Sampling Procedures

Acknowledgments

Principal Sampling and Survey Sites

Chihuahuan Desert

Sonoran Desert

Mojave Desert

Cismontane California

Primary Host Plant

Intrafloral Relationships of Bees Associated with Helianthus

Oligoleges of Compositae Primarily Associated with Helianthus

Oligoleges of Compositae Secondarily Associated with Helianthus

Regular Polyleges Associated with Helianthus

Casual Polyleges Associated with Helianthus

Nectar Visitors Not Known To Take Pollen from Helianthus

Parasitic Bees Known To Visit the Flowers of Helianthus

Species of Helianthus with Known Bee Visitors

Geographic Relationships of Bees Associated with Helianthus

Geographic Affinities of Helianthus Oligoleges and Polyleges

Seasonal Occurrence of Bees Associated with Helianthus

Diurnal Patterns of Pollen Collection

Species Accounts

Family COLLETIDAE

Family OXAEIDAE

Family ANDRENIDAE

Family HALICTIDAE

Family MELITTIDAE

Family MEGACHILIDAE

Family ANTHOPHORIDAE

Family APIDAE

Appendix: Tables

Literature Cited

Plates

Requirements for Smithsonian Series Publication

FRONTISPIECE.—Megachile parallela Smith (female) on flower of Helianthus.

Principal Sunflower Bees of North America with Emphasis on the Southwestern United States (Hymenoptera: Apoidea)

Paul D. Hurd, Jr., Wallace E. LaBerge, and E. Gorton Linsley

__________

Paul D. Hurd, Jr., Department of Entomology, National Museum of Natural History, Smithsonian Institution, Washington, DC 20560. Wallace E. LaBerge, Section of Faunistic Surveys and Insect Identification, Illinois Natural History Survey, Urbana, III. 61801. E. Gorton Linsley, Department of Entomological Sciences, University of California, Berkeley, Calif. 94720.

Introduction

The population aspects of bee-flower relationships in the southwestern United States, especially interspecific competition among pollenand nectar-seekers, have been studied for certain species in such diverse plant groups as the matinal flowering Camissonia, Cucurbita, Solanum, Cassia, and Kallstroemia, the late afternoon flowering Mentzelia, and the evening flowering Oenothera, where competition is often intense during the short diurnal blooming period (Linsley, 1978). Only recently have quantitative data become available on pollen and nectar utilization among flower visitors to plants that present nectar and pollen throughout the day (e.g. Larrea, Hurd and Linsley, 1975; Clarkia, MacSwain et al., 1973).

Clarification of the roles and competitive relationships of oligoleges, regular polyleges, and casual polyleges has provided new insights into unilateral and coevolution in insect-flower relationships. Perhaps the most characteristic and neglected of “all-day” plants in these regards are the sunflowers (Helianthus spp.), which provide a continuously favorable environment for pollenand nectar-seeking bees, both of which are capable of providing cross-pollination.

Heiser et al. (1969), in the most recent monograph of North American sunflowers, state that with the exception of H. agrestis and a certain cultivated strain of H. annuus, all species of Helianthus are self-incompatible and cross-pollination is obligate, and that no detailed study of pollinators has been made other than for cultivated forms of H. annuus (Free, 1964). These authors remark, however, that from observations in the field and in the experimental garden it is obvious that the principal pollinators are bees, including the introduced European honeybee. They note that butterflies visit sunflowers extremely rarely, and that their occasional visits have usually been to the pale primrose form (or strain) of H. debilis ssp. cucumerifolius.

While it is technically true that no detailed general study of Helianthus pollinators has been made (and this actually applies to the cultivated strains of H. annuuis), several preliminary lists of sunflower visitors in various parts of the country have been published (see “Intrafloral Relationships of Bees Associated with Helianthus” herein). These, along with scattered data in entomological monographs and local lists, as well as preliminary samples taken by us in 1973 and 1974, indicated that quantitative studies on diurnal and seasonal cycles and interspecific competition among bee visitors would hold promise of yielding interesting ecological and evolutionary data.

Reports concerning bees visiting particular species of Compositae in the southwestern United States are very few. Butler, Werner, and Levin (1966) made twelve locality-month collections in commercial fields of safflower (Carthamus tinctorius) in south central Arizona (primarily Tucson and vicinity) in late May and June. Although they report finding 40 species of native bees, excluding parasitic bees (actually, their list includes four species of cleptoparasitic Sphecodes), they record the sex of the bees only in the case of Agapostemon texanus and do not indicate which species were taking pollen. (In a companion paper, Levin and Butler, 1966, describe their sampling methods, times of day and length of the sampling periods).

Although the taxonomic representation among polyleges partial to safflower is not unlike that which we have found in the same general area on Helianthus annuus and Verbesina encelioides, e.g. mainly halictids (Halictus, Lasioglossum, Evylaeus, Dialictus, and Agapostemon), megachilids (Ashmeadiella and Megachile), Anthophoridae (Melissodes, Anthophora and Xylocopa), and Apidae (Bombus), the number of consistent visitors to the introduced safflower is considerably smaller than is usual for such native composites as sunflowers (Helianthus spp.), which reach their peak of nectar and pollen production in the period of July to September.

This project, following the methodology utilized by Hurd and Linsley (1975) in their recent treatment of Larrea bees, studied the diurnal, seasonal, and geographical occurrence of the principal bees visiting Helianthus. Primary emphasis was placed on the southwestern United States from the Upper Rio Grande Valley of New Mexico to the upper Mojave, the Colorado Desert, and the San Joaquin Valley of California. Specific objectives of this study were to determine the extent to which pollinators are specific to, or show a marked preference for, Helianthus, and to quantify data on interspecific competition among pollinators. Cockerell (1914b) has correctly remarked that male bees visiting sunflowers get covered with pollen, and must be almost as useful as females in the pollination of sunflowers. Thus we have included records of floral visits of male bees and nectar-seeking females as well as females that gather pollen.

Unfortunately, the manuscript was completed before the important and valuable book by Heiser (1976) entitled The Sunflower was received. Although we have tried to incorporate the findings reported therein, we have been unable to provide references to this work as uniformly as that work deserves. The same is true of Sunflower Science and Technology edited by Carter (1978).

METHODS OF STUDY.—The chief sources of data utilized in this study are published records of North American bees collected at Helianthus flowers, records obtained from specimens in museum collections, and especially our intensive field surveys and samples of bees at the flowers of Helianthus during the years of 1973–1977 in Arizona, California, and New Mexico. Of the literature records, we have cited primarily those that can be interpreted in terms of objectives of the project. Unfortunately some of these do not indicate whether or not visitors at the flowers of Helianthus were actually taking pollen.

Our field surveys and sampling of bees from Helianthus flowers have been directed primarily at desert areas in the southwestern United States and the cismontane areas of California including the San Joaquin Valley and coastal southern California. Analyses of data assembled from these various sources have been accomplished primarily by mapping and by plotting the frequency of collection of bees from the flowers of Helianthus in relation to other plant species and the proportion of females carrying Helianthus pollen against foreign pollens or no pollen at all. Relative frequencies of Helianthus flower records have permitted preliminary judgments as to whether the bee species are pollen specialists (oligoleges) or pollen generalists (polyleges) and estimates of their probable value as pollinators.

For data extracted from published records and museum specimens we have used the taxa of Helianthus as reported by the authors or collectors. Although H. lenticularis is currently regarded as a synonym of H. annus (Heiser, 1976), we have listed data for H. lenticularis separately in Table N and elsewhere because of the large number of records published under this name.

SAMPLING PROCEDURES.—Bees visiting sunflowers were sampled in the manner utilized by Hurd and Linsley (1975) in their study of Larrea bees. The bees were collected continuously in half-hour periods, and no bee was taken until it actually alighted on or was seen to visit a flower. This tended to result in an under-sampling of males of oligoleges that patrolled the flower, stopping for nectar only when it was needed for a fresh supply of energy. To minimize error in marking collection vials in the field and in labeling subsequently mounted specimens, the periods were actually recorded as 30 minutes each. Each period, however, started on the hour or half-hour (0600, 0630, etc.) and ended 29 minutes later when vials and labels were changed (0629, 0659). When the collection records were transcribed for analysis they were converted to 29-minute periods. Time periods are reported as Standard Time. Air temperatures were taken in the shade and recorded at the beginning of each sampling period.

The following initials are used in the species accounts for the principal collectors: Paul D. Hurd, Jr. (PDH), E. Gorton Linsley (EGL), Juanita M. (Mrs. E. G.) Linsley (JML), A. E. Michelbacher (AEM), and Martha M. (Mrs. A. E.) Michelbacher (MMM).

In the tables of collections from sampling sites (Tables A–M in the Appendix) the following abbreviations are used: P = carrying Helianthus pollen in the scopa, N = or taking nectar only, although either may be dusted with Helianthus pollen beneath and the female may be carrying pollen from some other plant in the scopa. Each column is headed with the beginning and ending time of the sample period and the air temperature expressed as °C. Observation periods in which bees in one or another category were not captured are indicated by a by a dash (-), periods in which no sampling was attempted, for personal reasons or for adverse weather conditions, are indicated by an asterisk (*). Bees sleeping on flower heads were sampled in comparative but small numbers, so as not to affect materially subsequent activity counts. They are not included in the flower visiting totals. All female honeybees reported were workers, as were bumblebees unless otherwise specified.

ACKNOWLEDGMENTS.—We are under heavy obligation to a number of individuals, as well as several supporting agencies, who have made this study possible. The opportunity afforded the authors to perform research, both in the laboratory and in the field, has been essential to the execution and completion of this study. We are, therefore, indebted to the authorities of of our respective institutions who have made this possible. We gratefully acknowledge the support of this project by the Leopold Edward Wrasse and Elvenia J. Slosson Endowment Funds of the Division of Agricultural Sciences, University of California, the Fluid Research Fund of the Smithsonian Institution, and the Smithsonian Research Foundation (SRF-430039 and SRF-450122).

We are particularly indebted to Professor A. E. Michelbacher (University of California, Berkeley), Mrs. A. E. Michelbacher, and Mrs. E. G. Linsley for their dedication to the objectives of the project and to their field efforts, especially during the sampling program, which provided much of the basic information on the intrafloral ecology of Helianthus bees in the southwestern United States. We also wish to express our gratitude for much appreciated field work on the project to Mont A. Cazier, Arizona State University, Tempe, and Marjorie Favreau, American Museum of Natural History, New York, for field collections they made in the vicinity of Rodeo, New Mexico. Thanks are due Thomas J. Zavortink, University of San Francisco, for providing us with valuable records of bees that he collected at the flowers of Helianthus. We also wish to thank Ms. Emma Kiesel of Oakland, California, for locating the sunflower site at Escalon, California, where we were able to obtain a valuable time count (Table M).

Throughout the course of the project we have relied upon P. H. Timberlake of the University of California, Riverside, for identification or verification of identifications of certain groups of bees, especially Exomalopis, Perdita, and Pseudopanurgus. We also wish to acknowledge the identifications supplied by the following: Howell V. Daly, University of California, Berkeley (Ceratina); George E. Eickwort, Cornell University, Ithaca (Halictines, especially Dialictus); Frank D. Parker, USDA SEA Bee Biology and Systematics Laboratory, Utah State University, Logan (Ashmeadiella); and Robbin W. Thorp, University of California, Davis (Bombus).

In the preparation of the maps (Figures 2–6, 8–11) we received much assistance from a number of individuals who supplied information for certain of these figures. We would therefore like to express our thanks to P. H. Timberlake for supplying locality data for Pseudopanurgus aethiops (Figure 3) and Nomia heteropoda (Figure 5) and to the following who furnished us with additional locality data for Figure 5: W. F. Barr, University of Idaho, Moscow; George W. Byers, University of Kansas, Lawrence; Wilbur R. Enns, University of Missouri, Columbia; Marjorie Favreau, American Museum of Natural History, New York; Gary F. Hevel, National Museum of Natural History (NMNH), Smithsonian Institution, Washington; Carl A. Olson and Floyd G. Werner, University of Arizona, Tucson; J. A. Powell and J. A. Chemsak, University of California, Berkeley; Roy R. Snelling, Los Angeles County Museum of Natural History, Los Angeles; Davis L. Stephan, North Carolina State University, Raleigh; and Robbin W. Thorp and Stephen L. Buchmann, University of California, Davis.

Thanks are also extended to Lloyd V. Knutson, Chairman, Insect Identification and Beneficial Insect Introduction Institute, Science and Education Administration, U.S. Department of Agriculture (USDA), who made possible the identification of certain sunflower-visiting insects by the staff of Systematic Entomology Laboratory, USDA.

We extend our thanks to Henry Schacht, Farm Reporter, San Francisco Chronicle, San Francisco, California, and to Benjamin H. Beard, Research Geneticist, USDA Department of Agronomy and Range Science, University of California, Davis, for information on sunflower seed production in California.

We are indebted to Edward S. Ross, California Academy of Sciences, San Francisco, for the photographs reproduced in the frontispiece and in Plates 1–3. Similarly we acknowledge our indebtedness to Dennis L. Briggs, University of California, Davis, for the photographs reproduced in Plates 4–5.

Throughout the course of the project we have been ably assisted in a variety of capacities by Kathleen Sorensen of the University of California, Berkeley. She has extracted much of the data from various collections, prepared the maps that accompany this study and has performed most of the preparation and curation of the specimens obtained during our field investigations.

The manuscript has been very helpfully reviewed by Verne Grant, Professor of Botany, Department of Botany, University of Texas, Austin; Charles B. Heiser, Jr., Professor of Botany Department of Biology, Indiana University, Bloomington; Jerome G. Rozen, Jr., Deputy Director for Research, American Museum of Natural History, New York; and Robbin W. Thorp, Professor of Entomology, Department of Entomology, University of California, Davis. We especially appreciate their critically useful comments and suggestions, which we regard as significant contributions to this study.

Finally, we would like to express our appreciation to David Bridge, Operations Manager, Automatic Data Processing (NMNH), Smithsonian Institution, Washington, for his helpful role in the processing of the information pertaining to the North American Helianthus-visiting bees embodied bodied in the data base for “Superfamily Apoidea,” Catalog of Hymenoptera in America North of Mexico (Hurd, 1979).

Principal Sampling and Survey Sites

For our field investigations of the intrafloral relationships of the bees associated with Helianthus, we selected 8 primary study sites for an intensive sampling and survey program in the southwestern United States (Tables A-M, in Appendix). These sites were chosen to represent as nearly as possible an east-west transect extending from western New Mexico across Arizona into cismontane southern California with this western terminus expanded northward into the Mojave Desert and the Great Valley of California (San Joaquin Valley).

These primary study sites and some others chosen at random in Arizona and California are grouped for discussion in this section into regions largely on the basis of ecogeographic similarities. The regions are arranged sequentially from east to west within each of the four major subdivisions of the total area studied: Chihuahuan Desert, Sonoran Desert, Mojave Desert, and cismontane California. In Table 1 we have listed those regions where time counts were made (Tables A-M) and have tabulated by study sites the numbers of specimens taken at these sites.

Summarized in Table 2 are the numbers of individuals for each of the 17 commonest pollen-collecting species of bees that were taken during our surveys at the primary sampling and survey sites in New Mexico, Arizona, and California (Tables A-M). From the foregoing it is readily apparent that the 17 commonest species of Helianthus bees (9036 specimens) represent more than 90 percent of the total specimens of bees (9964) obtained in the time counts during our sampling program at the eight primary study sites (Tables A-M).

TABLE 1.—Number of specimens collected in primary surveys, arranged by regions and study sites

TABLE 2.—Number of specimens of 17 commonest pollen-collecting species of bees taken at survey sites

The following accounts briefly characterize by regions, proceeding generally from east to west, the principal sampling and survey sites of our field program.

CHIHUAHUAN DESERT

Vargus Valley: Silver City, Grant County, New Mexico (Table A). Located approximately 90 km northeast of Deming, this one time gold, silver, and zinc mining town is now a flourishing city and trading center for cattle ranching and copper mining. Our samples were taken at an elevation of 1798 m, 8 km northwest of the city in a roadside ditch where a dense stand of Helianthus petiolaris was growing. Broken skies and afternoon rains inhibited sampling on the two days available, 11–12 September 1974. Only 174 bees were collected in nine half-hour counts between 0730 and 1600 hrs conducted when conditions were satisfactory for bee activity. The sample, nevertheless, included 26 species of bees, of which 103 were females taking pollen. The most prominent among these were Megachile inimica (which represented 40 percent of all the pollen collectors), M. parallela (15 percent), Melissodes montana (12 percent), Megachile agustini (7 percent), Melissodes sonorensis (6 percent), Syntrichalonia exquisita (4 percent), and Svastra obliqua (4 percent). Only 3 female Melissodes agilis were captured and none was taking pollen. This fact and the presence of relatively few Svastra obliqua suggest that either the season was just starting or that these species prefer Helianthus annuus, which was present in several areas in the vicinity of the city but was not yet in bloom.

Animas Valley: Animas, Hidalgo County, New Mexico (Table B). A small town in an agricultural community in the Animas Valley just east of the Pelancillo Mountains, at an elevation of 1341 m. Twenty-six half-hour samples were taken from Helianthus annuus near the edge of the town along the western shoulder of the highway heading northward to Cotton City. The counts were made over a two-day period without duplication of samples. More than 1,000 specimens were captured representing 43 species, of which females of at least 17 were taking pollen. The most numerous of these female pollen collectors were Megachile parallela, Melissodes agilis, Svastra machaerantherae, and Svastra obliqua. As at other desert localities, the females of Melissodes agilis were bimodal in their pollen collecting activity. Of 87 individuals, 58 took pollen between 0600 and 0900 hrs (37 of these between 0700 and 0800) and 29 between 1630 and 1830. Males of M. agilis were distributed rather evenly throughout the day patrolling the flowers but the 120 specimens were captured only when they paused for nectar. The most abundant males (210) were those of Melissodes tristis, the females of which are polylectic but were taking only nectar from the sunflowers.

San Simon Valley: Rodeo, Hidalgo County, New Mexico (Table C). A former railroad town on U.S. Highway 80, west of the Pelancillo Mountains in the San Simon Valley near the Arizona State border. The collection site was an established Helianthus annuus area one mile south of town in a seepage ditch just off the easterly edge of the highway shoulder, which received moisture from an old earthen-walled water tank. The plants were growing in a strip approximately 25 m long by 4–6 m wide, interspersed with dead stalks from previous years. When sampled on 2 September 1973, the plants had been in bloom for 6–8 weeks. The large number of parasitic bees present, especially Triepeolus, indicated that the bee populations were well established in the vicinity. Also, annual Compositae which had been in bloom earlier were largely gone to seed, making the sunflowers especially attractive to polylectic species.

The site was first visited at dawn but no bees were present until 30 minutes after sunrise. The first arrivals were pollen-collecting females of Melissodes agilis and Agapostemon angelicus. These also reappeared and took pollen late in the day. Svastra and Megachile were dominant between 0800 and 1800. Male Svastra and Melissodes patrolled the flowers most of the day, but were captured only when they paused on the flowers for nectar.

Of 1959 bees representing at least 54 species collected from the flowers between 0640 and 1900 hours, 849 (43 percent) were females taking pollen. The most numerous of these were Svastra machaerantherae (29 percent of all pollen gathering females), Melissodes agilis (18 percent), Megachile parallela (15 percent), Svastra obliqua (12 percent), Agapostemon angelicus (9 percent), and Melissodes submenuacha (4 percent).

Duncan Valley: Franklin, Graham County, Arizona. Collections were made from a strip of sunflowers (H. annuus) growing along the edge of a dry streambank about 7.5 m from the edge of the highway.

Sulphur Springs Valley: Double Adobe, Cochise County, Arizona (Table D). This locality, northwest of Douglas, is located in agricultural and range land and our collecting site was in a drainage ditch on the easterly edge of the highway just north of this small settlement. Sampling was difficult because of water in the ditch and the fact that most of the flowers faced eastward away from the very narrow highway shoulder. Thus, although consecutive all-day counts were not feasible, collections were taken from time to time and are recorded as a composite sample that gives an indication of the variety of species present. Collections were also made near Cochise, Cochise County, in roadside stands of H. annuus and were recorded but not tabulated.

San Pedro River Valley: Benson, Cochise County, Arizona (Table E). A modernized railroad town on Interstate Highway 10 in west central Cochise County about one-fourth of the distance between Tucson, Arizona, and Lordsburg, New Mexico. Samples were taken from a row of Helianthus annuus in a vacant lot near the edge of town on 14 September 1974. Although temperatures were adequate for flight, broken sky and clouds at midday and rain in the late afternoon precluded a full-day count; nevertheless, 211 individuals were captured between 0715 and 1430 hrs, of which 75 were pollen gathering females. Melissodes agilis, as usual, was the first to appear in the morning, all 43 females taking pollen between 0715 and 0930; 31 of these were active between 0800 and 0900 (rain prevented the normal late afternoon pollen flight). Pseudopanurgus aethiops, Andrena accepta, and Halictus ligatus were active primarily in the forenoon but this may have been the result of unstable afternoon weather. This was the only sunflower locality sampled in Arizona where a varied representation of bees were present and no Megachile appeared.

SONORAN DESERT

Santa Cruz River Valley: 1. Sonoita, 16 km E, Santa Cruz County, Arizona. At this locality, in the northeastern corner of the county, stands of Helianthus petiolaris were numerous along State Highway 82, with some mixed groups containing H. annuus and scattered small but pure stands of H. annuus. On 7 September 1977, sampling revealed that essentially the same species of bees were visiting both species; in mixed stands, individual bees were seen to move from one sunflower to another without hesitation. Pollen collecting was hindered, however, by the large numbers of cantharid beetles, Chauliognathus basalis Le Conte and C. marginatus (Fabricius), and mirid bugs, Adelphocoris superbus (Uhler), on the flower heads, making adequate sampling difficult and an all-day count unfeasible.

2. Patagonia and vicinity, Santa Cruz County, Arizona. From Patagonia northeastward toward Sonoita, H. annuus was just coming into full bloom in early and mid-September 1977. Stops were made at several sites up to six miles northeast of town and at each site bumblebees (Bombus pennsylvanicus sonorus) were literally swarming about the plants, often with two or three individuals taking nectar from a single flower head. Although a few other sunflower bees were captured, consistent sampling was impossible because of the large number of bumblebees present on the flowers.

3. Nogales, Santa Cruz County, Arizona. Just north of the city on U.S. Highway 18, a large stand of sunflowers was sampled in a vacant lot adjacent to an outdoor motion picture theater. Bombus workers were very abundant, mostly taking pollen, and could not be included proportionately in half-hour samples. Other sunflower bees were well represented but more difficult to capture than usual because of disturbance by the bumblebees and a large number of grasshoppers, Melanoplus femur-rubum (DeGeer) (det. W. W. Middlekauff) which crawled up the stems and onto the flowerheads where they apparently both lapped up nectar and fed on pollen. Half-hour samples of bees, nevertheless, were taken and recorded.

4. Sahuarita, Pima County, Arizona. At this site, samples were taken at noon on 15 June from scattered plants of H. annuus growing along a fence row adjacent to a pecan orchard. Only Diadasia enavata females were gathering pollen, but both sexes of D. rinconis, a cactus oligolege, were present in numbers seeking nectar. When a collection was made on 26 June at noon, no bees were taking pollen. Both sexes of Diadasia rinconis, Megachile texana, and Melissodes paroselae, however, were sipping nectar along with a female Diadasia enavata and numerous males of Melissodes tristis.

5. San Xavier, Pima County, Arizona. Collections made just after noon on 19 September from sunflowers (H. annuus) growing in an agricultural area adjacent to the Santa Cruz River where harvest had been completed. Only three of the bees captured were taking pollen. The principal species present, represented by one or both sexes, were Melissodes agilis, Svastra machaerantherae, Halictus confusus, H. ligatus, Dialictus sp., Agapostemon cockerelli, Megachile policaris, and M. occidentalis.

6. Rillito, 10 km W, Pima County, Arizona. Between 0830 and 0930 27 June females of Diadasia enavata and Svastra obliqua were taking pollen and/or nectar from H. annuus growing on a roadside dampened by irrigation drainage. Both sexes of Melissodes paroselae and M. tristis were taking nectar.

7. Marana, Pima County, Arizona. Samples were taken from sunflowers (H. annuus) growing along a roadside in an agricultural area devoted to field crops. Adequate moisture was provided by irrigation drainage. Between 1030 and 1100 on 27 June no bees were taking pollen. Nectar seekers included both sexes of Svastra obliqua and Megachile parallela, females of M. policaris, and males of M. sidalceae and Melissodes paroselae.

8. Eloy, Pinal County, Arizona. Samples were taken in an agricultural area on the edge of U.S. Interstate Highway 10, from Helianthus annuus growing along a fence adjacent to irrigated cultivated fields. Collections were made near midday on 14 June (temperatures 41.0°–41.5° C) and the principal bees taking pollen were females of Diadasia enavata and Megachile sidalceae. Males of these species and M. gentilis were also present.

Lower Colorado River Valley: 1. Theba, Maricopa County, Arizona. Collections were made on 28 June from sunflowers (H. annuus) growing along the edge of irrigated fields. Females and males were taking nectar during mid- and late morning. Males of Diadasia enavata, Svastra helianthelli, and S. obliqua were predominant, although Halictus ligatus and Megachile sidalceae were represented.

2. Tacna, Yuma County, Arizona. Collections were made at about 1300 on 28 June (temperature 44° C) from plants of H. annuus growing along an irrigation ditch. Only male bees were present, Svastra helianthelli, S. obliqua and Megachile sidalceae.

3. Wellton, Yuma County, Arizona. Samples were taken from scattered plants of H. annuus growing along the edge of citrus orchards. At 1100 on 5 September (temperature 37° C), males of Diadasia enavata and Svastra helianthelli were the predominant bees active, although nectar-gathering females of Halictus ligatus and Triepeolus were represented.

4. Yuma, Yuma County, Arizona. Collections were made from H. annuus growing in harvested cropland adjacent to U.S. Highway 8.

5. Blythe, Riverside County, California. Samples were taken in lower irrigated areas where plants of H. annuus were growing along fence rows and ditch banks.

Imperial Valley: Highway 8 from W of El Centro to Holtville, Imperial County, California. Sample sites were confined to irrigated agricultural lands, and collections were made from sunflowers (H. annuus) that were growing along fence rows, irrigation ditches, highway shoulders, and drainage areas.

Coachella Valley: Indio, Riverside County, California (Table F). Small samples of bees were taken on various dates and at various times from H. annuus growing along roadside ditches near the edge of the towns of Indio and Coachella. The largest collection (Table F), however, was made from plants growing in a recently cleared Indio citrus orchard from which the trees had been removed but dried fruits not fully decomposed still lay on the ground. Weeds were taking over the field and sunflower was the dominant plant. The most abundant sunflower pollinators at this site were Nomia heteropoda (see comments in the species account). This was one of the few sampling sites where significant numbers of worker honeybees were taking sunflower pollen.

MOJAVE DESERT

Owens Valley: 1. Tuttle Creek, 6 km W of Lone Pine, Inyo County, California. Samples were taken from a strip of H. annuus growing along the edge of a winding road that followed the course of a stream down the canyon toward Lone Pine.

2. Big Pine, Inyo County, California. The site (elev. 1219 m) at this locality was east of town and consisted of plants growing along a fence marking the edge of a road right-of-way. The dominant species was Bombus pennsylvanicus sonorus. Workers were present in large numbers, some taking pollen, along with nectar-seeking males. They made it difficult to sample other species, which they frequently displaced on the flower heads.

3. Bishop, Inyo County, California (Table G). Sunflowers growing in a vacant lot (elev. 1292 m) at the north end of town provided the sampling site at this locality. Melissodes agilis was the principal pollinator present on 27 August 1977 and was the first to appear in the morning, which is its usual period for gathering pollen. Other sunflower bees, however, including Diadasia enavata, appeared as the day progressed.

CISMONTANE CALIFORNIA

Coastal Southern California: 1. U.S. Highway 8 at Laguna Junction, San Diego County, California. Samples were collected from the flowers of H. gracilentus, which was growing along the roadside. The most abundant species at the flowers were Anthophora curta and Halictus farinosus.

2. Newport Beach, Orange County, California. Plants of H. annuus were growing in household gardens, and a large collection was made in an uncultivated field adjacent to the beach. Samples were taken at Costa Mesa and the University of California at Irvine, roadside areas, cultivated fields, and uncultivated areas adjacent to cultivated fields. Also collections were made in canyons in hilly regions and areas where growth was encouraged by favorable drainage conditions.

3. Pico Rivera, Los Angeles County, California. Samples were collected from the flowers of H. annuus growing in gardens and along roadsides in this metropolitan area.

4. Big Tujunga Canyon and vicinity, Los Angeles County, California. Collections were made from plants of H. annuus in isolated areas along the roadsides.

5. Calabasas, Los Angeles County, California. During late September and early October samples were taken from scattered plants of Helianthus growing along roadsides and in uncultivated fields in both residential and commercial areas.

6. Gorman, Los Angeles County, California. Samples were taken both from isolated plants and some dense stands of Helianthus growing in uncultivated fields and along roadsides.

San Joaquin Valley: 1. Bakersfield and vicinity, Kern County, California. Samples were taken on H. annuus along U.S. Highway 99 in a fence row adjacent to an alfalfa field. In the area east of the highway near and along Copus Road, a large collection was made from the flowers of H. annuus growing in an onion field that was ready for harvest. Samples were also taken from the flowers located at the edge of a vineyard and in a nearby uncultivated area.

2. Coalinga and vicinity, Fresno County, California. Collections were made along U.S. Interstate Highway 5 on flowers of H. annuus growing along the roadsides, about fence rows, ditch banks, and the edges of irrigated fields proceeding southward into Kern County on the way to Grapevine, the entrance to Tejon Pass.

3. Parlier, Fresno County, California. Collections were made at this locality from the flowers of H. annuus growing in a deep sandy wash that was being mined for industrial sand.

4. Corcoran, Kings County, California (Table H). At this locality collections were made late in the season along a roadside ditch in an agricultural and grazing area. Diadasia enavata represented more than 50 percent of the bees present. Unexpectedly, however, of 357 individuals taken, 349 were freshly emerged males. Likewise, of 238 Halictus ligatus, 184 were males.

5. Madera, Madera County, California (Tables I–K). Three collections were made at this city: on 24 July 1977, 21 September 1977, and 5 October 1975. The July and September collections, made about a month apart, were from a strip of H. annuus growing along an irrigation ditch beyond the shoulder of a north-south highway 6 km west of the center of town. On both of these dates Diadasia enavata were extremely abundant and completely dominated the flower heads. In October two years earlier, samples were taken from a vacant lot, since cleared for expansion of a residential area, one mile west of the center of the city. At this time the sunflower visitors were more varied, although Melissodes agilis, Svastra obliqua, and Diadasia enavata each made up about 25 percent of the bees present. These three species, however, were not equally distributed throughout the field, which was nearly a city block in size with somewhat separated, but extensive, groups of plants. Four collectors worked primarily in four different stations, thus attempting to assure adequate representation of the species present in the total area.

6. Atwater, Merced County, California. Samples were taken from the flowers of H. petiolaris growing in and about recently plowed fields and vacant lots.

7. Merced, Merced County, California (Table L). Samples were taken from H. annuus at the edge of a refuse recycling collection site in the northern part of town near the main highway. On 4 October 1975 Svastra obliqua was the dominant bee (constituting more than fifty percent of the sample), followed by Melissodes agilis (nearly twenty-five percent), and several other typical sunflower bees.

8. Escalon, San Joaquin County, California (Table M). A large vacant lot in the southern part of the town was the site selected for H. annuus sampling at this locality. The plant grew in a fairly solid strip along the western edge of the lot, strung out in a north-south direction and obtaining full exposure to the sun throughout the day. Collections were made on 22 July 1977. The principal species active were the characteristic Svastra obliqua, Melissodes agilis, and Diadasia enavata, but others were also represented.

9. Byron and vicinity, Contra Costa County, California. A number of collections were made along California State Highway 24 from the flowers of uncultivated Helianthus annuus growing in roadside situations. On Victoria Island, approximately 0.8 km east of Old River, samples were taken from the flowers of commercially grown sunflowers (H. annuus f. megacarpus). Due to the density of the planting it was possible to sample only the flowers at or near the edge of the field.

Primary Host Plant

The species of Helianthus are native to the Western Hemisphere where the majority of the species, about 50, occur in North America transcontinentally from southern Canada to south-central Mexico and an additional 18 species are present in northwestern South America (Heiser et al., 1969).

STRUCTURE OF THE SUNFLOWER, SELF COMPATIBILITY, AND CROSS POLLINATION.—Hurt (1948:47) describes some of the remarkable characteristics of the sunflower as follows:

The sunflower (Helianthus annuus) belongs to the largest natural order of flowering plants, the Compositae, which are characterized by the crowding together of individual flowers into heads. The heads of the Compositae are surrounded by an involucre or rosette of green bracts, which protect the unopened buds and perform the usual function of a calyx. The flowers open in centripetal succession, from the outer ring inwards (this showing why the central portion of the head is also the last to shed its florets, an important indication of seed ripeness…). In the sunflower the outer, or rayflorets, are larger and more conspicuous than the inner, owing to an enormous extension of the petals on the outer side of the floret. These ray florets are pistillate, having a pistil but no stamens, while the central or disc florets are hermaphrodite. The inferior ovary contains one ovule (attached to the base of the chamber), which ripens to form a dry one-seeded fruit, the seed being filled with the straight embryo.

The flower-heads of the sunflower are a perfect example of an adaptation for insect pollination as the crowding of the flowers ensures conspicuousness and the pollination of a maximum number of flowers by a single insect visit. The honey, secreted at the base of the style, is protected by the corolla tube from visits of short-tongued insects (which may be why even bumble bees seem sometimes to visit sunflower more readily than hive bees, the former having a longer proboscis). When the flower opens the receptive surfaces of the two stigmas are pressed together and occupy a position at the base of the tube formed by the united anthers; the latter split on the inside and the liberated pollen fills the cavity of the tube and exposes it to contact with visiting insects; finally the style protrudes right through the anther tube and the stigmas spread apart and expose their formerly hidden receptive surfaces. Thus the life history of the flower falls into two stages, the first male and the second female. This favours cross-pollination as compared with self-pollination.

According to Heiser (1976) the style spreads apart to expose the stigmatic surface and the floral mechanism doesn't prevent cross pollination of the flowers in the same head or on the same plant. Also see discussion of the flower process by Putt (1940).

Free and Simpson (1964:341) emphasize that “sunflower heads [presumably the monocephalic domesticated sunflower] isolated from insects set little or no seed, indicating that the florets are usually self-sterile. Cross-pollination by insects between heads of different plants resulted in a greater seed set than pollination between florets on the same head.” They add that

in sunflower floret the receptive lobes of the stigma are not exposed until the day after pollen presentation, thus discouraging pollination of a floret by its own pollen. However, toward the end of flowering the stigmatic lobes curl downwards and may touch pollen adhering to the style, and according to Hurt and Furgala a floret may sometimes be fertilized with its own pollen when it has failed to receive pollen from another. Several workers found that sunflower heads enclosed in paper or muslin bags produce fewer seeds than those exposed to insect visits, but it was not known whether a stigma needs pollen from another plant, or merely from another floret on the same flower or plant, for fertilization to occur, although circumstantial evidence indicated that the former was favoured.

Heiser (1965) states that among the 12 species of annual sunflowers, all of which are diploid, self-compatibility is rather rare. Self-compatibility, however, is known in many of the cultivars of the commercial sunflower. He adds that all of the widespread species of annual sunflowers are self-incompatible. The perennial sunflowers are mostly diploids and are also self-incompatible (Heiser, 1961). Thus the importance of pollinators is clear in the maintenance of species, in hybridization, and the presumed introgression that has been used to explain much of the evolution in groups of closely related species.

EXTRA-FLORAL NECTARIES.—Free (1970:33–34) comments that

many crop plants (e.g. Vicia faba, Ricinus communis, Helianthus annus, Cannabis sativus and Gossypium spp.) have extra-floral nectaries. [For a more complete list of taxonomic distribution of floral nectaries see Bentley (1977).] Although they undoubtedly served some useful biological function in their place of origin (see Ruppolt, 1961), they seem sometimes to have a detrimental effect on pollination, especially when they secrete nectar before the flowers open because bees that become conditioned to them do not visit the flowers and so do not pollinate.

Faegri and van der Pijl (1966:54–55), in their analysis of the role of such nectaries state:

Obviously, the easily available sugar of extra-nuptial nectaries is much sought after by sugar-consuming animals, especially in the Tropics extra-nuptial nectar (Zimmermann, 1932) forms an important part of the diet of many insects, for example primitive hymenopters. There is a whole complex of utilization of this nectar parallel to, but independent of and slightly different from the utilization of floral nectar. Many typical blossom visitors also visit extra-nuptial nectaries (Knoll, 1926), and negative observations (e.g. Springensgut, 1935) may be due to the fact that plants have been studied outside their natural region, as well as to an erroneous primary conception of the function of these nectaries. Utilization of extra-nuptial nectar seems, on the whole to be without primary ecological significance for the plant but more like an innocuous parasitic behaviour.

However, even if nectar and nectaries are thus possibly phylogenetically older than pollination, and even if floral nectar production and its attendant ecological function only represent the utilization of an already existing mechanism, there is no doubt that nectar production acquired a new aspect as the need for floral attractant of this type arose, and the occurrence, variability and productivity of floral nectaries far outweigh those of extra-floral ones. The occurrence of extra-floral, but nuptial nectaries (i.e. nectaries occurring outside the flowers, but playing a role in the visit of animals to the blossoms), is also more easily understood on this assumption. In the cyathia of Euphorbiaceae they are especially well-developed and form the only attractant produced—as such—by those blossoms. In Poinsettia they are so big and productive that they are even utilized by birds.

The extra-floral nectaries in H. annuus are located at the edges of the bracts and on the upper leaves. Bagnoli (1975) working in Italy found that about 10 percent of the honeybees visiting commercial sunflowers worked exclusively on extra-floral nectaries (see page 20).

GEOGRAPHICAL DISTRIBUTION.—Heiser (1949; Heiser et al., 1969) has summarized the distribution of the common sunflower, Helianthus annuus. He reports that it occurs as a weed throughout the greater part of the United States and adjacent parts of Canada and Mexico, and that domesticated forms of it are cultivated throughout most of the world. He adds that the species is extremely variable and that although part of the observed variation is due to ecological modification of the phenotype, a great deal of true diversity exists within the species.

According to Heiser (1949:157),

the wide distribution of H. annuus in the United States is probably a direct result of its weedy tendencies and its introduction by man into many regions. It is extremely doubtful if the species occurs in any area undisturbed by man. In many parts of the Middle West and occasionally in the eastern United States, the sunflower is found in railroad yards, about waste places, and to a lesser extent along roadsides. Throughout most of the western United States the sunflower is particularly common along roadsides and railroad rights of way. The race occurring in the western United States is in general much smaller than the eastern race and has fewer rays, a smaller disk, and leaves which may be truncate rather than cordate. The two races appear to intergrade freely in many regions and it is difficult to determine to which form a single herbarium specimen should be referred. However, when whole populations are examined or when the two forms are grown together in the experimental garden the differences are frequently striking. Both races occasionally may cross with the cultivated sunflower.

Hybridization with other species of annual sunflowers resulting in introgression has greatly increased the variability of this species. Reciprocal introgression between H. annuus and H. petiolaris is known to occur (Heiser, 1947) and, judging from circumstantial evidence, hybridization between H. annuus and H. debilis var. cucumerifolius in Texas also takes place. A successful cross between these two species has been reported by Cockerell (1915a) and has also been made by the writer.

As to California, Heiser (1949:158) concludes that in all probability H. annuus was not introduced into California until fairly recently. He reports that the early botanists in the state did not consider it indigenous and it may well have been introduced by Indians. He emphasizes that sunflower seeds were an important item in the diet of many Indians, and moreover, the “flowers” often had ceremonial usage.

VARIATION AND SUBSPECIATION.—Heiser (1954; Heiser et al., 1969) has discussed variation and subspeciation in H. annuus. As he has pointed out, it is a widely distributed and highly variable species comprising both cultivated and wild or weedy forms. Primarily through the culture of plants from many different areas in the experimental garden, variation of certain characters has been studied; thus purple anther color is found throughout the entire range of the species, red anther color is seen in plants from the west, black anther color is found in the cultivated sunflower and occasionally in plants in nature from the central and eastern United States.

He emphasizes that great variation is found to exist in ray number and disk diameter; plants with small disks and few rays occur in the west and Texas, whereas the more eastwardly plants have more numerous rays and larger disks. The achene length is quite variable in the west and east, although the plants from Texas are found to have the smallest achenes and there is a tendency for the eastern plants to have larger achenes. Certain exceptional western populations have been grown that have large heads and achenes, numerous rays, and occasionally black anthers; he suggests that they have arisen through hybridization of the native sunflowers of the region with the cultivated sunflower.

He states that there is also some evidence of hybridization of the cultivated sunflowers with the wild “races” in the east. Three subspecies, lenticularis, texanus, and annuus, and one variety, macrocarpus, were formally recognized and described by him (Heiser, 1954), but later (Heiser et al., 1969) he abandoned their formal recognition as subspecies. Some speculation is entertained in regard to the relationships of H. annuus and the origin of its subspecies. Heiser (1954) has concluded that the subspecies lenticularis is probably the most similar to the original form of the species, and that subspecies annuus arose from lenticularis and in turn gave rise to the variety macrocarpus. Subspecies texanus is thought to have arisen as the result of the introduction of either lenticularis or annuus into Texas with the subsequent introgression of genes from H. debilis var. cucumerifolius. Heiser regards it as probable that the complicated variation pattern exhibited by H. annuus can be explained largely by the weedy nature of the species and the extensive hybridization within the species and with the other annual sunflowers.

HABITATS OF WILD POPULATIONS OF Helianthus annuus.—While travelling through the Southwest seeking sampling sites for bees from Helianthus annuus, we found that its habitat preferences were abundantly clear. The plants tended to grow as dense weeds on disturbed land, particularly where moisture was available, as along irrigation and drainage ditches and road and highway shoulders. Many of the best and most accessible sites were recently abandoned fields in agricultural areas on the periphery of small towns. In such cases it was not uncommon to find sunflowers growing in dense stands in one or more portions of abandoned fields during the first year of non-cultivation. That this may be a widespread characteristic of the species is suggested by the studies of Booth (1941) and Wilson and Rice (1968) in abandoned fields in central Oklahoma and southeastern Kansas where H. annuus is the first stage dominant in old-field succession. They found that this stage characteristically lasted only two or three years. Wilson and Rice (1968) demonstrated that this dominance and its short duration were due not to successful competition but to allelopathy and resulted from the production of chemical inhibitors to plant growth. The inhibitors affected not only potential plant competitors but sunflower seedlings as well, thus explaining the short duration of the period of dominance.

In any event, the highly mobile Helianthus-visiting bees, especially the oligoleges and regular polyleges, quickly find the newly appearing plants and in no instance in our experience did we fail to find some species of bees present during the appropriate season under weather conditions conducive to flight.

ANTHESIS.—In our sampling of sunflower bees, we have noticed a considerable amount of variation in the diurnal cycle of pollen release in wild populations of Helianthus annuus. The factors influencing these variations were not investigated in detail but the most obvious as they affect initial anthesis in the morning are temperature and sunlight. On a cool morning after sunrise the bees will frequently arrive at the flower heads before the male florets have released pollen although nectar is available at that time. On other occasions we have observed anthesis taking place at or before sunrise. When the sky is cloudy in the east or the sky overcast, anthesis may be delayed for an hour or more and this is reflected in reduced bee activity.

Some wild populations of H. annuus apparently make pollen available more than once during the day and this is reflected in the size of the pollen loads carried by the bees. In other populations anthesis apparently takes place all at once with large quantities of pollen released early in the morning and when bees are abundant it is essentially removed by the bees before noon.

HYBRID SUNFLOWERS.—Hybridization among annual sunflowers occurring in nature, especially hybrids with the common sunflower Helianthus annuus, have been known for a number of years (see, for example, Cockerell, 1929), but have only recently been given serious analytical attention in terms of evolution and speciation by Heiser (1947, 1949, 1951a, 1951b, 1954, 1955, 1961, 1965; Heiser et al., 1969, etc., to cite a few of his important contributions to this field). More recently, however, attention has been given to improving the quality of commercial varieties of Helianthus, and hybrids are now being made available in various parts of the United States that are claimed to be superior to open-pollinated varieties (Anon., 1975a, 1975b). Nearly all of the hybrid sunflowers now grown in the United States result from use of cytoplasmic male sterility discovered by Leclerq (1970; Heiser, 1976). Hybridization also occurs among perennial sunflowers (Long, 1955, 1959, 1960).

HORTICULTURAL (ORNAMENTAL) VARIETIES.—The single-headed commercial variety of Helianthus annuus has long been utilized for ornamental purposes as a garden plant, and in recent years has been strongly recommended by groups interested in “organic gardening” as a home grown garden crop (Anon., 1961; Brinhart, 1961).

Heiser (Heiser et al., 1969:32) states that

in addition to H. annuus, several other species have ornamental value and are occasionally seen in gardens. The principal species employed are the two annuals: H. argophyllus (the silvery-leafed sunflower), H. debilis ssp. cucumerifolius (the cucumber-leaf sunflower), and several perennials: H. maximiliani, H. mollis, H. rigidus, H. salicifotius (the willow-leafed sunflower), and the hybrids, H. laetiflorus and H. × multiflorus.

And later, with reference in particular to H. annuus he comments (page 66) that the annual ornamentals

differ from the wild sunflowers chiefly in the number or the color of the rays—primrose, chestnut, plum—and their sometimes larger disk and achenes. The red-rayed forms are apparently all derived from a mutant plant found in the wild in Colorado by Mrs. T.D.A. Cockerell (Cockerell, 1912, 1918). The “double-flowered” forms probably originated in Europe shortly after the introduction of the sunflower there. Cockerell (see Watson, 1929:361) has given formal taxonomic recognition to many of the ornamental variants, but there seems little to be gained by trying to designate the various ornamental forms with Latin names.

Since the red sunflower was discovered by the wife of the eminent naturalist and distinguished Melittologist, T.D.A. Cockerell (see W. P. Cockerell, 1941, as well as T.D.A. Cockerell, 1912, 1918), the following quote from T.D.A. Cockerell (1938:117) seems appropriate.

In the summer of 1910, at Boulder, Colorado, my wife discovered a red sunflower growing by the roadside close to our house. It was a wild plant, one of a group of prairie sunflowers, Helianthus annuus lenticularis, a plant which is excessively common in this locality, growing especially in soil which has been disturbed. This form has comparatively small heads, bright orange rays, and nearly black discs. The dark color of the disc is due to an anthocyanin pigment dissolved in the sap, a pigment which is also found in many related plants. The new mutation was a plant in which this pigment had increased so that it invaded the rays, and produced a chestnut-red coloration in combination with the orange plastids already present. When we think of the red in the rays of the Gaillardia and other composites, this does not seem surprising; but in the genus Helianthus it was a new break, evidently of horticultural value. We dug the plant up with great care, and transferred it to our garden, where it continued to bloom. It was well that we did so, for a few days later a city official mowed down all the “weeds” in that row. This one plant, thus found and preserved, was the ancestor of all the red-rayed Helianthus annuus which are now well known in floriculture, in many parts of the world.

The perennial Jerusalem Artichoke, Helianthus tuberosus, normally grown for its edible tubers, is also grown as an ornamental plant in California (Anon., 1974).

COMMERCIAL SUNFLOWERS.—As Heiser (1951c: 432) comments,

the origin of cultivated plants has long challenged the imagination of both botanists and anthropologists. The problems relating to the tracing of such origins have been subject to renewed interest and scientific inquiry in recent years. The cultivated sunflower thus far has received relatively little attention in such studies, but it is of particular interest because it is one of the few crop plants to have been domesticated in temperate North America and it is one of the few plants whose wild progenitor still exists.

Hurt (1948:47) states that

the commercial sunflower of today is believed to have originated in Peru or Mexico, whence it was first introduced into Europe by the Spaniards in the sixteenth century. After its introduction to Spain, it spread to Bavaria in 1625, to France in 1787, and then to Hungary, Russia and other parts of Europe. Sunflower was reintroduced into the Argentine, as a commercial crop, in 1870.

Heiser (1976), however, does not find evidence that the commercial sunflower originated in Peru or Mexico.

According to Hurt (1948:47), “the AngloSaxon term was ‘Solsacce,’ the Spaniards calling them ‘Girasol’ and the French ‘Tournesol.’ All these terms imply ‘turning with the sun’ and seem to have been due to a rather imaginary belief that the flower turned with the sun…. Actually, however, the word sunflower is much more likely to originate from the resemblance of the flower to rays of the sun.” For a more extensive discussion of the origin of these terms see Salaman (1940) and Heiser (1976).

With regard to the sunflower's turning with the sun, Shinners (1956:88) remarks:

Contrary to Blake's famous poem, the heads during the summer face away from the sun, not toward it, even at times when the prevailing southerly winds are not strong enough to tip them northward. Purposeful or not, this behavior means that the open florets are partly shaded and (doubtless aided by evaporation from the enormous surface area exposed by the many individual flowers in the head) relatively cool. On the driest and hottest days of summer, individuals of the very common bee Diadasia enavata and one or two species of usually alert and swift Melissodes can be found resting sluggishly on the disk at the base of the ray florets. In windy weather, the rays (which produce no pollen) clearly serve as a partial windbreak, making it easier for flying insects to approach and land on the disk. Thus the structure of the sunflower head not only assists visitors to alight, but in addition shelters them against extremes of sun and wind, insuring the survival of a supply of pollinators for milder times.

Heiser (1951c:432), in his discussion of the sunflower among American Indians, emphasizes that “the common sunflower, Helianthus annuus L., comprises three varieties: H. annuus var. lenticularis (Dougl.) Ckll., the ‘wild’ sunflower; H. annuus var. annuus, the ‘weed’ or ‘ruderal’ sunflower; and H. annuus var. macrocarpus (D.C.) Ckll., the giant sunflower which is cultivated for its edible seeds.”

In 1955 Heiser summarized his views on the origin of the cultivated sunflower as follows (page 166):

From evidence now at hand it is clear that the sunflower was domesticated in temperate North America. It is not possible to reconstruct the definite steps leading to the origin of this plant but the following working hypothesis may be advanced. The wild sunflower (H. annuus ssp. lenticularis) in remote times became a food plant of the Indians of western North America. In time it became a camp-following weed and was carried into many new areas by the Indians. In the central and eastern United States the new weed became more or less stabilized and the race known as H. annuus ssp. annuus had its origin. This weed may actually have been brought into cultivation and with the selection of mutants restricting branching and increasing seed size this plant could have developed into the giant, monocephalic plant known today as H. annuus var. macrocarpus. It is not possible to point to one definite region as the center of origin of the new form but the present distribution of the weed sunflower and the distribution of the archaeological sunflowers strongly suggest the central United States as the place of origin.

The sunflower, then, is unique in having its origin in temperate North America, for the majority of American food plants were brought into domestication in Central or South America. Whether the sunflower was domesticated before these Indians had acquired other cultigens and thus agriculture had an independent origin in temperate North America or whether the sunflower was brought into cultivation after these Indians had acquired the knowledge of agriculture from other peoples is not clear. It may have been that the sunflower was a basic food before the introduction of maize. With the introduction of maize, a most superior food plant, the sunflower lost its dominant position and was kept mainly for its secondary uses as a dye and oil plant. However, as yet there are not enough facts to allow much more than speculation on this interesting subject.

Although the sunflower has long been grown as an oil crop abroad, especially in Russia where varieties with seeds of high oil content have been given special attention, only recently has oil seed production in the United States begun to assume major importance (Posey, 1969; McGregor, 1976). Russian cultivars, however, have been grown and developed along with new oil producing varieties since shortly after World War II. Originally much of the U.S. production was grown for silage (Atkinson, 1919; Cardon, 1922; Kucinsky and Eisenmenger, 1944) and still is (Gage, 1963), as well as for consumption as seed by birds and humans. More recently, the dehulled kernels have been roasted and sold as a confection.

Sunflower oil is useful for salad and cooking oils, shortening, and margarine due to its stable qualities and high ratio of polyunsaturated fatty acids (Anderson, 1970; Trotter, 1970) and sunflower meal has a number of potential uses (Talley, Brummett, and Burns, 1970). It is also a desirable ingredient in paints because of its low linolenic acid content (Anderson, 1970) and is used as an industrial lubricant (McGregor, 1976). North and South Dakota and Minnesota are the major oil producers in the United States with a million acres of sunflowers, three-fourths of them in the Red River Valley (Anon., 1975b). Throughout the world more than 17 million acres are grown annually in more than 50 countries (Burns, 1965).

According to Hurt (1948) there are some 50 cultivated varieties of H. annuus chiefly distinguished by height or by the color of their seed.

INSECTS INJURIOUS TO SUNFLOWERS.—It is not our object to review the status of insect pests of commercial sunflowers, even in North America, since they are mostly highly regionalized and many have been inadequately studied and evaluated from the economic and ecological viewpoint. Actually, the literature on sunflower pests is more extensive abroad, where, until recently, the plants have received more attention as seed and oil crops than in their native America.

Rajamokan (1976) has tabulated the reported sunflower pests of the world, the part of the plant attacked, the importance of the pests to the extent known at the time of publication, and provided a bibliography of published papers on the subject. Almost all such pests are endemic to the areas where commercial sunflowers are grown, either as native or introduced crops. Even in general textbooks emphasizing economic entomology in North America, the importance of sunflower insects has varied. We cite only Essig (1926), who lists 28 species of insects feeding upon wild and cultivated sunflower in the west, including tetranychid mites, thrips, membracids, leafhoppers, aphids, coccids, mealybugs, pentatomids, scarabs, chrysomelids, tephritids, agromyzids, nymphalids, arctiids, noctuids, and tortricids, and Metcalf and Flint (1962), who record only three sunflower pests.

In the course of our search of the North American literature for records of sunflower bees we have encountered a number of papers on commercial sunflower pests that cite other species of Helianthus, especially the wild H. annuus as alternate hosts, as would be expected, and other related Compositae (see, for example, Satherwait, 1946, 1948; Schulz, 1973; Teetes and Randolf, 1969; Westdal and Barrett, 1955).

To our knowledge, the first attempt to treat the general entomology of Helianthus was that of Cockerell (1914d), whose examples, in addition to those from abroad, included more precise data from the western United States, primarily Colorado and New Mexico. The most complete regional list of sunflower insects is that of Walker (1936) on the sunflower insects of Kansas. Other regional lists are provided by Adams and Gaines (1950), Beckham and Tippins (1972), Breland (1938, 1939), Phillips, Randolph, and Teetes (1973), Satherwait (1946, 1948), Satherwait and Swain (1946), and Seiss (1897). The most complete treatment of sunflower insects in North America is by Schulz (1978).

Since sunflower seeds are a preferred bird food, it is not surprising that many species of birds damage sunflowers. For a discussion of the most important species, factors affecting loss, and means of crop protection see Besser (1978).

Among the sunflower pests in the southwest, perhaps the most widespread are the sunflower moth, Homoeosoma electellum (Hulst) and the root feeding scarab, Bothynus gibbosus (DeGeer). Knowles and Lange (1954) and Carlson (1968) discuss the sunflower moth in California where it is not only the most important pest of commercial sunflower but also attacks wild sunflower and certain cultivated Compositae. They illustrate damage to flower heads and seeds, webbing and larval frass. Carlson briefly describes its habits and seasonal occurrence in that state and also illustrates the larva. More recently, Rogers (1978) has discussed the feeding behavior of the larva and Carlson et al. (1978) have investigated the flight activity of this moth. The most complete studies of this pest, however, have been made in Texas by Teetes and colleagues (Teetes and Randolf, 1969, 1970a, 1970b, and Randolf, Teetes, and Baxter, 1972). The muck or carrot beetle, Bothynus gibbosus, mentioned in many publications relating to sunflower pests of the South and Southwest, has been treated most thoroughly by Botrell and Brigham (1970).

Rogers (1977a) has recently published an account of the lace bug Corythuca morelli Osborn and Drake as a pest of sunflower in the southwest (Texas) as well as an account of cerambycid pests of sunflowers in the Southern Plains (Rogers, 1977b, see also Muma et al., 1950). Baerg (1921) has described injury to Jerusalem artichokes (Helianthus tuberosus) by a cerambycid girdler (Mecas sp.) growing in Arkansas. Rogers, Thompson, and Stoetzel (1978) have presented information about the distribution and hosts of the Aphidae of sunflowers in North America and Rogers, Thompson, and Gagné (1979) have developed similar data for the Cecidomyiidae. Resistance in wild Helianthus to the sunflower beetle, Zygogramma exclamationis (Fabricius), has been described by Rogers and Thompson (1978). In Manitoba, Westdal and Barrett (1960, 1962) have concluded that the trypetid Strauzia longipennis, although abundant and destroying the stem pith, is not an economic pest.

It is not surprising that new sunflower pests are still being discovered and will no doubt continue to be so. Schulz (1973) has described and illustrated damage to the heads of commercial sunflowers by the recently discovered (Gagné, 1972), cecidomyiid Contarinia schulzi, which severely infested 10 percent of the total acreage planted to sunflower in North Dakota and Minnesota in 1971. The species has also been collected from the wild sunflowers Helianthus annuus, H. petiolaris, and H. maximiliani.

Intrafloral Relationships of Bees Associated with Helianthus

All species of Helianthus in North America, with one principal exception, are obligate outcrossers since the flowers are self-incompatible. Also, insofar as known, all the species produce copious amounts of both nectar and pollen and, therefore, it is not surprising to find that the flowers are visited by a wide variety of anthophilous insects, especially native bees. Further, since the pollen readily clings to the body hairs and appendages of these various visitors, there is no reason to doubt that it is transported to other flowers and is thus available to effect pollination if it comes into contact with a receptive stigma. Among the insect visitors, however, with few exceptions, only the native bees have established significant intrafloral relationships with these flowers.

ENDEMIC BEE VISITORS TO Helianthus ABROAD.—The literature of eastern Europe and the Soviet Union contains many references to bee visitors to the introduced Helianthus annuus under the names of various commercial varieties. It is beyond the scope of this paper to summarize these but it may be of interest to note that as early as 1913 Alfken, in Bremen, recorded eight species of Bombus, three species of Psithyrus, two species of Megachile, one species each of Halictus, Coelioxys, and Anthidium, and Apis mellifera visiting cultivated Helianthus annuus. Recently Bagnoli (1975) in Italy discussed the importance of various species of native Apoidea along with certain other insects, including Coleoptera and Hemiptera, as pollinators of commercial sunflowers. With regard to the bees, he noted that fields separated by only a few tens of kilometers exhibited large differences in their density. At one locality there were numerous Ceratina spp., in other Halictus spp. and Andrena spp., and at a third, 60–70 percent of all the Apoidea were Bombus terrestris L. and B. lapidarius L.

Cockerell (1914b) commented that the perennial sunflowers in European gardens are visited by Bombus, Psithyrus, Halictus, Megachile, and Heriades. He added that in Australia, H. annuus is freely visited by Trigona carbonaria collecting pollen, while in New Zealand, in the absence of native long-tongued Apoidea, the only bee visitors are the introduced species of Bombus and Apis.

Kapil, Chaudhary, and Jain (1975) reported that a preliminary survey of insect pollinators of sunflower in Hisoar, India, during August–September 1974, showed that the flowers of this crop were visited by Xylocopa fenestrata (Fabricius), Xylocopa pubescens Spinola, Megachile tanata (Fabricicus), two unidentified Megachile spp., Nomia sp., Melissodes sp., Braunsapis sp., and Apis florea Fabricius. During April 1975, however, the flowers of this crop were visited by only four pollinators, namely an unidentified Megachile sp., X. fenestrata, Braunsapis sp., and A. florea. Among them the population of Braunsapis sp. was maximum, varying from 17 to 50 bees per 500 flowers during the second and third weeks of April.

With the exception of Braunsapis, these combinations of genera, both in Europe and India, are not much different from those that might be found in North America where Helianthus was either not endemic or not long established. Yet, to judge from books on the subject, one would be led to believe that the only important pollinators of sunflower are honeybees not only in those areas of the world where the sunflower is introduced, but also in the United States where it is native. Surely, where honeybees are available and are attracted to sunflowers there can be no doubt as to their importance as pollinators, where autogamy, cross-pollination, or outcrossing are desirable features in ornamental, commercial, or wild species. The role of other bees, however, also deserves attention and their potential should not be ignored.

Although wild sunflowers clearly provide a reservoir for pollination of ornamental and commercial sunflowers, they also provide a source of genetic contamination in inbred lines used for production of planting seed. Schacht (1979), an experienced farm reporter in California, had this to say about sunflower seed production in that state:

A few weeks ago I remarked here that California growers had been left out of the national boom in planting of sunflowers to produce “sun oil.”

True, but as Benjamin H. Beard, research geneticist in oilseed production at University of California-Davis, has been quick to inform me, they are taking part in this development in a different way. They are raising the seed which the farmers in states like North Dakota and Minnesota are planting.

According to Beard, perhaps 25 percent of all the seed of sunflower varieties raised for oil production is now harvested from California fields. As is so often the case, our climate and growing conditions make a specialized farming deal possible.

Beard says that “we have some unique conditions in California which allow farmers to grow high quality sunflower seed. Seed is produced from highly selected inbred lines. Six to ten rows of female plants are planted with two or more rows of male pollen-producing plants. Bees transfer the pollen from the male to the female plants. Only the female rows are harvested. This seed is planted commercially and the resulting plants are true hybrids which as in the case of hybrid corn produce more seed than the older open-pollinated varieties.”

An area stretching north from Dixon along the western side of the Sacramento Valley has proved particularly well suited to raising sunflower seed. For one thing, according to Beard, none of the major diseases of sunflowers are normally found there. A second and very important plus is that it seldom rains there during the growing season and this “assures clean bright seed.” Plenty of irrigation water is available so the plants need not suffer while they are developing their seed crop.

Just as important is the fact that the seed fields are isolated from contamination by unwanted varieties. Beard explains: “Another major factor is that there are only a few wild sunflowers there. In order to produce a uniform commercial crop the pollen must all come from the selected male inbred plant. Thus one requirement for hybrid sunflower seed production is that the field must be at least two miles minimum from other pollen-producing sunflowers.”

Concludes Beard: “So while California farmers are not producing much sunflower oil they are a necessary part of the sunflower oil boom.”

INTRODUCED HONEYBEE AND SUNFLOWER POLLINATION.—Cockerell (1914c) reported on a census of bees visiting cultivated sunflowers at Goodview, Colorado, and found the honeybee to be an insignificant factor in sunflower pollination. He was also informed by a beekeeper in Boulder that honeybees do not go to sunflowers unless the supply of other nectar runs short and that when they do make honey from sunflowers it is very yellow. Bees visiting commercial sunflowers at Goodview were Andrena helianthi, Halictus armaticeps, Dufourea marginata, Pseudopanurgus innuptus, Melissodes aurigenia (= M. agilis), M. confusiformis (= M. coreopsis), and Megachile agustini.

Robertson (1929) in a cumulative survey of insects visiting cultivated sunflowers at Carlinville, Illinois, presumably growing in his yard, between the dates of 11 July and 6 September, collected 42 species, of which 28 were bees as follows (nomenclature updated): Andrena accepta, 1; A. helianthi, 1; Apis mellifera, 65NP; Augochloropsis m. metallica, 11,; Bombus bimaculatus, 5; B. griseocollis, 12; B. impatiens, 26,NP; B. p. pennsylvanicus, 5NP; B.v. vagans, 2; Ceratina dupla. 1NP; Dialictus imitatus, 1P; D. p. pilosus, 1P; D. versatus, 1P; Halictus c. confusus, 1; H. ligatus, 50,P; Megachile brevis, 1; M. inimica, 1; M. mendica, 1NP; Melissodes agilis, 50,NP; M. bimaculata, 1, 1; M. boltoniae, 6,NP; M. coloradensis, 2NP; M. dentiventris, 1; M. trinodis, 4,NP; Psithyrus variabilis, 8,; Svastra obliqua, 6,NP; Triepeolus concavus, 1.

Guynn and Jaycox (1973) made some observations on sunflower pollination in Illinois after moving 15 two-story hives of honeybees to a 15acre commercial planting. Their experiments confirmed that sunflowers require insect pollination. The honeybees, however, did not collect and store much of the sunflower pollen, preferring to clean it off in the field, where much of it dropped onto leaves near the flower heads. The experimental colonies produced a golden-colored honey with a pleasing, mild flavor. Counts of honeybees at the sunflowers were relatively low and were not correlated with yields. Many other insects were observed but not accurately identified or counted. Commercial beekeepers had variable results in honey production from sunflowers, perhaps because of unfavorable weather. Their general conclusion, however, was that lack of competing nectar plants during sunflower bloom and the presence of other pollinators probably combined to bring available insects to the fields and helped to produce a respectable seed yield throughout the state.

In the most recent publication on the subject by an American author, McGregor (1976:349) summarizes the situation as follows:

All research on sunflower pollination indicates that honeybees are the primary pollinating agents, and that colonies should be provided to the field (Barbier and Abid 1966), and that they should be protected from harmful pesticides while they are in the field. The bees should be ready for the pollination task at the onset of flowering. The total flowering period is usually about 20 days, but 83 percent of the heads begin to open within 3 days after the first head opens. Evidence also indicates that the highest bee population and the highest production occur within a few hundred feet of the apiary. If adequate pollination throughout the field is provided, there should be no significant gradient of seed set in relation to apiary location.

The term “saturation pollination,” meaning the patterned distribution of groups of colonies, sometimes used on other crops to provide adequate coverage throughout the entire field, is equally applicable and needed in sunflower production.

After quoting different recommendations of the number of colonies per hectare or per acre required for sunflower pollination he comments that “the evidence is plain that, if the grower wants maximum seed production, he should not skimp on the use of bees.”

He adds that

the number of colonies per acre alone is not too meaningful. Distribution of colonies to give thorough coverage of all blooms is highly important, and strength and other conditions of the colony are equally important. The criterion the grower should use is the bee visits per floret or bees per head throughout his field. The presence of one bee per head throughout the day should provide adequate visitation, but additional research is needed to determine the exact bee population needed for maximum production of sunflower seed.

As might be expected, most of the studies on the role of honeybees in the pollination of the commercial varieties of Helianthus annuus are from those parts of the world where sunflower is an introduced crop, particularly from the U.S.S.R., eastern Europe, and from France, England, and India, for example, see Avetisyan (1965), Baculinschi (1957), Cirnu (1960), Free (1964), Katzarov (1971), Kurennoi (1957), Kushnir (1960), Radaeva (1954), Radoev (1954), Rangarajan, Mahadevan, and Iyemperumal (1974), Rozov (1933), Schelotto and Pereyras (1971).

Summarizing the results of observations and experiments with honeybees as pollinators of the sunflower in various zones of the U.S.S.R., Rozov (1933:305) states that

bees visit the flowers chiefly for the purpose of collecting nectar. The flowers in the antheral stage of florescence, as secreting more nectar, are visited by bees 3–5 times as often as in the stigmatic stage of florescence. In order to secure a complete pollination, the flowers must be visited by bees no less than ten times on an average.

Experiments conducted on fields sown with sunflower show that bees not only can replace wild pollen carriers but also increase the pollination and the fertilization of ovules considerably (no less than 25–30%). The role of bees as pollen carriers is more conspicuous when the plants are in good condition, since in that case they secrete a greater amount of nectar and thereby attract bees to a greater degree, on the one hand, and, on the other hand, they can provide for the development of a greater percentage of achenes.

…Large areas sown with sunflower must be provided with apiaries for pollinating purposes. The bees of such apiaries not only will replace wild pollen carriers, but, owing to their pollinating activity, will considerably increase the fertilization of ovules and, hence, the yield of sunflower seed. Moreover, such apiaries will pay well in honey.

Mel'nichenko (1976) has summarized the role of insects and the honeybee in increasing the yield of agricultural plants, including Helianthus, in Russia.

According to Free (1964), honeybees visiting sunflowers collect food from only a small proportion of florets per flower head. He states (1966) that pollen gatherers restrict their visits to florets in the male stage and only nectar-gatherers touch the female stage florets and pollinate them and also (1970:73) that since “nectar gatherers are the more valuable pollinators of Helianthus annuus which presents its pollen in the morning…for this crop it might be advantageous to delay releasing colonies until the peak of pollen presentation is finished for the day.”

Bagnoli (1975), in Italy, confirms that nectar-gathering honeybees are the most efficient pollinators; that when dusted with pollen while exploiting the nectar in the anther tube, the bee does lodge pollen in the corbiculae but almost totally discards the rest as it leaves the flower. He found that about 10 percent of the bees worked exclusively on extra-floral nectaries situated at the edges of bracts and the foliar laminae. He regards it as probable that the secretory organs of these cells begin activity shortly before the opening of the inflorescence in order to attract the attention of pollinating insects at the right moment. Although work in Italy demonstrates the importance of honeybees in sunflower pollination, it also reveals the useful role of native bees (see “Native Bee-Flower Relationships in North America,” immediately following).

Palmer-Jones and Forster (1975) have made some observations on sunflower pollination in New Zealand where the plant is being grown on an increasing scale, mainly as an oil crop. They note that few bees were seen carrying pollen in their corbiculae but that when forced to collect sunflower pollen, as in cages, they had no difficulty in gathering it. They found that bees from hives within range consistently collect nectar from the flowers. They conclude that

sunflowers are not fully dependent on honeybees for pollination, as a low yield of seeds, with a germination rate of 99%, formed in the cage that excluded bees. Crops with low bee coverage also yielded good quality seed, but yield was lower than when bee coverage was high. The number of plump seeds produced per head is considered to provide a reasonably accurate measure of the degree of pollination (1975:97).

In the desert valley areas of southern California, Lehman et al. (1973) note that sunflowers require honeybees or some other insect for pollination. In their tests, honeybees that were located in hives about a quarter of a mile from a planting and near a good source of water were found to be the main insect pollinators. They remark, however, that fairly high populations of moths, such as the beet army worm and the cabbage looper moth, were present in the May and June plantings, but conclude that the populations of these moths were too variable to be depended upon for good pollination. These investigations recorded honeybee populations during peak bloom on the variety Tchernianka eight times each day for four days at each planting date. They found that honeybee populations of 1.54 bees per flower were highest for the January planting and decreased to a low of about 0.23 bees per flower during the May and July planting. They state that pollination seemed satisfactory at all planting dates.

Furgala (1954, 1970), noting that sunflower ranks among the top four oilseed crops in the world, has proposed “that mission-oriented research in honeybee pollination of sunflowers will directly resolve the central objective of the industry in the United States; namely, how to effectively increase sunflower seed yields” (Furgala, 1970:37).

Our own observations on the behavior of honeybees at sunflowers have been largely limited to the arid southwestern United States where we have generally found them present at low levels or absent (see page 124).

COMPETITION AMONG Helianthus FLOWER VISITORS.—In Japan, Kikuchi (1963) studied dominance relationships among insects, especially syrphid flies, blow flies, bees, and bumblebees, visiting flowers of 22 species of plants representing 12 families, about one-third of them Compositae. Various patterns of avoidance behavior were identified among the insects competing for nectar from almost all of the plant species involved except sunflower (Helianthus). Probably Kikuchi was observing the cultivated form of H. annuus with the large composite flower head providing a platform with sufficient space and nectaries to minimize antagonism among nectar seekers.

On wild Helianthus annuus in the southwest we have seen intense competition between larger bees such as Bombus spp., Svastra spp., and Nomia heteropodo, when excessively abundant, and smaller bees such as the ubiquitous Melissodes agilis. This competition is sometimes minimized by early morning and late afternoon pollen collecting by the latter; however, at times they are practically excluded from the plants not only by much larger bees but by the slightly larger, faster, and more aggressive Diadasia enavata.

In the central valley of California during the dry period of late summer and fall, the presence of large numbers of syrphid flies—Eristalis tenax (L.), E. stipator Osten Sacken, and Eristalinus aeneus Scopoli (det. F. C. Thompson)—and skipper butterflies—particularly males of Hylephila phylaeus (Drury) and Lerodea eufala (Edwards)—can interfere with pollen- and nectar-seeking by a variety of solitary bees. The presence of Hylephila phylaeus is also particularly distracting in the sampling operation because as they alight on the flower with their forewings back to back and their yellowish hind wings spread laterally at a posteriorly directed angle, they bear a striking superficial resemblance to a female bee with heavy loads of Helianthus pollen. In southern Arizona bee activity is often markedly reduced by cantharids—Chauliognathus basalis LeConte and C. marginatus Fabricius (det. Robert D. Gordon)—and mirids—Adelphocoris superbus (Uhler)—swarming on the flowerhead and preventing access to the florets.

NATIVE BEE-FLOWER RELATIONSHIPS IN NORTH AMERICA.—Bee-flower relationships reflect various strategies on the part of both sets of participants. For the purpose of the present study we are concerned with the extent and degree to which bees in North America utilize the pollen and nectar of Helianthus for their survival as species or for the maintenance of populations dependent at least partly on the pollen or nectar or both of Helianthus. We also are concerned with the regularity of this relationship and its bearing on the pollination of Helianthus.

The two most commonly recognized behavioral categories with respect to pollen collection by bees are oligolecty and polylecty (see reviews by Grant, 1950, Linsley, 1958, and Baker and Hurd, 1968). Oligolectic bees are generally regarded as those in which all the members of the population, throughout its range and in the presence of other pollen sources, consistently and regularly collect pollen from a single plant species or a group of related plant species, turning to other sources, if at all, only locally in the face of an absence or shortage of pollen. Polylectic bees are those in which the species as a whole, regardless of the extent to which individual members of the population may exhibit flower constancy in the collection of pollen, are not sharply limited in the number and kind of pollen sources utilized in their economy. Although these categories are by nature relative and not always clearly recognizable, or even definable, they do represent modes in the flower relationships of pollen-collecting bees as a whole (Hurd and Linsley, 1975).

For purposes of the present study these relative categories are further subdivided as follows:

1. Primary oligoleges are those bees that, although oligolectic as a species on Compositae, are primarily associated with Helianthus.

2. Secondary oligoleges are those bees that, although oligolectic as a species on Compositae, are secondarily associated with Helianthus.

3. Regular polyleges are those bees that, although polylectic as a species (often on Compositae), regularly gather pollen from Helianthus where they occur within its range, either as individuals or as populations.

4. Casual polyleges are those bees that, although polylectic as a species, have a preference for the pollens of other plants, but as individuals visit the flowers of Helianthus for pollen, usually but not always, in small numbers.

Our data suggest that the evolutionary sequence leading to specific intrafloral relationships by differentiating faunas of bees may have initially commenced with casual polyleges of the Compositae, some of which evolve into regular polyleges. Later in the sequence some of the regular polyleges evolve into oligoleges of the Compositae, first secondarily associated with Helianthus and then ultimately into primary oligoleges which become nearly or entirely dependent upon the pollen, and to a large extent, the nectar of Helianthus, including even various subdivisions within that genus. Alternatively, the proposed evolutionary sequence could also proceed from any of the polylege categories (and perhaps even from oligoleges) during periods of environmental stress or prolonged periods of unusual pollen shortages (e.g., Diadasia enavata, the only oligolege of the Compositae in genus Diadasia).

This investigation reveals that there are at least 284 species of native bees that collect pollen from the flowers of Helianthus. Table 3 summarizes by family their relative dependence on the pollen of Helianthus.

In addition to these, there are 72 species of pollen-collecting bees that are known to visit the flowers of Helianthus for nectar only and 56 species of parasitic bees that also visit the flowers for nectar. Quite obviously the more consistent the relationship between the flower and its pollen vectors, the greater is the degree of pollination. Consequently it is those species of bees which have evolved a specialized intrafloral relationship with Helianthus that are the principal pollinators of that plant. Nonetheless, other insects and especially male bees, particularly those of the oligoleges and polyleges mentioned above, often assume important roles in the pollination of these flowers.

Several previous studies have been made of the insect pollinators of Helianthus, especially bees. The first such study known to us was made by Cockerell (1898c) who reported on the insect visitors at the flowers of Helianthus annuus in New Mexico. Subsequently in several papers, Cockerell (1911, 1914b, 1915b, 1916a, 1917a,b) listed and discussed bees visiting the flowers of H. annuus (and at two localities, H. lenticularis) in California, Colorado, Connecticut, and Virginia. He also discussed the bee visitors of Helianthus growing under introduced conditions in the Old World (Cockerell, 1914b, 1916a). Cockerell earlier in collaboration with Swenk (Swenk and Cockerell, 1907a,b and Swenk, 1907) discussed several sunflower-visiting bees from Nebraska. Of these, three species were recorded from H. petiolaris and seven species from H. annuus.

TABLE 3.—Relative dependence of native bees on pollen of Helianthus

Graenicher (1909) in his studies of Wisconsin flowers and their pollinators provides information on the bee visitors of H. giganteus (12 species) and H. strumosus (31 and 38 species from Milwaukee and Cedar Lake, respectively). In a series of papers on the bees of North Dakota, Stevens (1919, 1949a–c, 1950, 1951a–c) presents data on 31 species of bees visiting the flowers of seven species of Helianthus, including H. annuus (eight species), H. maximiliani (12 species), H. nuttallii (one species), H. petiolaris (21 species), H. rigidus (eight species), H. strumosus (one species), and H. tuberosus (eight species). Robertson (1922) discusses the sunflower and its insect visitors and later, in his volume entitled “Flowers and Insects” (Robertson, 1929), summarizes the information that he had developed on this subject commencing before the turn of the century. In this work he records and provides data for 68 species of bees obtained at the flowers of Helianthus growing in the Carlinville area of Illinois including H. annuus (25 species), H. divaricatus (51 species), H. grosseserratus (36 species), H. mollis (19 species), H. rigidus (17 species), H. strumosus (eight species), and H. tuberosus (32 species). He also presents information on the bee visitors of cultivated sunflower (28 species). In a study of the bee-fauna and vegetation of the Miami region of Florida, Graenicher (1930) reports on nine species of bees visiting the flowers of Helianthus debilis, an inhabitant of the sand dunes. Michener (1947) in his study of the bees of a limited area in southern Mississippi records sixteen species visiting the flowers of H. radula.

In addition to these studies, there is a wealth of floral visitation records pertaining to Helianthus in the literature of North American bees. Most of these records are listed in taxonomic publications and we have made a special effort to retrieve this information and incorporate it into the species accounts of this study.

From our studies in North America it seems clear that there are few, if any, oligolectic bees associated solely with Helianthus, although there are many oligoleges of Compositae that visit sunflowers for pollen and nectar, as well as others that prefer sunflower pollen, when available, to that of other composites. In the following lists we have tried to classify bee visitors as (1) oligoleges of Compositae primarily associated with sunflower, (2) those secondarily associated with sunflower, and general polyleges, which are either (3) regular or (4) casual visitors. In some cases the data presently available make the decision obvious. When data are limited we have taken the systematics of the bee into account and made an arbitrary assignment which may or may not be confirmed by future collections (for example, we have been faced with the problem of where to assign species for which the only known flower record for a female is based upon one individual taken at sunflower).

The list of nectar visitors not known to take sunflower pollen is based upon females and males of species whose females do not take sunflower pollen, since males, as well as females, are important pollinators. Obviously, this list will be expanded greatly with future collecting and some species from this list may be shifted to other categories with additional knowledge.

A list of parasitic bees taken at sunflowers is included because, in spite of their reduced body hairs, they do transport pollen and play a role in pollination. Also, many are cleptoparasites of sunflower oligoleges and are important factors in the population ecology of the pollen-collecting bees that visit the flowers of Helianthus.

In these lists each bee taxon is followed by the species of Helianthus it is known to visit.

OLIGOLEGES OF COMPOSITAE PRIMARILY ASSOCIATED WITH Helianthus

Andrena accepta: Helianthus angustifolius, H. annuus, H. divaricatus, H. giganteus, H. grosseserratus, H. lenticularis, H. maximiliani, H. mollis, H. petiolaris, H. radula, H.mrrigidus, H. salicifolius, H. strumosus, H. tuberosus

Andrena aliciae: Helianthus angustifolius, H. divaricatus, H. giganteus, H. microcephalus, H. strumosus, H. tuberosus

Andrena haynesi: Helianthus petiolaris

Andrena helianthi: Helianthus annuus, H. divaricatus, H. giganteus, H. grosseserratus, H. lenticularis, H. maximiliani, H. nuttallii, H. petiolaris, H. rigidus, H. strumosus, H. tuberosus

Andrena peckhami: Helianthus strumosus

Diadasia enavata: Helianthus annuus, H. gracilentus, H. lenticularis

Dufourea marginata: Helianthus annuus, H. divaricatus, H. grosseserratus, H. petiolaris, H. radula, H. rigidus, H. tuberosus

Exomalopsis pygmaea: Helianthus annuus, H. lenticularis

Hesperapis carnata: Helianthus annuus, H. lenticularis, H. petiolaris, H. rigidus

Heteranthidium cordaticeps: Helianthus annuus

Heteranthidium occidentale: Helianthus lenticularis

Heteranthidium zebratum: Helianthus annuus, H. lenticularis, H. petiolaris, H. pumilus, H. radula, H. rigidus

Megachile parallela: Helianthus annuus, H. atrorubens, H. divaricatus, H. gracilentus, H. lenticularis, H. maximiliani, H. mollis, H. nutlallii, H petiolaris, H. radula

Melissodes agilis: Helianthus annuus, H. atrorubens, H. bolanderi, H. cilians, H. divaricatus, H. grosseserratus, H. lenticularis, H. maximiliani, H. mollis, H. petiolaris, H. pumilus, H. radula, H. rigidus, H. salicifolius, H. strumosus, H. tuberosus

Melissodes coloradensis: Helianthus annuus, H. atrorubens, H. divaricatus, H. grosseserratus, H. mollis, H. petiolaris, H. rigidus, H. tuberosus

Melissodes coreopsis: Helianthus annuus, H. grosseserratus, H. maximiliani, H. petiolaris, H. salicifolius, H. tuberosus

Melissodes gelida: Helianthus annuus, H. petiolaris

Melissodes perlusa: Helianthus annuus, H. petiolaris

Melissodes robustior: Helianthus annuus, H. bolanderi, H. gracilentus, H. lenticularis, H. petiolaris

Melissodes trinodis: Helianthus annuus, H. atrorubens, H. divaricatus, H. giganteus, H. grosseserratus, H. maximiliani, H. mollis, H. salicifolius, H. strumosus, H. tuberosus

Nomia heteropoda: Helianthus annuus, H. lenticularis, H. petiolaris, H. radula

Nomia micheneri: Helianthus petiolaris

Nomia triangulifera: Helianthus annuus, H. lenticularis, H. maximiliani, H. petiolaris

Perdita albipennis: Helianthus annuus, H. lenticularis, H. occidentalis, H. petiolaris, H. rigidus

Perdila bequaerti: Helianthus divaricatus, H. radula

Perdita laticincta: Helianthus petiolaris

Perdita lingualis: Helianthus annuus, H. lenticularis, H. petiolaris

Perdita scopata: Helianthus annuus

Perdita tricincta: Helianthus annuus

Perdita tridentata: Helianthus petiolaris, H. rigidus

Pseudopanurgus aethiops: Helianthus annuus, H. lenticularis, H. petiolaris

Pseudopanurgus rugosus: Helianthus annuus, H. divaricatus, H. petiolaris, H. mollis, H. radula, H. tuberosus

Pterosarus helianthi: Helianthus annuus, H. petiolaris

Pterosarus innuptus: Helianthus annuus, H. maximiliani, H. nutiallii, H. petiolaris, H. rigidus, H. strumosus, H. tuberosus

Pterosarus piercei piercei: Helianthus annuus, H. maximiliani, H. petiolaris, H. rigidus, H. tuberosus

Pterosarus simulons: Helianthus annuus, H. maximiliani, H. petiolaris

Svastra helianthelli: Helianthus annuus, H. ciliaris

Svastra machaerantherae: Helianthus annuus, H. petiolaris

Svastra obliqua: Helianthus annuus, H. atrorubens, H. bolanderi, H. ciliaris, H. divaricatus, H. gracilentus, H. grosseserratus, H. lenticularis, H. maximiliani, H. microcephalia, H. mollis, H. petiolaris, H. rigidus, H. strumosus, H. tuberosus

OLIGOLEGES OF COMPOSITAE SECONDARILY ASSOCIATED WITH Helianthus

Andrena chromotricha: Helianthus annuus, H. giganteus, H. maximiliani, H. rigidus, H. strumosus, H. tuberosus

Andrena duplicata: Helianthus divaricatus, H. grosseserratus

Andrena pallidifovea: Helianthus gracilentus

Andrena pecosana: Helianthus petiolaris

Andrena simplex: Helianthus tuberosus

Anthocopa hemizoniae: Helianthus gracilentus

Ashmeadiella bucconos: Helianthus divaricatus, H. gracilentus, H. petiolaris

Ashmeadiella californica: Helianthus annuus, H. gracilentus

Calliopsis crypta: Helianthus sp.

Calliopsis pectidis: Helianthus sp.

Calliopsis pugionis: Helianthus gracilentus

Calliopsis rozeni: Helianthus annuus

Calletes compactus: Helianthus tuberosus

Colletes rufocinctus: Helianthus annuus, H. petiolaris

Colletes simulans armatus: Helianthus petiolaris

Colletes susannae: Helianthus petiolaris

Dianthidium curvatum sayi: Helianthus annuus, H. lenticularis, H. maximiliani, H. petiolaris

Hesperapis arenicola: Helianthus niveus

Heteranthidium timberlakei: Helianthus gracilentus

Megachile alata: Helianthus gracilentus

Megachile dakotensis: Helianthus sp.

Megachile helianthi: Helianthus lenticularis

Megachile inimica: Helianthus annuus, H. divaricatus, H. grosseserratus, H. petiolaris, H. rigidus, H. tuberosus

Megachile manifesta: Helianthus annuus, H. petiolaris

Megachile pugnata pugnata: Helianthus annuus, H. divaricatus, H. giganteus, H. grosseserratus, H. strumosus, H. tuberosus

Megachile sabinensis: Helianthus sp.

Megachile xerophila: Helianthus niveus

Melissodes appressa; Helianthus annuus

Melissodes bidentis: Helianthus annuus, H. maximiliani, H. tuberosus

Melissodes bimatris: Helianthus sp.

Melissodes brevipyga: Helianthus annuus

Melissodes composita: Helianthus annuus

Melissodes confusa: Helianthus annuus

Melissodes dentiventris: Helianthus annuus, H. divaricatus, H. grosseserratus, H. radula

Melissodes glenwoodensis: Helianthus petiolaris

Melissodes grindeliae: Helianthus sp.

Melissodes humilior: Helianthus annuus

Melissodes illata: Helianthus strumosus

Melissodes limbus: Helianthus annuus

Melissodes lupina: Helianthus annuus, H. gracilentus, H. nuttallii

Melissodes lustra: Helianthus sp.

Melissodes lutulenta: Helianthus sp.

Melissodes menuachus: Helianthus annuus, H. grosseserratus, H. petiolaris

Melissodes microsticta: Helianthus sp.

Melissodes montana: Helianthus annuus, H. petiolaris

Melissodes nivea: Helianthus annuus, H. atrorubens, H. divaricatus, H. grosseserratus

Melissodes pallidisignata: Helianthus sp.

Melissodes paulula: Helianthus annuus

Melissodes rivalis: Helianthus annuus

Melissodes rustica: Helianthus atrorubens, H. divaricatus, H. grosseserratus, H. maximiliani, H. petiolaris, H. radula, H. strumosus, H. tuberosus

Melissodes snowii: Helianthus petiolaris, H. rigidus

Melissodes stearnsi: Helianthus annuus

Melissodes subagilis: Helianthus annuus, H. maximiliani, H. petiolaris

Melissodes subillata: Helianthus maximiliani, H. petiolaris

Melissodes tincta: Helianthus maximiliani

Melissodes vernoniae: Helianthus divaricatus, H. tuberosus

Melissodes wheeleri: Helianthus annuus, H. debilis, H. petiolaris

Nomia apacha: Helianthus sp.

Nomia bolliana: Helianthus sp.

Osmia californica: Helianthus nuttallii

Osmia coloradensis: Helianthus gracilentus

Osmia montana: Helianthus annuus, H. gracilentus

Osmia texana: Helianthus sp.

Paranthidium jugatorium: Helianthus divaricatus, H. lenticularis, H. strumosus

Perdita affinis: Helianthus petiolaris

Perdita alexi: Helianthus petiolaris

Perdita aridella: Helianthus petiolaris

Perdita bruneri: Helianthus petiolaris

Perdita dolichocephala: Helianthus petiolaris, H. rigidus

Perdita fallax: Helianthus petiolaris

Perdita ignota crawfordi: Helianthus annuus

Perdita nebrascensis: Helianthus sp.

Perdita nigroviridis: Helianthus annuus

Perdita pratti: Helianthus debilis, H. petiolaris

Perdita prionopsidis: Helianthus petiolaris

Perdita swenki: Helianthus maximiliani

Perdita verbesinae: Helianthus annuus, H. petiolaris

Perdita xanthisma: Helianthus annuus, H. petiolaris

Pterosarus albitarsis: Helianthus divaricatus, H. mollis

Pterosarus labrosiformis labrosiformis: Helianthus divaricatus, H. strumosus, H. tuberosus

Pterosarus labrosus: Helianthus divaricatus, H. tuberosus

Pterosarus occiduus: Helianthus sp.

Pterosarus perlaevis: Helianthus annuus

Pterosarus renimaculatus: Helianthus maximiliani, H. petiolaris

Pterosarus rudbeckiae: Helianthus divaricatus

Pterosarus solidaginis: Helianthus grosseserratus, H. tuberosus

Pterosarus stigmalis: Helianthus lenticularis

Svastra aegis: Helianthus annuus, H. radula

Svastra petulca: Helianthus annuus

Svastra texana: Helianthus annuus, H. radula

Syntrichalonia exquisita: Helianthus petiolaris

REGULAR POLYLEGES ASSOCIATED WITH Helianthus

Agapostemon texanus: Helianthus annuus, H. gracilentus, H. grosseserratus, H. lenticularis, H. maximiliani, H. petiolaris

Bombus fratemus: Helianthus annuus, H. divaricatus, H. grosseserratus, H. petiolaris, H. rigidus

Bombus griseocollis: Helianthus anuus, H. divaricatus, H. giganteus, H. grosseserratus, H. maximiliani, H. petiolaris, H. rigidus, H. strumosus, H. tuberosus

Bombus morrisoni: Helianthus annuus

Bombus nevadensis: Helianthus annuus, H. grosseserratus, H. maximiliani, H. petiolaris, H. rigidus, H. tuberosus

Bombus pennsylvanicus pennsylvanicus: Helianthus annuus, H. divaricatus, H. giganteus, H. grosseserratus, H. lenticularis, H. maximiliani, H. mollis, H. petiolaris, H. rigidus, H. strumosus, H. tuberosus

Bombus pennsylvanicus sonorus: Helianthus annuus, H. petiolaris

Halictus ligatus: Helianthus annuus, H. debilis, H. divaricatus, H. grosseserratus, H. lenticularis, H. maximiliani, H. mollis, H. petiolaris, H. radula, H. rigidus, H. tuberosus

Heriades variolosa variolosa: Helianthus sp.

Hoplitis producta: Helianthus petiolaris

Megachile brevis: Helianthus annuus, H. divaricatus, H. grosseserratus, H. mollis, H. rigidus, H. strumosus, H. tuberosus

Megachile fidelis: Helianthus gracilentus, H. petiolaris

Megachile fortis: Helianthus petiolaris, H. rigidus

Megachile montivaga: Helianthus annuus, H. gracilentus

Megachile perihirta: Helianthus annuus, H. petiolaris

Megachile policaris: Helianthus annuus, H. petiolaris

Melissodes bimaculata bimaculata: Helianthus annuus, H. divaricatus, H. grosseserratus, H. tuberosus

Melissodes boltoniae: Helianthus annuus, H. divaricatus, H. grosseserratus, H. tuberosus

Melissodes communis communis: Helianthus annuus, H. debilis, H. lenticularis

Melissodes comptoides: Helianthus annuus, H. petiolaris

Melissodes sonorensis: Helianthus petiolaris

Melissodes tessellata: Helianthus annuus

CASUAL POLYLEGES ASSOCIATED WITH Helianthus

Agapostemon angelicus: Helianthus annuus, H. gracilentus

Agapostemon cockerelli: Helianthus annuus

Agapostemon femoratus: Helianthus gracilentus

Agapostemon melliventris: Helianthus annuus, H. niveus

Agapostemon sericeus: Helianthus grosseserratus, H. strumosus

Agapostemon splendens: Helianthus debilis

Agapostemon tyleri: Helianthus annuus

Agapostemon virescens: Helianthus sp.

Andrena lawrencei: Helianthus nuttallii

Andrena microchlora: Helianthus sp.

Andrena prunorum: Helianthus sp.

Andrena recta: Helianthus annuus

Anthidiellum notatum notatum: Helianthus sp.

Anthidiellum perplexum: Helianthus debilis

Anthidium paroselae: Helianthus mollis, H. petiolaris

Anthophora curta: Helianthus annuus, H. gracilentus, H. petiolaris

Anthophora maculifrons: Helianthus annuus

Anthophora montana: Helianthus annuus

Anthophora peritomae: Helianthus annuus

Apis mellifera: Helianthus annuus, H. giganteus, H. strumosus

Ashmeadiella foveata: Helianthus gracilentus

Augochlora pura: Helianthus debilis

Augochlorella aurata: Helianthus sp.

Augochlorella bracteata: Helianthus sp.

Augochlorella gratiosa: Helianthus sp.

Augochlorella persimilis: Helianthus mollis

Augochlorella striata: Helianthus giganteus, H. lenticularis, H. maximiliani, H. strumosus, H. tuberosus

Augochloropsis metallica metallica: Helianthus annuus, H. debilis, H. grosseserratus, H. mollis, H. strumosus

Augochloropsis sumptuosa: Helianthus sp.

Bombus affinis: Helianthus giganteus

Bombus appositus: Helianthus sp.

Bombus bimaculatus: Helianthus annuus

Bombus borealis: Helianthus sp.

Bombus californicus: Helianthus sp.

Bombus centralis: Helianthus strumosus

Bombus crotchii: Helianthus sp.

Bombus fervidus fervidus: Helianthus annuus

Bombus huntii: Helianthus sp.

Bombus impatiens: Helianthus annuus, H. grosseserratus

Bombus rufocinctus: Helianthus sp.

Bombus ternarius: Helianthus strumosus

Bombus terricola: Helianthus strumosus

Bombus vagans vagans: Helianthus annuus, H. giganteus, H. grosseserratus, H. strumosus, H. tuberosus

Callanthidium illustre: Helianthus sp.

Ceratina acantha: Helianthus gracilentus

Ceratina apacheorum: Helianthus gracilentus

Ceratina calcarata: Helianthus sp.

Ceratina dupla: Helianthus annuus, H. divaricatus, H. maximiliani, H. strumosus

Ceratina micheneri: Helianthus sp.

Ceratina nanula: Helianthus petiolaris

Ceratina neomexicana: Helianthus petiolaris

Ceratina pacifica: Helianthus annuus, H. petiolaris

Ceratina punctigena: Helianthus gracilentus, H. occidentalis

Ceratina shinnersi: Helianthus annuus

Ceratina strenua: Helianthus sp.

Chalicodoma angelarum: Helianthus annuus, H. gracilentus

Chalicodoma campanulae campanulae: Helianthus sp.

Chelostomopsis rubifloris: Helianthus sp.

Colletes fulgidus: Helianthus annuus

Dialictus imitatus: Helianthus annuus

Dialictus incompletus: Helianthus annuus

Dialictus marinus: Helianthus debilis

Dialictus nevadensis: Helianthus lenticularis

Dialictus pilosus pilosus: Helianthus annuus, H. divaricatus, H. mollis, H. rigidus, H. tuberosus

Dialictus pruinosiformis: Helianthus annuus, H. lenticularis, H. petiolaris

Dialictus punctatoventris: Helianthus sp.

Dialictus tegulariformis: Helianthus lenticularis

Dialictus veganus: Helianthus sp.

Dialictus versatus: Helianthus annuus, H. divaricatus, H. grosseserratus, H. mollis, H. rigidus

Dialictus zephyrus: Helianthus tuberosus

Dianthidium dubium dilectum: Helianthus gracilentus, H. petiolaris

Dianthidium ulkei: Helianthus petiolaris

Evylaeus kincaidii: Helianthus sp.

Evylaeus pectoralis: Helianthus divaricatus, H. rigidus, H. strumosus, H. tuberosus

Evylaeus pectoraloides: Helianthus annuus

Exomalopsis morgani: Helianthus sp.

Exomalopsis solani: Helianthus annuus

Exomalopsis solidaginis: Helianthus annuus

Halictus confusus: Helianthus annuus, H. divaricatus, H. strumosus

Halictus farinosus: Helianthus annuus, H. gracilentus

Halictus rubicundus: Helianthus annuus, H. maximiliani, H. strumosus

Halictus tripartitus: Helianthus annuus

Heriades carinata: Helianthus strumosus

Heriades occidentalis: Helianthus gracilentus

Hoplitis cylindrica: Helianthus strumosus

Hoplitis pilosifrons: Helianthus petiolaris

Hoplitis sambuci: Helianthus sp.

Hoplitis simplex: Helianthus strumosus

Hoplitis truncata truncata: Helianthus divaricatus

Lasioglossum coriaceum: Helianthus strumosus, H. tuberosus

Lasioglossum sisymbrii: Helianthus annuus, H. niveus

Lasioglossum titusi: Helianthus sp.

Megachile agustini: Helianthus annuus, H. petiolaris

Megachile albitarsis: Helianthus divaricatus, H. radula, H. tuberosus

Megachile casadae: Helianthus sp.

Megachile centuncularis: Helianthus annuus, H. strumosus

Megachile coquilletti: Helianthus gracilentus

Megachile dentitarsus: Helianthus petiolaris

Megachile frugalis: Helianthus gracilentus, H. petiolaris

Megachile gemula gemula: Helianthus giganteus

Megachile inermis: Helianthus giganteus

Megachile latimanus: Helianthus annuus, H. divaricatus, H. giganteus, H. grosseserratus, H. maximiliani, H. mollis, H. rigidus, H. strumosus, H. tuberosus

Megachile lippiae: Helianthus sp.

Megachile melanophaea: Helianthus giganteus

Megachile mendica: Helianthus annuus, H. divaricatus, H. radula, H. strumosus

Megachile mucorosa: Helianthus annuus

Megachile petulans: Helianthus atrorubens, H. divaricatus, H. mollis, H. strumosus

Megachile pruina pruina: Helianthus sp.

Megachile relativa: Helianthus giganteus, H. grosseserratus

Megachile texana: Helianthus annuus, H. grosseserratus

Megachile townsendiana: Helianthus annuus, H. debilis

Megachile xylocopoides: Helianthus ciliaris

Megachile zapoteca: Helianthus sp.

Melissodes desponsa: Helianthus annuus, H. grosseserratus, H. strumosus

Melissodes denticulata: Helianthus debilis

Melissodes opuntiella: Helianthus annuus

Melissodes paroselae: Helianthus annuus

Melissodes tepida: Helianthus annuus, H. bolanderi, H. petiolaris

Melissodes thelypodii thelypodii: Helianthus annuus

Melissodes tristis: Helianthus annuus, H. ciliaris, H. petiolaris

Nomia nortoni nortoni: Helianthus maximiliani

Osmia clarescens: Helianthus gracilentus

Osmia grinnelli: Helianthus gracilentus

Osmia marginata: Helianthus annuus, H. gracilentus, H. niveus

Osmia subfasciata subfasciata: Helianthus sp.

Perdita gerhardi dallasiana: Helianthus annuus

Prtandrena bancrofti: Helianthus sp.

Svastra atripes atripes: Helianthus annuus

Svastra cressonii: Helianthus annuus

Synhalonia actuosa: Helianthus nuttallii

Synhalonia edwardsii: Helianthus annuus

NECTAR VISITORS NOT KNOWN TO TAKE POLLEN FROM Helianthus

Anthidium maculosum: Helianthus annuus

Anthidium porterae: Helianthus annuus, H. petiolaris

Anthophora smithii: Helianthus annuus

Anthophora urbana urbana: Helianthus annuus, H. gracilentus

Anthophora walshii: Helianthus grosseserratus, H. petiolaris

Ashmeadiella titusi: Helianthus gracilentus

Augochlorella pomoniella: Helianthus annuus

Calliopsis andreniformis: Helianthus strumosus

Centris atripes: Helianthus annuus

Centris caesalpiniae: Helianthus annuus

Ceratina dallatorreana: Helianthus annuus

Ceratina tejonensis: Helianthus gracilentus

Chalicodoma chilopsidis: Helianthus sp.

Chalicodoma occidentalis: Helianthus annuus

Chalicodoma odontostoma: Helianthus sp.

Chalicodoma spinotulata: Helianthus sp.

Chalicodoma subexilis: Helianthus sp.

Colletes americanus: Helianthus divaricatus

Colletes louisae: Helianthus annuus

Colletes perileucus: Helianthus annuus

Colletes wootoni: Helianthus annuus

Diadasia afflicta afflicta: Helianthus sp.

Diadasia australis: Helianthus gracilentus

Diadasia bituberculata: Helianthus annuus

Diadasia diminuta: Helianthus annuus, H. gracilentus, H. petiolaris

Diadasia ochracea: Helianthus annuus

Diadasia rinconis rinconis: Helianthus annuus

Dialictus albipennis: Helianthus strumosus

Dialictus clematisellus: Helianthus annuus

Dialictus illinoensis: Helianthus divaricatus

Dialictus impavidus: Helianthus gracilentus, H. sp.

Dialictus microlepoides: Helianthus annuus

Dialictus oleosus: Helianthus annuus

Evylaeus aberrans: Helianthus petiolaris

Evylaeus amicus: Helianthus annuus

Evylaeus argemonis: Helianthus annuus

Evylaeus pectinatus: Helianthus tuberosus

Hoplitis biscutellae: Helianthus niveus

Lasioglossum mellipes: Helianthus gracilentus

Lithurge gibbosus: Helianthus sp.

Martinapis occidentalis: Helianthus niveus

Megachile coloradensis: Helianthus annuus

Megachile concinna: Helianthus annuus

Megachile gentilis: Helianthus annuus

Megachile nevadensis: Helianthus gracilentus

Megachile sidalceae: Helianthus annuus, H. ciliaris

Melissodes fimbriata: Helianthus petiolaris

Melissodes plumosa: Helianthus petiolaris

Melissodes velutina: Helianthus gracilentus

Melissodes verbesinarum: Helianthus annuus

Metapsaenythia abdominalis abdominalis: Helianthus annuus

Nomadopsis helianthi: Helianthus sp.

Nomia angustitibialis: Helianthus annuus

Nomia fedorensis: Helianthus sp.

Nomia melanderi: Helianthus sp.

Nomia mesillensis: Helianthus annuus

Nomia nevadensis angelesia: Helianthus annuus, H. gracilentus

Nomia nevadensis arizonensis: Helianthus annuus

Peponapis pruinosa: Helianthus annuus

Perdita zebrata zebrata: Helianthus petiolaris

Protandrena mexicanorum: Helianthus annuus

Protoxaea gloriosa: Helianthus annuus

Pterosarus expallidus: Helianthus sp.

Pterosarus leucopterus: Helianthus petiolaris

Ptilothrix sp. near sumichrasti: Helianthus annuus

Svastra grandissima: Helianthus annuus

Svastra sabinensis: Helianthus annuus

Svastra sila: Helianthus annuus

Xenoglossodes bishoppi: Helianthus sp.

Xenoglossodes eriocarpi: Helianthus annuus

Xenoglossodes helianthorum: Helianthus sp.

Xylocopa californica: Helianthus annuus

PARASITIC BEES KNOWN TO VISIT THE FLOWERS OF Helianthus

Coelioxys alternata: Helianthus divaricatus

Coelioxys banksi: Helianthus sp.

Coelioxys edita: Helianthus annuus

Coelioxys funeraria: Helianthus strumosus

Coelioxys germana: Helianthus divaricatus

Coelioxys menthae: Helianthus annuus

Coelioxys modesta: Helianthus strumosus

Coelioxys moesta: Helianthus giganteus

Coelioxys novomexicana: Helianthus sp.

Coelioxys octodentata: Helianthus divaricatus, H. mollis, H. strumosus

Coelioxys rufitarsus: Helianthus grosseserratus, H. strumosus

Coelioxys sayi: Helianthus divaricatus, H. strumosus

Coelioxys sodalis: Helianthus strumosus

Coelioxys texana: Helianthus strumosus

Dioxys aurifuscus: Helianthus sp.

Dioxys pomonae pomonae: Helianthus sp.

Epeolus autumnalis: Helianthus divaricatus, H. tuberosus

Epeolus bifasciatus: Helianthus divaricatus

Epeolus compactus: Helianthus divaricatus

Epeolus pusillus: Helianthus divaricatus

Holcopasites heliopsis: Helianthus sp.

Neolarra helianthi: Helianthus petiolaris

Neolarra verbesinae: Helianthus petiolaris

Nomada garciana: Helianthus sp.

Nomada graenicheri: Helianthus giganteus, H. strumosus

Nomada gutierreziae: Helianthus sp.

Nomada melanoptera: Helianthus petiolaris

Nomada texana: Helianthus sp.

Nomada vierecki: Helianthus petiolaris

Nomada vincta vincta: Helianthus grosseserratus, H. strumosus, H. tuberosus

Paranomada velutina: Helianthus sp.

Psithyrus ashtoni: Helianthus sp.

Psithyrus citrinus: Helianthus strumosus

Psithyrus insularis: Helianthus sp.

Psithyrus variabilis: Helianthus annuus, H. grosseserratus, H. petiolaris, H. rigidus

Sphecodes dichrous: Helianthus sp.

Triepeolus concavus: Helianthus annuus, H. divaricatus, H. grosseserratus, H. mollis, H. rigidus, H. strumosus, H. tuberosus

Triepeolus cressonni cressonii: Helianthus divaricatus, H. grosseserratus, H. mollis, H. strumosus

Triepeolus cyclurus: Helianthus petiolaris

Triepeolus dacotensis: Helianthus petiolaris

Triepeolus donatus: Helianthus divaricatus, H. grosseserratus, H. strumosus

Triepeolus helianthi: Helianthus divaricatus, H. grosseserratus

Triepeolus lestes: Helianthus annuus

Triepeolus lineatulus: Helianthus annuus, H. bolanderi

Triepeolus lunatus: Helianthus divaricatus, H. tuberosus

Triepeolus nevadensis: Helianthus divaricatus

Triepeolus norae: Helianthus annuus

Triepeolus pectoralis: Helianthus strumosus

Triepeolus rectangularis: Helianthus sp.

Triepeolus remigatus: Helianthus divaricatus, H. lenticularis

Triepeolus simplex: Helianthus divaricatus

Triepeolus subnitens: Helianthus annuus

Triepeolus texanus: Helianthus ciliaris

Triepeolus trichopygus: Helianthus annuus

Xeromelecta californica: Helianthus annuus, H. lenticularis

Xeromelecta interrupta: Helianthus annuus

SPECIES OF Helianthus WITH KNOWN BEE VISITORS

To facilitate future pollination studies of particular species of Helianthus we have listed below in alphabetical order the species of Helianthus with known bee visitors. The taxa of bees are then listed alphabetically for each of these species. It will be noticed that some species of Helianthus have fewer taxa of bees associated with them than others. Doubtless some of this is simply due to the lack of detailed field studies, but at least in some cases it may be that some species of Helianthus are less attractive than others. For example, Graenicher (1909:68) has commented on his studies of H. giganteus that these flowers do not seem to be as attractive to insects (including bees) as those of H. strumosus. Also, it is to be expected that those species of Helianthus with widespread distribution, e.g., H. annuus and H. petiolaris, will have a greater number of bee visitors than those species with more restricted distributions. Our knowledge of the oligoleges primarily associated with Helianthus is summarized in Table N.

Helianthus angustifolius: Andrena accepta, A. aliciae

Helianthus annuus: Agapostemon angelicus, A. cockerelli, A. melliventris, A. texanus, A. tyleri, Andrena accepta, A. chromotricha, A. helianthi, A. recta, Anthidium maculosum, A. porterae, Anthophora curta, A. maculifrons, A. montana, A. peritomae, A. smithii, A. urbana urbana, Apis mellifera, Ashmeadiella californica, Augochlorella pomoniella, Augochloropsis metallica metallica, Bombus bimaculatus, B. fervidus fervidus, B. fraternus, B. griseocollis, B. impatiens, B. morrisoni, B. nevadensis, B. pennsylvanicus pennsylvanicus, B. p. sonorus, B. vagans vagans, Calliopsis rozeni, Centris atripes, C. caesalpiniae, Ceratina dallatorreana, C. dupla, C. pacifica, C. shinnersi, Chalicodoma angelarum, C. occidentalis, Coelioxys edita, C. menthae, Colletes fulgidus, C. louisae, C. perileucus, C. rufocinctus, C. wootoni, Diadasia bituberculata, D. diminuta, D. enavata, D. ochracea, D. rinconis rinconis, Dialictus clematisellus, D. imitatus, D. incompletus, D. microlepoides, D. oleosus, D. pilosus pilosus, D. pruinosiformis, D. versatus, Dianthidium curvatum sayi, Dufourea marginata, Evylaeus amicus, E. argemonis, E. pectoraloides, Exomalopsis pygmaea, E. solani, E. solidaginis, Halictus confusus, H. farinosus, H. ligatus, H. rubicundus, H. tripartitus, Hesperapis carinata, Heteranthidium cordaticeps, H. zebratum, Lasioglossum sisymbrii, Megachile agustini, M. brevis, M. centuncularis, M. coloradensis, M. concinna, M. gentilis, M. inimica, M. latimanus, M. manifesta, M. mendica, M. montivaga, M. mucorosa, M. nevadensis, M. parallela, M. perihirta, M. policaris, M. pugnata pugnata, M. sidalceae, M. texana, M. townsendiana, Melissodes agilis, M. appressa, M. bidentis, M. bimaculata, bimaculata, M. boltoniae, M. brevipyga, M. coloradensis, M. communis communis, M. composita, M. comptoides, M. confusa, M. coreopsis, M. dentiventris, M. desponsa, M. gelida, M. humilior, M. limbus, M. lupina, M. menuachus, M. montana, M. nivea, M. opuntiella, M. paroselae, M. paulula, M. perlusa, M. rivalis, M. robustior, M. stearnsi, M. subagilis, M. submenuacha, M. tepida, M. tessellata, M. thelypodii thelypodii, M. trinodis, M. tristis, M. verbesinarum, M. wheeleri, Metapsaenythia abdominalis abdominalis, Nomia angustitibialis, N. heteropoda, N. mesillensis, N. nevadensis angelesia, N. n. arizonensis, N. triangulifera, Osmia marginata, O. montana, Paranomada velutina, Peponapis pruinosa, Perdita albipennis, P. ignota crawfordi, P. gerhardi dallasiana, P. lingualis, P. nigroviridis, P. scopata, P. tricincta, P. verbesinae, P. xanthisma, Protandrena mexicanorum, Protoxaea gloriosa, Pseudopanurgus aethiops, P. rugosus, Psithyrus variabilis, Pterosarus helianthi, P. innuptus, P. perlaevis, P. piercei piercei, P. simulans, Ptilothrix sp. near sumichrasti, Svastra aegis, S. atripes atripes, S. cressonii, S. grandissima, S. helianthelli, S. machaerantherae, S. obliqua, S. petulca, S. sabinensis, S. sila, S. texana, Synhalonia edwardsii, Triepeolus concavus, T. lestes, T. lineatulus, T. norae, T. subnitens, T. trichopygus, Xenoglossodes eriocarpi, Xeromelecta californica, X. interrupta, Xylocopa californica

Helianthus atrorubens: Megachile parallela, M. petulans, Melissodes agilis, M. coloradensis, M. nivea, M. rustica, M. trinodis, Svastra obliqua

Helianthus bolanderi: Melissodes agilis, M. robustior, M. tepida, Triepeolus lineatulus, Svastra obliqua

Helianthus ciliaris: Megachile sidalceae, M. xylocopoides, Melissodes agilis, M. tristis, Svastra helianthelli, S. obliqua, Triepeolus texanus

Helianthus debilis: Agapostemon splendens, Anthidiellum perplexum, Augochlora pura, Augochloropsis metallica metallica, Dialictus marinus, Halictus ligatus, Megachile townsendiana, Melissodes communis communis, M. denticulata, M. wheeleri, Perdita pratti

Helianthus divaricatus: Andrena accepta, A. aliciae, A. duplicata, A. helianthi, Ashmeadiella bucconis, Bombus fraternus, B. griseocollis, B. pennsylvanicus pennsylvanicus, Ceratina dupla, Coelioxys alternata, C. germana, C. octodentata, C. sayi, Colletes americanus, Dialictus illinoensis, D. pilosus pilosus, D. versatus, Dufourea marginata, Epeolus autumnalis, E. bifasciatus, E. compactus, E. pusitlus, Evylaeus pectoralis, Halictus confusus, H. ligatus, Hoplitis truncata truncata, Megachile albitarsis, M. brevis, M. inimica, M. latimanus, M. mendica, M. parallela, M. petulans, M. pugnata pugnata, Melissodes agilis, M. bimaculata bimaculata, M. boltoniae, M. coloradensis, M. dentiventris, M. nivea, M. rustica, M. trinodis, M. vernoniae, Paranthidium jugatorium, Perdita bequaerti, Pseudopanurgus rugosus, Pterosarus albitarsis, P. labrosiformis labrosiformis, P. labrosus, P. rudbeckiae, Svastra obliqua, Triepeolus concavus, T. cressonii cressonii, T. donatus, T. helianthi, T. lunatus, T. nevadensis, T. remigatus, T. simplex

Helianthus giganteus: Andrena accepta, A. aliciae, A. chromotricha, A. helianthi, Apis mellifera, Augochlorella striata, Bombus affinis, B. griseocollis, B. pennsylvanicus pennsylvanicus, B. vagans vagans, Coelioxys moesta, Megachile gemula gemula, M. inermis, M. latimanus, M. melanophaea, M. pugnata pugnata, M. relativa, Melissodes trinodis, Nomada graenicheri

Helianthus gracilentus: Agapostemon angelicus, A. femoratus, A. texanus, Andrena pallidifovea, Anthocopa hemizoniae, Anthophora curta, A. urbana urbana, Ashmeadiella bucconis, A. californica, A. foveata, A. titusi, Calliopsis pugionis, Ceratina acantha, C. apacheorum,

C. punctigena, C. tejonensis, Chalicodoma angelarum, Diadasia australis, D. enavata, Dialictus impavidus, Dianthidium dubium dilectum, Halictus farinosus, Heriades occidentalis, Heteranthidium timberlakei, Lasioglossum mellipes, Megachile alata, M. coquilletti, M. fidelis, M. frugalis, M. montivaga, M. nevadensis, M. parallela, Melissodes lupina, M. robustior, M. velutina, Nomia nevadensis angelesia, Osmia clarescens, O. coloradensis, O. grinnelli, O. marginata, O. montana, Svastra obliqua, Xeromelecta californica

Helianthus grosseserratus: Agapostemon serieus, A. texanus, Andrena accepta, A. duplicata, A. helianthi, Anthophora walshii, Augochloropsis metallica metallica, Bombus fraternus, B. griseocollis, B. impatiens, B. nevadensis, B. pennsylvanicus pennsylvanicus, B. vagans vagans, Coelioxys rufitarsus, Dialictus versatus, Dufourea marginata, Halictus ligatus, Megachile brevis, M. inimica, M. latimanus, M. pugnata pugnata, M. relativa, M. texana, Melissodes agilis, M. bimaculata bimaculata, M. boltoniae, M. coloradensis, M. coreopsis, M. dentiventris, M. desponsa, M. menuachus, M. nivea, M. rustica, M. trinodis, Nomada vincta vincta, Psithyrus variabilis, Pterosarus solidaginis, Svastra obliqua, Triepeolus concavus, T. cressonii cressonii, T. donatus, T. helianthi

Helianthus lenticularis: Agapostemon texanus, Andrena accepta, A. helianthi, Augochlorella striata, Bombus pennsylvanicus pennsylvanicus, Diadasia enavata, Dialictus nevadensis, D. pruinosiformis, D. tegulariformis, Dianthidium curvatum sayi, Exomalopsis pygmaea, Halictus ligatus, Hesperapis carinata, Heteranthidium occidentale, H. zebratum, Megachile helianthi, M. parallela, Nomia heteropoda, Melissodes agilis, M. communis communis, M. robustior, Nomia triangulifera, Paranthidium jugatorium, Perdita albipernnis, P. lingualis, Pseudopanurgus aethiops, Pterosarus stigmalis, Svastra obliqua, Triepeolus remigatus, Xeromelecta californica

Helianthus maximiliani: Agapostemon texanus, Andrena accepta, A. chromotricha, A. helianthi, Augochlorella striata, Bombus griseocollis, B. nevadensis, B. pennsylvanicus pennsylvanicus, Ceratina dupla, Dianthidium curvatum sayi, Halictus ligatus, H. rubicundus, Megachile latimanus, M. parallela, Melissodes agilis, M. bidentis, M. coreopsis, M. rustica, M. subagilis, M. subillata, M. tincta, M. trinodis, Nomia nortoni nortoni, N. triangulifera, Perdita swenki, Pterosarus innuplus, P. piercei piercei, P. renimaculatus, P. simulans, Svastra obliqua

Helianthus microcephalus: Andrena aliciae, Svastra obliqua

Helianthus mollis: Andrena accepta, Anthidium paroselae, Augochlorella persimilis, Augochloropsis metallica metallica, Bombus pennsylvanicus pennsylvanicus, Coelioxys octodentata, Dialictus pilosus pilosus, D. versatus, Halictus ligatus, Megachile brevis, M. latimanus, M. parallela, M. petulans, Melissodes agilis, M. coloradensis, M. trinodis, Pseudopanurgus rugosus, Pterosarus albitarsis, Svastra obliqua, Triepeolus concavus, T. cressonii cressonii

Helianthus niveus: Agapostemon melliventris, Hesperapis arenicola, Hoplitis biscutellae, Lasioglossum sisymbrii, Martinapis occidentalis, Megachile xerophila, Osmia marginata

Helianthus nuttallii: Andrena helianthi, A. lawrencei, Megachile parallela, Melissodes lupina, Osmia californica, Pterosarus innuptus, Synhalonia actuosa

Helianthus occidentalis: Ceratina punctigena, Perdita albipennis

Helianthus petiolaris: Agapostemon texanus, Andrena accepta, A. haynesi, A. helianthi, A. pecosana, Anthidium paroselae, A. porterae, Anthophora curta, A. walshii, Ashmeadiella bucconis, Bombus fraternus, B. griseocollis, B. nevadensis, B. pennsylvanicus pennsylvanicus, B. p. sonorus, Ceratina nanula, C. neomexicana, C. pacifica, Colletes rufocinctus, C. simulans armatus, C. susannae, Diadasia diminuta, Dialictus pruinosiformis, Dianthidium curvatum sayi, D. dubium dilectum, D. ulkei, Dufourea marginata, Evylaeus aberrans, Halictus ligatus, Hesperapis carinata, Heteranthidium zebratum, Hoplitis pilosifrons, H. producta, Megachile agustini, M. dentitarsus, M. fidelis, M. fortis, M. frugalis, M. inimica, M. manifesta, M. parallela, M. perihirta, M. policaris, Melissodes agilis, M. coloradensis, M. comptoides, M. coreopsis, M. fimbriata, M. gelida, M. glenwoodensis, M. menuachus, M. montana, M. perlusa, M. plumosa, M. robustior, M. rustica, M. snowii, M. sonorensis, M. subagilis, M. subillata, M. submenuacha, M. tepida, M. tristis, M. wheeleri, Neolarra helianthi, N. verbesinae, Nomada melanoptera, N. vierecki, Nomia heteropoda, N. micheneri, N. triangulifera, Perdita affinis, P. albipennis, P. alexi, P. aridella, P. bruneri, P. dolichocephala, P. fallax, P. laticincta, P. lingualis, P. pratti, P. prionopsidis, P. tridentata, P. verbesinae, P. xanthisma, P. zebrata zebrata, Pseudopanurgus aethiops, P. rugosus, Psithyrus variabilis, Pterosarus helianthi, P. innuptus, P. leucopterus, P. piercei piercei, P. renimaculatus, P. simulans, Svastra machaerantherae, S. obliqua, Syntrichalonia exquisita, Triepeolus cyclurus, T. dacotensis

Helianthus pumilus: Heteranthidium zebratum, Melissodes agilis

Helianthus radula: Andrena accepta, Dufourea marginata, Halictus ligatus, Heteranthidium zebratum, Megachile albitarsis, M. mendica, M. parallela, Melissodes agilis, M. dentiventris, M. rustica, Nomia heteropoda, Perdita bequaerti, Pseudopanurgus rugosus, Svastra aegis, S. texana

Helianthus rigidus: Andrena accepta, A. chromotricha, A. helianthi, Bombus fraternus, B. griseocollis, B. nevadensis, B. pennsylvanicus pennsylvanicus, Dialictus pilosus pilosus, D. versatus, Dufourea marginata, Evylaeus pectoralis, Halictus ligatus, Hesperapis carinata, Heteranthidium zebratum, Megachile brevis, M. fortis, M. inimica, M. latimanus, Melissodes agilis, M. coloradensis, M. snowii, Perdita albipennis, P. dolichocephala, P. tridentata, Psithyrus variabilis, Pterosarus innuptus, P. piercei piercei, Svastra obliqua, Triepeolus concavus

Helianthus salicifolius: Andrena accepta, Melissodes agilis, M. coreopsis, M. trinodis

Helianthus strumosus: Agapostemon sericeus, Andrena accepta, A. aliciae, A. chromotricha, A. helianthi, A. peckhami, Apis mellifera, Augochlorella striata, Augochloropsis metallica metallica, Bombus centralis, B. griseocollis, B. pennsylvanicus pennsylvanicus, B. termarius, B. terricola, B. vagans vagans, Calliopsis andreniformis, Ceratina dupla, Coelioxys funeraria, C. modesta, C. octodentata, C. sodalis, C. rufitarsus, C. sayi, C. texana, Dialictus albipennis, Evylaeus pectoralis, Halictus confusus, H. rubicundus, Heriades carinata, Hoplitis cylindrica, H. simplex, Lasioglossum coriaceum, Megachile brevis, M. centuncularis, M. latimanus, M. mendica, M. petulans, M. pugnata pugnata, Melissodes agilis, M. desponsa, M. illata, M. rustica, M. trinodis, Nomada graenicheri, N. vincta vincta, Paranthidium jugatorium, Psithyrus citrinus, Pterosarus innuptus, P. labrosifornis labrosiformis, Svastra obliqua, Triepeolus concavus, T. cressonii cressonii, T. donatus, T. pectoralis

Helianthus tuberosus: Andrena accepta, A. aliceae, A. chromotricha, A. helianthi, A. simplex, Augochlorella striata, Bombus griseocollis, B. nevadensis, B. pennsylvanicus pennsylvanicus, B. vagans vagans, Colletes compactus, Dufourea marginata, Dialictus imitatus, D. pilosus pilosus, D. zephyrus, Epeolus autumnalis, Evylaeus pectinatus, E. pectoralis, Halictus ligatus, Lasioglossum coriaceum, Megachile albitarsis, M. brevis, M. inimica, M. latimanus, M. pugnata pugnata, Melissodes agilis, M. bidentis, M. bimaculata bimaculata, M. boltoniae, M. coloradensis, M. coreopsis, M. rustica, M. trinodis, M. vernoniae, Nomada vincta vincta, Pseudopanurgus rugosus, Pterosarus innuptus, P. labrosiformis labrosiformis, P. labrosus, P. piercei piercei, P. solidaginis, Svastra obliqua, Triepeolus concavus, T. lunatus

While we are able to provide lists of bees for 24 North American species of Helianthus from all the sections and series recognized by Heiser et al. (1969), there is no information on bees available for the following species of Helianthus:

Section Annui: H. agrestis, H. anomalus, H. argophyllus, H. deserticola, H. neglectus, H. paradoxus, H. praecox, H. similis,

Section Ciliares
Series Pumili: H. cusickii
Series Ciliares: H. arizonensis, H. laciniatus

Section Divaricati
Series Divaricati: H. decapetalus, H. eggerti, H. hirsutus
Series Gigantei: H. californicus, H. resinosus, H. schweinitzii
Series Microcephali: H. glaucophyllus, H. laevigatus, H. longifolius, H. smithii
Series Angustifolii: H. floridanus, H. simulans
Series Atrorubentes: H. carnosus, H. heterophyllus, H. silphoides

Geographic Relationships of Bees Associated with Helianthus

In an attempt to learn something about the geographic relationships of the bees associated with Helianthus, the following listings of the oligoleges of Compositae primarily associated with Helianthus are presented in terms of their geographic occurrence in North America. For this purpose we have selected eight regions that are allopatric and possess rather distinctively different climates. These are Eastern North America, Texas Gulf Coast, Great Plains, Great Basin, Chihuahuan Desert, Sonoran Desert, Mojave Desert, and Cismontane Pacific Coast. Each of these regions is generally understood by biologists and each to some extent possesses a rather distinctive fauna of bees. Even so it should be kept in mind that some regions such as the adjacent Chihuahuan and Sonoran Deserts are more alike climatically than are the Great Basin and Eastern North America.

The regional relationships of the oligoleges of Compositae primarily associated with Helianthus are presented in Figure 1 and their relationships with the various species of Helianthus are summarized in Table N.

1. Species generally distributed throughout the range of Helianthus in North America (occupying all 8 geographic regions):

Megachile parallela

Melissodes agilis

Svastra obliqua

2. Species widely distributed within the range of Helianthus in North America (occupying 4, 5, or 6 geographic regions):

Andrena accepta: Eastern North America, Great Plains, Great Basin, Chihuahuan Desert, Sonoran Desert

Andrena helianthi: Eastern North America, Great Plains, Chihuahuan Desert, Great Basin

Diadasia enavata: Great Plains, Chihuahuan Desert, Sonoran Desert, Mojave Desert, Great Basin, Cismontane Pacific Coast

Nomia heteropoda: Eastern North America, Texas Gulf Coast, Great Plains, Great Basin, Chihuahuan Desert, Sonoran Desert

3. Species restricted to 3 geographic regions within the range of Helianthus in North America:

Dufourea marginata: Great Plains, Great Basin, Chihuahuan Desert

Melissodes coloradensis: Eastern North America, Great Plains, Great Basin

Nomia trangulifera: Great Plains, Great Basin, Chihuahuan Desert

Perdita albipennis: Great Plains, Great Basin, Chihuahuan Desert

Perdita lingualis: Great Plains, Great Basin, Chihuahuan Desert

Pseudopanurgus aethiops: Great Plains, Great Basin, Chihuahuan Desert

Pterosarus innuptus: Great Plains, Great Basin, Chihuahuan Desert

Svastra helianthelli: Great Plains, Chihuahuan Desert, Sonoran Desert

4. Species restricted to 2 geographic regions within the range of Helianthus in North America:

Andrena aliciae: Eastern North America, Great Plains

Hesperapis carinata: Great Plains, Great Basin

Heteranthidium occidentale: Great Plains, Chihuahuan Desert

Heteranthidium zebratum: Great Plains, Chihuahuan Desert

Melissodes coreopsis: Great Plains, Chihuahuan Desert

Melissodes perlusa: Great Plains, Great Basin

Melissodes robustior: Great Basin, Cismontane Pacific Coast

Melissodes trinodis: Eastern North America, Great Plains

Pseudopanurgus rugosus: Eastern North America, Great Plains

Svastra machaerantherae: Chihuahuan Desert, Sonoran Desert

5. Species restricted to a single geographic region within the range of Helianthus in North America:

Andrena haynesi: Great Plains

Andrena peckhami: Eastern North America

Exomalopsis pygmaea: Great Plains

Heteranthidium cordaticeps: Chihuahuan Desert

Melissodes gelida: Great Plains

Nomia micheneri: Chihuahuan Desert

Perdita bequaerti: Eastern North America

Perdita laticincta: Great Plains

Perdita scopata: Texas Gulf Coast

Perdita tricincta: Texas Gulf Coast

Perdita tridentata: Great Plains

Pterosarus helianthi: Great Plains

Pterosarus piercei piercei: Great Plains

Pterosarus simulans: Great Plains

Listed below by geographic regions are the species of oligoleges of Compositae primarily associated with Helianthus. In these lists those oligoleges restricted to the geographic region in which they are listed are preceded by an asterisk. In all other cases, the species entry is followed by the other geographic region(s) in which it is known to occur. For convenience the eight recognized geographic regions are arranged alphabetically below.

CHIHUAHUAN DESERT

Andrena accepta: Eastern North America, Great Basin, Great Plains, Sonoran Desert

Andrena helianthi: Eastern North America, Great Basin, Great Plains

Diadasia enavata: Cismontane Pacific Coast, Great Basin, Great Plains, Mojave Desert, Sonoran Desert

Dufourea marginata: Great Basin, Great Plains

*Heteranthidium cordaticeps

Heteranthidium occidentale: Great Plains

Heteranthidium zebratum: Great Plains

Megachile parallela: Cismontane Pacific Coast, Eastern North America, Great Basin, Great Plains, Mojave Desert, Sonoran Desert, Texas Gulf Coast

Melissodes agilis: Cismontane Pacific Coast, Eastern North America, Great Basin, Great Plains, Mojave Desert, Sonoran Desert, Texas Gulf Coast

Melissodes coreopsis: Great Plains

Nomia heteropoda: Eastern North America, Great Basin, Great Plains, Sonoran Desert, Texas Gulf Coast

*Nomia micheneri

Nomia triangulifera: Great Basin, Great Plains

Perdita albipennis: Great Basin, Great Plains

Perdita lingualis: Great Basin, Great Plains

Pseudopanurgus aethiops: Great Basin, Great Plains

Pterosarus innuptus: Great Basin, Great Plains

Svastra helianthelli: Great Plains, Sonoran Desert

Svastra machaerantherae: Sonoran Desert

Svastra obliqua: Cismontane Pacific Coast, Eastern North America, Great Basin, Great Plains, Mojave Desert, Sonoran Desert, Texas Gulf Coast

CISMONTANE PACIFIC COAST

Diadasia enavata: Chihuahuan Desert, Great Basin, Great Plains, Mojave Desert, Sonoran Desert

Megachile parallela: Chihuahuan Desert, Eastern North America, Great Basin, Great Plains, Mojave Desert, Sonoran Desert, Texas Gulf Coast

Melissodes agilis: Chihuahuan Desert, Eastern North America, Great Basin, Great Plains, Mojave Desert, Sonoran Desert, Texas Gulf Coast

Melissodes robustior: Great Basin

Svastra obliqua: Chihuahuan Desert, Eastern North America, Great Basin, Great Plains, Mojave Desert, Sonoran Desert, Texas Gulf Coast

EASTERN NORTH AMERICA

Andrena accepta: Chihuahuan Desert, Great Basin, Great Plains, Sonoran Desert

Andrena aliciae: Great Plains

Andrena helianthi: Chihuahuan Desert, Great Basin, Great Plains

*Andrena peckhami Megachile parallela: Chihuahuan Desert, Cismontane Pacific Coast, Great Basin, Great Plains, Mojave Desert, Sonoran Desert, Texas Gulf Coast

Melissodes agilis: Chihuahuan Desert, Cismontane Pacific Coast, Great Basin, Great Plains, Mojave Desert, Sonoran Desert, Texas Gulf Coast

Melissodes coloradensis: Great Basin, Great Plains

Melissodes trinodis: Great Plains

Melissodes trinodis: Great Plains

Nomia heteropoda: Chihuahuan Desert, Great Basin, Great Plains, Sonoran Desert, Texas Gulf Coast

*Perdita bequaerti

Pseudopanurgus rugosus: Great Plains

Svastra obliqua: Chihuahuan Desert, Cismontane Pacific Coast, Great Basin, Great Plains, Mojave Desert, Sonoran Desert, Texas Gulf Coast

GREAT BASIN

Andrena accepta: Chihuahuan Desert, Eastern North America, Great Plains, Sonoran Desert

Andrena helianthi: Chihuahuan Desert, Eastern North America, Great Plains

Diadasia enavata: Chihuahuan Desert, Cismontane Pacific Coast, Great Plains, Mojave Desert, Sonoran Desert

Dufourea marginata: Chihuahuan Desert, Great Plains

Hesperapis carinata: Great Plains

Megachile parallela: Chihuahuan Desert, Cismontane Pacific Coast, Eastern North America, Great Plains, Mojave Desert, Sonoran Desert, Texas Gulf Coast

Melissodes agilis: Chihuahuan Desert, Cismontane Pacific Coast, Eastern North America, Great Plains, Mojave Desert, Sonoran Desert, Texas Gulf Coast

Melissodes coloradensis: Eastern North America, Great Plains

Melissodes perlusa: Great Plains

Melissodes robustior: Cismontane Pacific Coast

Nomia heteropoda: Chihuahuan Desert, Eastern North America, Great Plains, Sonoran Desert, Texas Gulf Coast

Nomia triangulifera: Chihuahuan Desert, Great Plains

Perdita albipennis: Chihuahuan Desert, Great Plains

Perdita lingualis: Chihuahuan Desert, Great Plains

Pseudopanurgus aethiops: Chihuahuan Desert, Great Plains

Pterosarus innuptus: Chihuahuan Desert, Great Plains

Svastra obliqua: Chihuahuan Desert, Cismontane Pacific Coast, Eastern North America, Great Plains, Mojave Desert, Sonoran Desert, Texas Gulf Coast

GREAT PLAINS

Andrena accepta: Chihuahuan Desert, Eastern North America, Great Basin, Sonoran Desert

Andrena aliciae: Eastern North America

*Andrena haynesi

Andrena helianthi: Chihuahuan Desert, Eastern North America, Great Basin

Diadasia enavata: Chihuahuan Desert, Cismontane Pacific Coast, Great Basin, Mojave Desert, Sonoran Desert

Dufourea marginata: Chihuahuan Desert, Great Basin

*Exomalopsis pygmaea

Hesperapis carinata: Great Basin

Heteranthidium occidentale: Chihuahuan Desert

Heteranthidium zebratum: Chihuahuan Desert

Megachile parallela: Chihuahuan Desert, Cismontane Pacific Coast, Eastern North America, Great Basin, Mojave Desert, Sonoran Desert, Texas Gulf Coast

Melissodes agilis: Chihuahuan Desert, Cismontane Pacific Coast, Eastern North America, Great Basin, Mojave Desert, Sonoran Desert, Texas Gulf Coast

Melissodes coloradensis: Eastern North America, Great Basin

Melissodes coreopsis: Chihuahuan Desert

*Melissodes gelida

Melissodes perlusa: Great Basin

Melissodes trinodis: Eastern North America

Nomia heteropoda: Chihuahuan Desert, Eastern North America, Great Basin, Sonoran Desert, Texas Gulf Coast

Nomia triangulifera: Chihuahuan Desert, Great Basin

Perdita albipennis: Chihuahuan Desert, Great Basin

*Perdita laticincta

Perdita lingualis: Chihuahuan Desert, Great Basin

*Perdita simulans

*Perdita tridentata

Pseudopanurgus aethiops: Chihuahuan Desert, Eastern North America, Great Basin

*Pseudopanurgus rugosus: Eastern North America

*Pterosarus helianthi

Pterosarus innuptus: Chihuahuan Desert, Great Basin

*Pterosarus piercei piercei

Svastra helianthelli: Chihuahuan Desert, Sonoran Desert

Svastra obliqua: Chihuahuan Desert, Cismontane Pacific Coast, Eastern North America, Great Basin, Mojave Desert, Sonoran Desert, Texas Gulf Coast

MOJAVE DESERT

Diadasia enavata: Chihuahuan Desert, Cismontane Pacific Coast, Great Basin, Great Plains, Sonoran Desert

Megachile parallela: Chihuahuan Desert, Cismontane Pacific Coast, Eastern North America, Great Basin, Great Plains, Sonoran Desert, Texas Gulf Coast

Melissodes agilis: Chihuahuan Desert, Cismontane Pacific Coast, Eastern North America, Great Basin, Great Plains, Sonoran Desert, Texas Gulf Coast

Svastra obliqua: Chihuahuan Desert, Cismontane Pacific Coast, Eastern North America, Great Basin, Great Plains, Sonoran Desert, Texas Gulf Coast

SONORAN DESERT

Andrena accepta: Chihuahuan Desert, Eastern North America, Great Basin, Great Plains

Diadasia enavata: Chihuahuan Desert, Cismontane Pacific Coast, Great Basin, Great Plains, Mojave Desert

Megachile parallela: Chihuahuan Desert, Cismontane Pacific Coast, Eastern North America, Great Basin, Great Plains, Mojave Desert, Texas Gulf Coast

Melissodes agilis: Chihuahuan Desert, Cismontane Pacific Coast, Eastern North America, Great Basin, Great Plains, Mojave Desert, Texas Gulf Coast

Nomia heteropoda: Chihuahuan Desert, Eastern North America, Great Basin, Great Plains, Texas Gulf Coast

Svastra helianthelli: Chihuahuan Desert, Great Plains

Svastra machaerantherae: Chihuahuan Desert

Svastra obliqua: Chihuahuan Desert, Cismontane Pacific Coast, Eastern North America, Great Basin, Great Plains, Mojave Desert, Texas Gulf Coast

TEXAS GULF COAST

Megachile parallela: Chihuahuan Desert, Cismontane Pacific Coast, Eastern North America, Great Basin, Great Plains, Mojave Desert, Sonoran Desert

Melissodes agilis: Chihuahuan Desert, Cismontane Pacific Coast, Eastern North America, Great Basin, Great Plains, Mojave Desert, Sonoran Desert

Nomia heteropoda: Chihuahuan Desert, Eastern North America, Great Basin, Great Plains, Sonoran Desert

*Perdita scopata

*Perdita tricincta

Svastra obliqua: Chihuahuan Desert, Cismontane Pacific Coast, Eastern North America, Great Basin, Great Plains, Mojave Desert, Sonoran Desert

Geographic Affinities of Helianthus Oligoleges and Polyleges

As might be expected, an analysis of the groups of bees associated with Helianthus in their various dependent pollen-collecting roles reveals little about their geographic affinities. Furthermore, since species of the genus Helianthus in North America occupy various geographic ranges across the United States, southern Canada, and Mexico south into the State of Michoacan, the opportunity exists at present for many different geographically differentiating faunas of bees simultaneously to evolve specialized intrafloral relationships with Helianthus under several markedly different climatic regimes. As we have discussed earlier, however, a very high percentage of the pollen-collecting bee fauna associated with Helianthus in North America represents oligoleges of the family Compositae. No less than 46 percent of these Compositae oligoleges are either primarily dependent upon the pollen and nectar of Helianthus (14 percent) or are secondarily so (32 percent). Thus an analysis of the geographic affinities of the 39 species of those oligoleges primarily associated with Helianthus (Table N) seems not only appropriate, but essential to achieve an understanding of the evolutionary history of this bee-flower relationship.

Less than one-third of the 39 oligoleges of Compositae primarily associated with Helianthus belong to genera of Holarctic or greater Old World distribution including Andrena (5 species), Dufourea (1 species), Hesperapis (1 species), Megachile (1 species) and Nomia (3 species). It is probably significant that many species in the first four of these genera have repeatedly evolved oligolectic relationships with the flora both in the Old and New Worlds. All five of these genera either evolved in the Old World and subsequently invaded the Western Hemisphere (Dufourea, Hesperapis, Megachile) or have an ancient origin at a time when the northern continents were still in contact (Andrena, Nomia). Since Megachile and Nomia occur on all continents, each may have invaded the New World more than once and over different routes. Dufourea, Hesperapis, and Andrena, on the other hand, seem to have migrated from the Old World to the New only by northern land routes and, perhaps, more than once. Andrena, although an Holarctic genus, should be associated with New World genera when discussing primary oligoleges of Helianthus, since all five species of Andrena associated with sunflowers are members of subgenera (Callandrena and Cnemidandrena) that arose in the New World (LaBerge, 1967, Donovan, 1977) and are restricted to the New World (Callandrena) or occur primarily here (Cnemidandrena).

It is noteworthy that the very large and diverse genus Megachile contains only one species (M. parallela) that has established a primary relationship with Helianthus, even though a number are oligoleges of Compositae. Similar comments also apply to the other genera just discussed, except Andrena.

It is significant that the genera of Holarctic or greater Old World distribution (excepting Andrena) number only one-fifth (6) of the primary oligoleges attached to Helianthus, and that four-fifths (24) of such species belong to genera or subgenera (in the case of Andrena) that evolved in the New World and are found only or primarily here. Most of these genera are either present only in North America (Heteranthidium, Perdita, Pseudopanurgus, Pterosarus, Andrena) or are most diverse and numerous on this continent even though they are also represented in South America (Diadasia, Exomalopsis, Melissodes, and Svastra). In view of this we conclude that these are the genera or subgenera of bees that established the initial relationship with Helianthus and that only later in the evolutionary history of this bee-flower relationship did the invading genera from the Old World (viz., Dufourea, Hesperapis, Megachile, and Nomia) establish their relationships with Helianthus. This not only seems to explain their fewer numbers in relation to the species of Helianthus, but also suggests that the center of origin for the genus and its initially associated bee fauna was located to the south of its present center of distribution in North America, probably in the area of the Mexican Plateau (Figure 1).

FIGURE 1.—Regional relationships of the oligoleges of Compositae primarily associated with Helianthus. (Arrows indicate probable main avenues of derivation and differentiation of these oligoleges following the presumed origin of this bee-flower relationship; numbers in boxes refer to number of bee taxa (on left) and number of Helianthus species (on right) involved in each of the regional relationships; drawn by Celeste Green, Department of Entomological Sciences, University of California, Berkeley.)

Seasonal Occurrence of Bees Associated with Helianthus

In the northern tier of states (e.g., Wisconsin, see Graenicher, 1909) where the species of Helianthus mostly bloom in July, August, and September (H. grosseserratus somewhat later), most of the bee visitors (oligoleges, casuals, and nectar seekers) are active during this time. In fact, throughout the range of the genus, even in the southern regions, by far the majority of visitors are bees of the summer and fall (including such primary oligoleges as Megachile parallela).

Among the solitary bees, the most widespread species (e.g., Svastra obliqua and M. agilis) have the longest flight periods, which in the more southern parts of their ranges may cover the period June to November; the same is true of Diadasia enavata in the Southwest. Presumably these species have multiple or overlapping broods. The eusocial bees (e.g., Apis, Bombus) and primitively eusocial bees (e.g., Halictus, especially H. ligatus) are in flight throughout the sunflower season, in both the northern and southern regions.

In areas where sunflower blooms early, as along the Pacific Coast and in the southeast and southwest, early season bees such as the species of Osmia which fly in March, April, and May avail themselves of the nectar or pollen.

Diurnal Patterns of Pollen Collecting

Although weather conditions, the mixture of species of pollen-collecting bees at a given site, and the size (and thus relative competitive advantage) of the local population affect the diurnal patterns of pollen collection in bees that exploit the flowers of Helianthus, when a sufficient number of samples are available to minimize or eliminate these variables, it is clear that several patterns of behavior are involved. These are essentially similar to the patterns described by Hurd and Linsley (1975) for visitors to the creosote bush, Larrea tridentata, a desert plant that likewise has pollen and nectar available throughout the day.

Our field sampling data, recorded in Tables A-M and supplemented in the species accounts, suggest a number of generalizations, of which a few may be selected for special emphasis. Unlike Larrea, which makes pollen available before dawn, the Helianthus species with which we have worked do not do so until sunrise or shortly afterward. We have seen pollen-seeking females cruising flowers or sipping nectar before anthesis, but, in general, they arrive to coincide with anthesis.

Other things being equal, the first pollen-collecting females to reach the flowers are such primary oligoleges as Melissodes agilis (Tables B-H, J-M), Nomia heteropoda (Tables C, D, F) and Diadasia enavata (Tables I-K, M), when abundant, although they may arrive somewhat later under intense competition. Melissodes agilis, however, under favorable conditions, collects pollen primarily for the first two or three hours after sunrise and returns at a comparable period before sunset, with scattered nectar-seekers and even pollen-collectors in the interim. Nomia heteropoda, Diadasia enavata, and the regular polylege Halictus ligatus, also start early when pollen is abundant but continue throughout the day as long as pollen is available although successive pollen loads become smaller and smaller. Bombus pennsylvanicus sonorus (Tables D, E) may sometimes start early, but may also concentrate in the middle of the day (Tables G, L).

Other all-day pollen-collectors that tend to concentrate in the early morning are Andrena accepta (Tables B, G), Svastra machaerantherae (Tables B-D), and S. obliqua (Tables B, C, K, L) to name a few. On the other hand, Megachile parallela (Tables A-C), an all-day pollen-seeker, tends to be more abundant in the afternoon.

Parasitic bees, presumably seeking the burrows of their hosts in the morning, as well as throughout the period of host activity, tend to be most abundant at sunflowers from midmorning to late afternoon.

Species Accounts

In the discussions that follow, the species are arranged in the phylogenetic sequence of the recently published “Superfamily Apoidea” (Hurd, 1979) in Catalog of Hymenoptera in America North of Mexico. Each species is classed on the basis of intrafloral relationship according to the criteria set forth in the section “Intrafloral Relationships of Bees Associated with Helianthus” herein. The list contains 131 oligoleges (39 primary oligoleges, 92 secondary oligoleges), 153 polyleges (22 regular polyleges, 131 casual polyleges), 72 nectar-seeking species not known to take pollen from these flowers, and 56 parasitic species. Doubtless additional species will be discovered to visit these flowers in North America, particularly when detailed investigations are undertaken in those regions not specially emphasized in this study.

COLLETIDAE

1.

Colletes americanus

nectar visitor

2.

Colletes compactus

secondary oligolege

3.

Colletes fulgidus

casual polylege

4.

Colletes louisae

nectar visitor

5.

Colletes perileucus

nectar visitor

6.

Colletes rufocinctus

secondary oligolege

7.

Colletes simulans armatus

secondary oligolege

8.

Colletes susannae

secondary oligolege

9.

Colletes wootoni

nectar visitor

OXAEIDAE

1.

Protoxaea gloriosa

nectar visitor

ANDRENIDAE

1.

Andrena (Callandrena) accepta

primary oligolege

2.

Andrena (Callandrena) aliciae

primary oligolege

3.

Andrena (Callandrena) duplicata

secondary oligolege

4.

Andrena (Callandrena) haynesi

primary oligolege

5.

Andrena (Callandrena) helianthi

primary oligolege

6.

Andrena (Callandrena) pecosana

secondary oligolege

7.

Andrena (Callandrena) simplex

secondary oligolege

8.

Andrena (Cnemidandrena) chromotricha

secondary oligolege

9.

Andrena (Cnemidandrena) peckhami

primary oligolege

10.

Andrena (Euandrena) lawrencei

casual polylege

11.

Andrena (Leucandrena) recta

casual polylege

12.

Andrena (Micrandrena) microchlora

casual polylege

13.

Andrena (Plastandrena) prunorum

casual polylege

14.

Andrena (Simandrena) pallidifovea

secondary oligolege

15.

Protandrena bancrofti

casual polylege

16.

Protandrena mexicanorum

nectar visitor

17.

Pseudopanurgus aethiops

primary oligolege

18.

Pseudopanurgus rugosus

primary oligolege

19.

Pterosarus albitarsis

secondary oligolege

20.

Pterosarus expallidus

nectar visitor

21.

Pterosarus helianthi

primary oligolege

22.

Pterosarus innuptus

primary oligolege

23.

Pterosarus labrosiformis labrosiformis

secondary oligolege

24.

Pterosarus labrosus

secondary oligolege

25.

Pterosarus leucopterus

nectar visitor

26.

Pterosarus occiduus

secondary oligolege

27.

Pterosarus perlaevis

secondary oligolege

28.

Pterosarus piercei piercei

primary oligolege

29.

Pterosarus renimaculatus

secondary oligolege

30.

Pterosarus rudbeckiae

secondary oligolege

31.

Pterosarus simulans

primary oligolege

32.

Pterosarus solidaginis

secondary oligolege

33.

Pterosarus stigmalis

secondary oligolege

34.

Metapsaenythia abdominalis abdominalis

nectar visitor

35.

Nomadopsis (Micronomadopsis) helianthi

nectar visitor

36.

Calliopsis (Calliopsis) andreniformis

nectar visitor

37.

Calliopsis (Calliopsima) crypta

secondary oligolege

38.

Calliopsis (Calliopsima) pectidis

secondary oligolege

39.

Calliopsis (Calliopsima) pugionis

secondary oligolege

40.

Calliopsis (Calliopsima) rozeni

secondary oligolege

41.

Perdita (Cockerellia) albipennis

primary oligolege

42.

Perdita (Cockerellia) bequaerti

primary oligolege

43.

Perdita (Cockerellia) lingualis

primary oligolege

44.

Perdita (Cockerellia) scopata

primary oligolege

45.

Perdita (Cockerellia) tricincta

primary oligolege

46.

Perdita (Cockerellia) verbesinae

secondary oligolege

47.

Perdita (Hexaperdita) alexi

secondary oligolege

48.

Perdita (Hexaperdita) ignota crawfordi

secondary oligolege

49.

Perdita (Hexaperdita) pratti

secondary oligolege

50.

Perdita (Hexaperdita) xanthisma

secondary oligolege

51.

Perdita (Pentaperdita) nigroviridis

secondary oligolege

52.

Perdita (Perdita) affinis

secondary oligolege

53.

Perdita (Perdita) aridella

secondary oligolege

54.

Perdita (Perdita) bruneri

secondary oligolege

55.

Perdita (Perdita) dolichocephala

secondary oligolege

56.

Perdita (Perdita) fallax

secondary oligolege

57.

Perdita (Perdita) gerhardi dallasiana

casual polylege

58.

Perdita (Perdita) laticincta

primary oligolege

59.

Perdita (Perdita) prionopsidis

secondary oligolege

60.

Perdita (Perdita) swenki

secondary oligolege

61.

Perdita (Perdita) tridentata

primary oligolege

62.

Perdita (Perdita) zebrata zebrata

nectar visitor

63.

Perdita (Pygoperdita) nebrascensis

secondary oligolege

HALICTIDAE

1.

Dufourea (Halictoides) marginata

primary oligolege

2.

Nomia (Curvinomia) angustitibialis

nectar visitor

3.

Nomia (Curvinomia) fedorensis

nectar visitor

4.

Nomia (Curvinomia) mesillensis

nectar visitor

5.

Nomia (Acunomia) nortoni nortoni

casual polylege

6.

Nomia (Acunomia) melanderi

nectar visitor

7.

Nomia (Epinomia) micheneri

primary oligolege

8.

Nomia (Epinomia) nevadensis angelesia

nectar visitor

9.

Nomia (Epinomia) nevadensis arizonensis

nectar visitor

10.

Nomia (Epinomia) triangulifera

primary oligolege

11.

Nomia (Dieunomia) apacha

secondary oligolege

12.

Nomia (Dieunomia) bolliana

secondary oligolege

13.

Nomia (Dieunomia) heteropoda

primary oligolege

14.

Augochloropsis (Paraugochloropsis) metallica metallica

casual polylege

15.

Augochloropsis (Paraugochloropsis) sumptuosa

casual polylege

16.

Augochlora (Augochlora) pura

casual polylege

17.

Augochlorella aurata

casual polylege

18.

Augochlorella bracteata

casual polylege

19.

Augochlorella gratiosa

casual polylege

20.

Augochlorella persimilis

casual polylege

21.

Augochlorella pomoniella

nectar visitor

22.

Augochlorella striata

casual polylege

23.

Agapostemon angelicus

casual polylege

24.

Agapostemon cockerelli

casual polylege

25.

Agapostemon femoratus

casual polylege

26.

Agapostemon melliventris

casual polylege

27.

Agapostemon sericeus

casual polylege

28.

Agapostemon splendens

casual polylege

29.

Agapostemon texanus

regular polylege

30.

Agapostemon tyleri

casual polylege

31.

Agapostemon virescens

casual polylege

32.

Halictus (Halictus) farinosus

casual polylege

33.

Halictus (Halictus) ligatus

regular polylege

34.

Halictus (Halictus) rubicundus

casual polylege

35.

Halictus (Seladonia) confusus

casual polylege

36.

Halictus (Seladonia) tripartitus

casual polylege

37.

Lasioglossum coriaceum

casual polylege

38.

Lasioglossum mellipes

nectar visitor

39.

Lasioglossum sisymbrii

casual polylege

40.

Lasioglossum titusi

casual polylege

41.

Evylaeus aberrans

nectar visitor

42.

Evylaeus amicus

nectar visitor

43.

Evylaeus argemonis

nectar visitor

44.

Evylaeus kincaidii

casual polylege

45.

Evylaeus pectinatus

nectar visitor

46.

Evylaeus pectoralis

casual polylege

47.

Evylaeus pectoraloides

casual polylege

48.

Dialictus albipennis

nectar visitor

49.

Dialictus clematisellus

nectar visitor

50.

Dialictus illinoensis

nectar visitor

51.

Dialictus imitatus

casual polylege

52.

Dialictus impavidus

nectar visitor

53.

Dialictus incompletus

casual polylege

54.

Dialictus marinus

casual polylege

55.

Dialictus microlepoides

nectar visitor

56.

Dialictus nevadensis

casual polylege

57.

Dialictus oleosus

nectar visitor

58.

Dialictus pilosus pilosus

casual polylege

59.

Dialictus pruinosiformis

casual polylege

60.

Dialictus punctatoventris

casual polylege

61.

Dialictus tegulariformis

casual polylege

62.

Dialictus veganus

casual polylege

63.

Dialictus versatus

casual polylege

64.

Dialictus zephyrus

casual polylege

65.

Sphecodes dichrous

cleptoparasite

MELITTIDAE

1.

Hesperapis (Panurgomia) arenicola

secondary oligolege

2.

Hesperapis (Panurgomia) carinata

primary oligolege

MEGACHILIDAE

1.

Lithurge (Lithurgopsis) gibbosus

nectar visitor

2.

Heteranthidium cordaticeps

primary oligolege

3.

Heteranthidium occidentale

primary oligolege

4.

Heteranthidium timberlakei

secondary oligolege

5.

Heteranthidium zebratum

primary oligolege

6.

Paranthidium (Paranthidium) jugatorium

secondary oligolege

7.

Anthidium (Anthidium) maculosum

nectar visitor

8.

Anthidium (Anthidium) paroselae

casual polylege

9.

Anthidium (Anthidium) porterae

nectar visitor

10.

Callanthidium illustre

casual polylege

11.

Dianthidium curvatum sayi

secondary oligolege

12.

Dianthidium dubium dilectum

casual polylege

13.

Dianthidium ulkei

casual polylege

14.

Anthidiellum notatum notatum

casual polylege

15.

Anthidiellum perplexum

casual polylege

16.

Dioxys aurifuscus

cleptoparasite

17.

Dioxys pomonae pomonae

cleptoparasite

18.

Heriades (Neotrypetes) variolosa variolosa

regular polylege

19.

Heriades (Physostetha) carinata

casual polylege

20.

Heriades (Physostetha) occidentalis

casual polylege

21.

Chelostomopsis rubifloris

casual polylege

22.

Hoplitis (Andronicus) cylindrica

casual polylege

23.

Hoplitis (Dasyosmia) biscutellae

nectar visitor

24.

Hoplitis (Alcidamea) pilosifrons

casual polylege

25.

Hoplitis (Alcidamea) producta

regular polylege

26.

Hoplitis (Alcidamea) sambuci

casual polylege

27.

Hoplitis (Alcidamea) truncata truncata

casual polylege

28.

Hoplitis (Robertsonella) simplex

casual polylege

29.

Anthocopa (Eremosmia) hemizoniae

secondary oligolege

30.

Ashmeadiella (Ashmeadiella) bucconis

secondary oligolege

31.

Ashmeadiella (Ashmeadiella) California

secondary oligolege

32.

Ashmeadiella (Ashmeadiella) foveata

casual polylege

33.

Ashmeadiella (Ashmeadiella) titusi

nectar visitor

34.

Osmia (Chalcosmia) coloradensis

secondary oligolege

35.

Osmia (Chalcosmia) texana

secondary oligolege

36.

Osmia (Cephalosmia) californica

secondary oligolege

37.

Osmia (Cephalosmia) grinnelli

casual polylege

38.

Osmia (Cephalosmia) montana

secondary oligolege

39.

Osmia (Nothosmia) marginata

casual polylege

40.

Osmia (Chenosmia) clarescens

casual polylege

41.

Osmia (Diceratosmia) subfasciata subfasciata

casual polylege

42.

Megachile (Litomegachile) brevis

regular polylege

43.

Megachile (Litomegachile) coquilleitt

casual polylege

44.

Megachile (Litomegachile) gentilis

nectar visitor

45.

Megachile (Litomegachile) lippiae

casual polylege

46.

Megachile (Litomegachile) mendica

casual polylege

47.

Megachile (Litomegachile) texana

casual polylege

48.

Megachile (Cressoniella) zapoteca

casual polylege

49.

Megachile (Megachile) centuncularis

casual polylege

50.

Megachile (Megachile) inermis

casual polylege

51.

Megachile (Megachile) montivaga

regular polylege

52.

Megachile (Megachile) relativa

casual polylege

53.

Megachile (Eutricharaea) concinna

nectar visitor

54.

Megachile (Delomegachile) gemula gemula

casual polylege

55.

Megachile (Delomegachile) melanophaea

casual polylege

56.

Megachile (Phaenosarus) agustini

casual polylege

57.

Megachile (Phaenosarus) fortis

regular polylege

58.

Megachile (Derotropis) xerophila

secondary oligolege

59.

Megachile (Xeromegachile) alata

secondary oligolege

60.

Megachile (Xeromegachile) casadae

casual polylege

61.

Megachile (Xeromegachile) coloradensis

nectar visitor

62.

Megachile (Xeromegachile) dakotensis

secondary oligolege

63.

Megachile (Xeromegachile) manifesta

secondary oligolege

64.

Megachile (Xeromegachile) nevadensis

nectar visitor

65.

Megachile (Argyropile) mucorosa

casual polylege

66.

Megachile (Argyropile) parallela

primary oligolege

67.

Megachile (Argyropile) sabinensis

secondary oligolege

68.

Megachile (Argyropile) townsendiana

casual oligolege

69.

Megachile (Xanthosarus) dentitarsus

casual polylege

70.

Megachile (Xanthosarus) latimanus

casual polylege

71.

Megachile (Xanthosarus) perihirta

regular polylege

72.

Megachile (Leptorachis) petulans

casual polylege

73.

Megachile (Pseudocentron) pruina pruina

casual polylege

74.

Megachile (Pseudocentron) sidalceae

nectar visitor

75.

Megachile (Acentron) albitarsis

casual polylege

76.

Megachile (Melanosarus) xylocopoides

casual polylege

77.

Megachile (Sayapis) fidelis

regular polylege

78.

Megachile (Sayapis) frugalis

casual polylege

79.

Megachile (Sayapis) helianthi

secondary oligolege

80.

Megachile (Sayapis) inimica

secondary oligolege

81.

Megachile (Sayapis) policaris

regular polylege

82.

Megachile (Sayapis) pugnata pugnata

secondary oligolege

83.

Chalicodoma (Chelostomoides) angelarum

casual polylege

84.

Chalicodoma (Chelostomoides) campanulae campanulae

casual polylege

85.

Chalicodoma (Chelostomoides) chilopsidis

nectar visitor

86.

Chalicodoma (Chelostomoides) occidentally

nectar visitor

87.

Chalicodoma (Chelostomoides) odontostoma

nectar visitor

88.

Chalicodoma (Chelostomoides) spinotulata

nectar visitor

89.

Chalicodoma (Chelostomoides) subexilis

nectar visitor

90.

Coelioxys (Coelioxys) sodalis

cleptoparasite

91.

Coelioxys (Boreocoelioxys) banksi

cleptoparasite

92.

Coelioxys (Boreocoelioxys) moesta

cleptoparasite

93.

Coelioxys (Boreocoelioxys) novomexicana

cleptoparasite

94.

Coelioxys (Boreocoelioxys) octodentata

cleptoparasite

95.

Coelioxys (Boreocoelioxys) rufitarsus

cleptoparasite

96.

Coelioxys (Boreocoelioxys) sayi

cleptoparasite

97.

Coelioxys (Xerocoelioxys) edita

cleptoparasite

98.

Coelioxys (Schizocoelioxys) funeraria

cleptoparasite

99.

Coelioxys (Synocoelioxys) alternata

cleptoparasite

100.

Coelioxys (Synocoelioxys) texana

cleptoparasite

101.

Coelioxys (Neocoelioxys) menthae

cleptoparasite

102.

Coelioxys (Glyptocoelioxys) germana

cleptoparasite

103.

Coelioxys (Cyrtocoelioxys) modesta

cleptoparasite

ANTHOPHORIDAE

1.

Neolarra helianthi

cleptoparasite

2.

Neolarra verbesinae

cleptoparasite

3.

Holcopasites heliopsis

cleptoparasite

4.

Epeolus autumnalis

cleptoparasite

5.

Epeolus bifasciatus

cleptoparasite

6.

Epeolus compactus

cleptoparasite

7.

Epeolus pusillus

cleptoparasite

8.

Triepeolus concavus

cleptoparasite

9.

Triepeolus cressonii cressonii

cleptoparasite

10.

Triepeolus cyclurus

cleptoparasite

11.

Triepeolus dacotensis

cleptoparasite

12.

Triepeolus donatus

cleptoparasite

13.

Triepeolus helianthi

cleptoparasite

14.

Triepeolus lestes

cleptoparasite

15.

Triepeolus lineatulus

cleptoparasite

16.

Triepeolus lunatus

cleptoparasite

17.

Triepeolus nevadensis

cleptoparasite

18.

Triepeolus norae

cleptoparasite

19.

Triepeolus pectoralis

cleptoparasite

20.

Triepeolus rectangularis

cleptoparasite

21.

Triepeolus remigatus

cleptoparasite

22.

Triepeolus simplex

cleptoparasite

23.

Triepeolus subnitens

cleptoparasite

24.

Triepeolus texanus

cleptoparasite

25.

Triepeolus trichopygus

cleptoparasite

26.

Nomada (Heminomada) graenicheri

cleptoparasite

27.

Nomada (Pachynomada) vincta vincta

cleptoparasite

28.

Nomada (Micronomada) garciana

cleptoparasite

29.

Nomada (Micronomada) gutierreziae

cleptoparasite

30.

Nomada (Micronomada) melanoptera

cleptoparasite

31.

Nomada (Micronomada) texana

cleptoparasite

32.

Nomada (Micronomada) vierecki

cleptoparasite

33.

Paranomada velutina

cleptoparasite

34.

Exomalopsis (Phanomalopsis) solani

casual polylege

35.

Exomalopsis (Phanomalopsis) solidaginis

casual polylege

36.

Exomalopsis (Anthophorisca) morgani

casual polylege

37.

Exomalopsis (Anthophorisca) pygmaea

primary oligolege

38.

Ptilothrix sp. near sumichrasti

nectar visitor

39.

Diadasia afflicta afflicta

nectar visitor

40.

Diadasia australis

nectar visitor

41.

Diadasia bituberculata

nectar visitor

42.

Diadasia diminuta

nectar visitor

43.

Diadasia enavata

primary oligolege

44.

Diadasia ochracea

nectar visitor

45.

Diadasia rinconis rinconis

nectar visitor

46.

Synhalonia actuosa

casual polylege

47.

Synhalonia edwardsii

casual polylege

48.

Syntrichalonia exquisita

secondary oligolege

49.

Svastra (Brachymelissodes) cressonii

casual polylege

50.

Svastra (Epimelissodes) aegis

secondary oligolege

51.

Svastra (Epimelissodes) atripes atripes

casual polylege

52.

Svastra (Epimelissodes) grandissima

nectar visitor

53.

Svastra (Epimelissodes) helianthelli

primary oligolege

54.

Svastra (Epimelissodes) machaerantherae

primary oligolege

55.

Svastra (Epimelissodes) obliqua

primary oligolege

56.

Svastra (Epimelissodes) petulca

secondary oligolege

57.

Svastra (Epimelissodes) sabinensis

nectar visitor

58.

Svastra (Epimelissodes) sila

nectar visitor

59.

Svastra (Epimelissodes) texana

secondary oligolege

60.

Xenoglossodes bishoppi

nectar visitor

61.

Xenoglossodes eriocarpi

nectar visitor

62.

Xenoglossodes helianthorum

nectar visitor

63.

Peponapis (Peponapis) pruinosa

nectar visitor

64.

Melissodes (Melissodes) bimaculata bimaculata

regular polylege

65.

Melissodes (Melissodes) communis communis

regular polylege

66.

Melissodes (Melissodes) comptoides

regular polylege

67.

Melissodes (Melissodes) paroselae

casual polylege

68.

Melissodes (Melissodes) tepida

casual polylege

69.

Melissodes (Melissodes) tessellata

regular polylege

70.

Melissodes (Melissodes) thelypodii thelypodii

casual polylege

71.

Melissodes (Apomelissodes) fimbriata

nectar visitor

72.

Melissodes (Heliomelissodes) desponsa

casual polylege

73.

Melissodes (Heliomelissodes) rivalis

secondary oligolege

74.

Melissodes (Tachymelissodes) opuntiella

casual polylege

75.

Melissodes (Tachymelissodes) sonorensis

regular polylege

76.

Melissodes (Eumelissodes) agilis

primary oligolege

77.

Melissodes (Eumelissodes) appressa

secondary oligolege

78.

Melissodes (Eumelissodes) bidentis

secondary oligolege

79.

Melissodes (Eumelissodes) bimatris

secondary oligolege

80.

Melissodes (Eumelissodes) boltoniae

regular polylege

81.

Melissodes (Eumelissodes) brevipyga

secondary oligolege

82.

Melissodes (Eumelissodes) confusa

secondary oligolege

83.

Melissodes (Eumelissodes) coreopsis

primary oligolege

84.

Melissodes (Eumelissodes) denticulata

casual polylege

85.

Melissodes (Eumelissodes) dentiventris

secondary oligolege

86.

Melissodes (Eumelissodes) gelida

primary oligolege

87.

Melissodes (Eumelissodes) grindeliae

secondary oligolege

88.

Melissodes (Eumelissodes) humilior

secondary oligolege

89.

Melissodes (Eumelissodes) illata

secondary oligolege

90.

Melissodes (Eumelissodes) limbus

secondary oligolege

91.

Melissodes (Eumelissodes) lutulenta

secondary oligolege

92.

Melissodes (Eumelissodes) menuachus

secondary oligolege

93.

Melissodes (Eumelissodes) microsticta

secondary oligolege

94.

Melissodes (Eumelissodes) montana

secondary oligolege

95.

Melissodes (Eumelissodes) nivea

secondary oligolege

96.

Melissodes (Eumelissodes) pallidisignata

secondary oligolege

97.

Melissodes (Eumelissodes) paulula

secondary oligolege

98.

Melissodes (Eumelissodes) perlusa

primary oligolege

99.

Melissodes (Eumelissodes) robustior

primary oligolege

100.

Melissodes (Eumelissodes) rustica

secondary oligolege

101.

Melissodes (Eumelissodes) snowii

secondary oligolege

102.

Melissodes (Eumelissodes) subagilis

secondary oligolege

103.

Melissodes (Eumelissodes) subillata

secondary oligolege

104.

Melissodes (Eumelissodes) submenuacha

secondary oligolege

105.

Melissodes (Eumelissodes) tincta

secondary oligolege

106.

Melissodes (Eumelissodes) trinodis

primary oligolege

107.

Melissodes (Eumelissodes) tristis

casual polylege

108.

Melissodes (Eumelissodes) velutina

nectar visitor

109.

Melissodes (Eumelissodes) verbesinarum

nectar visitor

110.

Melissodes (Eumelissodes) vernoniae

secondary oligolegi

111.

Melissodes (Eumelissodes) wheeleri

secondary oligolegi

112.

Melissodes (Callimelissodes) coloradensis

primary oligolege

113.

Melissodes (Callimelissodes) composita

secondary oligolegi

114.

Melissodes (Callimelissodes) glenwoodensis

secondary oligolegi

115.

Melissodes (Callimelissodes) lupina

secondary oligolegi

116.

Melissodes (Callimelissodes) lustra

secondary oligolegi

117.

Melissodes (Callimelissodes) plumosa

nectar visitor

118.

Melissodes (Callimelissodes) stearnsi

secondary oligolegi

119.

Martinapis (Martinapis) occidentalis

nectar visitor

120.

Anthophora (Anthophora) montana

casual polylege

121.

Anthophora (Anthophora) smithii

nectar visitor

122.

Anthophora (Anthophora) urbana urbana

nectar visitor

123.

Anthophora (Anthophora) walshii

nectar visitor

124.

Anthophora (Micranthophora) curta

casual polylege

125.

Anthophora (Micranthophora) maculifrons

casual polylege

126.

Anthophora (Micranthophora) peritomae

casual polylege

127.

Xeromelecta (Melectomorpha) californica

cleptoparasite

128.

Xeromelecta (Melectomorpha) interrupta

cleptoparasite

129.

Centris (Paracentris) atripes

nectar visitor

130.

Centris (Paracentris) caesalpiniae

nectar visitor

131.

Ceratina (Zadontomerus) acantha

casual polylege

132.

Ceratina (Zadontomerus) apacheorum

casual polylege

133.

Ceratina (Zadontomerus) calcarata

casual polylege

134.

Ceratina (Zadontomerus) dupla

casual polylege

135.

Ceratina (Zadontomerus) micheneri

casual polylege

136.

Ceratina (Zadontomerus) nanula

casual polylege

137.

Ceratina (Zadontomerus) neomexicana

casual polylege

138.

Ceratina (Zadontomerus) pacifica

casual polylege

139.

Ceratina (Zadontomerus) punctigena

casual polylege

140.

Ceratina (Zadontomerus) shinnersi

casual polylege

141.

Ceratina (Zadontomerus) strenua

casual polylege

142.

Ceratina (Zadontomerus) tejonensis

nectar visitor

143.

Ceratina (Euceratina) dallatorreana

nectar visitor

144.

Xylocopa (Xylocopoides) californica

nectar visitor

APIDAE

1.

Bombus (Bombus) affinis

casual polylege

2.

Bombus (Bombus) terricola

casual polylege

3.

Bombus (Fraternobombus) fraternus

regular polylege

4.

Bombus (Bombias) nevadensis

regular polylege

5.

Bombus (Separatobombus) griseocollis

regular polylege

6.

Bombus (Separatobombus) morrisoni

regular polylege

7.

Bombus (Crotchiibombus) crotchii

casual polylege

8.

Bombus (Cullumanobombus) rufocinctus

casual polylege

9.

Bombus (Pyrobombus) bimaculatus

casual polylege

10.

Bombus (Pyrobombus) centralis

casual polylege

11.

Bombus (Pyrobombus) huntii

casual polylege

12.

Bombus (Pyrobombus) impatiens

casual polylege

13.

Bombus (Pyrobombus) ternarius

casual polylege

14.

Bombus (Pyrobombus) vagans vagans

casual polylege

15.

Bombus (Subterraneobombus) appositus

casual polylege

16.

Bombus (Subterraneobombus) borealis

casual polylege

17.

Bombus (Fervidobombus) californicus

casual polylege

18.

Bombus (Fervidobombus) fervidus fervidus

casual polylege

19.

Bombus (Fervidobombus) pennsylvanicus pennsylvanicus

regular polylege

20.

Bombus (Fervidobombus) pennsylvanicus sonorus

regular polylege

21.

Psithyrus ashtoni

social parasite

22.

Psithyrus citrinus

social parasite

23.

Psithyrus insularis

social parasite

24.

Psithyrus variabilis

social parasite

25.

Apis mellifera

casual polylege

Family COLLETIDAE

Although this family is represented in America north of Mexico by more than 150 species, only a relatively few species of the genus Colletes are known to visit the flowers of Helianthus. None of the more than 50 species of Hylaeus present in North America has been observed at these flowers. It thus appears that the members of this family are relatively less important as pollinators of Helianthus than those of several other families of bees.

Genus Colletes Latreille

This is a large genus of bees that is found throughout much of the world except Australia. More than 90 species are known to occur in America north of Mexico (Hurd, 1979) and doubtless other species than those discussed below will be found at the flowers of Helianthus. Even so, it seems most unlikely that any additional species will be discovered that have established an oligolectic relationship with this genus of plants.

Nine species of this genus have been found at the flowers of Helianthus. Of these, four were seeking nectar only, four have been observed to have established the role of oligoleges secondarily associated with Helianthus, and one species (Colletes fulgidus) only occasionally takes pollen from the flowers of Helianthus and thus is regarded by us as a casual polylege of this plant.

1. Colletes americanus Cresson

This species has been reported as a visitor to various Compositae, including nectar-sipping at Helianthus divaricatus in Illinois by Robertson (1929). It occurs in southern Canada (Quebec and Manitoba) and the United States, east of the Rocky Mountains to the Atlantic seaboard (Hurd, 1979). Stephen (1954) reports it flying during the fall (August–October) and Mitchell (1960) comments that in Florida males have been collected as early as May.

2. Colletes compactus Cresson

The female of Colletes compactus proper, an oligolege of the Compositae secondarily associated with Helianthus, has been recorded by Robertson (1929) collecting pollen from the flowers of Helianthus tuberosus and other Compositae in Illinois. This subspecies ranges from Nova Scotia to Georgia, west to Wisconsin, Missouri, Colorado, and Arizona (Hurd, 1979). It is primarily autumnal in flight (Stephen, 1954), although Mitchell (1960) notes that in the eastern United States it flies from mid-July until mid-November.

3. Colletes fulgidus Swenk

The nominate subspecies ranges from British Columbia, Alberta, Montana, and South Dakota, south to California, Nevada, northern Utah, Colorado, Wyoming, and Texas (Hurd, 1979). It flies from May to October, but is most abundant in the summer months (Stephen, 1954). It has been recorded from flowers of a number of Compositae, but apparently not previously from Helianthus and thus is regarded by us as a casual polylege of H. annuus.

We have taken it on Helianthus as follows:

CALIFORNIA.—TULARE COUNTY: Dinuba, 5.5 mi S, 7 Oct 75, H. annuus, 0110-01129, 1P (EGL, JML, AEM, MMM).

4. Colletes louisae Cockerell

This species ranges through the southwestern deserts from western Texas and adjacent northern Mexico to the Mojave and Colorado Deserts of California and Baja California Norte (Hurd and Linsley, 1975). It is principally an autumnal species visiting Compositae but has a spring flight period in which the females visit desert shrubs as well as composites (Timberlake, 1943). Its relationship with Helianthus appears to be that of a nectar visitor (Table C).

5. Colletes perileucus Cockerell

This species is apparently active in the spring and early summer. It has been collected primarily at the flowers of Prosopis and has been recorded from southern California (Panamint Mountains), Arizona (Cochise County), Texas (Big Bend Park), and Mexico (Baja California and Sonora) by Stephen (1954). It appears to visit the flowers of Helianthus only for nectar (Table D).

6. Colletes rufocinctus Cockerell

Stevens (1950) has recorded this species from the flowers of Helianthus petiolaris, as well as from other Compositae in North Dakota. It ranges from Minnesota west to Alberta, south to South Dakota, Colorado, and Arizona. Stephen (1954) notes that the species is known to be on the wing from 3 August to 15 September. Its relationship with Helianthus appears to be that of a secondary oligolege (Table C) since it is known to visit other Compositae, especially Aster, Grindelia, Solidago, and Taraxacum.

7. Colletes simulans armatus Patton

This subspecies is known to occur on sunflowers in North Dakota (Stevens, 1950) and apparently is an oligolege of autumnal flowering Compositae secondarily associated with Helianthus. It ranges from southern Canada (Alberta, Manitoba, Quebec, and Nova Scotia), south into the northern Great Plains states and south to Georgia in the eastern United States (Hurd, 1979). According to Mitchell (1960), this subspecies flies from May to November, and is found in abundance throughout the northern Great Plains to the Atlantic seaboard (Stephen, 1954).

8. Colletes susannae Swenk

Colletes susannae, an apparent oligolege of the Compositae secondarily associated with Helianthus, visits H. petiolaris in North Dakota (Stevens, 1950). It occurs from Illinois, Wisconsin, and Manitoba west to Colorado and Alberta, flying from July 1 to mid-August (Mitchell, 1960).

9. Colletes wootoni Cockerell

Colletes wootoni is a common polylectic species, ranging from southern Texas into Arizona. Stephen (1954) lists a wide range of flower records, not including Helianthus. Hurd and Linsley (1975) found it to be a regular visitor to Larrea tridentata and it apparently only occasionally seeks nectar at the flowers of Helianthus (Tables C, D).

Family OXAEIDAE

This is a small family of New World bees that as a group are centered in the tropics (Hurd and Linsley, 1976). Insofar as known, the intrafloral relationships of these bees suggest a rather narrow dependence upon relatively few sources of pollen including only certain genera within the plant families Leguminosae, Solanaceae, and Zygophyllaceae. Both males and females, however, take nectar from a comparatively wide variety of plants since the flowers of some of their preferred pollen sources produce little or no nectar and large quantities of nectar are required to meet the bioenergetic requirements of these fast-flying bees (Hurd and Linsley, 1976:1).

Two genera of these bees, Mesoxaea and Protoxaea, are represented within the range of Helianthus in North America but only a single species of Protoxaea has been taken at the flowers of this plant.

Genus Protoxaea Cockerell and Porter

This genus is composed of three species that are found in North America.

1. Protoxaea gloriosa (Fox)

The females of this species are narrow polyleges of certain Leguminosae, Zygophyllaceae, and Solanaceae but both sexes visit a variety of plants for nectar. Hurd and Linsley (1976:9) have recorded the male at flowers of Helianthus annuus, but this is no doubt a rare occurrence and an unimportant factor in the pollination ecology of this plant.

Family ANDRENIDAE

This is the largest family of bees in North America, containing over 1200 species currently assigned to 15 genera (Hurd, 1979). Most of the species, however, belong to the genera Andrena and Perdita, each of which includes more than 500 species in America north of Mexico. No less than eight of the 15 genera contain species that are involved in the pollination of Helianthus, viz., Andrena (14), Calliopsis (5), Metapsaenythia (1), Nomadopsis (1), Perdita (23), Protandrena (2), Pseudopanurgus (2), and Pterosarus (16). A large percentage of these species are oligoleges of the Compositae either primarily or secondarily associated with Helianthus. Thus these species are considered by us as among the most important pollinators of sunflowers.

Genus Andrena Fabricius

Although species of six subgenera of this genus have been found at the flowers of Helianthus, most of the species (7) belong to the subgenus Callandrena whose species mostly obtain their pollen from the flowers of Compositae. Of these, four are primarily dependent upon the pollen of Helianthus while three additional ones are secondarily so dependent. Two species of the subgenus Cnemidandrena are oligoleges of Compositae, one (A. peckhami) being primarily associated with Helianthus and the other (A. chromotricha) is secondarily associated with Helianthus. A. (Simandrena) pallidifovea is similarly secondarily associated with Helianthus, while the remaining three species, A. lawrencei, A. microchlora, and A. prunorum each belonging to different subgenera (Euandrena, Micrandrena, and Plastandrena) are casual polyleges of Helianthus.

1. Andrena (Callandrena) accepta Viereck

FIGURE 2

This is an oligolege of Compositae, with a primary preference for Helianthus. Of 219 females bearing flower records examined by LaBerge (1967), 218 were taken from members of this plant family and of these, 194 were from Helianthus, including H. angustifolius, H. giganteus, H. maximiliani, H. petiolaris, H. salicifolius, and H. scaberrimus. Robertson (1894, 1898) recorded A. accepta from five species of sunflower in Illinois, including H. mollis. Later (1929) he provided additional data, listing the female taking nectar from H. annuus, both sexes at H. divaricatus (the females frequent and taking pollen), the female taking pollen from H. rigidus and nectar from H. strumosus, and both sexes abundant at H. tuberosus (the females gathering pollen). Cockerell (1914b) reported this bee at H. lenticularis in New Mexico, Michener (1947) from H. radula in Mississippi, and Bohart et al. (1950) and Rozen (1973) from H. annuus in Utah and Arizona, respectively. The species is widespread and ranges from New Jersey south to South Carolina, west to Alberta, eastern Oregon, eastern California (Owens Valley), Arizona, zona, and southward into Chihuahua, Mexico. It is absent from the Sonoran Desert. Graenicher (1909) did not find it on Helianthus in Wisconsin, nor did Stevens (1949a) in North Dakota.

FIGURE 2.—Distribution of Andrena (Callandrena) accepta Viereck.

For a discussion of the biology of Andrena accepta, see Rozen (1973). Details of collections of this species are presented in Table A–E, G.

Additional records are as follows:

ARIZONA.—COCHISE COUNTY: Cochise, 8 Sep 75, H. annuus, 0800–0859 1P, 1N (EGL, JML). SANTA CRUZ COUNTY: Sonoita 10 mi E, 7 Sep 77, H. petiolaris, 0830–0859, 1P (EGL, JML).

CALIFORNIA.—INYO COUNTY: Big Pine, 28 Aug 77, H. annuus, 0800–0829, 3P (EGL, JML).

2. Andrena (Callandrena) aliciae Robertson

This species, an oligolege of the Compositae primarily associated with Helianthus, was reported (Robertson, 1894 and 1929) as taking pollen from Helianthus tuberosus in Illinois and from H. strumosus in Wisconsin (Graenicher, 1909) as well as nectar from H. giganteus. LaBerge (1967) included Helianthus sp., H. angustifolius, H. divaricatus, H. giganteus, H. microcephalus, H. strumosus, and H. tuberosus among his flower records for A. aliciae. Of 53 specimens bearing floral data examined by him, 28, representing eight collections, were from Helianthus. The range extends from New York south to Georgia and west to Minnesota, Nebraska, and Kansas.

3. Andrena (Callandrena) duplicata Mitchell

LaBerge (1967) recorded this species from Helianthus sp., H. divaricatus, H. grosseserratus, Bidens coronata, and Solidago sp. He lists it from New Jersey, North Carolina, Ohio, Illinois and Missouri. It is apparently an oligolege of the Compositae, secondarily associated with Helianthus.

4. Andrena (Callandrena) haynesi Viereck and Cockerell

Viereck and Cockerell (1914) described this species from a female taken on Helianthus sp. in War Bonnet Canyon, Sioux County, Nebraska, in June (J. C. Crawford, collector), and subsequently, Cockerell (1923) recorded a female from H. petiolaris at Xenia, Colorado. LaBerge (1967), regards it as an oligolege of Helianthus and reports that of 43 collections (74 females and 61 males) with floral data, 42 (72 females and 52 males) were from some species of this genus, mostly H. petiolaris. Andrena haynesi ranges from Alberta and North Dakota, south through Wyoming and Colorado to Texas. It flies primarily in July and August.

5. Andrena (Callandrena) helianthi Robertson

This species is an oligolege of the Compositae primarily associated with Helianthus. It was recorded taking nectar and pollen from Helianthus grosseserratus in Illinois by Robertson (1894), who later (Robertson, 1922, 1929) listed it among the most regular visitors to sunflowers in Carlinville, Illinois, where he had found it at five of the “eight” local species of Helianthus, including males taking nectar from H. annuus and H. divaricatus, both sexes numerous at H. grosseserratus and H. rigidus (the females taking pollen from each), and the female taking nectar from H. tuberosus. In Wisconsin, Graenicher (1909) reported females gathering pollen from both H. giganteus and H. strumosus.

Cockerell (1898a,b, 1911, 1914b) recorded females at H. lenticularis in Sterling and Boulder, Colorado, H. annuus in Albuquerque, New Mexico, and H. annuus coronatus at Goodville, Colorado. He regarded it as the most important sunflower bee in Colorado and Stevens (1949a) stated that it was a common sunflower bee all over the state of North Dakota, reporting only single specimens from Grindelia and two species of Solidago. LaBerge (1967) provided a summary of floral records from specimens examined by him. These included 234 females and 130 males, of which 215 and 119, respectively, were from some species of Helianthus. He listed H. sp., H. annuus, H. coloradensis, H. coronatus, H. divaricatus, H. giganteus, H. grosseserratus, H. maximiliani, H. petiolaris, H. rigidus, H. subrhomboideus, and H. tuberosus as flower hosts. In California, Moldenke and Neff (1974) recorded two males and four females from H. annuus in Siskiyou County, California.

A collection record of this species at a major sampling site is presented in Table A. A previously unpublished record is as follows:

ARIZONA.—APACHE COUNTY: Nutrioso 8 mi N, 16 Aug 64, H. annuus, 1 (C. D. Michener, collector; specimen at University of Kansas, Lawrence.)

6. Andrena (Callandrena) pecosana Cockerell

LaBerge (1967) lists Helianthus among the few known flower hosts for this species, all Compositae (Grindelia, Gutierrezia sarothrae, Heliopsis, and Viguiera annua). It occurs from Colorado and Utah to Arizona, New Mexico and south into Mexico (Chihuahua, Hidalgo, Jalisco, and Zacatecas). Collection records for this species at flowers of H. petiolaris may be found in Table A. It is evidently an oligolege of the Compositae secondarily associated with Helianthus.

7. Andrena (Callandrena) simplex Smith

This species is an oligolege of Compositae secondarily associated with Helianthus, preferring Solidago and Aster (LaBerge, 1967), but it has been taken on Helianthus tuberosus. It ranges from New Hampshire to North Carolina, west to Minnesota, Nebraska, and Kansas.

8. Andrena (Cnemidandrena) chromotricha Cockerell

This species, more commonly known as A. clypeonitens Cockerell, was recorded by Graenicher (1909) taking pollen from H. giganteus and H. strumosus in Wisconsin. Stevens (1949a), under the names A. clypeonitens and A. integra Smith, recorded females of what is presumed to be this species at the flowers of H. annuus, H. rigidus, and H. tuberosus and both sexes at H. maximiliani in North Dakota. Mitchell (1960) reported a female of A. recta Mitchell (declared a synonym of A. chromotricha herein, page 00) on H. annuus at Crookston, Minnesota, in July. Donovan (1977) reported females taking pollen and nectar from H. sp., H. maximiliani, and H. tuberosus. Andrena chromotricha has been recorded from southern Canada (Ontario and Manitoba) south into New York, Ohio, Iowa, and Nebraska and west to Colorado, Utah, and Arizona. It appears to be an oligolege of the Compositae, but only secondarily associated with Helianthus.

9. Andrena (Cnemidandrena) peckhami Cockerell

Andrena peckhami was stated by Graenicher (1910b) to be oligolectic on Compositae, mostly sunflowers, in Wisconsin. Mitchell (1960) recorded Baptisia and Solidago as floral hosts, and Donovan (1977) listed pollen and nectar records from Cirsium arvense and Sonchus arvensis. The species ranges from southern Canada (Manitoba and Ontario) south to North Carolina and is an oligolege of the Compositae primarily associated with Helianthus.

10. Andrena (Euandrena) lawrencei Viereck and Cockerell

This is apparently a polylectic bee ranging from British Columbia to northern California, Utah, and Nebraska. Moldenke and Neff (1974) listed five females from Helianthus nuttallii in Eldorado County, California. LaBerge and Ribble (1975) also included Helianthus nuttallii among their flower records. It is apparently a casual polylege of Helianthus.

11. Andrena (Leucandrena) recta Mitchell

Mitchell (1960) reported a female of this species on Helianthus annuus at Crookston, Minnesota, in July. Since the completion of this study, one of us (LaBerge) has examined the holotype and finds that this is a synonym of Andrena (Cnemidandrena) chromotricha Cockerell (new synonymy).

12. Andrena (Micrandrena) microchlora Cockerell

Helianthus is included by Ribble (1968) among 17 genera of plants recorded on specimens of this species examined by him. The species is primarily confined to western North America and appears to be a casual polylege of Helianthus.

13. Andrena (Plastandrena) prunorum Cockerell

This is a polylectic species visiting a wide variety of plants for pollen and/or nectar. LaBerge (1969) listed 77 genera containing host plants, including Helianthus. It is primarily a western North American species, the nominate form ranging from southern British Columbia east to southern Saskatchewan and western North Dakota and south to Texas and Baja California; the subspecies A. p. sinaloa from Sinaloa and Baja California to southern Arizona. It is not regarded as an important pollinator of sunflowers since it appears to be only a casual polylege.

14. Andrena (Simandrena) pallidifovea (Viereck)

Andrena pallidifovea is a common Pacific Coast species ranging from Washington to Utah and southern California. According to Timberlake (1951) it is a late vernal species that collects pollen from Compositae, including Helianthus gracilentus in southern California. It thus appears to be an oligolege of the Compositae secondarily associated with Helianthus.

Genus Protandrena Cockerell

This is a North American genus of panurgine bees whose species were recently revised by Timberlake (1976). Only the two species discussed below have been taken at the flowers of Helianthus.

15. Protandrena bancrofti Dunning

Timberlake (1976) has reported a number of genera containing floral hosts for this polylectic species, including Helianthus. It ranges from Wyoming, North Dakota, and Illinois to Arizona, New Mexico, and Texas and south into central Mexico. It is apparently a casual polylege of Helianthus.

16. Protandrena mexicanorum (Cockerell)

Females have been recorded from flowers of Kallstroemia grandiflora and Solanum rostratum and males from Asclepias (Timberlake, 1955). Insofar as is known, this species visits the flowers of Helianthus for nectar only (Table D).

Genus Pseudopanurgus Cockerell

Two of the 12 species of this genus, which is found only in North America, are oligoleges of the Compositae primarily associated with Helianthus. Insofar as is known, the species of this genus, recently revised by Timberlake (1973), all visit flowers of the Compositae and it therefore seems likely that some additional species will be found to visit sunflowers.

17. Pseudopanurgus aethiops (Cresson)

FIGURE 3

This is the largest species of the genus and is common from Nebraska, Kansas, and Texas west to Utah and southeastern Arizona (Timberlake, 1973). The species is restricted to Compositae and is primarily found on Helianthus, but also collects pollen from Baileya, Encelia, Grindelia, Heterotheca, Melampodium, Prionopsis, and Verbesina. Cockerell (1898b) recorded it from Helianthus annuus at Albuquerque, New Mexico, and from Helianthus sp. in Mesilla Valley, New Mexico (Cockerell, 1898a, 1906b).

Collection records of P. aethiops at major sampling sites may be found in Table A–E. Additional data are as follows:

FIGURE 3.—Distribution of Pseudopanurgus aethiops (Cresson).

ARIZONA.—COCHISE COUNTY: Cochise, 8 Aug 75, H. annuus, 0830–0859, 1P (EGL, JML); Sonoita, 16 Aug 74, H. annuus, 0800–0829, 1P (EGL, JML); Sonoita 10 mi E, 7 Sep 77, H. petiolaris, 0830–0859, 1P (EGL, JML).

18. Pseudopanurgus rugosus Robertson

This species, which occurs from Maryland to Georgia and west to Illinois, Nebraska, Kansas, and Texas, is an oligolege of the Compositae primarily associated with Helianthus. It has been recorded taking pollen from flowers of Helianthus divaricatus and H. tuberosus, and nectar from H. mollis in Illinois by Robertson (1929), from H. radula in Mississippi by Michener (1947), and from H. annuus and H. petiolaris in Kansas by Timberlake (1973), who listed Heterotheca subaxillaris as “Helianthus subaxillaris.” Timberlake also provided Helianthus records from Georgia and Nebraska. In addition, Robertson (1929) reported the species at Heliopsis, Rudbeckia, and Silphium and in Kansas both sexes have also been taken at the flowers of Silphium speciosum (Timberlake, 1973).

Genus Pterosarus Timberlake

More than 40 species of this genus are known from North America and based upon current information all of the species are presumed to be oligoleges of the Compositae. Of those species associated with Helianthus, four are primarily attached, nine are secondarily so, and two are known only from males, thus making it impossible to assess the intrafloral relationships of these species. Almost certainly as additional field investigations are undertaken other species of this genus will be discovered at sunflowers.

It seems worthwhile to mention that Graenicher (1909, 1910b, 1935) did not find any species of this genus in his surveys of bees visiting Helianthus in Wisconsin.

19. Pterosarus albitarsis (Cresson)

In Illinois, females of this species were taken at flowers of Helianthus by Pearson (1933) and both sexes were reported by Robertson (1929) at H. divaricatus and H. mollis (the females collecting pollen). It ranges from Connecticut to Georgia and west to Illinois, Colorado, New Mexico, and Texas. In addition to the floral information presented above, the species also visits flowers of Asterericoides villosus, Brauneria pallida, B. purpurea, Coreopsis palmata, Lepachys pinnata, Rudbeckia hirta, R. laciniata, R. subtomentosa, Verbesina helianthoides (Robertson, 1929) and is thus apparently an oligolege of Compositae secondarily associated with Helianthus.

20. Pterosarus expallidus (Swenk and Cockerell)

This species was described by Swenk and Cockerell (1907b) from a male captured at Helianthus. The female remains unknown and thus we have only a nectar record for this species.

21. Pterosarus helianthi (Mitchell)

Mitchell (1960) described this species from a female captured on Helianthus annuus in Tippecanoe County, Indiana, in August. Subsequently the species has been collected at the flowers of Helianthus petiolaris in New Mexico (Table A) and at flowers of H. annuus in Arizona (Table E). It is evidently an oligolege of the Compositae primarily associated with Helianthus.

22. Pterosarus innuptus (Cockerell)

This species was reported from Helianthus annuus and H. petiolaris in Nebraska by Swenk and Cockerell (1907b), from H. annuus var. coronatus in Colorado by Cockerell (1914b), and from H. annuus, H. maximiliani, H. petiolaris, H. rigidus, H. rydbergii, H. strumosus, and H. tuberosus in North Dakota by Stevens (1919, 1950), where he considered it the most common species in the genus. This species ranges from Alberta, North Dakota, and Nebraska to Colorado, New Mexico, and Arizona and is considered by us to be an oligolege of the Compositae primarily associated with Helianthus.

23. Pterosarus labrosiformis labrosiformis (Robertson)

Both sexes of this subspecies have been recorded from Helianthus divaricatus and H. tuberosus (the females taking pollen), and the female taking nectar from H. strumosus, as well as other Heliantheae (Robertson, 1929). It has been reported from Illinois, North Carolina, and Georgia (Mitchell, 1960) and is apparently an oligolege of the Compositae secondarily associated with Helianthus.

24. Pterosarus labrosus (Robertson)

Both sexes were recorded by Robertson (1929) at Helianthus divaricatus and H. tuberosus in Illinois, the females taking pollen. He also reported the species at Rudbeckia triloba. Mitchell (1960) added R. lanceolata and Heliopsis to these records. The species occurs from New York to North Carolina and west to Minnesota and is evidently an oligolege of the Compositae secondarily associated with Helianthus.

25. Pterosarus leucopterus (Cockerell)

This species was described from six males collected at flowers of Helianthus petiolaris at Xenia, Colorado (Cockerell, 1923), and since the female remains unknown we are unable to assess its intrafloral relationships.

26. Pterosarus occiduus (Timberlake)

This species appears to be primarily associated with Haplopappus and Heterotheca, but a female has been recorded from Helianthus in Madera Canyon, Santa Rita Mountains, Arizona (Timberlake, 1967). The species is known only from Arizona (Cochise and Pima counties) and is apparently an oligolege of the Compositae secondarily associated with Helianthus.

27. Pterosarus perlaevis (Cockerell)

Recorded from flowers of Helianthus annuus at Las Cruces, New Mexico, by Cockerell (1898c), the species is known from Colorado, New Mexico, and Arizona. Pending further information on its floral relationships we have classed this species as a probable oligolege of the Compositae secondarily associated with Helianthus.

28. Pterosarus piercei piercei (Crawford)

This subspecies has been recorded from Helianthus annuus in Nebraska (Swenk and Cockerell, 1907b) and H. annuus, H. maximiliani, H. petiolaris, H. scaberrimus, H. tuberosus, Grindelia, and Solidago in North Dakota (Crawford, 1915, Stevens, 1919). It occurs from North Dakota and Nebraska to Colorado and New Mexico and is evidently an oligolege of the Compositae primarily associated with Helianthus.

29. Pterosarus renimaculatus (Cockerell)

Stevens (1919, 1950) recorded this species from flowers of Helianthus petiolaris, H. maximiliani, and other Compositae in North Dakota. It ranges from Wyoming, North Dakota, and Nebraska to Colorado, New Mexico, and Texas. From the published records it appears to be an oligolege of the Compositae secondarily associated with Helianthus.

30. Pterosarus rudbeckiae (Robertson)

Robertson (1929) included a male visiting Helianthus divaricatus among the flower records for this species, along with four species of Rudbeckia and Bidens aristosa. Mitchell (1960) has added Aster and Solidago. The species is known from Illinois and Wisconsin and is apparently an oligolege of the Compositae secondarily associated with Helianthus.

31. Pterosarus simulans (Swenk and Cockerell)

Swenk and Cockerell (1907b) described this species from examples of both sexes taken at Helianthus sp. and H. annuus in Nebraska. Subsequently, Crawford (1915) and Stevens (1919) recorded it from cultivated H. annuus, H. maximiliani, H. petiolaris, and Taraxacum in North Dakota. Thus the species appears to be an oligolege of the Compositae primarily associated with Helianthus.

32. Pterosarus solidaginis (Robertson)

Robertson (1929) recorded both sexes of this species from Helianthus grosseserratus (the females taking pollen), as well as a male at H. tuberosus. He also listed as hosts, species of Bidens, Boltonia, Rudbeckia, and Solidago. It ranges from northeast ern United States to Mississippi and Illinois and is apparently an oligolege of the Compositae secondarily associated with Helianthus.

33. Pterosarus stigmalis (Swenk and Cockerell)

Both sexes were recorded from Helianthus in Nebraska by Swenk and Cockerell (1907b) and subsequently reported by Cockerell (1923) at flowers of H. annuus lenticularis at Benkleman, Nebraska. The species visits other flowers of Compositae for nectar and pollen and is therefore apparently an oligolege of these plants with a secondary association with Helianthus.

Genus Metapsaenythia Timberlake

Included in this genus is a single species, Metapsaenythia abdominalis (Cresson), whose females collect pollen from flowers of Monarda (Labiatae), but visit these and a variety of other flowers, including Helianthus for nectar. The taxonomic relationships of this genus have been discussed by Timberlake (1973).

34. Metapsaenythia abdominalis abdominalis (Cresson)

This subspecies is common in Kansas and Texas. Females take pollen from Monarda, but specimens have also been recorded at other flowers, including Helianthus (Timberlake, 1969a).

Genus Nomadopsis Ashmead

Of the 39 currently recognized species of this North American genus, only a single female of one species has been found at the flowers of Helianthus. The species of this genus seem sufficiently well known (Rozen, 1958, 1959, 1963, 1967) that it seems unlikely that any will be found to depend on the pollen of these flowers.

35. Nomadopsis (Micronomadopsis) helianthi (Swenk and Cockerell)

A female of this species was collected on Helianthus in Nebraska (Swenk and Cockerell, 1907b) and it has also been taken on Helianthus in southeastern Arizona (Rozen, 1973). Nomadopsis helianthi occurs from Nebraska and New Mexico west to California and Mexico (Baja California) and appears to visit Helianthus and a variety of other flowers for nectar. The females are known to collect pollen from the flowers of Euphorbia, including E. albomarginata and E. polycarpa (Rozen, 1958), which appears to be its only pollen source. Since the completion of this study, Dr. J. G. Rozen, Jr. (pers. comm.) has informed us that he has observed this species collecting pollen from Lepidium in Arizona and New Mexico.

Genus Calliopsis Smith

This is a New World genus that occurs from southern Canada to Panama. All four subgenera recognized by Shinn (1967) are represented in America north of Mexico where 28 species have thus far been discovered. Of these, only the subgenera Calliopsis (1 species) and Calliopsima (4 species) have been found at sunflowers. The single species of the subgenus Calliopsis (C. andreniformis Smith) appears to seek nectar from these flowers, while the four species of the subgenus Calliopsima are oligoleges of the Compositae secondarily associated with Helianthus.

36. Calliopsis (Calliopsis) andreniformis Smith

A nectar-seeking female of this bee was taken on Helianthus strumosus in Wisconsin by Graenicher (1909). This is a polylectic species whose known sources of pollen include the flowers of Aster ericoides villosus, Convolvulus, Desmodium marilandicum, D. paniculatum, Erigeron canadensis, Gerardia tenuifolia, Hedyotis purpurea, Lippia lanceolata, Lycopus sinuatus, Lythrum alatum, Malva neglecta, M. rotundifolia, Melilotus alba, M. officinalis, Oxalis stricta, Polygala sanguinea, Polygonum buxiforme, Psoralea onybrichis, Pycnanthemum pilosum, Trifolium pratense, T. procumbens, T. repens, Verbena bracteata, V. hastata, V. utricifolia, and Verbesina helianthoides, but the species visits these and a wide variety of other flowers for nectar (Shinn, 1967). Recently, at 66 localities east of the Rocky Mountains, Dyer and Shinn (1978) have made a study of the floral taxa from which the females collect pollen to provision their nests. Calliopsis andreniformis ranges from southeastern Canada (including the Maritime Provinces) south to Florida and west to Montana, Utah, Oklahoma, and eastern Texas.

37. Calliopsis (Calliopsima) crypta Shinn

Calliopsis crypta is known from the Chiricahua Mountains of southern Arizona and Chihuahua, Mexico. Shinn (1965) states that it collects pollen from Heterotheca subaxillaris, but notes that it also visits flowers of Cirsium and Helianthus. It is apparently an oligolege of Compositae secondarily associated with Helianthus.

38. Calliopsis (Calliopsima) pectidis Shinn

This species is primarily associated with Compositae in the southwestern United States and northwestern Mexico. It ranges through the deserts from western New Mexico to souther California and Baja California Sur.Helianthus is included among the flower records listed by Shinn (1965) and the species appears to be an oligolege of Compositae secondarily associated with this plant.

39. Calliopsis (Calliopsima) pugionis Cockerell

This southern California species is partial to Compositae (shinn, 1967). A male has been recorded from Helianthus gracilentus in Riverside County by Moldenke and Neff (1974). Apparently C. pugionis is an oligolege of the Compositae and may be secondarily associated with Helianthus.

40. Calliopsis (Calliopsima) rozeni Shinn

Calliopsis rozeni occurrs from western Texas to southeastern Arizona and south into Chihuaha and Coahuila, Mexico. Although it collects pollen primarily from Heterotheca subaxillaris, Helianthus is listed among the flower records provided by Shinn (1967). It is evidently an oligolege of Compositae and may be secondarily associated with Helianthus.

We have taken this species at sunflower as follows:

ARIZONA.—GRAHAM COUNTY: Franklin, 6 Jul 75, H. annuus, 1130–1159, 1 (EGL, JML).

Genus Perdita Smith

This is a very large genus of North American bees that has established through its component species a predominantly oligolectic relationship with the flora. Even though the genus occurs transcontinentally in southern Canada, the United States, and Mexico to as far south as Central America (Guatemala), it is centered in the more arid areas of northern Mexico and the adjacent southwestern United States. To date 23 species of Perdita belonging to five subgenera are now associated with Helianthus. Excluding P. zebrata, which apparently visits sunflowers only for nectar, there are 21 species of Perdita that are oligoleges of the Compositae either primarily associated with Helianthus (7 species) or secondarily so (14 species). In addition, one species (P. gerhardi dallasiana Cockerell) is apparently a casual polylege of Helianthus. In terms of subgenera, most species of Perdita visiting Helianthus (11) belong to the nominate subgenus and all of these are members of the octomaculata species group. Membership in the other subgenera of Perdita includes Cockerellia (6 species), Hexaperdita (4 species) and Pygoperdita (1 species).

It is to be anticipated that as field studies progress, additional species of Perdita will be found to be involved in the intrafloral ecology of Helianthus.

41. Perdita (Cockerellia) albipennis Cresson

FIGURE 4

This is an extremely variable species with several currently recognized synonyms, most commonly used of which has been P. lactipennis Viereck and Cockerell. Perdita albipennis is an oligolege of the Compositae primarily associated with Helianthus. Four subspecies are presently recognized (Hurd, 1979).

Perdita (C.) albipennis albipennis ranges from Idaho and Wyoming to Wisconsin and southward to Texas, New Mexico, Arizona, and Sonora. It has been recorded from Helianthus sp. in New Mexico (Cockerell, 1898a), from H. annuus in Nebraska (Swenk and Cockerell, 1907a), Colorado (Cockerell, 1922; Timberlake 1953), and North Dakota (Timberlake, 1968). Timberlake (1953) also has reported both sexes as very abundant at H. petiolaris in western Kansas, Graenicher (1910a) at H. occidentalis in Wisconsin, and Cockerell (1911) at H. lenticularis in Colorado. New data are presented in Table D.

Perdita (C.) a. canadensis Crawford, which occurs from Alberta and North Dakota to Idaho and Utah, has been recorded from Helianthus annuus, H. petiolaris, H. rigidus, and H. scaberrimus in North Dakota (Stevens, 1919, 1950) and H. petiolaris in Colorado (Cockerell, 1936).

Perdita (C.) a. heliophila Cockerell, which ranges from Utah, Colorado, and New Mexico to Chihuahua, was described originally from Helianthus at Mesilla, New Mexico, by Cockerell (1916b), who later recorded it from Helianthus at Mesa Verde National Park, Colorado. Timberlake (1964, 1968) has provided additional records from Utah (H. annuus) and New Mexico (H.. sp.).

FIGURE 4.—Distribution of Perdita (Cockerellia) albipennis Cresson.

Perdita (C.) a. pallidipennis Graenicher occurs from eastern Kansas and Nebraska to Wisconsin and Indiana. The type series (Graenicher, 1910a) included specimens from various localities in Burnett County, Wisconsin, mostly taken at Helianthus occidentalis or Rudbeckia hirta. In 1914, Graenicher recorded P. (C.) a. pallidipennis from elsewhere in Wisconsin, including the dune region along Lake Michigan in southeastern Wisconsin and northeastern Illinois, gathering pollen from H. occidentalis and other sunflower-type Compositae, including Rudbeckia hirta and Lepachys pinnata. Timberlake (1953) recorded it from Helianthus in eastern Nebraska.

42. Perdita (Cockerellia) bequaerti Viereck

Two subspecies are recognized by Timberlake (1954), P. (C.) bequaerti bequaerti ranging from New Jersey to Florida, Mississippi and Minnesota, and P. (C.) bequaerti indianensis Cockerell occurring in Indiana, Oklahoma, and Tennessee. The first has been recorded from Helianthus radula in Mississippi by Michener (1947) and from H. divaricatus by Mitchell (1960). The species is an oligolege of the Compositae primarily associated with Helianthus.

43. Perdita (Cockerellia) lingualis Cockerell

Cockerell (1923) recorded this species from Helianthus annuus lenticularis at Oxford and Benkleman, Nebraska (as P. albipennis). It has also been reported at flowers of Helianthus in Utah and Kansas. The species ranges from Nebraska and Kansas to Utah, New Mexico, Texas, and Mexico (Tamaulipas). Collection records for this species may be found in Table C. It is apparently an oligolege of the Compositae primarily associated with Helianthus.

44. Perdita (Cockerellia) scopata Timberlake

This species occurs along the Gulf Coast of Texas where it has been taken at the flowers of Coreopsis and Helianthus annuus (Timberlake, 1953). It is closely related to P. (C.) albipennis Cresson (Timberlake, 1954) and like that species is an oligolege of the Compositae primarily associated with Helianthus.

45. Perdita (Cockerellia) tricincta Timberlake

This species, which may prove to be a geographic race of P. albipennis Cresson, is apparently an oligolege of the Compositae primarily associated with Helianthus. It occurs in southern Texas (Cameron, Hidalgo, and Starr counties) on Helianthus annuus (Timberlake, 1953).

46. Perdita (Cockerellia) verbesinae Cockerell

Although this species is primarily found at flowers of Verbesina encelioides, Cockerell (1896) also recorded a female and male at Helianthus annuus in New Mexico and a male at Helianthus sp. in Arizona (Tucson). The species ranges from Texas to Arizona and northern Mexico and is apparently an oligolege of Compositae secondarily associated with Helianthus. Collection records for males of this species at sunflower are given in Table A, E.

47. Perdita (Hexaperdita) alexi Timberlake

Perdita alexi was described (Timberlake, 1968) from a female captured on Heterotheca subaxillaris at College Station, Brazos County, Texas, on 29 October. One additional specimen, a female paratype, was from near Aetna, Barber County, Kansas, on Helianthus petiolaris in July (LaBerge). On the basis of the known floral information, P. alexi is considered to be an oligolege of the Compositae secondarily associated with Helianthus.

48. Perdita (Hexaperdita) ignota crawfordi Cockerell

This subspecies is principally associated with Grindelia squarrosa but is also found on Helianthus annuus (Swenk and Cockerell, 1907a). It ranges from Nebraska to Oklahoma and Colorado. Like the other subspecies (P. i. basalis Timberlake, P. i. ignota Cockerell, P. i. isopappi Timberlake) this subspecies is an oligolege of the Compositae, but unlike those subspecies, which have not been taken at the flowers Helianthus, P. i. crawfordi has established a secondary association with sunflowers.

49. Perdita (Hexaperdita) pratti Cockerell

This species has been taken on Helianthus petiolaris and H. cucumerifolius, as well as Heterotheca latifolia, H. subaxillaris, and Prionopsis petiolaris (Timberlake, 1956). It is known to occur in Texas, Oklahoma, and Kansas and is regarded by us as an oligolege of the Compositae secondarily associated with sunflowers.

50. Perdita (Hexaperdita) xanthisma Cockerell

This species occurs from Wyoming to Nebraska and southward to Texas, New Mexico, and Arizona. It is apparently an oligolege of Compositae secondarily associated with Helianthus. Cockerell (1914b) reported it at Helianthus in Clarendon, Donley County, Texas, and Timberlake (1956, 1958) from H. annuus at Cullison, Pratt County, and Coldwater, Meade County, Kansas, and H. petiolaris, five miles north of Hutchison, Reno County, Kansas. Most recorded collection dates range between June and September.

51. Perdita (Pentaperdita) nigroviridis Timberlake

Timberlake (1968) reported the capture of five females on Helianthus annuus at San Antonio, Bexar County, Texas; previously he had reported this species from the flowers of Gaillardia pulchella and Helenium (Timberlake, 1958). It is apparently an oligolege of the Compositae secondarily associated with Helianthus.

52. Perdita (Perdita) affinis Cresson

Males have been taken at flowers of Helianthus petiolaris and Helianthus sp. in Colorado (Timberlake, 1960). The habits of the female are not well known but it is presumably an oligolege of Compositae having been collected at the flowers of Grindelia inornata, G. squarrosa, Haplopappus gracilis, and Solidago. Its intrafloral relationship with Helianthus appears to be secondary. It has also been taken in New Mexico.

53. Perdita (Perdita) aridella Timberlake

Timberlake (1960) has recorded nine females and two males from Helianthus sp. at Oak City, Millard County, Utah, in June, and a male from H. petiolaris at Jensen, Uinta County, Utah, also in June. The species has been collected at the flowers of Gutierrezia sarothrae. It also occurs in Navajo County, Arizona. Evidently P. aridella is an oligolege of the Compositae secondarily associated with Helianthus.

54. Perdita (Perdita) bruneri Cockerell

Recorded from Helianthus petiolaris and other Compositae in North Dakota by Stevens (1919). The species ranges from southern Canada (Manitoba and Alberta) to Texas and is apparently an oligolege of the Compositae secondarily associated with Helianthus.

55. Perdita (Perdita) dolichocephala Swenk and Cockerell

Males of this species were recorded from Helianthus at Neligh, Antelope County, Nebraska (as Perdita nebraskensis, misidentification), and both sexes from Niobarra, Knox County, Nebraska, at H. sp. (as P. dolichocephala) by Swenk and Cockerell (1907a). Timberlake (1960) provided additional records of females and/or males from Helianthus including H. subrhomboideus and H. petiolaris in Nebraska and Kansas. Females were also reported at flowers of Heterotheca subaxillaris. The species ranges from Nebraska to Kansas and Colorado and is apparently an oligolege of the Compositae secondarily associated with Helianthus.

56. Perdita (Perdita) fallax Cockerell

This species frequents Helianthus, especially H. petiolaris but also occurs on other composites, including Verbesina, Baileya, Heterotheca, and Grindelia. It ranges from Nebraska and Montana to Colorado, Texas, New Mexico, and Arizona (Timberlake, 1960). It is an oligolege of the Compositae secondarily associated with Helianthus.

57. Perdita (Perdita) gerhardi dallasiana Cockerell

Females of this subspecies have been taken at flowers of Helianthus annuus, as well as those of Monarda, the more usual host. Published records (Timberlake, 1960) are all from Texas. The nominate subspecies from Wisconsin, Illinois, and Indiana has thus far only been taken from the flowers of Monarda punctata. Perdita g. dallasiana is judged to be a casual polylege of Helianthus.

58. Perdita (Perdita) laticincta Swenk and Cockerell

This species ranges from North Dakota, Nebraska, and Wyoming to Kansas and New Mexico. The females visit Helianthus, especially H. petiolaris (Swenk and Cockerell, 1907a; Cockerell, 1923; Stevens, 1950), but some specimens have been taken at the flowers of Amorpha canescens, Haplopappus ciliatus, and Melilotus. It is an oligolege of the Compositae apparently primarily associated with Helianthus.

59. Perdita (Perdita) prionopsidis Timberlake

Females have been taken at flowers of Helianthus petiolaris in Kansas as well as at the flowers of Boltonia asteroides, Haplopappus ciliatus, and Heterothera subaxillaris (Timberlake, 1960). Evidently the species is an oligolege of the Compositae secondarily associated with Helianthus.

60. Perdita (Perdita) swenki Crawford

Recorded from Helianthus maximiliani in North Dakota by Stevens (1919), the species also occurs in Nebraska, North Dakota, Minnesota, Michigan, Wisconsin, Illinois, and New York (Long Island) and visits, in addition, the flowers of Chrysopsis, Grindelia, Liatris, Solidago juncea, and S. rigida. It is an oligolege of the Compositae secondarily associated with Helianthus.

61. Perdita (Perdita) tridentata Stevens

This species was described from males collected on Helianthus petiolaris and H. scaberrimus in North Dakota (Stevens, 1919) and has been recorded from H. petiolaris in Nebraska and Kansas by Timberlake (1960). It has also been found at the flowers of Haplopappus and thus appears to be an oligolege of Compositae primarily associated with Helianthus.

62. Perdita (Perdita) zebrata zebrata Cresson

Although P. z. zebrata has been recorded from Helianthus petiolaris in Nebraska by Swenk and Cockerell (1907a) and Timberlake (1958), Cockerell (1896) remarked that it visits only the flowers of Cleome and Stevens (1950) has found it only at the flowers of Cleome serrulata in North Dakota (Cannon Ball, Medora, and Minot) from 3 August to 20 August. Custer (1929a) has discussed its nesting habits and described the nest and the larva. Rozen (1967) has presented some aspects of its life history, figured the larva and nest architecture and has confirmed that P. zebrata zebrata provisions its cells with pollen from the flowers of Cleome. He also has established that Neolarra pruinosa Ashmead is cleptoparasitic in the nests that he studied in Arizona.

63. Perdita (Pygoperdita) nebrascensis Swenk and Cockerell

The type of this species is a female from Neligh, Antelope County, Nebraska taken on Helianthus, (Swenk and Cockerell, 1907a). No other flower data are known to us and we tentatively conclude that this species is an oligolege of the Compositae secondarily associated with Helianthus.

Family HALICTIDAE

Sixty-five species of 11 genera of this family have been associated with the flowers of Helianthus. All except the cleptoparasitic species Sphecodes dichrous are pollen-collecting species, many of which, however, visit these flowers for nectar only. There are a few species that are oligoleges of the Compositae either primarily or secondarily associated with sunflower. The majority of the species are apparently casual polyleges of Helianthus that visit also a variety of other flowers for pollen, nectar, or both. There are a few regular polyleges that visit these flowers (e.g., Agapostemon texana, Halictus ligatus) and are, like the oligoleges of the Compositae associated with Helianthus, decidedly important pollinators of these plants.

While we expect that some additional species in certain genera of the Halictidae will be found to be involved in the intrafloral ecology of Helianthus (e.g., Dialictus), we believe that the chief role of this family in the pollination of sunflowers is as discussed on the following pages.

Genus Dufourea Lepeletier

More than 60 species of this chiefly Holarctic genus are present in North America and many of the species are apparently highly restricted in their intrafloral relationships and thus oligolecty is a relatively common phenomenon. Only one species, treated below, is known to visit the flowers of Helianthus. It is an oligolege of the Compositae and is primarily associated with sunflower.

1. Dufourea (Halictoides) marginata (Cresson)

Swenk (1907) reported what is currently regarded as D. (H.) marginata marginata as flying in great abundance at flowers of the various species of Helianthus throughout the state of Nebraska; Robertson (1898, 1922, 1929) recorded it as one of the most regular visitors to Helianthus at Carlinville, Illinois, including the species H. divaricatus (,P), H. rigidus (P), and H. tuberosus (N); and Stevens (1919) identified it as a common bee in North Dakota, especially at sunflowers (H. petiolaris, H. scaberrimus, H. tuberosus). Graenicher (1910b) recorded it from Helianthus in Wisconsin, Pearson (1933) from the Chicago area, and Michener (1947) in Mississippi. Records from H. annuus have been provided by Cockerell (1914b) for Colorado and Bohart et al. (1950) for Utah. It occurs from Alberta, Minnesota, Wisconsin, and Illinois to Mississippi, Colorado, and Utah.

Under the names Panurgus halictulus Cresson and Halictoides marginatus Cresson (subsequently re-named Dufourea (Halicotoides) marginata halictella Michener), Cockerell (1897b, 1898c) recorded it from Helianthus at Santa Fe, New Mexico, in August and from H. annuus at Las Cruces, New Mexico, in September in great numbers.

Dufourea marginata is an oligolege of the Compositae primarily associated with Helianthus. Collection records of this species in the principal sampling sites are presented in Table A, E.

Genus Nomia Latreille

This is primarily an Old World genus of bees that is represented by only 19 species in the Western Hemisphere, none being known south of Mexico. Of these, 12 have been found to visit the flowers of Helianthus but half of these only for nectar. The remaining six species are mostly oligoleges of the Compositae either primarily (3 species) or secondarily (2 species) associated with Helianthus. One species (Nomia nortoni) appears to be a casual polylege of sunflowers.

2. Nomia (Curvinomia) angustitibialis Ribble

Nomia angustitibialis is a relatively little-known species ranging from southeastern Arizona to Guerrero, Mexico. Most published flower records involve the introduced Melilotus alba, a highly attractive nectar source for Aculeate Hymenoptera and other insects. It has also been recorded from flowers of Baccharis glutinosa, Condalia lycioides, and Larrea tridentata. We have found females taking nectar from sunflower and other plants, but have not encountered them gathering pollen.

Our collection records for N. angustitibialis are as follows:

ARIZONA.—COCHISE COUNTY: Cochise, 8 Jul 75, H. annuus, 0830–0859, 1N (EGL, JML). PIMA COUNTY: Rillito 5 mi W, 30 Jul 75, H. annuus, 1345–1359, 1N (AEM, MMM).

3. Nomia (Curvinomia) fedorensis Cockerell

According to Ribble (1965) this species occurs from southwestern Kansas to Vera Cruz, New Mexico, but is primarily known from southern and central Texas. He includes a record of a male at Helianthus sp. in his relatively short list of flowers visited (Compositae and Leguminosae). The species appears to visit the flowers of Helianthus for nectar only.

4. Nomia (Curvinomia) mesillensis Cockerell

Ribble (1965), under the name N. foxii Dalla Torre, records two males from Helianthus (locality not given), among a wide variety of flower records.

We have taken a male at sunflower as follows:

ARIZONA.—COCHISE COUNTY: Cochise, 8 Aug 75, H. annuus, 0800–0829, 1 (EGL, JML).

Apparently the species visits Helianthus for nectar only.

5. Nomia (Acunomia) nortoni nortoni Cresson

This is a polylege of a wide variety of plants. It has been recorded from H. maximiliani at Dallas, Texas, by Cockerell (1914b), and from Helianthus sp. by Ribble (1965). This subspecies occurs from Pennsylvania south to Florida and west to Idaho, Colorado, New Mexico, and northern Mexico (Coahuila). It appears to be a casual polylege of Helianthus.

6. Nomia (Acunomia) melanderi Cockerell

This is a polylectic species important in the pollination of alfalfa grown for seed, ranging from Washington to Wyoming and southern California. Ribble (1965) recorded it from Helianthus and it appears that this species probably visits the flowers of Helianthus for nectar only.

7. Nomia (Epinomia) micheneri Cross

A male of this species was recorded by Cross (1958) from Helianthus in Durango, Mexico. He reports the species from the Mexican Plateau, southern Arizona, and Texas. Collection records for this species in western New Mexico appear in Table A. Additional material of this species has been collected by Dr. T. J. Zavortink in Arizona (10.4 mi E Nogales) at the flowers of Haplopappus gracilis () and in New Mexico (1.4 mi SW Rodeo) at the flowers of Heterotheca subaxillaris (P). The species is evidently an oligolege of the Compositae and may be primarily associated with Helianthus.

8. Nomia (Epinomia) nevadensis angelesia Cockerell

This subspecies ranges along the Pacific Coast of North America from Oregon to Nevada, southern California, and Baja California Norte, Mexico. It is polylectic. A nectar gathering female has been collected by P. H. Timberlake from Helianthus gracilentus in southern California just west of Perris, Riverside County. A collection record from one of our principal survey sites is presented in Table F. Like the following subspecies, this bee apparently visits the flowers of Helianthus for nectar only.

9. Nomia (Epinomia) nevadensis arizonensis Cockerell

Cross (1958) recorded males of this bee from Helianthus and one or both sexes from a variety of plants, mostly Compositae, especially Grindelia squarrosa. It turned up only once in our samples as follows:

ARIZONA.—COCHISE COUNTY: Cochise, 8 Aug 75, H. annuus, 0800–0859, 2, 1N (EGL, JML).

This subspecies apparently visits the flowers of Helianthus for nectar only. It occurs from Utah Arizona, and southern California (Colorado Desert) south to Jalisco, Mexico.

10. Nomia (Epinomia) triangulifera Vachal

This species was reported many years ago at flowers of Helianthus in New Mexico (Cockerell, 1899b, 1906b, 1914b) and H. annuus in Nebraska (Swenk, 1907). Recently, Cross (1958) more specifically recorded males and females from H. annuus, and H. lenticularis and males from H. maximiliani and H. petiolaris. Cross and Bohart (1960), however, in reporting on the nesting habits and provisioning of this species in a wide variety of soils from sand to clay in Utah and Kansas, concluded that H. annuus was the preferred host, although a few females with pollen loads have been taken on Bidens involucrata, Grindelia squarrosa, Helianthus lenticularis, Rudbeckia triloba, and Silphium perfoliatum. Cockerell (1898c), under the synonymous name N. persimilis, stated that females of this species mimic Andrena helianthi to such a degree that when collecting them he did not distinguish the two species.

Nomia triangulifera is an oligolege of the Compositae primarily associated with Helianthus.

11. Nomia (Dieunomia) apacha Cresson

Two females were recorded from Helianthus at Victoria, Texas, by Cockerell (1910). The species ranges from Nebraska to Colorado, New Mexico, and Texas and is possibly an oligolege of the Compositae secondarily associated with Helianthus.

12. Nomia (Dieunomia) bolliana Cockerell

This species is known from New Mexico and Texas. A female of the nominate subspecies was recorded from Helianthus at Wichita Falls, Texas, and both sexes from Rudbeckia amplexicaulis at Denton, Texas, by Cockerell (1910). He recorded the subspecies N. b. helenii from near Tilden, Texas, taking pollen and nectar from both Helenium microcephalum and Polypteris texana (Cockerell, 1936). In view of our knowledge of the other Helianthus-visiting species of Nomia, it appears best at this time to regard this species as an oligolege of the Compositae secondarily associated with Helianthus.

13. Nomia (Dieunomia) heteropoda (Say)

FIGURE 5; PLATE 1

This is typically a sunflower bee. It was first recorded from Helianthus at Victoria, Texas, by Cockerell (1910). It is primarily associated with H. annuus, but unpublished records indicate that it is also commonly taken on H. petiolaris. Michener (1947) also reported it at H. radula in Mississippi. It ranges from Maryland to Florida and west to Nebraska, Utah, Arizona, and southern California (see Figure 5). However, it occurs discontinuously throughout this range, even where Helianthus is abundant, because of a marked preference for sand or sandy soil for a nesting substrate. The species has frequently been taken in sand dunes (Blair, 1935, and unpublished data by Lutz, 1919, and others). Hicks records burrows extending vertically in the sand for three to four feet. In a more detailed account, Cross and Bohart (1960), describe and figure a burrow of this species where females were nesting in alluvial sand deposits at Lawrence, Kansas, along with those of Nomia (Epinomia) triangulifera with which they were collecting pollen from Helianthus annuus. The burrow excavated had a vertical shaft 94 cm deep, the last 14 cm of which was in a silt layer underlying the sand. The silt material was used to line the cells and the tunnel through the sand.

FIGURE 5.—Distribution of Nomia (Dieunomia) heteropoda Say.

Perhaps because of the discontinuities in distribution that presumably have historically isolated some populations, numerous names have been applied to these as well as to individual variants, and the status of these remains to be determined (see comments by Mitchell, 1960).

Nomia heteropoda is a rapid pollen collector and is able to carry large amounts on the hind legs and to some extent on the abdomen. The males also become covered with pollen on the underside when visiting the flowers for nectar and may be seen periodically resting on the stems removing pollen with the legs. Mating takes place on the flowers and other males frequently attempt to dislodge the first male to achieve copulation. Most of the day they cruise the flowers like Svastra or Melissodes. When abundant, as at Indio, California, in September, the females can collect most of the pollen from a field of wild sunflowers between 0600 and 0900 hrs.

When a box of freshly pinned specimens was opened a strong lemony smell was evident. The collective odor in the box of dead specimens was definite but could not be identified with individual bees. Also, since both males and females were stored in the box it is not clear as to whether the odor is produced by one or both sexes.

The species is an oligolege of the Compositae primarily associated with Helianthus.

Details of collections of N. heteropoda in major sampling areas may be found in Tables B-D and F.

In addition, Dr. Thomas J. Zavortink has collected males of this species at 7 mi NNW Animas, Hidalgo County, New Mexico, on 30 August 1974 from the flowers of H. annuus between 1430 and 1500 MST.

Genus Augochloropsis Cockerell

This is a Western Hemisphere genus of bees that seems to be centered in the tropics but extends into the temperate regions of North and South America. Of the three species that occur in the United States two have been taken at the flowers of Helianthus with sufficient regularity to be considered casual polyleges of that plant.

14. Augochloropsis (Paraugochloropsis) metallica metallica (Fabricius)

Robertson (1929) reported both sexes of this species taking nectar from H. annuus, females taking nectar from H. tuberosus and pollen from H. rigidus, as well as both sexes at H. divaricatus and H. grosseserratus, from which the females were taking pollen. In Wisconsin, Graenicher (1909) found the bee collecting pollen from H. strumosus. The species and its subspecies are polylectic and widely distributed in eastern and southern United States to Panama but has been collected as far west as Arizona. It appears to be a casual polylege of Helianthus.

15. Augochloropsis (Paraugochloropsis) sumptuosa (Smith)

This species is reported by Mitchell (1960) from Helianthus, along with other flower records. The species ranges from Maine to Florida and west to South Dakota, Colorado, Arizona, and Texas. It is judged to be a casual polylege of Helianthus.

Genus Augochlora Smith

This is a large genus of chiefly tropical American bees some of whose species extend into the temperate regions of both North and South America. Of the five species present in America north of Mexico only the one discussed below has been found at the flowers of Helianthus.

16. Augochlora (Augochlora) pura (Say)

Mitchell (1960) recognizes two subspecies, the wide ranging nominate form occurring throughout most of North America east of the Dakotas and Texas, and A. pura mosieri Cockerell from southern Florida. He includes Helianthus among the many flower records for A. p. pura but not in his records for A. p. mosieri. Graenicher (1930) reported this species at Helianthus debilis in the Miami region of Florida (as “A. festiva”). Since he also included “A. pura” in his list of species, it is possible that his record from Helianthus debilis refers to the subspecies mosieri.

This species appears to be a casual polylege of Helianthus.

Genus Augochlorella Sandhouse

Bees of this genus are found only in the Western Hemisphere and are found on both the North and South American continents. Eight species are present in America north of Mexico and of these, six are known to visit the flowers of Helianthus. All are casual polyleges of that plant except Augochlorella pomoniella, which apparently visits the flowers for nectar only.

17. Augochlorella aurata (Smith)

This is a polylectic species ranging from eastern United States (North Carolina, Georgia, Florida, and Alabama) to Texas and northern Mexico. Robertson (1898, 1929) provides a long list of flower records from Illinois, including Helianthus, but his records attributed to this species are misidentifications since A. aurata is not known to occur in Illinois (Ordway, 1966a). Apparently this species is a casual polylege of Helianthus.

18. Augochlorella bracteata Ordway

This polylectic species was described from individuals taken on Prosopis, but Ordway (1966a) also includes Helianthus among her flower records. The range extends from eastern Texas to Hidalgo, Mexico. It appears to be a casual polylege of Helianthus.

19. Augochlorella gratiosa (Smith)

Ordway (1966a) includes Helianthus among her flower records for this species, which ranges from Florida west to Texas. Presumably the species is a casual polylege of Helianthus.

20. Augochlorella persimilis (Viereck)

In Illinois, Robertson reported the females of A. persimilis taking pollen from Helianthus mollis. Although A. persimilis has been recorded from Helianthus in field studies by Ordway (1966a), she reports that females ignored sunflowers in the laboratory, even when they were producing an excess of pollen, apparently preferring other pollen sources (Ordway, 1966b). The species ranges over most of the eastern United States except northeast Florida and the coastal areas of the southeast and occurs as far west as Texas and Minnesota. It is evidently a casual polylege of Helianthus.

21. Augochlorella pomoniella (Cockerell)

Augochlorella pomoniella ranges from southwestern Utah, western Nevada, and central California southward to the Cape Region of Baja California and Costa Rica. The females are polylectic. Ordway (1966a) includes Helianthus among her flower records for the species. Apparently this species visits the flowers of Helianthus for nectar only:

Our single record from sunflower is the following:

ARIZONA.—COCHISE COUNTY: Cochise, 8 Aug 75, H. annuus, 0800–0829, 1 (EGL, JML).

22. Augochlorella striata (Provancher)

The female of this species was reported taking pollen from Helianthus giganteus and H. strumosus in Wisconsin by Graenicher (1909) and at H. lenticularis in Colorado by Cockerell (1911) (as Augochlora coloradensis). Stevens (1921) found males at H. maximiliani and H. tuberosus in North Dakota. It ranges from Quebec to Florida and west to New Mexico and South Dakota.

Although Ordway (1966a) lists Helianthus among the flowers from which this species has been collected, in the laboratory she found that the females ignored sunflowers even when they produced so much pollen that it dropped off of the flower head (Ordway, 1966b), even though other composites were utilized as pollen sources.

The species is evidently a casual polylege of Helianthus that visits a great variety of other flowers for nectar and/or pollen (Hurd, 1979).

Genus Agapostemon Guerin-Meneville

This is a Western Hemisphere genus of bees that occurs on both the North and South American continents as well as the West Indies. Fourteen species are known to be present in America north of Mexico (Roberts, 1969, 1972a,b, 1973a), and many of these (9 species) have been taken at the flowers of Helianthus. Except Agapostemon texana Cresson, which is a regular polylege of sunflowers, the other eight species appear to be casual polyleges.

23. Agapostemon angelicus Cockerell

Agapostemon angelicus is a common polylectic species in the arid southwest and northern Mexico. It ranges from North Dakota, Colorado, and Iowa south to Texas, New Mexico, Arizona, southern California, and Mexico (Chihuahua, Durango and Sonora). Females gather pollen most actively early and late in the day. They have been reported at flowers of Cucurbita, Mentzelia, Camissonia, Oenothera, and Larrea (Hurd and Linsley, 1975), and by Moldenke and Neff (1974) from Helianthus annuus in Kern, Los Angeles, and Riverside counties, California, and H. gracilentus in Riverside, Los Angeles, and San Diego counties. The species is apparently a casual polylege of Helianthus.

Collections of A. angelicus are reported in Tables B-E. In addition we have taken an individual from sunflower as follows:

ARIZONA.—SANTA CRUZ COUNTY: Sonoita, 16 Aug 74, H. annuus, 1 (PDH, AEM, MMM).

24. Agapostemon cockerelli Crawford

This polylectic species is particularly abundant in southeastern Arizona, southern New Mexico, western Texas, and the Mexican Plateau, but actually ranges northward through Colorado to Wyoming. Like other desert Agapostemon, females take pollen early and late in the day. They have been captured at flowers of Cucurbita, Camissonia, Oenothera, Mentzelia, and Larrea (Hurd and Linsley, 1975) but have not been reported previously from Helianthus. The species is apparently a casual polylege of this plant.

Collection records from sunflowers are reported in Table D, E (mostly males). An additional record is as follows:

ARIZONA.—PIMA COUNTY: San Xavier, 19 Aug 74, H. annuus, 1200–1229, 1 (PDH, AEM, MMM).

25. Agapostemon femoratus Crawford

This is a widely distributed species ranging from British Columbia, Alberta, and North Dakota south to New Mexico, Arizona, Nevada, California, and Mexico (Baja California). Moldenke and Neff (1974) record three females and two males from Helianthus gracilentus in Riverside County, California. The species appears to be a casual polylege of Helianthus.

26. Agapostemon melliventris Cresson

Agapostemon melliventris is a widespread species in the western United States (Montana, Idaho, South Dakota, south to Texas, New Mexico, Arizona, and California) and northern Mexico. Females are polylectic and gather pollen in the early morning and late afternoon. They have been reported from flowers of Cucurbita, Datura, Camissonia, and Larrea (Hurd and Linsley, 1975) but not previously from Helianthus. Timberlake (pers. comm.) captured a female taking pollen from Helianthus niveus, 18 mi S of Indio, Riverside County, California, in March. The species is apparently a casual polylege of Helianthus.

In addition to data on A. melliventris recorded in Table E, we have taken specimens at sunflower as follows:

CALIFORNIA.—INYO COUNTY: Big Pine, 28 Aug 77, Helianthus annuus, 0630–0729, 1, 1P (EGL, JML).

27. Agapostemon sericeus (Forster)

This is a polylectic species of eastern North America ranging from Ontario and Maine to Florida and westward to Manitoba, North Dakota, Nebraska, Kansas, Oklahoma, and Texas. Graenicher (1909) recorded a male at Helianthus strumosus in Wisconsin and Robertson (1929) includes H. grosseserratus (, P) among his many flower records. It appears to be a casual polylege of Helianthus.

28. Agapostemon splendens (Lepeletier)

Graenicher (1930) recorded this widespread polylege from Helianthus debilis in Florida. This species ranges from Ontario and Maine west to Saskatchewan and south to Florida, Alabama, Mississippi, Louisiana, Texas, and New Mexico. It is evidently a casual polylege of Helianthus.

29. Agapostemon texanus Cresson

This is a widely distributed polylectic species that occurs transcontinentally from southern Canada and the United States to central Costa Rica. Cockerell (1923) collected a male from the flowers of Helianthus lenticularis at Oxford, Nebraska, and subsequently the species has been reported by Robertson (1929) taking pollen and nectar from H. tuberosus in Illinois. Females were collected from the flowers of cultivated H. annuus and from H. petiolaris and males from those of H. maximiliani in North Dakota (Stevens, 1921). Fischer (1950) recorded the species from Helianthus in Kansas but without stating the sex. Among the unpublished records in the P. H. Timberlake collection are a pollen-collecting female taken on H. annuus at 5.2 mi E of Sunset, Lincoln County, New Mexico, and a nectar seeking female at 1.5 mi W of Perris, Riverside County, California on H. gracilentus.

On the basis of this information and the detailed records cited below we regard this species as a regular polylege of Helianthus.

Details of collections of this species at major sampling sites are presented in Table F, H, K, and M. Additional records include the following:

ARIZONA.—COCHISE COUNTY: Cochise, 8 Aug 75, H. annuus, 0800–0829, 14, 12P, 4N (EGL, JML). PINAL COUNTY: Eloy, 26 Jun 74, H. annuus, 0630–0659, 1 (AEM, MMM).

CALIFORNIA.—FRESNO COUNTY: Parlier, 7 Sep 75, H. annuus, 1400–1429, 1P, 1N (EGL, JML, AEM, MMM). Los ANGELES COUNTY: Pico Rivera, 4 Jun 75, H. annuus, 1630–1659, 1 (AEM, MMM), 11 Aug 75, H. annuus, 0830–0900, 3, 2P (AEM, MMM). ORANGE COUNTY: Newport Beach, 27 Aug 76, H. annuus, 1400–1429, 8 (AEM, MMM), 13 Sep 75, 1015–1029, 1 (AEM, MMM), 21 Sep 75, 1500–1514, 1 (AEM, MMM), 25 Sep 77, 0800–0830, 1P (AEM, MMM). TULARE COUNTY: Tulare, 6 Oct 75, H. annuus 1600–1629, 1 (EGL, JML, AEM, MMM).

TEXAS.—TRAVIS COUNTY: Austin, 18 Sep 78, H. annuus, 1700–1729, 3, 5P (PDH).

30. Agapostemon tyleri Cockerell

This species ranges from eastern Arizona and southern New Mexico to Tehuacan, Puebla, Mexico. It has been reported from flowers of Larrea tridentata (Hurd and Linsley, 1975) but we have not been able to find other published flower records. It is evidently a casual polylege of Helianthus (Table C).

In addition, specimens have been taken as follows:

ARIZONA.—COCHISE COUNTY: Cochise, 8 Sep 75, H. annuus, 0800–0829, 3P (EGL, JML). SANTA CRUZ COUNTY: Duquesne Road, 6.9 mi SE Highway 82, 29 Aug 1973, H. annuus, 1000–1030, 2P (T. J. Zavortink).

31. Agapostemon virescens (Fabricius)

This species was recorded from Helianthus in Kansas by Walker (1936). It occurs throughout the eastern and central United States and southern Canada to the Pacific Northwest. Like other Agapostemon it is polylectic and its relationship to Helianthus appears to be casual.

Genus Halictus Latreille

Five species of this chiefly Holarctic genus have been found to visit the flowers of Helianthus. Only one of these, H. ligatus, whose range extends considerably beyond that of Helianthus in North America, visits the flowers with sufficient regularity to be classed as a regular polylege. The other species are evidently less regular in their floral visitation and are considered by us to be casual polyleges of Helianthus. Nonetheless, the species of this genus discussed below are regarded as important pollinators of these plants.

32. Halictus (Halictus) farinosus Smith

This is a western American species occurring from Montana and Nebraska west to British Columbia and south to New Mexico, Arizona, and California. The females, as their congeners, are polylectic. Moldenke and Neff (1974) record 12 females and two males from San Diego County, California, on Helianthus gracilentus.

On the basis of our sampling program this species is considered by us to be a casual polylege of Helianthus.

During the surveys this species was taken on sunflowers only once:

CALIFORNIA.—SAN DIEGO COUNTY: Vicinity of Laguna Junction and Interstate Highway 8, 13 Jun 74, H. gracilentus, 1300–1415, 11P, 7N (AEM, MMM).

33. Halictus (Halictus) ligatus Say

This widespread highly polylectic bee (see Roberts, 1973b) has been recorded from Helianthus many times throughout the country. Robertson (1894, 1898, 1922, 1929) reported it as one of the most regular visitors to Helianthus at Carlinville, Illinois, where he found it taking pollen from six species: H. annuus, H. divaricatus, H. grosseserratus, H. mollis, H. rigidus, and H. tuberosus. Cockerell recorded it from sunflower in Virginia (at H. annuus coronatus), in California and Colorado (H. annuus lenticularis) and Texas (H. maximiliani) (Cockerell, 1911, 1914b, 1915b,c, 1916a, 1923). It has also been collected at H. debilis in Florida by Graenicher (1930); H. radula in Mississippi by Michener (1947); and H. sp. in North Dakota by Stevens (1951c) and in Ontario (Knerer and Atwood, 1962). The species ranges from southern Canada to the West Indies and northern South America (Colombia to Trinidad). For discussions of its habits, see Roberts (1973b), Michener and Bennett (1977), and Litte (1977). The species is a regular polylege of Helianthus.

Although we have found males present in small numbers throughout the principal blooming period of sunflower in the sites sampled, beginning in June, we found them most abundant at Corcoran, California, on 5 October 1975. Between 0700 and 1400 hrs, 184 males were taken, along with 54 females (of which 48 were taking pollen), the two sexes together representing 35.6 percent of the bees visiting the flower heads during that period.

H. ligatus was found on sunflowers at all primary sites but one (see Tables A-F, H-M for details). Additional records from secondary survey sites are as follows:

ARIZONA.—COCHISE COUNTY: Cochise, 8 Aug 75, H. annuus, 0800–0859, 2, 5P, 14N (EGL, JML). GRAHAM COUNTY: Franklin, 6 Aug 75, H. annuus, 1130–1159, 1P (EGL, JML). MARICOPA COUNTY: Theba, 28 Jun 74, H. annuus, 1130–1159, 1, 1P, 1N (AEM, MMM). PIMA COUNTY: Rillito, 2 Aug 75, H. annuus, 0700–0729, 13P, 1N (AEM, MMM); San Xavier, 19 Aug 74, H. annuus, 1200–1259, 2, 2N (PDH, AEM, MMM). PINAL COUNTY: Eloy, 26 Jun 74, H. annuus, 0630–0659, 2, 2N (AEM, MMM), 30 Aug 75, H. annuus, 0815–0929; 2, 5P, 2N (AEM, MMM). YUMA COUNTY: Wellton, 5 Sep 74, H. annuus, 1100–1129, 1N (AEM, MMM).

CALIFORNIA.—CONTRA COSTA COUNTY: Byron 4 mi E, 21 Jul 77, H. annuus, 0800–0829, 2P (EGL, JML, AEM, MMM). FRESNO COUNTY: Highway 99, Visalia-Hanford Junction, 22 Aug 76, H. annuus, 0730–0829, 3P (AEM, MMM). IMPERIAL COUNTY: El Centro, 29 Jul 75, H. annuus, 1000–1014, 3P, 1N (AEM, MMM); Holtville 3 mi W, 29 Jul 75, H. annuus, 1100–1140, 1P (AEM, MMM). KERN COUNTY: Copus Road between Highways 5 and 99, 22 Aug 76, H. annuus, 1130–1159, 6P (AEM, MMM); Lost Hills 3 mi S, 29 Aug 76, H. annuus, 1100–1129, 1P (AEM, MMM). LOS ANGELES COUNTY: Pico Rivera, 11 Aug 75, H. annuus, 7P, 2N (AEM, MMM); Sunland, Tujunga Canyon, 14 May 75, H. annuus, 1230–1244, 1P (AEM, MMM). MERCED COUNTY: Gustine 10 mi S, 27 Sep 76, H. annuus, 2P (AEM, MMM). RIVERSIDE COUNTY: Blythe, 29 Jun 74, H. annuus, 0800–0829, 1, 9N (AEM, MMM); Coachella, 8 Jun 76, H. annuus, 0900–0929, 1P (EGL, JML); Indio, 8 Jun 76, H. annuus, 0700–0829, 8P, 1N (EGL, JML). SAN JOAQUIN COUNTY: Manteca 7.5 mi N, 21 Aug 77, H. annuus, 1100–1129, 1, 3P (EGL, JML, AEM, MMM). STANISLAUS COUNTY: Patterson, 21 Aug 76, H. annuus, 1315, 1P (AEM, MMM), 27 Jul 77, H. annuus, 0930–0959, 6P (EGL, JML, AEM, MMM).

TEXAS.—TRAVIS COUNTY: Austin, 18 Sep 78, H. annuus, 0900–1700, 4, 21P, 5N (PDH).

34. Halictus (Halictus) rubicundus (Christ)

This is a Holarctic polylectic species, ranging in North America from Alaska and Canada south to California, Arizona, Texas, and Florida. Graenicher (1909) reported both sexes at Helianthus strumosus in Wisconsin, the females taking pollen. Stevens (1951c) has recorded the species from H. maximiliani in North Dakota and Moldenke and Neff (1974) have listed it from an unidentified Helianthus in Los Angeles County, California. It is judged to be a casual polylege of Helianthus.

35. Halictus (Seladonia) confusus Smith

Halictus confusus is a widely distributed, polylectic bee occurring from the Atlantic to the Pacific in southern Canada and the United States. Two subspecies are recognized, H. confusus confusus, which occurs from Alaska to Nova Scotia, south to Florida, west to North Dakota and Texas, and H. confusus arapahonum Cockerell, which occurs from North Dakota to New Mexico and west to British Columbia, Oregon, and California. The nominate subspecies has been taken on Helianthus strumosus (, P) in Wisconsin (Graenicher, 1909) and H. annuus (11) and more frequently at H. divaricatus (, P) in Illinois (Robertson, 1929). Roberts (1972b) reports the bee essential to the production of marigold seed and of considerable importance in the production of Zinnia seed in Oregon. The subspecies H. c. arapahonum occurred in two of our samples taking nectar as follows:

ARIZONA.—PIMA COUNTY: Rillito 6 mi W, 27 May 74, H. annuus, 0830–0859, 1N (AEM, MMM); San Xavier, 19 Sep 74, H. annuus, 1230–1259, 1N (PDH, AEM, MMM).

It is apparently a casual polylege of Helianthus.

36. Halictus (Seladonia) tripartitus Cockerell

Halictus tripartitus is a species of western North America, ranging from Washington to California and Baja California, Mexico, and west to Idaho, Colorado, Arizona, New Mexico, and Texas. It is polylectic and among records of flowers visited in southern California, Moldenke and Neff (1974) include instances of a female and male at Helianthus sp. in Riverside and Fresno counties, respectively, and a female from H. annuus in Riverside County. The relationship of this species to Helianthus appears to be that of a casual polylege.

Genus Lasioglossum Curtis

Although this genus is represented in North America by 19 species including one Holarctic species, only the four species discussed below are known to visit the flowers of Helianthus. Except for Lasioglossum mellipes (only males of which have been taken at the flowers of Helianthus gracilentus), the species appear to be casual polyleges of Helianthus.

37. Lasioglossum coriaceum (Smith)

This is wide ranging species having been reported from Nova Scotia to Georgia and west to Alberta and New Mexico, extending southward in the Mississippi Valley to Illinois. It is a highly polylectic species obtaining pollen and nectar from a wide variety of plants. Robertson (1894, 1929) notes that it takes pollen and nectar from Helianthus tuberosus and Graenicher (1909) includes H. strumosus as a source of nectar and pollen in Wisconsin. It is regarded by us as a casual polylege of Helianthus.

38. Lasioglossum mellipes (Crawford)

As presently known, this is a species of southern California and Baja California Norte, Mexico. Males have been taken at flowers of Helianthus gracilentus in San Diego County, California (Moldenke and Neff, 1974).

39. Lasioglossum sisymbrii Cockerell

Lasioglossum sisymbrii occurs widely in the west from British Columbia to Wyoming and New Mexico and south to Arizona and through California to Baja California, Mexico. It is polylectic and females have been reported at flowers of Helianthus sp. in Los Angeles County and Helianthus niveus in Riverside County, California, by Moldenke and Neff (1974). Hurd and Linsley (1975) reported females taking pollen from Larrea tridentata. In 1936, a female taking nectar from H. annuus was collected in Westwood Hills, Los Angeles County, California (EGL). It is evidently a casual polylege of Helianthus.

40. Lasioglossum titusi (Crawford)

This is a species of the west coast of North America, thus far known from Oregon and California. Among the flower records provided by Moldenke and Neff (1974) are 16 females from Helianthus sp. in Los Angeles County, California, and it appears that this species is a casual polylege of Helianthus.

Genus Evylaeus Robertson

Six species of this genus have been found visiting the flowers of Helianthus. Except Evylaeus aberrans (Crawford) whose females principally obtain their pollen from the flowers of Oenothera, the others are polylectic species that visit Helianthus for pollen and nectar (3 species) or for nectar only (3 species).

41. Evylaeus aberrans (Crawford)

This a rather wide ranging species having been reported from North Dakota, Nebraska, Colorado, New Mexico, Oregon, California, and Canada (Alberta). The female collects pollen principally from flowers of Oenothera (Onagraceae), but also visits these and a wide variety of other plants for nectar or occasionally pollen. The floral relationships and nesting biology of this species (as E. galpinsiae) have been discussed by Bohart and Youssef (1977b). Stevens (1921) has reported the capture of two females and nine males at the flowers of Helianthus petiolaris in North Dakota. Presumably they were seeking nectar.

42. Evylaeus amicus (Cockerell)

This polylectic southwestern species occurs from New Mexico to California. Described originally from females taken at Sisymbrium and plum in the Mesilla Valley, New Mexico (Cockerell, 1897b), we have taken it at a variety of desert plants in Arizona and California. For our only sunflower collection, a male, see Table E.

43. Evylaeus argemonis (Cockerell)

This species is not very well known in the literature. The female was described by Cockerell (1897a) from Paso de Telaya, Vera Cruz, Mexico, on flowers of Argemone mexicana, and E. latifrons (Viereck), regarded as a synonym, from Santa Clara County, California. Our only record from Helianthus is as follows:

CALIFORNIA.—LOS ANGELES COUNTY: Pico Rivera, 15 May 75, H. annuus, 1N (AEM, MMM).

44. Evylaeus kincaidii (Cockerell)

Evylaeus kincaidii is a species of the Pacific Coast of North America, ranging from Washington to California. Among the flower records for this species in southern California provided by Moldenke and Neff (1974) are four females from Helianthus sp. in Los Angeles County. It appears to be a casual polylege of sunflower.

45. Evylaeus pectinatus (Robertson)

This is a polylectic species of eastern North America (Connecticut, New Jersey, Maryland, Illinois, and Missouri) that has been reported taking nectar from Helianthus tuberosus by Robertson (1929).

46. Evylaeus pectoralis (Smith)

This is also a polylectic species ranging from eastern Canada to Florida, west to Wisconsin, Nebraska, and Texas. Robertson (1894, 1898, 1929) includes Helianthus in his extensive list of flower records, the females taking pollen from H. divaricatus, H. laetiflorus, and H. tuberosus. Graenicher (1909) also reported it at H. strumosus (, P) in Wisconsin. It is apparently a casual polylege of Helianthus.

47. Evylaeus pectoraloides (Cockerell)

This widespread polylectic species ranges from southwestern Canada to Colorado, New Mexico, Arizona, California, and northern Mexico. Cockerell (1897b) records a wide range of floral hosts in New Mexico. We have taken a single female from Helianthus (Table E). The species is evidently a casual polylege.

Genus Dialictus Robertson

Nearly 200 species of this very large genus are known to occur in America north of Mexico. Insofar as is known, all of the species are polylectic, although Dialictus ornduffi is reported (Hurd, 1970) to be narrowly polylectic obtaining all or most of its pollen from the flowers of Jepsonia heterandra (Saxifragaceae). Thus far 17 species of this genus have been found at the flowers of Helianthus. Of these 11 are casual polyleges of that plant and six apparently seek nectar only. At certain localities, Dialictus pruinosiformis has been found in relatively large numbers at sunflower (Table D). It is expected that many more species of this genus will be found to visit the flowers of Helianthus as field studies progress. We have records of two unidentified species (both males) taken at the flowers of Helianthus annuus at Benson, Arizona and Corcoran, California. These are in addition to the species discussed below.

48. Dialictus albipennis (Robertson)

Graenicher (1909) reported a male of this species at flowers of H. strumosus in Wisconsin. The species is polylectic and ranges from Nova Scotia to Oregon and south to North Carolina, Illinois, and Colorado.

49. Dialictus clematisellus (Cockerell)

This species ranges in the southwest from New Mexico and Utah to California. Cockerell (1904) reported that it occurred in numbers at flowers of Clematis ligusticifolia at Pecos, New Mexico, but we know of no other published flower records. We have encountered females taking nectar from H. annuus (Table E).

50. Dialictus illinoensis (Robertson)

This eastern North American species (Nebraska and Minnesota to Nova Scotia and south to Texas and Georgia) is polylectic. Among the wide range of reported flowers visited, Robertson (1929) includes a male at Helianthus divaricatus.

51. Dialictus imitatus (Smith)

This is a highly polylectic bee that has been recorded taking pollen from Helianthus annuus and H. tuberosus at Carlinville, Illinois (Robertson, 1929, as Chloralictus sparsus). It ranges from Quebec and the New England states to Florida and west to Minnesota and California. It is apparently a casual polylege of Helianthus.

52. Dialictus impavidus (Sandhouse)

Thus far this species has been recorded from California, Arizona, and Nevada. Moldenke and Neff (1974) list a female at Helianthus in San Diego County in their treatment of bees of California. Since no additional records of this species are known to us from Helianthus we regard this species as a nectar visitor to that plant.

53. Dialictus incompletus (Crawford)

This is a common polylectic species of the southwestern United States, primarily found in the desert areas of New Mexico, Arizona, southern Nevada, and California. Moldenke and Neff (1974) report the capture of three females at flowers of Helianthus annuus in Riverside County and one at Helianthus sp. in Los Angeles County, California. It is apparently a casual polylege of Helianthus. We have collected the following specimens:

CALIFORNIA.—CONTRA COSTA COUNTY: 4 mi E of Byron, 21 Jul 77, H. annuus, 0800–0829, 1P (EGL, JML, AEM, MMM). STANISLAUS COUNTY: 6.5 mi N of Grayson, on Kasson Road, 27 Jul 77, H. annuus, 1100–1129, 3N (EGL, JML, AEM, MMM).

54. Dialictus marinus (Crawford)

Recorded from Helianthus debilis in Florida by Graenicher (1927, 1930) and from Alternanthera floridana, Bidens, Helianthus, and Parthenocissus by Mitchell (1960), this species occurs along the Atlantic seaboard from Massachusetts to Florida and is considered by us to be a casual polylege of Helianthus. The type series was swept from grass (Scirpus, Ammophila, etc.) growing along the strand within the beach at Ocean City, New Jersey, and possibly the bees were flying up from their nests in the sand.

55. Dialictus microlepoides (Ellis)

This is a polylectic species occurring from New Mexico to California and northern Mexico. We have found it visiting sunflower but only for nectar. In addition to the data in Table E we record:

ARIZONA.—PIMA COUNTY: San Xavier, 19 Sep 74, H. annuus, 1230–1259, 1N (PDH, AEM, MMM).

56. Dialictus nevadensis (Crawford)

Cockerell (1916a) recorded this species from Helianthus lenticularis at Orange, California. Earlier he had noted that this species occurs at the flowers of a wide range of plants including the flowers of peach, almond, and apricot. The species, which occurs in the southwestern United States, is apparently a casual polylege of Helianthus.

57. Dialictus oleosus (Cockerell)

This is a southwestern species ranging from Colorado and New Mexico to Arizona. We have not encountered published flower records for either sex. Our sunflower collection is recorded in Table E; the species appears to visit Helianthus for nectar only.

58. Dialictus pilosus pilosus (Smith)

Dialictus pilosus, which is widely distributed from Colorado and Minnesota to southern Canada (Nova Scotia) and south to Georgia, is a highly polylectic species. It appears to be a casual polylege of Helianthus since the nominate subspecies was recorded by Robertson (1922, 1929) from five species of sunflower, one of which, H. divaricatus, it visited regularly.

59. Dialictus pruinosiformis (Crawford)

This is a common and widespread species in central and southwestern United States, ranging from Alberta, Canada, through South Dakota, Nebraska, and Iowa to Texas, New Mexico, Arizona, and California. The species is polylectic and is apparently a casual polylege of Helianthus, but not many of its host flowers have been reported in the literature. The female has been recorded from Helianthus annuus lenticularis (Cockerell, 1911) and H. petiolaris (Cockerell, 1923) in Colorado. Hurd and Linsley (1975), in their surveys of bee visitors to Larrea tridentata, found it the most abundant species of Dialictus at flowers of this plant, collecting 184 females and 181 males in May and June at sites ranging from western New Mexico to Tucson, Arizona. For details of collections for this species at sunflowers, see Table C, D.

60. Dialictus punctatoventris (Crawford)

Known thus far only from southern California and Baja California Norte, Mexico, D. punctatoventris has been recorded from flowers of Helianthus based upon a female from San Diego County, California (Moldenke and Neff, 1974). It is evidently a casual polylege of Helianthus.

61. Dialictus tegulariformis (Crawford)

This is a widely distributed western North American polylectic species having been recorded from Idaho, Utah, Nevada, New Mexico, Arizona, California, and Mexico (Baja California). It visits a wide variety of flowers for pollen and nectar. Cockerell (1916a) has recorded it from Helianthus lenticularis (as Halictus helianthi). It is considered by us to be a casual polylege of Helianthus.

62. Dialictus veganus (Cockerell)

This western species, ranging from Colorado to New Mexico and southern California has been reported at flowers of Helianthus sp. (1) in Los Angeles County, California (Moldenke and Neff, 1974). It is judged to be a casual polylege of Helianthus.

63. Dialictus versatus (Robertson)

This is a highly polylectic species which has been recorded from Helianthus annuus (P), H. divaricatus (), H. grosseserratus (P), H. mollis (P), and H. rigidus (P) in Illinois by Robertson (1929). It collects pollen from a wide variety of plants and is a casual polylege of Helianthus. It is an eastern North American species ranging from southern Canada (Ontario) to Minnesota and south to Georgia and Louisiana.

64. Dialictus zephyrus (Smith)

This species is also highly polylectic and the female has been reported taking pollen from Helianthus tuberosus (Robertson, 1929). It occurs from the New England states to Ontario, Minnesota, Colorado, Georgia, and Texas. Much is known about the biology of this species (Hurd, 1979:1973). It is a casual polylege of Helianthus.

Genus Sphecodes Latreille

This is a large and nearly worldwide genus of parasitic bees. The majority of the species belong to the nominate subgenus, which is the only group present in America north of Mexico (Michener, 1978). While most of the species are cleptoparasites in the nests of other Halictidae, some are parasitic in the nests of certain species of Andrenidae, Anthophoridae, Colletidae, and Melittidae. Doubtless other species of Sphecodes will be found to visit the flowers of Helianthus perhaps in company with their host species.

65. Sphecodes dichrous Smith

Viereck (1916) has recorded this parasitic bee from sunflower in Connecticut. The species ranges from Nova Scotia to Georgia, Missouri, and Minnesota. It is known to be cleptoparasitic in the nests of Halictus rubicundus (Christ), a casual polylege of Helianthus.

Family MELITTIDAE

With the exception of the subfamily Ctenoplectrinae, which is found only in the Ethiopian, Oriental, and Australian regions, this family is represented in North America by three subfamilies (Melittinae, Dasypodinae, and Macropodinae) also present in the Eastern Hemisphere. None of these is known to occur in the Neotropical Region, but the Dasypodinae, which contains Helianthus-visiting species, is represented by about 20 species in the United States and adjacent northern Mexico. Of these, only two species of the genus Hesperapis have been found at the flowers of Helianthus. Like most members of this family, these species appear to have evolved as oligoleges and are considered to be important pollinators of sunflowers.

Genus Hesperapis Cockerell

There are about 20 species of this genus known from North America and nearly all of these are centered in the more arid parts of the southwestern United States and northern Mexico. Only the two species discussed below have established a known relationship with Helianthus.

1. Hesperapis (Panurgomia) arenicola Crawford

This species has been recorded from Helianthus niveus in San Bernardino County, California (11 males, 2 females), by Moldenke and Neff (1974). Also, in the Timberlake collection there are 11 males and two females collected by P. H. Timberlake from H. niveus in Riverside County, California, as follows: Mecca (near), 1, 19 Mar 20; Indio (near), 10, 1, 18 Mar 27; Indio (5 mi W), 1N, 25 Mar 36.

Stage (1966) investigated the floral relationships of this species on the basis of museum collections and reports that the majority of the specimens have been taken at the flowers of the vernal composite, Geraea canescens, from which the only females bearing pollen have been collected. He notes that the species has also been found to visit the flowers of Baileya pleniradiata, Dysodia, Encelia californica, E. farinosa, Helianthus niveus, Lycium parishii, Melilotus, Oenothera deltoides, Phacelia crenulata, and Rafinesquia neomexicana. He suggests that the species is an oligolege of Geraea canescens. Thus most of the floral records pertain to the Compositae and in the absence of detailed field studies we consider this species to be an oligolege of the Compositae secondarily associated with Helianthus.

Hesperapis arenicola is known to occur on the Mojave and Colorado deserts being found thus far from Nevada (Clark County), California (Imperial, Riverside, San Bernardino, and San Diego counties), Arizona (Yuma County), and Mexico (Baja California Norte and Sonora).

2. Hesperapis (Panurgomia) carinata Stevens

Stage (1966) records this species from North Dakota, Nebraska, Kansas, Utah, Nevada, Oregon, and Idaho. He states that H. carinata rodecki Cockerell, originally described from Colorado, is a different species and so treats it in his revision of this group. H. carinata was described from males taken at flowers of Helianthus scaberrimus and H. petiolaris at Sheldon, North Dakota (Stevens, 1919). Subsequently, Stevens recorded females from flowers of H. petiolaris at the same locality. Stage (1966) lists the floral records from museum specimens that indicate that H. carinata has most frequently been collected from the flowers of Helianthus (H. annuus, H. lenticularis, H. petiolaris, and H. scaberrimus), but it has also been taken at the flowers of Chrysothamnus viscidiflorus (males and females) and Cucurbita (a male). Stage (1966) notes, however, that at two sites in Nevada, H. carinata exclusively visited the flowers of Helianthus for pollen and nectar even though two other composites (Chrysothamnus nauseosus and Haplopappus lanceolatus) were in bloom nearby.

It appears that H. carinata is an oligolege of the Compositae primarily associated with Helianthus.

Family MEGACHILIDAE

This is one of the largest families of bees and more than 100 species have been found to visit the flowers of Helianthus. The majority of these are pollen-collecting bees (87 species), but a number of cleptoparasitic species (16) have also been taken at the flowers, sometimes in company with the pollen-collecting species in whose nests they are parasitic. Of the pollen-collecting species, the family is represented by one species of Lithurginae and 86 species of Megachilinae including 14 species of Anthidiini and 72 species of Megachilini (one-third of which are osmiines). While the majority of the pollen-collecting species of Megachilidae that visit sunflowers are polyleges or nectar seekers (65 species), a significant number of species (22) are oligoleges of the Compositae either primarily associated with Helianthus (4 species) or secondarily so (18 species). Unquestionably the bees of this family are of much importance as pollinators of sunflowers.

Genus Lithurge Latreille

Only 6 species of this genus, which is found in both the Western and Eastern Hemispheres, are present in North America. Of these, as is discussedpresent in North America. Of these, as is discussed below, a single species has been found visiting sunflowers, apparently for nectar since our species are presumably all oligoleges of the Cactaceae.

1. Lithurge (Lithurgopsis) gibbosus (Smith)

This is a southeastern cactus oligolege ranging from North Carolina to Florida and Texas. Mitchell (1962) provides some additional flower records, including Helianthus, which was presumably being visited for nectar.

Genus Heteranthidium Cockerell

This is a North American genus containing 11 species, four of which are oligoleges of Compositae either primarily associated with Helianthus (3 species) or secondarily so (1 species). It seems possible that some of the other species of this genus for which we have incomplete or no intrafloral information may be found to be associated with sunflower. Insofar as is known, the species of this genus tend to be oligoleges, for example, H. bequaerti Schwarz on Dalea spinosa, and H. larreae (Cockerell) on Larrea tridentata.

2. Heteranthidium cordaticeps Michener

This striking but rarely encountered species was described originally from three females, one of which was taken at Austin, Texas (Michener, 1949). Males have since been recorded from New Mexico and southeastern Arizona (Snelling, 1975). One male was taken on Helianthus annuus, 0.5 miles north of Apache, 4 September 1972 (Snelling), and a second on either H. annuus or Heterotheca subaxillaris, 1020–1050, at Apache, Cochise County, Arizona, 24 August 1969 (T. J. Zavortink). Details of the collection of this species at sunflower in Rodeo, New Mexico, are given in Table C.

The species is apparently an oligolege of the Compositae primarily associated with Helianthus.

3. Heteranthidium occidentale (Cresson)

A female was taken from Helianthus lenticularis on 29 August 1907 in Colorado by Cockerell (1907a). The species is known from Colorado, New Mexico, and southern Mexico (Puebla). Since some related species of Heteranthidium are primarily associated with sunflower, we have tentatively classed H. occidentale as an oligolege of the Compositae primarily associated with Helianthus.

4. Heteranthidium timberlakei Schwarz

Heteranthidium timberlakei has been taken on a number of composites in Riverside County, California, including Helianthus gracilentus (Grigarick and Stange, 1968). It also visits other flowers such as Clarkia and Salvia (but presumably for nectar) and ranges from Oregon to southern California and western Nevada. It appears to be an oligolege of Compositae secondarily associated with Hellianthus

5. Heteranthidium zebratum (Cresson)

Recorded by Mitchell (1962) from Helianthus and Gaillardia, this species ranges from Michigan south to Mississippi and west to South Dakota, Nebraska, Colorado, and New Mexico. Swenk (1914) records it from H. annuus, H. petiolaris, and H. subrhomboideus in Nebraska, Cockerell (1909) at H. pumilus at Boulder, Colorado, and Michener (1947) at H. radula in Mississippi. The species is evidently an oligolege of Compositae primarily associated with Helianthus.

Genus Paranthidium Cockerell and Cockerell

Included in this genus are three North American species. Only one of these, P. jugatorium, is known to be associated with sunflowers, but nothing is known about the floral relationships of P. sonorum Michener (Arizona and northern Mexico) and P. macrurum (Cockerell) described from Guerrero, Mexico.

6. Paranthidium (Paranthidium) jugatorium (Say)

Paranthidium (P.) jugatorium is apparently largely oligolectic on Helianthus. Although treated as “species” by Schwarz (1926), four subspecies are currently recognized: P. jugatorium jugatorium (New York and New Jersey to Minnesota and Nebraska), P. j. lepidum (Cresson) (Kentucky and Virginia to Georgia), P. j. perpictum (Cockerell) (Colorado, New Mexico, and Arizona), and P. j. butleri Snelling (Arizona). The first of these has been recorded from Helianthus strumosus in New Jersey (Schwarz, 1926) and Wisconsin (, P) (Graenicher, 1909) and from H. divaricatus in Nebraska (Swenk, 1914). Paranthidium j. perpictum was reported at Helianthus in Boulder, Colorado, by Cockerell (1941b). Females of P. j. butleri were collected from the flowers of Helianthus and Erigeron in the Chiricahua Mountains, Arizona, at elevations ranging from 7000 to 8000 ft in September (Snelling, 1962). The species appears on the basis of current information to be an oligolege of Compositae secondarily associated with Helianthus.

Genus Anthidium Fabricius

This genus is represented by numerous species in the Old World as well as on the North and South American continents. Of the 25 species present in America north of Mexico, only the three species discussed below have been taken at the flowers of Helianthus and only one of these (A. paroselae) is known to collect pollen from these flowers.

7. Anthidium (Anthidium) maculosum Cresson

Anthidium maculosum ranges through the western states (South Dakota and Texas west to Oregon and California) into northern Mexico. Its pollen preferences are not known but it has been captured at a variety of plants representing several families, mainly Compositae and Leguminosae (Grigarick and Stange, 1968; Moldenke and Neff, 1974). Parker and Bohart (1966) found the species nesting in stems of Sambucus in Nevada. Based upon our collections (Table B, C), both sexes visit Helianthus for nectar only.

8. Anthidium (Anthidium) paroselae Cockerell

Anthidium paroselae is a polylectic bee ranging across the southwestern deserts from Texas to southern California and Sonora, Mexico. Grigarick and Stange (1968) recorded females from flowers of Palafoxia, Prosopis, and Larrea in southern California, as well as from Helianthus petiolaris var. canescens (Borrego, San Diego County, California). Hurd and Linsley (1975) found it widespread at flowers of Larrea tridentata from Las Cruces, New Mexico, to Palm Springs, California, and Hurd (1979) considers the species to be polylectic, listing additional floral information. It nests in hard sand and has two flight periods, one in the spring and one in the autumn. The species is a casual polylege of Helianthus.

9. Anthidium (Anthidium) porterae Cockerell

Recorded from Helianthus petiolaris in Nebraska (Swenk, 1914), this species occurs from British Columbia, Montana, Wyoming, Colorado, and Nebraska to Arizona, New Mexico, and Texas. Females in our limited samples at H. annuus were not taking pollen (Tables B-D). Since this species visits a variety of other flowers including Asclepias, Erigeron, Penstemon coloradensis, P. occidentata, Petalostemon, Phacelia distans, and Psilostrophe, its relationship to the flora remains unknown.

Genus Callanthidium Cockerell

Included in this genus, which is found only in the western United States and adjacent northern Mexico, are two species, only one of which appears to visit sunflowers.

10. Callanthidium illustre (Cresson)

This is a western North American polylectic species ranging from Oregon and Utah south to New Mexico, Arizona, and southern California to Baja California Norte, Mexico. It has been collected from a wide range of flowers, including Helianthus, in California (Grigarick and Stange, 1968; Moldenke and Neff, 1974). Johnson (1904) reported the species nesting in deserted burrows of Anthophora in Colorado, Hicks (1929) in dead flower stalks of yucca and oak stumps in southern California and Parker and Bohart (1966) in trap-nests. Its relationship with Helianthus is that of a casual polylege.

Genus Dianthidium Cockerell

This genus, which also occurs in the Old World, is most abundantly represented by numerous species in the Western Hemisphere. Nineteen species are known to be present in America north of Mexico, of which only three have been taken at sunflowers. Two of these are casual polyleges of Helianthus while the third, D. curvatum (Smith), is apparently an oligolege of the Compositae, visiting flowers of Aster, Chrysopsis, Helenium, Helianthus, Koellia, and Psoralea.

11. Dianthidium curvatum sayi Cockerell

This subspecies, which ranges from Alberta and Idaho to Kansas, Texas, Arizona, and eastern California, has been recorded from flowers of Helianthus annuus at Albuquerque, New Mexico, by Cockerell (1898b), from Helianthus sp. in Boulder, Colorado, by Cockerell (1914b), from H. annuus, H. petiolaris, and H. maximiliani in Nebraska by Swenk (1914), and from H. annuus in North Dakota by Stevens (1949c), who reported both sexes common on sunflowers at a site in Slope County, where they were very inactive, sucking nectar from the flowers and resting on the leaves. An additional record is as follows:

CALIFORNIA.—INYO COUNTY: 15 mi N of Bishop, 5 Aug 48, H. sp., , P (P. D. Hurd, Jr., and J. W. MacSwain).

This subspecies has been found nesting in aggregations in the soil and uses resin from the stems and leaves of Helianthus petiolaris for nest construction (Hicks, 1926; Custer and Hicks, 1927; Fischer, 1951).

Although D. c. sayi has thus far been taken only at the flowers of Helianthus, the nominate subspecies is not known to visit Helianthus despite the fact that it visits several other composites. Because of this and since no floral information is available for the subspecies D. c. xerophilum Cockerell, we regard D. c. sayi as an oligolege of the Compositae secondarily associated with Helianthus.

12. Dianthidium dubium dilectum Timberlake

Grigarick and Stange (1968) report a female of this subspecies visiting Helianthus at Tanbark Flat, Los Angeles County, California, and Moldenke and Neff (1974) record a male at Helianthus gracilentus in San Diego County, California. It is primarily confined to central and southern California and is polylectic, visiting a wide variety of flowers (see Hurd, 1979). It is apparently a casual polylege of Helianthus.

13. Dianthidium ulkei (Cresson)

The nominate subspecies was recorded from Helianthus petiolaris in Nebraska by Swenk (1914) and in California by Grigarick and Stange (1968). This subspecies occurs from British Columbia, Montana, and South Dakota south to California, Nevada, Utah, New Mexico, and Nebraska. Although it visits a wide variety of flowers (Hurd, 1979), it is possibly an oligolege of the Compositae, but is evidently only a casual visitor to Helianthus. No floral data are available for the subspecies D. u. cooleyi Schwarz, known only from Montana. The subspecies D. u. perterritum Cockerell, known from Nebraska, New Mexico, and Arizona, has been investigated by Linsley and Hurd (1959) near Portal, Arizona. They report on the mating habits of this subspecies and comment that it was very abundant on flowers of Haplopappus gracilis, Aster tanacetifolius, Helianthus, and Heterotheca subaxillaris. Thus, like the nominate subspecies, D. u. perterritum appears to be an oligolege of Compositae but its role at the flowers of Helianthus is not thoroughly understood.

Pending further field investigations we have elected to classify D. ulkei as a casual polylege of Helianthus.

Genus Anthidiellum Cockerell

Species of this genus occur on all continents. Two of the three species present in America north of Mexico have been found visiting Helianthus as casual polyleges.

14. Anthidiellum notatum notatum (Latreille)

Mitchell (1962) includes Helianthus among the several plant genera listed as hosts for this subspecies. It is thus a casual polylege of Helianthus. It ranges from Massachusetts west to Illinois and south to Florida and Mississippi. Its flight period is reported as April to September. The mating behavior has been described by Turell (1976). Other subspecies are known from western North America, but have not been found visiting sunflowers.

15. Anthidiellum perplexum (Smith)

Graenicher (1930) recorded this species at flowers of Helianthus debilis in Florida. Turell (1976) described the mating behavior on other plants. The species ranges from North Carolina to Florida and visits a number of flowers many of which are Compositae (Mitchell, 1962). It appears to be a casual polylege of Helianthus.

Genus Dioxys Lepeletier and Serville

The bees of this Holarctic genus are cleptoparasites in the nests of other megachilids. Five species are present in the Nearctic Region, two of which have been collected at the flowers of Helianthus.

16. Dioxys aurifuscus (Titus)

A western species ranging from Oregon and Idaho to Colorado and southern California, it is a cleptoparasite of Callanthidium illustre Cresson and possibly also Anthidium maculosum Cresson. Hurd (1958) lists a female at flowers of Helianthus sp. in southern California.

17. Dioxys pomonae pomonae Cockerell

This is a western subspecies ranging from Oregon and Idaho to New Mexico, Arizona, and southern California except the Sonoran Desert. It is cleptoparasitic in the nests of certain species of Anthidium, Chalicodoma, and Osmia. Hurd (1958) records both sexes from flowers of Helianthus in southern California.

Genus Heriades Spinola

Species of this genus occur in the Ethiopian, Oriental, and Holarctic Regions and are intrusively represented in the Neotropical Region (as far south as Panama). Eleven species are present in America north of Mexico and three of these have been found visiting the flowers of Helianthus, one as a regular polylege and two as casual polyleges.

18. Heriades (Neotrypetes) variolosa variolosa (Cresson)

The nominate subspecies ranges from Maine and Ontario to Florida and west to British Columbia, Washington, Oregon, Utah, New Mexico, Texas, and northern Mexico. Although a variety of flowers are known to be visited, most records involve Compositae, including Helianthus (Hurd and Michener, 1955). This subspecies appears to be a regular polylege of Helianthus.

19. Heriades (Physostetha) carinata Cresson

Heriades carinatus is widely distributed from coast to coast in southern Canada and the United States, and a wide variety of hosts have been recorded (Hurd and Michener, 1955; Mitchell, 1962), including Helianthus at Logan, Utah. The females are polylectic. Among the flowers listed for Wisconsin by Graenicher (1909) is H. strumosus, from which females were taking pollen, and by Medler and Lussenhop (1968), Helianthus sp. The nesting habits have been described by Matthews (1965) and Krombein (1967). It is a casual polylege of Helianthus.

20. Heriades (Physostetha) occidentalis Michener

Heriades occidentalis is a west coast species known from Oregon and California. Apparently polylectic, it has been reported from Helianthus sp. in Los Angeles County and H. gracilentus in San Diego County, California, by Moldenke and Neff (1974). We regard it as a casual polylege of Helianthus.

Genus Chelostomopsis Cockerell

This is a monotypic genus and is known only from the western United States.

21. Chelostomopsis rubifloris (Cockerell)

Recorded from Helianthus in southern California by Hurd and Michener (1955), the species is highly polylectic and ranges from Washington to California, but is also known from two localities in Arizona. It is a casual polylege of Helianthus.

Genus Hoplitis Klug

Although many species of this genus are present in the Holarctic and Ethiopian Regions, only 24 species are known from the Western Hemisphere (one introduced from Europe) where they are restricted to the Nearctic Region. Seven of these species have been associated with the flowers of Helianthus, five as casual polyleges, one as a regular polylege, and one as a nectar-seeking species.

22. Hoplitis (Andronicus) cylindrica (Cresson)

Females of H. cylindrica were reported gathering pollen from Helianthus strumosus in Wisconsin by Graenicher (1909). This species is polylectic, and visits flowers of many families, principally Leguminosae, Compositae, and Labiatae. It ranges from Ouebec and Nova Scotia to Florida, west to Northwest Territories, British Columbia, Colorado, and Texas. It is a casual polylege of Helianthus.

23. Hoplitis (Dasyosmia) biscutellae (Cockerell)

A male of this species was recorded by Moldenke and Neff (1974) from Helianthus niveus in Imperial County, California. It ranges from Texas to southwestern Utah, Nevada, and southern California, and is an oligolege of Larrea tridentata (Hurd and Linsley, 1975).

24. Hoplitis (Alcidamea) pilosifrons (Cresson)

Recorded from Helianthus petiolaris in North Dakota (Stevens, 1949b), this species is found from Quebec and Massachusetts to Florida and west to Alberta, Colorado, and Texas. Michener (1955), who reports that it excavates its nest in the pithy stem of Helianthus tuberosus, observed the species to store pollen of Amorpha fruticosa and Melilotus in its cells. H. pilosifrons is a polylectic species that appears to be a casual polylege of Helianthus.

25. Hoplitis (Alcidamea) producta (Cresson)

Six subspecies are currently recognized. Hoplitis producta producta has been recorded from Helianthus sp. in Wisconsin, along with other flowering plants, by Medler (1961) and Medler and Lussenhop (1968). Hoplitis producta interior Michener has been taken on Helianthus petiolaris in Colorado and H. producta bernardina Michener on Helianthus sp. in southern California (Hurd and Michener, 1955). The species as a whole is polylectic and occurs in southern Canada and throughout the United States except along the southern border and the desert areas. It appears to be a regular polylege of Helianthus.

26. Hoplitis (Alcidamea) sambuci Titus

Hoplitis sambuci is a polylectic bee occurring from British Columbia and Idaho to California, Nevada, and Utah. Hurd and Michener (1955) reported it from flowers of many plant species, including Helianthus, in southern California. It evidently is a casual polylege of that plant. Clement and Rust (1976) have provided information on the nesting habits of this species.

27. Hoplitis (Alcidamea) truncata (Cresson)

The female of this species has been recorded as taking pollen from Helianthus divaricatus in Illinois by Robertson (1929). It is apparently polylectic and visits a wide variety of flowers including Baptisia, Berlandiera, Ceanothus, Cleome, Convolvulus, Erigeron, Gillenia, Ilex, Melilotus, Oenothera, Penstemon, Pogonia graminifolia, Rubus, Tephrosia virginiana, Trifolium, Vaccinium, and Vicia. Hoplitis truncata ranges from Quebec and Maine to Florida and west to North Dakota, Wyoming, Colorado, and Arizona. It appears to be a casual polylege of Helianthus.

28. Hoplitis (Robertsonella) simplex (Cresson)

Graenicher (1909) has reported females of this species gathering pollen from Helianthus strumosus in Wisconsin. It may be that this record is a misidentification of H. gleasoni (Titus) since H. simplex ranges from Texas to Connecticut (Mitchell, 1962). Both of these species, and also H. micheneri Mitchell, occur in the eastern United States, but there are no recent records for any of these species from Wisconsin. In any case, whichever species is involved apparently is a casual polylege of Helianthus.

Genus Anthocopa Lepeletier

This rather large genus of chiefly Holarctic bees occurs in Eurasia, Africa, and western North America (west of the Great Plains). Only a single species of the more than two dozen that occur in North America has been found at the flowers of Helianthus. As is discussed below, this species is apparently an oligolege of Compositae secondarily associated with Helianthus.

29. Anthocopa (Eremosmia) hemizoniae (Cockerell)

This species was originally described from a female taken at flowers of Helianthus in Riverside County, California. The male has been taken at Helianthus gracilentus by P. H. Timberlake (Hurd and Michener, 1955) and the female is known to visit flowers of Hemizonia paniculata. Since the species may be an oligolege of the Compositae, we have classed it as secondarily associated with Helianthus.

Genus Ashmeadiella Cockerell

This Nearctic genus is represented in America north of Mexico by 50 species, the majority of which are centered in the more arid parts of the southwestern United States and adjacent Mexico. Many of the species have evolved a specialized relationship with the flora and oligolecty is a relatively common phenomenon. However, only four species are known to visit the flowers of Helianthus and only two of these are oligoleges of the Compositae secondarily associated with Helianthus. Of the remaining two species, one is a casual polylege of Helianthus and the other visits the flowers for nectar only.

30. Ashmeadiella (Ashmeadiella) bucconis (Say)

This species, which includes two subspecies, is an oligolege of Compositae secondarily associated with Helianthus.

The nominate subspecies occurs in the central United States (North Dakota south to New Mexico and Texas and east to Wisconsin, Illinois, Indiana, Missouri, and Arkansas) and has been collected on Helianthus divaricatus in Illinois by Robertson (1929); and it is reported as taking pollen on H. sp. in Nebraska and on H. petiolaris in Kansas (Hurd and Michener, 1955). Mitchell (1962) also records this bee as visiting Helianthus and Robertson (1929) provides other flower records, mostly Helianthus and Astereae.

Ashmeadiella bucconis denticulata (Cresson) has been taken on Helianthus in Arizona, Nebraska, and in Modoc County, California (Hurd and Michener, 1955). This subspecies occurs primarily west of the Rocky Mountains from British Columbia southward to southern California and Arizona, but extends eastward into Montana, Wyoming, Colorado, New Mexico, and western Texas.

This latter subspecies was collected once in our sunflower surveys as follows:

CALIFORNIA.—SAN DIEGO COUNTY: 13 Jun 74, H. gracilentus, 1300–1415, 2N (AEM, MMM).

31. Ashmeadiella (Ashmeadiella) californica (Ashmead)

This species occurs along the Pacific Coast from British Columbia to northern Baja California and in the Rocky Mountain region south to New Mexico. Most of the flower records for females are from Compositae. The subspecies A. c. sierraensis Michener has been taken on Helianthus and Solidago in Sierra County, California, and A. c. californica on Helianthus sp. in Los Angeles County (Hurd and Michener, 1955) and on H. gracilentus in San Diego County, California (Moldenke and Neff, 1974). The species is apparently an oligolege of the Compositae secondarily associated with Helianthus.

We have taken this species (a male) in our principal sunflower surveys only once (Table D). An additional collection was made as follows:

CALIFORNIA.—SAN DIEGO COUNTY: Vicinity of Laguna at junction with Highway 8, 13 Jun 74, H. gracilentus, 1300–1415, 2N (AEM, MMM).

32. Ashmeadiella (Ashmeadiella) foveata Michener

This species has been recorded from flowers of Helianthus gracilentus in the San Bernardino Mountains of southern California by Hurd and Michener (1955). However, the species is apparently polylectic, occurring from California to Arizona, Nevada, and Utah where it visits a wide variety of flowers. It is apparently a casual polylege of Helianthus.

33. Ashmeadiella (Ashmeadiella) titusi Michener

A male of this southern California bee has been recorded from Helianthus gracilentus in San Bernardino County, California, by Hurd and Michener (1955) who also list the species from flowers of Lotus scoparius (females, males) and Phacelia ramosissima (females). Ashmeadiella titusi is possibly an oligolege of Lotus.

Genus Osmia Panzer

More than 130 species of this Holarctic genus of bees are known to occur in America north of Mexico. Only eight species have established an intrafloral relationship with Helianthus, four as oligoleges of Compositae secondarily associated with sunflowers and four as casual polyleges of these plants. A few species visit sunflowers for nesting materials and thus it is important to distinguish the purpose of such visits when assessing the intrafloral relationships of these bees.

34. Osmia (Chalcosmia) coloradensis Cresson

This is a western North American oligolege of Compositae secondarily associated with Helianthus. Moldenke and Neff (1974) have recorded females from Helianthus sp. in Los Angeles County and H. gracilentus in San Diego County, California. Rust (1974) reports the species as common on Helianthus, Aster, and Senecio. The species ranges from Nebraska to Texas and west to British Columbia, Washington, Oregon, California, and northern Mexico.

35. Osmia (Chalcosmia) texana Cresson

Rust (1974) records a number of genera in six families as floral hosts for this species. Most are Compositae, including Helianthus, but the pollen-gathering relationships of O. texana to these is not reported. It appears to be an oligolege of the Compositae secondarily associated with Helianthus. Osmia texana is primarily a western species but extends to the east coast through Michigan and Ohio to New York.

36. Osmia (Cephalosmia) californica Cresson

Although Rust (1974) records this western North American species from plants in a number of genera in several plant families, most are Compositae (including Helianthus) and most of his records were from Cirsium. The species appears to be an oligolege of the Compositae secondarily associated with Helianthus. It occurs from British Columbia to California and east to Montana, Wyoming, and Colorado.

37. Osmia (Cephalosmia) grinnelli Cockerell

This is a western species ranging from Idaho to Utah, Nevada, and California. Rust (1974) provides a number of flower records including Helianthus. P. H. Timberlake has taken females on Helianthus gracilentus in the San Bernardino Mountains of southern California (Lytle Creek and Mill Creek). The species is apparently polylectic to judge from available information and is perhaps only a casual polylege of Helianthus.

38. Osmia (Cephalosmia) montana Cresson

This is a western North American species, with two recognized subspecies: the nominate form extending from the Rocky Mountain states to eastern Washington, Oregon, and California and O. m. quadriceps Cresson from southern Washington to California, Nevada, and southern Arizona (Santa Catalina Mountains). Both subspecies appear to be primarily associated with Compositae. Rust (1974) includes Helianthus in his list of genera visited by O. m. montana and Timberlake collected O. m. quadriceps at the flowers of H. gracilentus (males and females) in the San Bernadino Mountains of southern California (Mill Creek) on 18 May 1934.

The species is an oligolege of Compositae secondarily associated with Helianthus. This is borne out by analyzed pollen stores reported by Rust (1974), which indicate reliance on the Compositae for pollen including Balsamorrhiza sagittata, Cosmos, Helianthus annuus, and Wyethia amplexicaulis.

39. Osmia (Nothosmia) marginata Michener

Restricted, so far as is known at present, to the Colorado Desert of southern California, this appears to be a polylectic species flying in the spring (Hurd and Linsley, 1975). Moldenke and Neff (1974) have recorded a female from Helianthus niveus in San Diego County and Hurd (1979) lists it from H. annuus and H. gracilentus. For the present, we consider the species to be a casual polylege of Helianthus.

40. Osmia (Chenosmia) clarescens Cockerell

This is a species of the southwestern deserts from New Mexico to southern California. It is polylectic, flying in the spring (Hurd and Linsley, 1975). Moldenke and Neff (1974) record a female from Helianthus gracilentus in San Bernardino County, California. It is evidently a casual polylege of Helianthus.

41. Osmia (Diceratosmia) subfasciata subfasciata Cresson

This polylectic form ranges along the Atlantic Coast to Florida and west to the deserts of southern California (Owens Valley to the southern Colorado Desert) and northern Mexico. It was recorded from Helianthus at Falfurrias, Texas, by Cockerell (1914b). It is apparently a casual polylege of Helianthus.

Genus Megachile Latreille

This genus, which is nearly cosmopolitan in distribution, is represented in America north of Mexico by 115 species. More than 40 of these have been found at the flowers of Helianthus with only nine species being oligoleges of the Compositae either primarily (1 species) or secondarily (8 species) associated with Helianthus. The remaining species are polyleges (27) or nectar seekers (5). Nonetheless, as is readily apparent in Plate 1 and the Frontispiece, these bees, possibly because of their behavior on the flower, become liberally dusted with pollen (both females and males) and such pollen is available to effect pollination.

42. Megachile (Litomegachile) brevis Say

Megachile brevis occurs throughout the United States and Canada and is highly polylectic, visiting a wide variety of plants in many families, especially Compositae, Leguminosae, and Labiatae, including Helianthus (Viereck, 1916; Stevens, 1949b; Mitchell, 1962). Robertson (1894, 1922, 1929) regarded it as one of the most regular visitors to Helianthus in Illinois, where he found it at five local species of sunflower, H. divaricatus (N), H. grosseserratus (,P), H. mollis (), H. rigidus () and H. tuberosus (N). In Wisconsin, Graenicher (1909) found the female taking pollen from H. strumosus. Michener (1953) provides an excellent account of the biology of the species. He gives a number of flower records, but Helianthus is not included, although he reports the females nesting in dried stems of sunflower, along with other weeds and in other sites. In California females have been recorded from Helianthus sp. in Orange County and from H. annuus in Riverside County (Moldenke and Neff, 1974). These authors also report the subspecies M. b. onobrychidis Cockerell from Helianthus sp. in Fresno County. In the southeastern United States, along the coastal plain from North Carolina to Florida and the Gulf Coast to Mississippi and Georgia, the subspecies M. b. pseudobrevis Mitchell has also been recorded from Helianthus (Mitchell, 1962).

The species is a regular polylege of Helianthus.

For collecting records from principal sampling sites, see Tables B, I, and M. It has also been taken from sunflower as follows:

CALIFORNIA.—KERN COUNTY: Bakersfield 8 mi S on Highway 99, 22 Aug 76, H. annuus, 1030–1059, 1 (AEM, MMM).

43. Megachile (Litomegachile) coquilletti Cockerell

This is a western polylectic species ranging from British Columbia and Idaho to Utah, Arizona, and southern California. Moldenke and Neff (1974) have recorded one individual visiting Helianthus gracilentus in Riverside County, California. The species appears to be a casual polylege of Helianthus.

44. Megachile (Litomegachile) gentilis Cresson

This is a widespread polylectic leaf-cutter bee occurring from Texas to California, Nevada, Oregon, and Idaho (it is adventive in Hawaii). Butler (1965) records it from Helianthus in Arizona; Moldenke and Neff (1974) report females from Helianthus sp. in Kings County and H. annuus in Riverside County, California. The life history and nesting habits have been summarized by Krombein (1967). The species apparently visits the flowers of Helianthus for nectar only.

In our samples, we have not found females taking sunflower pollen. In addition to the record in Table D, it has been collected as follows:

ARIZONA.—COCHISE COUNTY: Cochise, 8 Sep 75, H. annuus, 0830–0859, 2N (EGL, JML). PINAL COUNTY: Eloy, 14 Jun 74, H. annuus, 123–1259, 1N (AEM, MMM).

45. Megachile (Litomegachile) lippiae Cockerell

This is another widespread polylectic species ranging from Montana and Nebraska to Texas, New Mexico, Arizona, and California. Butler (1965) includes Helianthus in his list of flower records for Arizona. Presumably the species is a casual polylege of Helianthus.

46. Megachile (Litomegachile) mendica Cresson

This is a widespread polylectic species which ranges from Ontario and Maine south to Florida and west to South Dakota, Colorado, Arizona, and California. Pollen-collecting females of the nominate subspecies have been collected at Helianthus strumosus in Wisconsin by Graenicher (1909) and at H. annuus in Illinois by Robertson (1929). Robertson also took the male at H. divaricatus and the species has been recorded from flowers of H. radula in Mississippi by Michener (1947). Krombein (1967) has described the life history and nesting habits. Coelioxys sayi Robertson recorded by Krombein (1967) and Medler and Lussenhop (1968) among the parasites of this species, was taken at the flowers of Helianthus by Pearson (1933).

We have taken the male of the subspecies M. m. snowi Mitchell, which occurs in Colorado, New Mexico, and Arizona, at sunflower in Cochise County, Arizona (Table D).

The species is a casual polylege of Helianthus.

47. Megachile (Litomegachile) texana Cresson

Megachile texana is a widespread polylectic species occurring across the United States and southern Canada. Robertson (1929) has recorded the female of this bee taking nectar from Helianthus in Illinois. Michener (1947) reported it at sunflower in Mississippi and Butler (1965) in Arizona. It is evidently a casual polylege of Helianthus.

Our sampling has yielded only nectar visitors (Table B) and the following accessory records:

ARIZONA.—PIMA COUNTY: Sahuarita, 26 Jun 74, H. annuus, 1200–1229, 3, 1N (AEM, MMM).

48. Megachile (Cressoniella) zapoteca Cresson

This is a Mexican and Central American species that extends into southeastern Arizona, where it has been taken on Helianthus and several other plants (Butler, 1965). The species is presumably polylectic, having been taken at the flowers Asclepias, Helenium, Lathyrus, Melilotus, and Monarda. In relationship with Helianthus it appears to be that of a casual polylege.

49. Megachile (Megachile) centuncularis (Linnaeus)

This is a Holarctic species and obviously polylectic. Males and females taking pollen from Helianthus strumosus have been recorded by Graenicher (1909) in Wisconsin. It has also been reported from Helianthus by Mitchell (1935) and Stevens (1949b). Krombein (1967) has summarized the known information on the nesting habits and parasites of this species in North America, where it is principally northern, but occurs south to Florida, Missouri, Colorado, Nevada, and Arizona. It apparently is a casual polylege of Helianthus.

50. Megachile (Megachile) inermis Provancher

Megachile inermis is a wide ranging, polylectic species that occurs from Nova Scotia to Georgia, west to British Columbia, and south to California, Utah, Colorado, New Mexico, and Texas. It has been recorded from Helianthus sp. and H. giganteus in Wisconsin by Medler (1958a) and Medler and Lussenhop (1968). Its nesting habits are well known, having been described from various localities (for references see Hurd, 1979). It is apparently a casual polylege of Helianthus.

51. Megachile (Megachile) montivaga Cresson

A widely distributed polylectic species ranging from Nova Scotia to North Carolina, west to Mexico, California and British Columbia, M. montivaga has been reported as a visitor to Helianthus by Mitchell (1935, 1962), Butler (1965), and Moldenke and Neff (1974). We collected the species only once during our surveys (Table C); in that instance it was taking pollen and nectar from H. annuus. It appears to be a regular polylege of Helianthus.

52. Megachile (Megachile) relativa Cresson

Megachile relativa is a widespread polylectic species having been found from Mackenzie to Newfoundland and south to California, Arizona, Illinois, Tennessee, and Georgia. It has been taken at flowers of Helianthus giganteus and H. grosseserratus in Wisconsin (Medler and Lussenhop, 1968). Its nesting habits have been described by Medler, (1958b), Medler and Koerber (1958), Mitchell (1962), and Medler and Lussenhop (1968). Megachile relativa is apparently a casual polylege of Helianthus.

53. Megachile (Eutricharaea) concinna Smith

An introduced species from the Palaearctic Region which is now known throughout the United States, M. concinna has been recorded from a wide range of pollen and nectar plants but not previously from Helianthus.

A single male was taken in our sunflower surveys as follows:

CALIFORNIA.—KERN COUNTY: Bakersfield 9 mi S on Highway 99, 22 Aug 76, H. annuus, 1030–1059, 1 (AEM, MMM).

54. Megachile (Delomegachile) gemula gemula Cresson

This is a widespread polylectic subspecies ranging over most of North America. Medler and Lussenhop (1968) have reported it visiting Helianthus giganteus and other flowers in Wisconsin. It appears to be a casual polylege of Helianthus.

55. Megachile (Delomegachile) melanophaea Smith

Distributed across Canada and the northern United States to Colorado, New Mexico, Arizona, and California, this polylectic species has been recorded from Helianthus by Mitchell (1935, 1962) and Butler (1965). It is parasitized by Coelioxys (Boreocoelioxys) rufitarsis which has been taken with it at flowers of Helianthus giganteus by Medler and Lussenhop (1968) in Wisconsin. It evidently is a casual polylege of Helianthus.

56. Megachile (Phaenosarus) agustini Cockerell

Megachile agustini has been recorded from Helianthus annuus in Colorado by Mitchell (1936) and Helianthus and other Compositae in Arizona by Butler (1965). The species occurs in Colorado, Utah, Arizona, and New Mexico and is apparently a casual polylege of Helianthus.

In our samples, M. agustini is represented in Table A, C, and D (New Mexico and Arizona).

57. Megachile (Phaenosarus) fortis Cresson

Megachile fortis occurs from South Dakota to Arizona and eastward and southward to Illinois, Texas, and Louisiana. Mitchell (1936) lists several collections from Helianthus, including H. petiolaris and H. subrhomboideus. The species appears to be polylectic and a regular polylege of Helianthus.

58. Megachile (Derotropis) xerophila Cockerell

Mitchell (1936) records a female of this species from Borrego Valley, San Diego County, California, 26 March, on Helianthus niveus, P. H. Timberlake, collector. The species is known only from the deserts of southern California and Arizona, flying in March, April, and May. It appears to be an oligolege of the Compositae secondarily associated with Helianthus.

59. Megachile (Xeromegachile) alata Mitchell

This species is principally associated with Compositae in Arizona, southern California, and Baja California Norte, Mexico. Moldenke and Neff (1974) have recorded a male at flowers of Helianthus gracilentus in Riverside County, California. To judge from the available floral information, this species is apparently an oligolege of the Compositae secondarily associated with Helianthus.

60. Megachile (Xeromegachile) casadae Cockerell

The species has been recorded from South Dakota, Nebraska, Oklahoma, Texas, Wyoming, Colorado, New Mexico, Utah, Arizona, and California, Mitchell (1937a) recorded the male from Helianthus in Sioux County, Nebraska. The pollen host of the female has not been reported, but the species presumably is a casual polylege of Helianthus.

61. Megachile (Xeromegachile) coloradensis Mitchell

We have found no published flower records for this species, which previously was known only from Colorado.

Our only collection of this species at sunflower is as follows:

ARIZONA.—PINAL COUNTY: Eloy, 30 Jul 75, H. annuus, 1N (AEM, MMM).

62. Megachile (Xeromegachile) dakotensis Mitchell

This species is recorded from Helianthus and other plants, mostly Compositae, by Mitchell (1937a, 1962). It has been collected in Minnesota, Iowa, Illinois, Montana, North and South Dakota, Nebraska, and Texas. The species appears to be an oligolege of the Compositae secondarily associated with Helianthus.

63. Megachile (Xeromegachile) manifesta Cresson

The male of M. manifesta was recorded from sunflower in Colorado by Mitchell (1937a). The species ranges from Alberta, Montana, and North Dakota to New Mexico, Arizona, and southern California. Most recorded flower hosts are Compositae, including Helianthus (Butler, 1965), and the species apparently is an oligolege of the Compositae secondarily associated with Helianthus.

We have taken this species on sunflowers in New Mexico (Table A) and in California as follows:

CALIFORNIA.—Los ANGELES COUNTY: Sunland, Tujunga Canyon, 14 May 75, H. annuus, 1230–1259, 3, 1P (AEM, MMM).

64. Megachile (Xeromegachile) nevadensis Cresson

This is a western species occurring from Washington and California east to Montana, Wyoming, Colorado, and New Mexico. It has been associated with a wide range of Compositae. Moldenke and Neff (1974) report it from Helianthus in Inyo County, California. It is apparently an oligolege of autumnal flowering Compositae (see Hurd, 1979), but is not known to collect pollen from Helianthus.

Our samples included only one specimen as follows:

CALIFORNIA.—SAN DIEGO COUNTY: Vicinity of Laguna Junction and Highway 8, 13 Jun 74, H. gracilentus, 1300–1415, 1 (AEM, MMM).

65. Megachile (Argyropile) mucorosa Cockerell

Mitchell (1934) recorded this species from Helianthus in War Bonnet Canyon, Sioux County, Nebraska (as M. nebraskana Mitchell) and Butler (1965) recorded it from Helianthus in Arizona. It is a species of the Great Plains and southwestern United States and occurs from Nebraska and Kansas to Wyoming, Colorado, Utah, Arizona, New Mexico, and Texas.

One example was taken in our surveys as follows:

ARIZONA.—SANTA CRUZ COUNTY: Sonoita, 16 Aug 74, H. annuus, 1N (PDH, AEM, MMM).

The species has, in addition to Helianthus, been collected at the flowers of Eustoma issenianum, Monarda, and Ratibida columnaris. It is judged to be a casual polylege of Helianthus.

66. Megachile (Argyropile) parallela Smith

FIGURE 6; PLATE 1, FRONTISPIECE

Megachile parallela is transcontinentally distributed in southern Canada and the United States and is found as far south as the Isthmus of Tehuantepec. It has been reported visiting a wide variety of flowers, notably those of the Compositae (Hurd, 1979), but seems to be primarily associated with Helianthus. It has been reported from flowers of Helianthus maximiliani at Dallas, Texas, by Cockerell (1914b), at H. annuus lenticularis in Nebraska by Cockerell (1923), at H. petiolaris in Nebraska and Colorado by Mitchell (1937b), and H. radula in Mississippi by Michener (1947). In California, both sexes have been recorded from H. annuus in Riverside County, from H. gracilentus in San Diego County and a female from H. nuttallii in Lassen County (Moldenke and Neff, 1974). Records provided by Robertson (1929) including H. divaricatus (P) and H. mollis () suggest a preference for species of Heliantheae and Astereae. The nest has been described by Fischer (1951) and by Medler and Lussenhop (1968).

This primary oligolege of Helianthus was taken in most of our principal survey sites (see Table A–D, F, G, K, L), and also as follows:

ARIZONA.—COCHISE COUNTY: Cochise, 8 Sep 75, H. annuus, 0800–0859, 2, 13P, 15N (EGL, JML). GRAHAM COUNTY: Franklin, 6 Aug 75, H. annuus, 1130–1159, 1 (EGL, JML). PIMA COUNTY: Marana, 27 Jun 74, H. annuus, 1030–1059, 1, 1N (AEM, MMM). SANTA CRUZ COUNTY: Nogales, 15 Sep 77, H. annuus, 0800–0859, 6 (EGL, JML); Patagonia, 7 Sep 77, H. annuus, 0730–0759, 1P (EGL, JML); Sonoita, 16 Aug 74, H. annuus, 4, (PDH, AEM, MMM); Sonoita, 10 mi E, 7 Sep 77, H. petiolaris, 0830–0859, 1 (EGL, JML). YUMA COUNTY: Tacna, 29 Jul 75, H. annuus, 1415–1429, 1P (AEM, MMM).

FIGURE 6.—Distribution of Megachile (Argyropile) parallela Smith.

CALIFORNIA.—FRESNO COUNTY: Parlier, 7 Sep 75, H. annuus, 1400–1429, 1N (EGL, JML, AEM, MMM). IMPERIAL COUNTY: El Centro, 29 Jul 75, H. annuus, 1015–1029, 3 (AEM, MMM). INYO COUNTY: Tuttle Creek, 4 mi W of Lone Pine, 29 Aug 77, H. annuus, 1030–1059, 1N (EGL, JML); KERN COUNTY: Bakersfield 8 mi S on Highway 99, 22 Aug 76, H. annuus, 1030–1059, 1, 1N (AEM, MMM). MERCED COUNTY: Atwater, 23 Jul 77, H. annuus, 1100–1129, 1N (EGL, JML, AEM, MMM). ORANGE COUNTY: Newport Beach, 25 Sep 76, H. annuus, 1 (AEM, MMM). RIVERSIDE COUNTY: Coachella, 8 Jun 76, H. annuus, 0900–0929, 2, 4P, 3N (EGL, JML); Indio, 8 Jun 76, H. annuus, 0800–0829, 3 (EGL, JML).

67. Megachile (Argyropile) sabinensis Mitchell

This species is presently known only from Arizona, New Mexico, and Texas. Butler (1965) has recorded it from Helianthus, as well as Aster, Baileya, Eriogonum, and Haplopappus. It appears to be an oligolege of the Compositae secondarily associated with Helianthus.

68. Megachile (Argyropile) townsendiana Cockerell

This species has been recorded from Helianthus debilis in Florida by Graenicher (1930) and from H. sp. in Arizona by Butler (1965). The species ranges from North Carolina to Florida and west to Oklahoma, Texas, Colorado, New Mexico, Arizona, southeastern California, and northern Mexico. We have encountered it once in our surveys as follows:

ARIZONA.—COCHISE COUNTY: Cochise, 8 Sep 75, H. annuus, 0830–0859, 1 (EGL, JML).

It appears to be a casual polylege of Helianthus.

69. Megachile (Xanthosarus) dentitarsus Sladen

This species has been recorded from Alberta, Washington, Montana, North and South Dakota, Wyoming, Nebraska, Colorado, Utah, New Mexico, and Arizona. Mitchell (1936) lists it from Helianthus petiolaris in Nebraska. It is apparently polylectic, visiting a number of different kinds of flowers, and appears to be a casual polylege of Helianthus.

70. Megachile (Xanthosarus) latimanus Say

This is a largely northern species ranging from Nova Scotia to Alberta and on the southern extreme from Georgia to Kansas, Colorado, and Wyoming. Robertson (1894, 1922, 1929) classed it as one of the most regular visitors to sunflowers in Illinois, where he found it on all local species, including Helianthus divaricatus (P), H. grosseserratus (, P), H. mollis (, P), H. rigidus (, N) and H. tuberosus (N). In Wisconsin, Graenicher (1909) found it at H. giganteus() and H. strumosus (, P). Mitchell (1936, 1962) also recorded it from Helianthus, along with other Compositae, a group for which he suggested the bees had preference, and Stevens (1949b) recorded it from H. maximiliani and H. rigidus in North Dakota and Medler and Lussenhop (1968) from H. giganteus and H. grosseserratus in Wisconsin.

Megachile latimanus, however, appears to be mainly dependent upon the pollen of a wide variety of other plants (Hurd, 1979) and is judged to be a casual polylege of Helianthus.

71. Megachile (Xanthosarus) perihirta Cockerell

This species ranges from British Columbia to Mexico and east to Nebraska and Texas (Mitchell, 1962). It has been recorded from Helianthus annuus by Mitchell (1936), H. sp. in Arizona by Butler (1965) and Moldenke and Neff (1974), who also report females at H. petiolaris in Stanislaus County and H. sp. elsewhere in California. Megachile perihirta is polylectic and evidently is a regular polylege of Helianthus.

Our records of this species at sunflower are from coastal southern California:

CALIFORNIA.—Los ANGELES COUNTY: Pico Rivera, 11 Aug 75, H. annuus, 1 (AEM, MMM). ORANGE COUNTY: Newport Beach, 21–25 Aug 75, H. annuus, 1500–1545, 2, 4P, 4N (AEM, MMM).

72. Megachile (Leptorachis) petulans Cresson

This polylectic species visits a wide variety of composites and legumes (Robertson, 1929; Mitchell, 1962) and ranges from New Jersey to Florida and west to North Dakota, Nebraska,—1 166Arizona, and Mexico. Robertson (1929) records Arizona, and Mexico. Robertson (1929) records it from the flowers of H. divaricatus (, P), H. mollis (N) and strumosus () in Illinois and Mitchell (1937b) lists it from H. atrorubens and H. sp. in North Carolina. It appears to be a casual polylege of Helianthus.

73. Megachile (Pseudocentron) pruina pruina Smith

Mitchell (1937b) recorded this subspecies from Helianthus in Florida. It ranges from North Carolina to Florida and also occurs on Bermuda. It is apparently a casual polylege of Helianthus.

74. Megachile (Pseudocentron) sidalceae Cockerell

Recorded from Helianthus ciliaris at Mesilla, New Mexico, by Cockerell (1900) and H. sp. in Arizona by Butler (1965), this species ranges from Texas to southern California and Mexico and is generally common throughout its range. It is polylectic and apparently visits Helianthus for nectar only.

Our collections of this species from sunflower sampling sites are mostly males, as follows:

ARIZONA.—COCHISE COUNTY: Cochise, 8 Aug 75, H. annuus, 8 Aug 75, 0800–0829, 1N (EGL, JML). MARICOPA COUNTY: Theba, 28 Jun 74, H. annuus, 0955–1200, 4, 1N (AEM, MMM). PIMA COUNTY: Marana, 27 Jun 74, H. annuus, 1030–1059, 1 (AEM, MMM), 30 Jul 75, H. annuus, 1100–1114 2 (AEM, MMM); Sahuarita, 26 Jun 74, H. annuus, 1200–1229, 6 (AEM, MMM). PINAL COUNTY: Eloy, 14 Jun 74, H. annuus, 1130–1159, 1 (AEM, MMM). YUMA COUNTY: Tacna, 14 Jun 74, H. annuus, 1305–1325, 1 (AEM, MMM).

75. Megachile (Acentron) albitarsis Cresson

This is a polylectic species ranging from Michigan and Indiana to North Carolina and Florida and west through Texas to Arizona and northern Mexico (Mitchell, 1962). Michener (1947) has recorded it from Helianthus radula in Mississippi, Robertson (1894, 1898) from H. divaricatus and H. tuberosus. It appears to be a casual polylege of Helianthus.

76. Megachile (Melanosarus) xylocopoides Smith

This polylectic leaf-cutter bee ranges from Maryland to Florida and through the Gulf States to Texas. Cockerell (1900) recorded it from Helianthus ciliaris in New Mexico. The life history and parasites have been treated by Krombein (1967). It appears to be a casual polylege of Helianthus.

77. Megachile (Sayapis) fidelis Cresson

Recorded from Helianthus petiolaris by Mitchell (1937b) (locality not specified), from Helianthus in Arizona by Butler (1965), and from H. gracilentus in southern California, this species ranges from Montana, South Dakota, Nebraska, and New Mexico, west to Idaho, Oregon, and California. It is a polylectic species that appears to be a regular polylege of Helianthus.

78. Megachile (Sayapis) frugalis Cresson

The nominate subspecies was recorded from Helianthus by Butler (1965). Mitchell (1962) gives the range as Pennsylvania and New Jersey to Florida and west to California and Mexico. A female of M. frugalis pseudofrugalis taking pollen from Helianthus gracilentus was captured by P. H. Timberlake at The Gavilan, Riverside County, California, in June.

Megachile frugalis is a polylectic species whose relationship with Helianthus is judged to be that of a casual polylege.

79. Megachile (Sayapis) helianthi Cockerell

This species was described by Cockerell (1908) from material collected from Helianthus lenticularis at Boulder, Colorado, and later was again recorded from this plant by Cockerell (1914b). No additional floral information is available. It is possibly an oligolege of the Compositae and may be secondarily associated with Helianthus.

80. Megachile (Sayapis) inimica Cresson

Three subspecies, M. (S.) inimica sayi Cresson (northern), M. (S.) i. inimica Cresson (southern), and M. (S.) i. jacumbensis Mitchell (California, Baja California) are recognized by Mitchell (1962) and others. The northern subspecies was regarded as one of the most regular visitors to sunflowers in Illinois by Robertson (1894, 1922, 1929) who found it at Helianthus divaricatus (P), H. grosseserratus (P), H. rigidus (P), and H. tuberosus (P). Mitchell (1937b) included Helianthus petiolaris among the flower hosts for M. inimica and Medler and Lussenhop (1968) listed it from Helianthus spp. in Wisconsin. Butler (1965) recorded two of the subspecies from Arizona, but only M. inimica sayi from Helianthus. The life histories and nest structures of each subspecies have been described by Krombein (1967).

Megachile inimica is evidently an oligolege of the Compositae secondarily associated with Helianthus.

This important pollinator of sunflowers was taken at our primary sampling sites (Table A–C, K) as well as the following:

ARIZONA.—GRAHAM COUNTY: Franklin, 6 Aug 75, H. annuus, 1130–1159, 2 (EGL, JML). SANTA CRUZ COUNTY: Sonoita, 16 Sep 74, H. annuus, 3 (PDH, AEM, MMM).

81. Megachile (Sayapis) policaris Say

Recorded from Helianthus by Mitchell (1962) and Butler (1965), this species ranges from Georgia and Florida west to California and south into Mexico. Krombein (1967) described the nesting habits in Arizona. Pollen analysis revealed that females were storing pollen from mesquite (Prosopis). The species, however, is polylectic, especially preferring flowers of the Compositae, and is a regular polylege of Helianthus.

Documenting M. policaris as an important pollinator of sunflowers, data from our collections are available in Table A–C and G. It was also taken as follows:

ARIZONA.—PIMA COUNTY: Marana, 27 Jun 74, H. annuus, 1030–1059, 3N (AEM, MMM); San Xavier, 19 Sep 74, H. annuus, 1200–1229, 1 (AEM and MMM).

CALIFORNIA.—IMPERIAL COUNTY: Holtville 3 mi W, 29 Jul 75, H. annuus, 1100–1114, 1P (AEM, MMM).

82. Megachile (Sayapis) pugnata pugnata Say

Recorded from Helianthus tuberosus by Mitchell (1937b), from H. divaricatus (P) in Illinois by Robertson (1929), from H. strumosus (, P) by Graenicher (1909) and H. giganteus and H. grosseserratus in Wisconsin by Medler (1964) and Medler and Lussenhop (1968), this subspecies occurs transcontinentally in the United States and southern Canada, but is absent in the lower Mississippi Valley and Gulf Coast. It is an oligolege of the Compositae secondarily associated with Helianthus.

We have collected this species at sunflower once as follows:

ARIZONA.—SANTA CRUZ COUNTY: Nogales, 15 Sep 77, H. annuus, 0930–0959, 1N (EGL, JML).

Genus Chalicodoma Lepeletier

This genus, which is represented in North America by two subgenera, also contains a number of subgenera in the Old World and one in South America. Nineteen species are known from America north of Mexico, of which seven visit sunflowers, two as casual polyleges and the others as nectar visitors.

83. Chalicodoma (Chelostomoides) angelarum (Cockerell)

This species occurs from British Columbia to southern California, Nevada, and Arizona, exclusive of the desert areas. The females are polylectic and visit a wide variety of plants for pollen. Moldenke and Neff (1974) report a female at Helianthus sp. in Stanislaus County and a male at H. gracilentus in San Diego County, California.

In addition to the record in Table K, one example was taken in the sunflower surveys as follows:

CALIFORNIA.—KERN COUNTY: Bakersfield 8 mi S on Highway 99, 22 Aug 76, H. annuus, 1030–1059, 1N (AEM, MMM).

The species is evidently only a casual polylege of Helianthus.

84. Chalicodoma (Chelostomoides) campanulae campanulae (Robertson)

Medler and Lussenhop (1968) provide a number of flower records for this species in Wisconsin, including Helianthus sp. The nesting habits have been reported by Medler (1966), Medler and Lussenhop (1968), Krombein (1967), and others. It ranges from Quebec and Massachusetts to Florida and west to Iowa, Wisconsin, Minnesota, Nebraska, Kansas, and Texas. It appears to be polylectic and presumably is a casual polylege of Helianthus. The other subspecies, C. c. wilmingtoni (Mitchell) occurs along the coastal areas from Virginia to Florida but is not known to visit sunflowers.

85. Chalicodoma (Chelostomoides) chilopsidis (Cockerell)

Chalicodoma chilopsidis was reported as a visitor to Helianthus in Arizona by Butler (1965). It is a southwestern species ranging from Texas to southern California and northern Mexico taking pollen primarily from flowering desert trees and shrubs, especially Leguminosae. It presumably visits Helianthus only for nectar.

86. Chalicodoma (Chelostomoides) occidentalis (Fox)

This species ranges across the southwestern deserts from western Texas to southern California. It is polylectic and is often found at flowering trees and shrubs. Butler (1965) has recorded it from Helianthus in Arizona.

Our records, based upon casual nectar visitors, may be found in Table C and F and as follows:

ARIZONA.—PIMA COUNTY: San Xavier, 19 Jun 74, H. annuus, 1200–1229, 2P (PDH, AEM, MMM).

It thus appears to seek only nectar from sunflowers.

87. Chalicodoma (Chelostomoides) odontostoma (Cockerell)

Butler (1965) recorded this species as a Helianthus visitor in Arizona. It occurs in the deserts of southern California, Arizona, New Mexico, and northwestern Mexico, primarily at flowering trees and shrubs, but it has also been taken at annuals presumably questing for nectar.

88. Chalicodoma (Chelostomoides) spinotulata (Mitchell)

This species is a polylege expecially of desert trees and shrubs. It occurs through the southwestern deserts from western Texas to southern California. The male has been reported at Helianthus sp. in Los Angeles County, California, by Moldenke and Neff (1974).

89. Chalicodoma (Chelostomoides) subexilis (Cockerell)

This species ranges from Nebraska, Colorado, and Utah, south to New Mexico, Arizona, and California. It has been reported as a visitor to flowers of Helianthus at Boulder, Colorado, by Mitchell (1937b). It has been recorded from a variety of flowering plants and is apparently polylectic.

Genus Coelioxys Latreille

These bees, which are cleptoparasites primarily in the nests of Megachile and relatives, occur on all continents. Nearly 50 species are found in America north of Mexico and a number of these (14 species) have been taken at the flowers of Helianthus, sometimes in the company of their host species. Doubtless additional species of this genus will be found visiting sunflowers.

90. Coelioxys (Coelioxys) sodalis Cresson

Graenicher (1909) records the female of this species at flowers of Helianthus strumosus in Wisconsin. The species ranges from Alaska and Canada (N.W.T.), south to California, Arizona, and New Mexico in the west and the Great Lakes and New England states in the east.

91. Coelioxys (Boreocoelioxys) banksi Crawford

A male and female have been recorded by Moldenke and Neff (1974) from Helianthus without locality data. The species is widespread, ranging transcontinentally from Quebec and North Carolina to British Columbia and south to New Mexico, Arizona, and California.

92. Coelioxys (Boreocoelioxys) moesta Cresson

Coelioxys moesta is widely distributed from Alaska to Nova Scotia and southward to Virginia, New Mexico, Arizona, and California. Medler and Lussenhop (1968) include Helianthus giganteus among their flower records for Wisconsin.

93. Coelioxys (Boreocoelioxys) novomexicana Cockerell

This species ranges from Texas to California and Oregon and southward into northern Mexico. Moldenke and Neff (1974), without locality data, list a male at flowers of Helianthus sp.

94. Coelioxys (Boreocoelioxys) octodentata Say

Both sexes of this bee have been recorded from Helianthus strumosus in Wisconsin by Graenicher (1909) and males from H. divaricatus and H. mollis in Illinois by Robertson (1929). The species occurs transcontinentally in the United States, southern Canada and south into Mexico.

95. Coelioxys (Boreocoelioxys) rufitarsus Smith

This species has been reported at flowers of Helianthus in Illinois by Pearson (1933) and more specifically at H. grosseserratus () by Robertson (1929). In Wisconsin it has been taken at H. strumosus () by Graenicher (1909) and H. giganteus by Medler and Lussenhop (1968). Host species for this parasite include Megachile latimanus and M. melanophaea (Graenicher, 1905) both of which also visit Helianthus. The species occurs transcontinentally in the United States, southern Canada and south into Mexico.

96. Coelioxys (Boreocoelioxys) sayi Robertson

Coelioxys sayi has been recorded from Helianthus divaricatus at Carlinville (Robertson, 1929) and in the Chicago, Illinois, area by Pearson (1933). Graenicher (1909) found the male at H. strumosus in Wisconsin. The species occurs from New York to Florida and west to Nebraska, Colorado, and Arizona. It is a parasite of Megachile (Litomegachile) mendica (Medler, 1965; Krombein, 1967), which has also been taken at flowers of Helianthus.

97. Coelioxys (Xerocoelioxys) edita Cresson

This parasitic bee has been recorded from the flowers of Helianthus annuus by Mitchell (1973) and by Moldenke and Neff (1974). It is a wide ranging species extending across the continent (Florida, Illinois, Missouri, Arkansas, and Texas, west to Alberta, Washington, Oregon, and California).

Details of the capture of this species at sunflower in the principal sampling sites in New Mexico are given in Table B and C. In addition, a male was taken as follows:

CALIFORNIA.—RIVERSIDE COUNTY: Indio, 8 Jun 76, H. annuus, 0800–0829, I (EGL, JML).

98. Coelioxys (Schizocoelioxys) funeraria Smith

A male of this species was taken on flowers of Helianthus strumosus in Wisconsin by Graenicher (1910a). The species ranges from Alaska, Yukon, and British Columbia east to Nova Scotia, south to Illinois, Indiana, Pennsylvania, and Georgia in the east, and south to California, Utah, and New Mexico in the west. It parasitizes the nests of several species of Megachile including M. latimanus and M. relativa, which also visit sunflowers.

99. Coelioxys (Synocoelioxys) alternata Say

Robertson (1929) recorded the capture of a female of this species at Helianthus divaricatus. The species ranges from Quebec to North Carolina and west to British Columbia, Washington, Utah, and Arizona. Medler and Lussenhop (1968) report the species to be cleptoparasitic in the nests of Megachile pugnata, a species that commonly visits sunflowers.

100. Coelioxys (Synocoelioxys) texana Cresson

Graenicher (1909) found the male of this species at Helianthus strumosus. Mitchell (1973) also reported this species as a visitor to Helianthus. It is a parasite of Megachile policaris (Krombein, 1967), which also visits Helianthus. The species occurs from Florida, Missouri, Kansas, Oklahoma, and Texas, west to southern California, and south into Central America.

101. Coelioxys (Neocoelioxys) menthae Cockerell

This species is thus far known primarily from Arizona and New Mexico, but it ranges south through Mexico into Central America (San Salvador). Presumably parasitic in the nest of Megachile, its host has not been reported. Both sexes seek nectar from a variety of flowers. The capture of a male at H. annuus is reported in Table C.

102. Coelioxys (Glyptocoelioxys) germana Cresson

This species of Coelioxys was reported as a visitor to Helianthus divaricatus at Carlinville, Illinois, by Robertson (1929) and Helianthus sp. in the Chicago region of Illinois, by Pearson (1933). It ranges from Illinois to New Jersey and south to Florida.

103. Coelioxys (Cyrtocoelioxys) modesta Smith

A male was taken at Helianthus strumosus by Graenicher (1909) in Wisconsin. The species ranges from Quebec and the New England states west to Nebraska and south into Florida and Texas.

Family ANTHOPHORIDAE

This is one of the largest families of bees and more than 140 species have been found to visit the flowers of Helianthus. The majority of these are pollen-collecting bees (109 species), but a number of cleptoparasitic species (35) have also been taken at the flowers, sometimes in company with the pollen-collecting species in whose nests they are parasitic. Of the pollen-collecting species, the family is represented by relatively few Xylocopinae (14 species) but by numerous species of the Anthophorinae (95), many of which are members of the tribe Eucerini (74 species). While the majority of the pollen-collecting species of Anthophoridae that visit sunflowers are polyleges (35 species) or nectar seekers (27 species), a very significant number of species (47) are oligoleges of the Compositae either primarily associated with Helianthus (12 species) or secondarily so (35 species). In this regard only the Andrenidae contains more species of oligoleges (50) either primarily associated with Helianthus (18) or secondarily so (32). Clearly the bees of this family are of much importance in the pollination of sunflowers.

Genus Neolarra Ashmead

The bees of this North American genus are very small-sized cleptoparasites in the nests of Perdita and Nomadopsis. Fourteen species are known from the United States, only two of which have been found in Mexico (Shanks, 1977).

1. Neolarra helianthi Cockerell

This small parasitic bee was described by Cockerell (1936) from a male captured at Helianthus petiolaris in Colorado. Since the completion of this study, it has been placed as a synonym of the following species by Shanks (1977).

2. Neolarra verbesinae (Cockerell)

Recorded from flowers of Helianthus in Nebraska by Swenk (1907) and H. petiolaris in North Dakota by Stevens (1951a), this species ranges south to New Mexico, Arizona, and Texas according to Shanks (1977), who also records it from Helianthus sp. as well as other flowers. An additional Helianthus record was published for this species under the name Neolarra helianthi Cockerell (see above species account).

Genus Holcopasites Ashmead

Insofar as is known, the species of this North American genus are cleptoparasites in the nests of pollen-collecting bees belonging to the subfamily Panurginae of the family Andrenidae. Of the 15 species known, only the species treated below has been found at sunflowers.

3. Holcopasites heliopsis (Robertson)

This species, which ranges from Alberta, Montana, Colorado, and Illinois south to Arkansas and Kansas, has been recorded from Helianthus in Nebraska by Hurd and Linsley (1972). It may be a parasite of Calliopsis nebraskensis Crawford, which has not been found visiting Helianthus.

Genus Epeolus Latreille

Insofar as is known, the species of this chiefly Holarctic genus are cleptoparasitic in the nests of the genus Colletes. Of the 50 species known from America north of Mexico, only four have been taken at sunflowers.

4. Epeolus autumnalis Robertson

Robertson (1929) recorded the males as frequent at the flowers of Helianthus divaricatus in Carlinville, Illinois, and found both sexes visiting H. tuberosus at the same locality. It is believed that this species may be a parasite of Colletes compactus, an oligolege of Compositae secondarily associated with Helianthus.

5. Epeolus bifasciatus Cresson

Two subspecies are recognized: one, the nominate form, ranging from New England to Florida, west to Minnesota, Colorado, and Texas, and south into northern Mexico, has been collected by Robertson (1929) at Helianthus divaricatus (male only); the other, E. b. obscuripes Cockerell, ranges from Mexico to Panama and has not been taken at sunflower. Epeolus bifasciatus proper may be a parasite of Colletes latitarsis Robertson, which has not been taken at sunflowers.

6. Epeolus compactus Cresson

This species, which ranges from Illinois west to Texas, Colorado, Nevada, and California, has been reported at flowers of Helianthus divaricatus by Robertson (1898).

7. Epeolus pusillus Cresson

Robertson (1898, 1929) recorded a male of this species from flowers of Helianthus divaricatus in Illinois. It occurs from Maine to Florida and west to Texas and Wyoming. It is parasitic in the nests of several Colletes including those of C. compactus, an oligolege of the Compositae secondarily associated with Helianthus.

Genus Triepeolus Robertson

While most of the known host information suggests that these bees are cleptoparasites in the nests of eucerine bees (e.g., Melissodes, Peponapis, Svastra, and Xenoglossa), at least some species are known to be parasites of other Anthophoridae (e.g., Anthophora, Centris) as well as Colletidae (Ptiloglossa), Oxaeidae (Protoxaea), and Halictidae (Nomia). The genus is almost exclusively New World in occurrence, with most of the species centered in North America, although a few species are present in South America and one of these ranges well northward into Central America. More than 100 species are found in America north of Mexico and 18 of these have been taken at the flowers of Helianthus. We have also collected a number of undescribed species from these flowers and anticipate that a great many more species of this genus will be found to visit sunflowers. Thus in the accounts that follow, only the described species are discussed.

8. Triepeolus concavus (Cresson)

FIGURE 7

This species, a parasite in the nest of Svastra obliqua (Custer, 1928, 1929b), is, like its host bee, a frequent visitor to Helianthus, from which both sexes extract nectar. Robertson (1922, 1929) designates it as one of the most regular visitors to sunflowers at Carlinville, Illinois, where he found it at seven local species of Helianthus: H. annuus (, ), H. divaricatus (, ), H. grosseserratus ( frequent), H. mollis (), H. rigidus (, ), H. strumosus () and H. tuberosus (). Cockerell (1923) recorded it from H. annuus lenticularis at Oxford and Friend, Nebraska. The species ranges from North Carolina and Florida west to Illinois, Wisconsin, Colorado, and California.

Records of the collection of this species at principal sampling sites are presented in Table K and M. Additional records are as follows:

ARIZONA.—GRAHAM COUNTY, Franklin, 6 Aug 75, H. annuus, 1130–1159, 1 (EGL, JML). YUMA COUNTY: Tacna, 29 July 75, H. annuus, 1415–1429, 1 (AEM, MMM); Wellton, 5 Sep 74, H. annuus, 1100–1120, 1 (AEM, MMM).

CALIFORNIA.—RIVERSIDE COUNTY: Blythe, 29 Jun 74, H. annuus, 0800–0829, 1 (AEM, MMM). SAN JOAQUIN COUNTY: Victoria Island 0.5 mi E of Old River, 21 Jul 77, H. annuus (commercial sunflowers), 0930–0959, 3, at nest site of Svastra obliqua at edge of field of commercial sunflower, 1 (EGL, JML, AEM, MMM). STANISLAUS COUNTY: Patterson, 27 Jul 77, 0930–0959, 2 (EGL, JML, AEM, MMM).

FIGURE 7.—Tripeolus concavus (Cresson), female. (Drawn by Elaine R. Hodges, Department of Entomology, Smithsonian Institution.)

At all the sites recorded above, T. concavus was visiting H. annuus in the company of Svastra obliqua.

9. Triepeolus cressonii cressonii (Robertson)

Robertson (1922) reported that this subspecies was one of the most regular visitors to Helianthus at Carlinville, Illinois, where he found it visiting five of the eight local species, including H. divaricatus (, , frequent), H. grosseserratus (, frequent), H. mollis (), and H. strumosus () (Robertson, 1929). It ranges from the New England states to North Carolina, Tennessee, and Minnesota.

Floral information is unavailable concerning the other subspecies, T. c. fraseri Cockerell, described from New Mexico.

10. Triepeolus cyclurus Cockerell

Described originally from a female taken at flowers of Helianthus petiolaris near Wiggins, Colorado (Cockerell, 1923), no additional material has come to our attention.

11. Triepeolus dacotensis (Stevens)

A male and female have been recorded from flowers of Helianthus petiolaris in North Dakota by Stevens (1919, 1951a). The species is also known from Utah.

12. Triepeolus donatus (Smith)

Triepeolus donatus has been reported at flowers of Helianthus divaricatus (, , frequent) and H. grosseserratus (, ) by Robertson (1929), from H. strumosus () by Graenicher (1909), and H. sp. by Mitchell (1962). It occurs from the New England states and southern Canada to Wisconsin and Georgia.

13. Triepeolus helianthi (Robertson)

The typical subspecies has been recorded from flowers of Helianthus by Robertson (1898) and Mitchell (1962), and more specifically from H. grosseserratus (, , abundant) by Robertson (1929). Several subspecies have been recognized but their status needs review in the light of subsequent material. Collectively these occur from Wisconsin and Illinois to Colorado, New Mexico, and Arizona. The host of the nominate subspecies is Melissodes (Eumelissodes) trinodis (Graenicher, 1905) an oligolege of Compositae, primarily associated with Helianthus. Hurd and Linsley (1959) present information that suggests that this species is also parasitic in the nests of M. (Callimelissodes) composita, an oligolege of Compositae, secondarily associated with Helianthus. Robertson (1929) has recorded it in Illinois from Helianthus divaricatus and so does Pearson (1933).

14. Triepeolus lestes Cockerell

Known from Colorado and California, this species has been recorded from flowers of Helianthus annuus in Riverside County, California, by Moldenke and Neff (1974).

The capture of this species at sunflower in a principal survey site is reported in Table F. In addition, it was taken in another sample as follows:

CALIFORNIA.—INYO COUNTY: Tuttle Creek, 4 mi W of Lone Pine, 29 Aug 77, H. annuus, 1030–1059, 1, 1 (EGL, JML).

At the sites where this species was taken, it was visiting the flowers in the company of Melissodes agilis.

15. Triepeolus lineatulus Cockerell and Sandhouse

Triepeolus lineatulus is a southwestern species, presently known from California and Arizona. In California it has been recorded at flowers of Helianthus annuus, H. bolanderi, and H. sp. by Moldenke and Neff (1974). Our collections of this species were made at two of the principal collecting sites (Table H and K).

16. Triepeolus lunatus (Say)

This species has been recorded from Helianthus divaricatus (, , frequent) and H. tuberosus () in Illinois by Robertson (1898, 1929). Mitchell (1962) recognizes two subspecies, T. lunatus lunatus and T. lunatus concolor, both of which appear to have similar geographical ranges and both of which have been taken on Helianthus as well as other hosts. The species has been demonstrated to be a parasite of Melissodes (Melissodes) bimaculata bimaculata, which is a regular polylege of Helianthus.

17. Triepeolus nevadensis (Cresson)

Robertson (1898, 1929) reported this species at flowers of Helianthus divaricatus () in Illinois. It ranges from North Carolina and Georgia west to Nebraska, Nevada, and New Mexico.

18. Triepeolus norae Cockerell

We have been unable to find any prior flower records for this parasitic bee, which occurs in New Mexico and southern Arizona. We found this species in numbers at only one of our primary sampling sites (Table C).

19. Triepeolus pectoralis (Robertson)

Graenicher (1909) found females of this species visiting the flowers of Helianthus strumosus in Wisconsin. Triepeolus pectoralis ranges from Maine to Georgia and west to Minnesota, Colorado, and Utah. Melissodes (Eumelissodes) rustica, suspected of being one of its hosts, is an oligolege of the Compositae, secondarily associated with Helianthus.

20. Triepeolus rectangularis Cockerell

Triepeolus rectangularis is a western species (Colorado, Utah, Oregon, and California) that has been recorded as visiting flowers of Helianthus in California by Moldenke and Neff (1974).

21. Triepeolus remigatus (Fabricius)

This species has been recorded from Helianthus at Clarendon, Texas (Cockerell, 1914b), from H. annuus lenticularis at Friend, Nebraska (Cockerell, 1923), and H. divaricatus () in Illinois by Robertson (1929). It is a widespread species ranging from New Jersey to Florida, west to Minnesota, Colorado, and California, and south to Texas, New Mexico, Arizona, and northern Mexico.

22. Triepeolus simplex Robertson

Recorded from Helianthus divaricatus () in Illinois by Robertson (1929) and from the same plant near Chicago by Pearson (1933), this species ranges from Wisconsin, Illinois, and Michigan south to North Carolina and Georgia.

23. Triepeolus subnitens Cockerell and Timberlake

This species was described from a female captured at Helianthus annuus, at Riverside, California, in June.

We collected a single specimen in our surveys as follows:

CALIFORNIA.—SAN JOAQUIN COUNTY: Victoria Island 0.5 mi E of Old River, 21 Aug 77, entering burrow of Svastra obliqua on edge of commercial sunflower field, 0930–0959, 1 (EGL, JML, AEM, MMM).

The presumed host, S. obliqua, is an oligolege of the Compositae primarily associated with Helianthus.

24. Triepeolus texanus (Cresson)

Cockerell (1898a) has recorded the male of Triepeolus texanus var. nigripes from flowers of Helianthus ciliaris from Mesilla, New Mexico. Currently this is regarded as a subspecies of T. texanus, the nominate subspecies is known only from Texas.

25. Triepeolus trichopygus Cockerell and Timberlake

This species was described from Riverside, California. Females were taken at Senecio douglasii, a male at Gutierrezia sarothrae. It was taken at one of our principal survey sites in New Mexico (Table C) visiting sunflowers.

Genus Nomada Scopoli

The bees of this genus are wasp-like in appearance and are present on all continents and many of the islands. They are cleptoparasites in the nests of other bees, principally those of the genus Andrena, but are also known to parasitize the nests of certain Halictidae, Melittidae, and Anthophoridae. As with many cleptoparasitic bees, they are often encountered either flying about the nesting sites of their hosts or sipping nectar with them at the same flowers.

The genus is represented in the Nearctic Region by nearly 300 species, of which seven have been taken at sunflowers. In addition to those discussed below, females of unidentified species of the subgenus Micronomada were taken at two localities in New Mexico (Animas and Rodeo) visiting flowers of Helianthus annuus in early September (EGL, JML).

26. Nomada (Heminomada) graenicheri Cockerell

Graenicher (1909) found this species visiting flowers of Helianthus giganteus () and H. strumosus (, ) in Wisconsin. This is the only locality known for the species.

27. Nomada (Pachynomada) vincta vincta Say

Both sexes of the nominate subspecies were recorded from Helianthus in Illinois by Robertson (1894) and Pearson (1933). In 1929, Robertson more specifically listed H. grosseserratus (, , frequent) and H. tuberosus (). In Wisconsin, Graenicher (1909) found males at H. strumosus. This subspecies is widespread east of the Rocky Mountains and has been reported at flowers of other Compositae (Grindelia, Solidago, Rudbeckia, and Aster).

28. Nomada (Micronomada) garciana Cockerell

Recorded by Cockerell (1914b) from Helianthus at Falfurrias, Texas, this species is known only from New Mexico and Texas.

29. Nomada (Micronomada) gutierreziae Cockerell

The type specimen was taken on Gutierrezia in Mesilla Valley, New Mexico. The species is also known from Colorado and Arizona.

Examples were taken at sunflowers as follows:

ARIZONA.—SANTA CRUZ COUNTY: Patagonia, 5 Sep 75, H. annuus, 0900–1000, 3, 10 (EGL, JML).

30. Nomada (Micronomada) melanoptera Cockerell

Stevens (1951a) reported this species at flowers of Helianthus petiolaris in North Dakota. The species was described from Colorado and is known only from these two states.

31. Nomada (Micronomada) texana Cresson

This species ranges from Massachusetts south to North Carolina and Alabama and west to Michigan, Colorado, and Arizona. Cockerell (1914b) recorded the species at Helianthus in Falfurrias, Texas, and Mitchell (1962) included this host among his flower records.

32. Nomada (Micronomada) vierecki Cockerell

Recorded from Helianthus petiolaris in North Dakota (Stevens, 1951a), this species also occurs in Nebraska, Colorado, New Mexico, Texas, and Mexico.

Genus Paranomada Linsley and Michener

The species of this genus are found only in the southwestern United States and adjacent northern Mexico (Arizona, California, and Baja California). They are parasites in the nests of Exomalopis. One of the three known species has been taken at flowers of Helianthus.

33. Paranomada velutina Linsley

This parasitic bee has not been recorded previously from Helianthus, but a single example was collected during our primary surveys (Table C). Previously the species was known only from Arizona and Baja California, but is now known to occur in New Mexico. Rozen (1977) has recently established that this species is a parasite in the nests of Exomalopsis solani, which is a casual polylege of Helianthus.

Genus Exomalopsis Spinola

Although primarily a genus of Neotropical bees, 31 species are present in America north of Mexico and four of these have been found to visit sunflowers. Three are casual polyleges and Exomalopsis pygmaea is an oligolege of the Compositae, primarily associated with Helianthus.

34. Exomalopsis (Phanomalopsis) solani Cockerell

Exomalopsis solani ranges from Texas to Colorado and Arizona and south into Mexico. Timberlake (1947) gives a wide range of flower records for this species but apparently it has not been recorded previously from Helianthus. Females, including some pollen collectors, were taken at primary study sites in New Mexico and Arizona (Table C and D). It appears to be a casual polylege of Helianthus.

35. Exomalopsis (Phanomalopsis) solidaginis Cockerell

This species is related to E. solani but is generally smaller and differs in several structural characters. It visits many Compositae, including Helianthus, and ranges from Texas to southern California and south into Mexico. It appears to be a casual polylege of Helianthus.

One example of this species was taken at a principal sampling site (Table C). In addition, specimens were taken at sunflowers as follows:

ARIZONA.—COCHISE COUNTY: Cochise, 8 Sep 75, H. annuus, 0800–0829, 2, 1N (EGL, JML). SANTA CRUZ COUNTY: Sonoita, 16 Sep 74, H. annuus, 1N (PDH, AEM, MMM).

36. Exomalopsis (Anthophorisca) morgani Cockerell

This species was described originally from a female taken on flowers of Helianthus at Falfurrias, Texas (Cockerell, 1914a). The species ranges from Texas to southern Arizona and southward to Oaxaca, Mexico. It evidently is a casual polylege of Helianthus.

37. Exomalopsis (Anthophorisca) pygmaea (Cresson)

Records of this species from Helianthus have largely been reported under the name “bruneri.” Thus, Crawford (1902) reported the species from H. annuus at Lincoln, Nebraska, Cockerell (1911) from H. lenticularis at Sterling, Colorado, where both sexes were common on the flowers, and from H. sp. at Dallas, Texas (Cockerell, 1914a).

Timberlake (in litt.) in his review of the genus, examined 262 specimens from Kansas, mainly from Lawrence and vicinity and mostly from flowers of Helianthus. In addition he listed the following records:

ARIZONA.—COCHISE COUNTY: 1.5 mi W of Saint David, 9 Sep 61, H. annuus, 6 (P. D: Hurd, Jr.).

COLORADO.—LOGAN COUNTY: Sterling, 3 Aug 11, H. lenticularis, 1, 3 (T.D.A. Cockerell).

TEXAS.—BEXAR COUNTY: 22 Jun 63, on Helianthus, 1 (A. H. Alex). BRAZOS COUNTY: 13 Oct 54, on Aster, 1 (A. H. Alex). DALLAS COUNTY: Dallas, 22 Sep 05, on Helianthus, 2 (F. C. Bishop). KARNES COUNTY: Range, 24 Sep 04, on Helianthus, 1 (J. C. Crawford). TRAVIS COUNTY: 10 mi SE of Austin, 27 Sep 65, on Chrysopsis viscida, 1 (G. E. Bohart).

The species is an oligolege of the Compositae, primarily associated with Helianthus.

Genus Ptilothrix Smith

This is a Neotropical genus that occurs on both the North and South American continents and contains relatively few species. Only two of these are known to occur in America north of Mexico and only the one treated below is known to visit sunflowers.

38. Ptilothrix sp. near sumichrasti Cresson

This species was recorded as P. sumichrasti from Kallstroemia grandiflora by Cazier and Linsley (1974); however, although closely related it is apparently an undescribed species. We record the following collection of this Ptilothrix sp.:

ARIZONA.—PIMA COUNTY: 6 mi W of Rillito, 12 Aug 75, H. annuus, 0930–0959, 1 (EGL, JML).

Genus Diadasia Patton

Bees of this genus occur only in the Americas and are distributed chiefly in the warm temperate areas of North and South America, although a few species are present in the moist tropics. Most, if not at all, species are oligolectic, obtaining pollen primarily from the Malvaceae (Callirhoe, Sida, Sidalcea, and Sphaeralcea), Convolvulaceae (Calystegia, Convolvulus), Compositae (Helianthus), Cactaceae (Opuntia), and the Onagraceae (Clarkia). Twenty-five species are currently recognized from America north of Mexico and seven of these have been taken from sunflowers. Of these, all are nectar visitors except Diadasia enavata, which is an oligologe of the Compositae, primarily associated with Helianthus.

39. Diadasia afflicta afflicta (Cresson)

A female was recorded from Helianthus at Falfurrias, Texas, by Cockerell (1914b). She carried only a little pollen on the legs, both cactaceous and from sunflower and had Helianthus grains on the wings. This subspecies occurs in Texas and New Mexico and collects pollen normally from flowers of Callirhoe and presumably visit Helianthus for nectar only.

40. Diadasia australis (Cresson)

Cockerell (1914b) reported a female of D. australis australis, an oligolege of Cactaceae, at Helianthus at Falfurrias, Texas. She had collected much yellow pollen on the legs. The large smooth grains were apparently cactaceous, but there were small grains of Helianthus scattered about. Males of the far western subspecies, D. australis californica Timberlake, have been recorded from sunflower at San Bernardino, California, by Viereck (1902) and Cockerell (1914b), and from Helianthus gracilentus at The Gavilan, Riverside County, California, by Timberlake (1940).

The species, which occurs from Texas to California and Colorado and also is present in Mexico, appears to visit Helianthus for nectar.

41. Diadasia bituberculata (Cresson)

Diadasia bituberculata is an oligolege of Convolvulaceae in California. The male occasionally visits sunflower for nectar. We record:

CALIFORNIA.—LOS ANGELES COUNTY: Tujunga Canyon, Sunland, 14 May 75, H. annuus, 1245–1259, 1 (AEM, MMM).

42. Diadasia diminuta (Cresson)

This species, which ranges from British Columbia to California and east to Nebraska, Kansas, and Texas, was formerly believed to be an oligolege of Opuntia. Cazier and Linsley (1974) found females taking pollen from Kallstroemia grandiflora. It occasionally visits sunflower for nectar.

One male of this species was taken at sunflower in a principal survey site (Table D). In addition, a single collection was made as follows:

CALIFORNIA.—SAN DIEGO COUNTY: Vicinity of Laguna Junction on Highway 8, 13 Jul 74, H. petiolaris, 1300–1415, 1 (AEM, MMM).

43. Diadasia enavata (Cresson)

FIGURE 8; PLATE 2

Diadasia enavata is an oligolege of Compositae, primarily Helianthus (Linsley and MacSwain, 1957, 1958). Females have been reported at flowers of Helianthus sp. at Fedor, Texas (Cockerell, 1906a), H. annuus (later recorded as H. lenticularis, 1914b) at Mesilla, New Mexico (Cockerell, 1905), at Delta, Utah (Bohart, et al., 1950), and in Fresno County, California (Moldenke and Neff, 1974), H. lenticularis at Orange, California (Cockerell, 1916a), and H. gracilentus in Riverside County, California (Moldenke and Neff, 1974). The nest architecture has been figured by Bohart (1952) and described and illustrated by Linsley and MacSwain (1957). It is characterized by a long, erect entrance turret, a long vertical shaft (approximately 13 cm), branching at the bottom of the shaft to provide for numerous cells (14–42) many of which are arranged in semivertical series. In California, the species is parasitized by larvae of the bombyliid, Anthrax nidicola Cole. At Delta, Utah, Bohart et al. (1950) found the females nesting gregariously in dry, hard-packed, sandy soil; near Pittsburg, Contra Costa County, California, Linsley and MacSwain (1957), found them nesting in well-separated burrows associated with grass in a flat pastureland.

As a species, D. enavata has a long flight season, suggesting more than one annual generation. In the San Joaquin Valley of California, both sexes have been collected from June to October. On 6 October 1975, between 0800 and 1400 hrs at Corcoran, Kings County California, 319 freshly emerged males, representing nearly 50 percent of all the bees present (the total including only eight females), were visiting the flowers of H. annuus. Males also sleep on the flower heads, usually, but not always, singly.

FIGURE 8.—Distribution of Diadasia enavata (Cresson).

Diadasia enavata was present at most of the sunflower sites sampled except those in the Chihuahuan desert areas of southeastern Arizona and western New Mexico. Adlakha (1969), however, cites localities in this region. The only female of this species collected in this area is recorded as follows:

NEW MEXICO.—HIDALGO COUNTY: 1 mi SW of Rodeo, 15 Aug 72, H. annuus, 1110–1140, 1P (T. J. Zavortink).

Adlakha (1969) lists as nectar sources for one or both sexes of D. enavata, species in two genera of Capparidaceae, 13 genera of Compositae, one genus each of Cruciferae and Cucurbitaceae, three of Leguminosae, and one each of Scrophulariaceae and Verbenaceae. Of the pollen-bearing females examined by him, 143 were from Helianthus, 21 from Grindelia, and three from Coreopsis lanceolata. He states, however, that the species is restricted to Compositae, the preferred genera being Helianthus, Grindelia, and Centaurea in the order given, although he lists only 10 males and a nectar-seeking female from the latter genus.

This is the most wide-ranging species of the genus in America north of Mexico. It ranges from Washington south to California and into Mexico and east to South Dakota, Nebraska, Missouri, Oklahoma, and Texas. It is the only North American species of the genus oligolectic on composites and has a finely plumose scopa well adapted to carry the fine pollen grains of these plants.

Diadasia enavata was represented in most of our principal surveys (Tables G-M) in California. Additional samples were taken as follows:

ARIZONA.—MARICOPA COUNTY: Theba, 28 Jun 74, H. annuus, 0955–1005, 16, 1130–1159, 38, 2N (AEM, MMM). PIMA COUNTY: Marana, 30 Jul 75, H. annuus, 1100–1114, 2 (AEM, MMM); Rillito, 6 mi W, 27 Jun 74, H. annuus, 0830–0929, 8P (AEM, MMM), 30 Jul 75, H. annuus, 1345–1514, 29, 23P, 19N (EGL, JML, AEM, MMM), 12 Aug 75, H. annuus, 0930–1059, 28, 6P, 10N (EGL, JML); Sahuarita, 15 Jun 74, H. annuus, 1200–1229, 6, 2P, 1N (AEM, MMM). PINAL COUNTY: Eloy, 14 Jun 74, H. annuus, 1130–1259, 55, 17P, 24N (AEM, MMM), 26 Jun 74, H. annuus, 0630–0659, 2 (AEM, MMM), 30 Jul 75, H. annuus, 0815–0929, 7, 13P, 12N (AEM, MMM); Stanfield, 30 Jul 75, H. annuus, 0730, 1 (AEM, MMM). YUMA COUNTY: Tacna, 29 Jul 75, H. annuus, 1415–1429, 2 (AEM, MMM); Wellton, 5 Oct 74, H. annuus, 1100–1129, 9 (AEM, MMM).

CALIFORNIA.—CONTRA COSTA COUNTY: Byron 4 mi E, 21 Jul 77, H. annuus, 0800–0829, 1 1P (EGL, JML, AEM, MMM). FRESNO COUNTY: Coalinga 10 mi N, junction with Highway 5, 10 Sep 75, H. annuus, 1115–1144, 10, 3P (AEM, MMM); Parlier, 7 Sep 75, H. annuus, 1400–1429, 2 (EGL, JML, AEM, MMM). IMPERIAL COUNTY: El Centro, 29 Jul 75, H. annuus, 1000–1029, 13, 7P, 1N (AEM, MMM). KERN COUNTY: Bakersfield 8 mi S on Highway 99, 22 Aug 76, H. annuus, 1030–1059, 1, 1N (AEM, MMM); Junction Highway 5 with 99, H. annuus, 1230–1259, 14, 6P, 6N (AEM, MMM); Highway 5 at Old River Road, 10 Sep 75, H. annuus, 1400–1415, 5 (AEM, MMM); Highway 5, 3 mi S Lost Hills, Paso Robles Junction with Highway 46, 29 Jul 76, H. annuus, 1100–1129, 2P (AEM, MMM); Copus Road between Highway 5 and 99, H. annuus, 1130–1159, 35, 12 (AEM, MMM), 1430–1445, 7, 2P, 1N (AEM, MMM); Metler, 23 Sep 76, H. annuus, 1200, 4 (AEM, MMM); Wheeler Ridge, 23 Sep 76, H. annuus, 1245, 3P (AEM, MMM). LOS ANGELES COUNTY: Gorman, 29 Aug 76, H. annuus, 0800–0829, 2P (AEM, MMM). MERCED COUNTY: Atwater, 23 Jul 77, H. annuus, 1100–1129, 2, 21P, 4N (EGL, JML, AEM, MMM). RIVERSIDE COUNTY: Blythe, 29 Jun 74, H. annuus, 0800–0829, 4 (AEM, MMM); Coachella, 8 Jun 76, H. annuus, 0800–0829, 32, 1P, 1N (EGL, JML); Indio, 8 Jun 76, H. annuus, 0700–0829, 47, 1400–1429, 20 (EGL, JML). SAN JOAQUIN COUNTY: Manteca, 7.5 mi N, 21 Jul 77, H. annuus, 1100–1129, 4, 2P (AEM, MMM). STANISLAUS COUNTY: Grayson 6.5 mi N, 27 Jul 77, H. annuus, 1100–1129, 38, 4P (EGL, JML, AEM, MMM); Modesto, 3 Oct 75, H. annuus, 0745–0759, 2 (EGL, JML); Modesto 10 mi S, 27 Jul 77, H. annuus, 0800–0829, 1, 46P (EGL, JML, MMM); Patterson, 27 Jul 77, H. annuus, 0930–0959, 2, 1P (EGL, JML, AEM, MMM). TULARE COUNTY: Dinuba 5.5 mi S, 7 Sep 75, H. annuus, 1530, 2 (EGL, JML, AEM, MMM); Tulare, 6 Sep 75, H. annuus, 1600–1629, 1 (EGL, JML, AEM, MMM).

TEXAS.—TRAVIS COUNTY: Austin, 12–18 Sep 78, H. annuus, 79, 183P, 9N (PDH).

44. Diadasia ochracea (Cockerell)

This species ranges along the Pacific Coast states from Washington to southern California, west to Texas, and south into Mexico. At one time thought to be an oligolege of Sphaeralcea (Linsley and MacSwain, 1957) it was reported taking pollen from Kallstroemia grandiflora by Cazier and Linsley (1974). Both sexes occasionally visit Helianthus for nectar. A few specimens of this species were taken at the principal study sites (Table B, C).

45. Diadasia rinconis rinconis Cockerell

This species ranges from Texas to southern California and south into Mexico (Baja California). The females collect pollen from Opuntia, but both sexes visit other flowers for nectar including Helianthus.

Specimens have been taken at sampling sites as follows:

ARIZONA.—PIMA COUNTY: Rillito, 5 mi W, 30 Jul 75, H. annuus, 1330–1344, 1 (AEM, MMM); Sahuarita, 15 Jul 74, H. annuus, 5, 6N, 26 Jun 74, H. annuus, 4, 4N (AEM, MMM).

Genus Synhalonia Patton

The bees of this North American genus fly primarily during the spring months and are observed only exceptionally during the summer. A second generation may occur in some species since specimens have been taken as late as August. Usually, the females do not collect pollen from flowers of Compositae, but visit the flowers of a wide range of plant families, including especially the Ranunculaceae, Leguminosae, Hydrophyllaceae, Boraginaceae, and Saxifragaceae (Timberlake, 1969b).

More than 50 species are known from America north of Mexico and only two of these visit sunflowers and possibly may be casual polyleges of those plants.

46. Synhalonia actuosa (Cresson)

Recorded by Timberlake (1969b) from a long list of flower genera, including Helianthus nuttallii, this species is polylectic and ranges from Washington and Idaho south to California, Utah, Arizona, and New Mexico. It may be a casual polylege of Helianthus.

47. Synhalonia edwardsii (Cresson)

This is a western North American species ranging from British Columbia to Montana and southward to New Mexico, Arizona, California, and Baja California Norte. It is highly polylectic. Timberlake (1969b) includes Helianthus among the wide range of flowers visited. The species may be a casual polylege of Helianthus.

Genus Syntrichalonia LaBerge

This is a monotypic genus found only in the southwestern United States and adjacent Mexico as far south as the state of Jalisco and the Federal District.

48. Syntrichalonia exquisita (Cresson)

This elegant species ranges from Texas to Arizona and south into Mexico (D. F., Durango, Jalisco, and Zacatecas).

Zavortink (1975) comments on this species as follows:

In southeastern Arizona, exquisita occurs most commonly in montane, forested regions, where it visits the flower heads of several species of Compositae for both nectar and pollen during the warmest part of the day in the late summer and early fall. All my records of this species are from composites with large, showy, yellow, radiate heads in the related predominantly American tribes Helenieae and Heliantheae, namely: Helenium hoopesii Gray, Helianthus annuus L., Heliopsis parvifolia Gray, Verbesina encelioides (Cav.) Benth. & Hook., and Viguiera dentata (Cav.) Spreng. Other specimens of exquisita that I have examined were collected on Asclepias sp. (Asclepiadaceae), Chrysopsis sp. (Compositae, Astereae), Encelia sp. (Compositae, Heliantheae), Helianthus annuus, and Verbesina oreophila Woot. & Standl.

At Rucker Canyon, Chiricahua Mountains, in 1974, exquisita was active between 0930 and 1615 MST (Table 3). The air temperature in the upper, narrow part of the canyon, where exquisita visited flowers of Viguiera dentata, varied from 20–24° C during this time interval; the air temperature in the lower, broad part of the canyon, where it visited Verbesina encelioides, was 27° C at the time specimens were collected in the afternoon. At Rodeo, New Mexico, a male exquisita was collected from Helianthus annuus by E. G. and J. M. Linsley between 1630 and 1659 MST when the temperature was 34° C.

Females of exquisita alight on the disks of the composite heads and gather the fine pollen grains characteristic of these plants in their dense, highly plumose scopal hairs. Males fly rapidly around and over the flower-bearing plants and alight occasionally to drink nectar. The foraging of females and the patrolling of males continue, but at reduced levels, when the sun is obscured by clouds for either short or long intervals.

The seasonal flight period of exquisita in southwestern United States is during and after the summer rainy season. The earliest and latest collection dates are 10 August and 4 October, and the greatest number of specimens has been collected in September. The seasonal flight period in Mexico is known to extend from 27 July to December

It is thus an oligolege of the Compositae, secondarily associated with Helianthus.

Pollen-collecting records for this species at sunflowers are listed in Table A and C. In addition, it was captured at an additional site as follows:

ARIZONA.—SANTA CRUZ COUNTY: Nogales, 17 Sep 74, H. annuus, 1N (PDH, AEM, MMM).

Genus Svastra Holmberg

The bees of this genus are found only in the Western Hemisphere. The nominate subgenus is represented by three species in South America (Argentina and Chile) and two subgenera (Brachymelissodes and Epimelissodes), which include about 15 species from North and Central America. Most of these (14 species) occur in America north of Mexico and the majority of these (11) have been taken at sunflowers. Six of these are oligoleges of Compositae either primarily (3 species) or secondarily (3 species) associated with Helianthus. The remaining species (5) are either casual polyleges (2) or nectar seekers (3).

These are among the larger-sized bees found at sunflowers and are, as a group, exceptionally valuable pollinators of this plant.

49. Svastra (Brachymelissodes) cressonii (Dalla Torre)

This apparently polylectic bee has been recorded from Helianthus annuus by LaBerge (1956a). The species ranges from Iowa, Nebraska, and eastern Colorado through Kansas and western Oklahoma to Durango, Mexico. It is known to collect pollen from the flowers of Euphorbia marginata and also possibly Vernonia. It may be a casual polylege of Helianthus.

50. Svastra (Epimelissodes) aegis (LaBerge)

Svastra (E.) aegis was recorded by LaBerge (1956a) and Mitchell (1962) from Helianthus and related Compositae, LaBerge specifically listing H. annuus and H. radula. The species ranges from North Carolina to Florida and Texas. It appears to be an oligolege of the Compositae secondarily associated with Helianthus.

51. Svastra (Epimelissodes) atripes atripes (Cresson)

LaBerge (1956a) includes Helianthus annuus among the flower records for this subspecies, which ranges from Illinois, Missouri, and Louisiana, west to New Mexico and Colorado. To judge from the available floral data, this subspecies is evidently a casual polylege of Helianthus.

52. Svastra (Epimelissodes) grandissima (Cockerell)

Svastra grandissima has not been recorded from Helianthus previously. The species is known from southeastern Texas and, with the new record cited below, Arizona. It has been taken on Verbesina encelioides and possibly visits Helianthus for nectar only.

Our only record of this species from sunflower is as follows:

ARIZONA.—YUMA COUNTY: Wellton, 28 Jun 74, H. annuus, 1400–1410, 1 (AEM, MMM).

53. Svastra (Epimelissodes) helianthelli (Cockerell)

This species occurs from western Texas and Kansas to southern California and northern Baja California. It was described originally from Helianthus ciliaris at Mesilla, New Mexico. LaBerge (1956a) recorded the capture of both sexes on Helianthus sp., and H. ciliaris. Subsequently he (LaBerge, 1958) provided additional Arizona records from Helianthus sp. and a southern California record from H. annuus. It appears from the available floral data to be an oligolege of the Compositae, primarily associated with Helianthus.

Details of the collection of this species from a principal survey site are to be found in Table C. Additional records from sampling sites are as follows:

ARIZONA.—MARICOPA COUNTY: Theba, 28 Jun 74, H. annuus, 0955–1159, 4 (AEM, MMM). PIMA COUNTY: Rillito, 6 mi W, 31 Jul 75, H. annuus, 0805, 1P, 1500–1515, 1 (EGL, JML, AEM, MMM). YUMA COUNTY: Tacna, 28 Jun 74, H. annuus, 1305–1325, 5 (AEM, MMM), 29 Jul 75, H. annuus, 1415–1429, 8 (AEM, MMM); Wellton, 28 Jun 74, H. annuus, 1100–1129, 6 (AEM, MMM); Yuma, 29 Jul 75, H. annuus, 1300–1314, 2 (AEM, MMM).

CALIFORNIA.—IMPERIAL COUNTY: El Centro, 29 Jul 75, H. annuus, 1000–1029, 5 (AEM, MMM).

54. Svastra (Epimelissodes) machaerantherae (Cockerell)

LaBerge (1956a) recorded both sexes of this species from Helianthus sp. and males from H. annuus. It ranges from Texas (EI Paso) to southern California and south into northern Mexico. Males “sleep” in large, massed balls on the tallest dried flower stalks, gathering noisily at about sunset (observations at Rodeo, Hidalgo County, New Mexico, and near Apache, Cochise County, Arizona). During the day they patrol the flower heads continuously, at about the level of the tallest plants, pausing briefly for nectar from time to time.

The species is evidently an oligolege of the Compositae, primarily associated with Helianthus.

Details of the collections of this species at the principal survey sites are presented in Table A-D. Additional records are as follows:

ARIZONA.—COCHISE COUNTY: Cochise, 8 Sep 75, H. annuus, 0830–0859, 1 (EGL, JML). PIMA COUNTY: San Xavier, 19 Sep 74, H. annuus, 1200–1229, 1 (PDH, AEM, MMM). SANTA CRUZ COUNTY: Sonoita, 16 Sep 74, H. annuus, 1, 2N (PDH, AEM, MMM).

CALIFORNIA.—RIVERSIDE COUNTY: Indio, 18 Sep 77, H. annuus, 0800–0829, 1 (EGL, JML).

55. Svastra (Epimelissodes) obliqua (Say)

FIGURE 9; PLATE 3

This widespread, variable species ranges from coast to coast in the United States and southern Canada and into northern Mexico. Graenicher (1909) recorded males from Helianthus strumosus and Robertson (1929) listed this species from H. annuus (, P), H. divaricatus (,P, abundant), H. grosseserratus (,P), H. mollis (,P, frequent), H. rigidus (, P), H. strumosus (, P, frequent), and H. tuberosus (P, abundant). LaBerge (1956a) summarized flower records for 1128 individuals, of which 730 were females. Of these, all but 48 were from Compositae. He concluded that they prefer Heliantheae, Vernonicae, Astereae, and Helenieae in that order. Three subspecies are recognized by LaBerge: S. obliqua caliginosa (Cresson) occurring along the Atlantic coast states from New Jersey to Georgia; S. obliqua obliqua ranging from southern Ontario and eastern Montana, south to New Mexico and New Jersey and west of the Appalachians to Florida and Mexico (Tamaulipas and Coahuila); and S. obliqua expurgata (Cockerell) ranging from Washington and Idaho to northern Baja California, Arizona, and western Colorado. Svastra obliqua caliginosa has been recorded from Helianthus sp., H. atrorubens, H. microcephalus, and H. zonatus; S. obliqua from Helianthus sp., H. annuus, H. divaricatus, H. grosseserratus, H. laetiflorus, H. maximiliani, H. mollis, H. petiolaris, H. scaberrimus, H. strumosus, and H. tuberosus; and S. obliqua expurgata from Helianthus sp., H. annuus, H. bolanderi, H. ciliaris, and H. petiolaris.

FIGURE 9.—Distribution of Svastra (Epimelissodes) obliqua) (Say)

The nesting habits of this species have been described by Custer (1928) and Rozen (1964).

It, along with Melissodes agilis, is one of the most ubiquitous of sunflower bees. Males cruise the flower heads throughout the day, flying about the highest plants. Svastra obliqua is an oligolege of the Compositae, primarily associated with Helianthus.

Details of collections of the subspecies, S. o. expurgata at primary sampling sites may be found in Tables A-D and H-M. Additional collections are as follows:

ARIZONA.—MARICOPA COUNTY: Theba, 28 Jun 74, H. annuus, 0955–1159, 3 (AEM, MMM). PIMA COUNTY: Marana, 27 Jun 74, H. annuus, 1030–1059, 5, 2N (AEM, MMM), 30 Jul 75, H. annuus, 1100–1114, 1P, 1N (AEM, MMM); Rillito 6 mi W, 27 Jun 74, H. annuus, 0830–0929, 1, 2P, 1N (AEM, MMM), 31 Jul 75, H. annuus, 1500–1529, 1, 3P (EGL, JML, AEM, MMM), 12 Aug 75, H. annuus, 0930–1059, 1, 1P (EGL, JML). PINAL COUNTY: Eloy, 26 Jun 74, H. annuus, 0630–0659, 1, 1N (AEM, MMM), 30 Jul 75, H. annuus, 0815–0829, 1 (AEM, MMM). SANTA CRUZ COUNTY: Nogales, 15 Sep 77, H. annuus, 0800–0829, 1, 4P (EGL, JML); Sonoita 10 mi E, 7 Sep 77, H. petiolaris, 0830–0859, 1, 2P (EGL, JML). YUMA COUNTY: Tacna, 28 Jun 74, H. annuus, 1305–1325, 7 (AEM, MMM), 29 Jul 75, H. annuus, 1415–1429, 1 (AEM, MMM); Yuma, 29 Jul 75, H. annuus, 1300–1314, 2P (AEM, MMM).

CALIFORNIA.—FRESNO COUNTY: Parlier, 7 Oct 75, H. annuus, 1400–1429, 1, 5P, 1N (EGL, JML, AEM, MMM); Selma, 6 Oct 75, H. annuus, 1030, 1P (EGL, JML, AEM, MMM). IMPERIAL COUNTY: Holtville 3 mi W, 29 Jul 75, H. annuus, 1100–1114, 1, 3P, 3N (AEM, MMM). INYO COUNTY: Big Pine, 28 Aug 77, H. annuus, 0800–0829, 1P (EGL, JML). KERN COUNTY: Bakersfield 8 mi S, 22 Aug 76, H. annuus, 1030–1059, 1P, 1N (AEM, MMM); Copus Road between Highways 5 and 99, 22 Aug 76, H. annuus, 1130–1159, 1, 4N (AEM, MMM); Highway 5 junction with Highway 99, 22 Aug 76, H. annuus, 1230–1259, 1, 1N (AEM, MMM); Highway 5, 3 mi S of Lost Hills, Paso Robles Junction, 29 Jul 76, H. annuus, 1100–1129, 1, 12P, 3N (AEM, MMM); Highway 99, Visalia-Hanford Junction, 22 Aug 76, H. annuus, 0730–0829, 17P, 6N (AEM, MMM). MERCED COUNTY: Atwater, 23 Jul 77, H. petiolaris, 1200–1229, 1, 1P (EGL, JML, AEM, MMM). RIVERSIDE COUNTY: Blythe, 29 Jun 74, H. annuus, 0800–0829, 2, 1N (AEM, MMM), 5 Jun 77, H. annuus, 1200, 1 (EGL, JML). SAN JOAQUIN COUNTY: Manteca, 27 Jul 77, H. annuus, 1230–1259, 3 (EGL, JML, AEM, MMM); Manteca 7.5 mi N, 27 Jul 77, H. annuus, 1100–1129, 4 (EGL, JML); Victoria Island 0.5 mi E of Old River, 21 Jul 77, H. annuus (commercial field), 0930–0959, 2, 1P, 1N (EGL, JML, AEM, MMM). STANISLAUS COUNTY: Grayson 6.5 mi N, 27 Jul 77, H. annuus, 1100–1129, 1 (EGL, JML, AEM, MMM); Modesto 10 mi S, 27 Jul 77, H. annuus, 0800–0829, 1P (EGL, JML, AEM, MMM); Patterson, 27 Jul 77, H. annuus, 0930–0959, 27, 6P (EGL, JML, AEM, MMM). TULARE COUNTY: Dinuba 5.5 mi S, 7 Sep 75, H. annuus, 1200–1230, 2, 3P (EGL, JML, AEM, MMM).

56. Svastra (Epimelissodes) petulca (Cresson)

Two subspecies are recognized by LaBerge (1956a), S. (E.) petulca petulca (Cresson), ranging from eastern Texas north through Kansas to Illinois, east to Florida, and north along coast to New Jersey. He records it from Helianthus sp. and other composites. The other subspecies, S. (E.) petulca suffusa (Cresson), occurs from northeastern Kansas and eastern Colorado to Texas, New Mexico, and northern Arizona and is reported from Helianthus sp., H. annuus, and other flowers, mostly Compositae. The species appears to be an oligolege of Compositae, secondarily associated with Helianthus.

For records of Svastra petulca suffusa, see Table C. An additional specimen was taken as follows:

ARIZONA.—COCHISE COUNTY: Cochise, 8 Sep 75, H. annuus, 0830–0859, 1N (EGL, JML).

57. Svastra (Epimelissodes) sabinensis (Cockerell)

LaBerge (1956a) recognizes three subspecies of S. sabinensis: S. s. nubila (LaBerge) from southern California and Baja California, S. s. sabinensis from southern California to New Mexico, and S. s. laterufa (Cockerell) from New Mexico and Texas to Mexico. The male holotype of the subspecies nubila was collected on Helianthus annuus at Riverside, California, on 8 July 1927. Practically all examples collected subsequently have been males at various species of Compositae, in particular Gutierrezia. The preferred pollen sources of the female are not known, but probably involve Compositae. Moldenke and Neff (1974) class S. s. sabinensis as an “oligolege of sunflowers,” but our own observations (LaBerge, 1956a; Cazier and Linsley, 1974) do not bear out this conclusion, although we have taken females gathering pollen from Helianthus (Table B and below):

ARIZONA.—COCHISE COUNTY: Cochise, 5 Sep 75, H. annuus, 0800–0829, 1 (EGL, JML). SANTA CRUZ COUNTY: Nogales, 15 Sep 77, H. annuus, 0930–0959, 1P (EGL, JML).

58. Svastra (Epimelissodes) sila (LaBerge)

Not previously recorded from Helianthus, this species is known to occur from Texas to Arizona and southward into Mexico (Baja California and Chihuahua). Although it is an oligolege of Compositae, especially Baileya pleniradiata and Heterotheca psammophila, we have only found it taking nectar from Helianthus (Table B).

59. Svastra (Epimelissodes) texana (Cresson)

LaBerge (1956a) recognizes two subspecies, S. (E.) texana texana (Cresson), which ranges from eastern Colorado and Kansas south through Oklahoma and Texas, and S. (E.) texana eluta (LaBerge), which occurs in the desert areas of southern California, Arizona, and northern Mexico (Chihuahua and Coahuila). Females of the former have been taken on Helianthus sp. and of the latter on Helianthus annuus (see also Table C and D). The species appears to be an oligolege of Compositae, secondarily associated with Helianthus.

Genus Xenoglossodes Ashmead

This genus, which occurs only in North America, contains 18 species, of which three have been taken at the flowers of Helianthus while seeking nectar. In addition, we have collected a number of specimens, (16, 1P, 5N) representing two or more species at flowers of Helianthus annuus in Arizona (Cochise and Santa Cruz Counties) and New Mexico (Rodeo and Silver City) during September.

60. Xenoglossodes bishoppi (Cockerell)

Described originally from a male taken at Helianthus in Paris, Texas, this species remains known only from the type specimen.

61. Xenoglossodes eriocarpi (Cockerell)

Xenoglossodes eriocarpi is primarily associated with flowers of desert Compositae and ranges from Texas to southern California, but Hurd and Linsley (1975) have recorded a female from Larrea tridentata.

We have taken the species in our sunflower surveys as follows:

ARIZONA.—COCHISE COUNTY: Cochise, 8 Sep 75, H. annuus, 0800–0859, 4 (EGL, JML).

The species evidently visits Helianthus for nectar only.

62. Xenoglossodes helianthorum Cockerell

Described by Cockerell (1914b) from a male captured on sunflower at Falfurrias, Texas, this species remains known only on the basis of the male.

Genus Peponapis Robertson

The bees of this genus occur only in the Western Hemisphere and the females obtain pollen exclusively from squashes, gourds, and pumpkins (Cucurbita). While both sexes take nectar chiefly from the flowers of these plants, Hurd and Linsley (1964:380) list a number of other plants that are known to be visited for nectar. Only the following species has been found to visit flowers of Helianthus.

63. Peponapis (Peponapis) pruinosa (Say)

This species, which ranges from Maine to Georgia, west to Idaho and California, and south into Mexico (Central Plateau and west coast south to Oaxaca), is an oligolege of uncultivated xerophytic Cucurbita including C. foetdissima and C. galleotti as well as most, if not all domestic Cucurbita grown within its range. A nectar-seeking female was taken at the flowers of Helianthus annuus (Table M) and two males were collected on the same flower at 7.5 mi N Manteca, San Joaquin County, California, on 21 July 1977, 1100–1129 (EGL, JML, AEM, MMM).

Genus Melissodes Latreille

This large genus, although present in both North and South America as well as the West Indies, is especially well represented by numerous species in North America. Of the 99 species known to be present in America north of Mexico, 55 have been taken at the flowers of Helianthus. Most of these are oligoleges of the Compositae (38), either primarily (7 species) or secondarily (31 species) associated with Helianthus. Of the remaining species (17), 13 are polyleges (six regulars and seven casuals) and four seek only nectar from these flowers.

These bees are among the most important pollinators of sunflower.

64. Melissodes (Melissodes) bimaculata bimaculata (Lepeletier)

Recorded by Robertson (1929) from flowers of Helianthus annuus (N), H. grosseserratus (, P), and H. tuberosus (N) in Illinois, LaBerge (1956a) has added H. divaricatus to this list. The species ranges from North Dakota to Maine, Florida, Texas, northeastern New Mexico, and eastern Colorado. The other subspecies, M. b. nulla LaBerge, occurs in southern Florida and the adjacent Keys, but so far has been found only at flowers of Lythrum lineare. The nominate subspecies is apparently a regular polylege of Helianthus.

65. Melissodes (Melissodes) communis communis Cresson

This subspecies visits a wide range of flowers, including Helianthus and other Compositae, along with members of other plant families. It ranges from Wyoming and North Dakota to the New England States and south to Florida, Chihuahua, and Tamaulipas, Mexico. Recorded specifically from Helianthus annuus and H. lenticularis (LaBerge, 1958) and H. debilis (Graenicher, 1930), this subspecies appears to be a regular polylege of Helianthus.

66. Melissodes (Melissodes) comptoides Robertson

This species ranges from New Jersey to Florida and west to South Dakota, Colorado, and Arizona (LaBerge, 1956a). It has been recorded from Helianthus sp., H. annuus, and H. petiolaris, but according to LaBerge (1956a) it appears to prefer pollen of Euphorbia marginata, Medicago sativa, and Melilotus alba. Melissodes comptoides appears to be possibly a regular polylege of Helianthus.

67. Melissodes (Melissodes) paroselae Cockerell

This species ranges from southwestern Texas to southeastern California and Mexico (Baja California, Sonora, Chihuahua, and Nayarit). It is polylectic and has been recorded from Helianthus sp. and H. annuus by LaBerge (1956a). Its relationship with Helianthus appears to be that of a casual polylege.

Records for this species at the principal survey sites appear in Table B–E. Data from additional survey sites are as follows:

ARIZONA.—COCHISE COUNTY: Cochise, 8 Sep 75, H. annuus, 0800–0829, 2, 2P, 1N (EGL, JML). PIMA COUNTY: Marana, 27 Jun 74, H. annuus, 1030–1059, 8 (AEM, MMM); Rillito, 6 mi W, 27 Jun 74, H. annuus, 0830–0929, 10, 3N (AEM, MMM), 2 Aug 75, H. annuus, 0715–0729, 1 (AEM, MMM), 12 Aug 75, H. annuus, 0930–0959, 1 (EGL, JML); Sahuarita, 26 Jun 74, H. annuus, 1200–1229, 11, 1N (AEM, MMM). PINAL COUNTY: Eloy, 30 Jul 75, H. annuus, 0915–0929, 1 (AEM, MMM). SANTA CRUZ COUNTY: Sonoita, 16 Sep 74, 4 (PDH, AEM, MMM).

68. Melissodes (Melissodes) tepida Cresson

Of the three subspecies recognized by LaBerge (1956a), two have been reported from Helianthus: M. (M.) tepida tepida Cresson, ranging from northwestern Oregon and southern Idaho to northern Utah, Nevada, and northern California and M. (M.) tepida timberlakei LaBerge, which occurs in southern Oregon and central and southern California. These have been taken on Helianthus sp., H. annuus, H. bolanderi, and H. petiolaris. The species is evidently a casual polylege of Helianthus

69. Melissodes (Melissodes) tessellata LaBerge

Recorded from Helianthus sp. and H. annuus in southern California by LaBerge (1956a), this polylectic species ranges from central California to Mexico (Baja California and Jalisco). It appears to be a regular polylege of Helianthus.

70. Melissodes (Melissodes) thelypodii thelypodii Cockerell

This polylectic subspecies has been collected on Helianthus annuus but is more abundant on other plants. It ranges from southern California to southeastern Texas and south to northern Durango (LaBerge, 1956a). Our collection records are recorded in Table B and C. It appears to be a casual polylege of Helianthus.

71. Melissodes (Apomelissodes) fimbriata Cresson

This species, which obtains both pollen and most of its nectar supply from flowers of Oenothera, ranges from Virginia to Georgia and west to Texas and Kansas. LaBerge (1956b) has recorded the species visiting flowers of Helianthus petiolaris for nectar.

72. Melissodes (Heliomelissodes) desponsa Smith

The male of this species was recorded from Helianthus strumosus in Wisconsin by Graenicher (1909). LaBerge (1956b) adds H. annuus and H. grosseserratus and Mitchell (1962) includes Helianthus among his floral records. It occurs along the Atlantic Coast from Nova Scotia to North Carolina and Alabama and west to North Dakota and Oklahoma. It collects pollen principally from flowers of Cirsium but appears to be a casual polylege of Helianthus.

73. Melissodes (Heliomelissodes) rivalis Cresson

LaBerge (1956b) reported this species as oligolectic on Compositae, especially Cirsium. Among his flower records is Helianthus annuus. It ranges from northern California to southern British Columbia, east to southern Manitoba and northwestern Minnesota and south to Texas, New Mexico, and Arizona. It may be secondarily dependent upon Helianthus.

74. Melissodes (Tachymelissodes) opuntiella Cockerell

This polylectic species obtains pollen from such flowers as Cirsium, Lindheimera texana, Sphaeralcea pedatifolia, Verbesina encelioides, and Helianthus annuus according to LaBerge (1956b). It ranges from Texas to California and Utah, south into Mexico (Coahuila, Mexico, and Zacatecas). It is apparently a casual polylege of Helianthus.

75. Melissodes (Tachymelissodes) sonorensis LaBerge

Melissodes sonorensis was described from specimens taken five and 15 miles south of Navajoa, Mexico, on Kallstroemia grandiflora (LaBerge, 1963). We have not found additional published records of collections of this species which is now recorded from the United States (New Mexico). Our data are to be found in Table A and indicate that this species is possibly a regular polylege of Helianthus.

76. Melissodes (Eumelissodes) agilis Cresson

FIGURE 10; PLATE 4

LaBerge (1961) regards this species as an oligolege of Helianthus. The summary of floral records presented by him clearly indicates a very strong preference for plants of this genus and our field collections clearly support his conclusion. We found it at practically every site sampled. Of 520 females tabulated by LaBerge, 428 were from a species of Helianthus, 63 from Compositae other than Helianthus, and only 29 from plants other than Compositae. The species ranges throughout the United States (except Florida), southern Canada, and northern Mexico. Helianthus species visited include H. annuus, H. atrorubens, H. bolanderi, H. ciliaris, H. coronatus, H. divaricatus, H. grosseserratus, H. laetifloris, H. lenticularis, H. maximiliani, H. mollis, H. petiolaris, H. pumilus, H. radula H. rigidus, H. salicifolius, H. scaberrimus, H. subrhomboideus, and H. tuberosus.

FIGURE 10.—Distribution of Melissodes (Eumelissodes) agilis Cresson

Males patrol the flower heads of sunflower throughout the day along with those of Svastra spp., Diadasia enavata, and other species of Melissodes, cruising about the tops of the tallest plants. At night they gather gregariously on flower heads for “sleeping” ranging in numbers from two or three to a very crowded 25 or 30, although sometimes they occur singly. They remain on the flowers until after the sun's rays reach them or until the air temperature is sufficiently high to permit flight. This may be as much as an hour after females have begun collecting pollen.

Graenicher (1909) recorded the species from flowers of Helianthus strumosus (, P) in Wisconsin and Robertson (1929) found it to visit seven species of Helianthus in Carlinville, Illinois, including H. annuus (, N), H. divaricatus (, P), H. grosseserratus (, P, abundant), H. mollis (, P), H. rigidus (, P), and H. tuberosus (, P, frequent). The species is clearly an oligolege of the Compositae, primarily associated with Helianthus.

M. agilis was found at all our primary sampling sites (Tables A-M) as well as other collecting areas as follows:

ARIZONA.—COCHISE COUNTY: Cochise, 8 Sep 75, H. annuus, 0800–0859, 7, P, 3N (EGL, JML). GRAHAM COUNTY: Franklin, 6 Aug 75, H. annuus, 1130–1159, 4 (EGL, JML). PIMA COUNTY: San Xavier, 19 Sep 74, on flowers of H. annuus, 1200–1259, 1, 1N (PDH, AEM, MMM). SANTA CRUZ COUNTY: Nogales, 17 Sep 74, H. annuus, 1210–1240, 26, 4P, 4N (PDH, AEM, MMM), 15 Sep 77, H. annuus, 0700–0759, 13, 87P, 1600–1629, 1P (EGL, JML); Patagonia, 7 Sep 77, H. annuus, 0730–0759, 3, 16P (EGL, JML); Sonoita, 16 Sep 74, H. annuus, 3 (PDH, AEM, MMM); Sonoita 10 mi E, 7 Sep 77, H. petiolaris, 0830–0859, 2P (EGL, JML).

CALIFORNIA.—CONTRA COSTA COUNTY: Byron 4 mi E, 21 Jul 77, H. annuus, 0800–0829, 12, 7P (EGL, JML, AEM, MMM). FRESNO COUNTY: Coalinga 10 mi N, 10 Sep 75, H. annuus, 1045–1144, 66, 2P, 1N (AEM, MMM); Highway 99, Visalia-Hanford Junction, 22 Aug 76, 0730–0759, 14P (AEM, MMM); Parlier, 7 Sep 75, H. annuus, 1400–1429, 2, 5P, 1N (EGL, JML, AEM, MMM); Selma, 6 Sep 75, H. annuus, 1030, 2P, 1N (EGL, JML, AEM, MMM). INYO COUNTY: Big Pine, 28 Aug 77, H. annuus, 0630–0729, 1, 36P, 0730–0829, 2, 14P (EGL, JML); Tuttle Creek 4 mi W of Lone Pine, 29 Aug 77, H. annuus, 1030–1059, 18, 3P, 2N (EGL, JML). KERN COUNTY: Bakersfield 8 mi S, 22 Aug 76, H. annuus, 1030–1059, 2, 1N (AEM, MMM); Copus Road between Highway 5 and 99, 22 Aug 76, H. annuus, 1130–1159, 1230–1259, 4 (AEM, MMM); Highway 5 junction with Copus Road, 10 Sep 75, H. annuus, 1430–1445, 4, 1N (AEM, MMM); Highway 5 at Old River Road, 10 Sep 75, H. annuus, 1400–1415, 4, 1N (AEM, MMM). LOS ANGELES COUNTY: Calabasas, 29 Sep 75, H. annuus, 0915–0920, 58, 3N (AEM, MMM); Gorman, 19 Aug 76, H. annuus, 0800–0829, 1, 4P (AEM, MMM). MERCED COUNTY: Atwater, 23 Jul 77, H. annuus, 1100–1229, 11, 1N (EGL, JML, AEM, MMM). ORANGE COUNTY: Newport Beach, 13 Sep 75, H. annuus, 1015–1029 (overcast), 14, 4N, 28P (AEM, MMM), 27 Aug 76, H. annuus, 1400–1429 (overcast), 23, 3P, 6N (AEM, MMM). RIVERSIDE COUNTY: Blythe, 29 Jun 74, H. annuus, 0800–0829, 1, 6P (AEM, MMM); Coachella, 8 Jun 76, H. annuus, 0900–0929, 1, 1N (EGL, JML); Indio, 8 Jun 76, H. annuus, 0700–0829, 6, 5P, 2N (EGL, JML), 1400–1429, 2 (EGL, JML). SAN JOAQUIN COUNTY: Manteca 7.5 mi N, 21 Jul 77, H. annuus, 1100–1129, 10, 7N (EGL, JML); Victoria Island, 0.5 E of Old River, 21 Jul 77, H. annuus (commercial field), 0930–0959, 16, 12N, 3P (EGL, JML, AEM, MMM). STANISLAUS COUNTY: Ceres, 27 Jul 77, H. annuus, 0800–0829, 27, 45P (EGL, JML, AEM, MMM); Grayson 6.5 mi N, 27 Jul 77, H. annuus, 1100–1129, 2, 1P, 4N (EGL, JML, AEM, MMM); Modesto, 3 Sep 75, H. annuus, 0745–0815, 21, 29P, 2N (EGL, JML, AEM, MMM); Patterson, 21 Jul 76, H. annuus, 1315, 4 (AEM, MMM), 27 Jul 77, H. annuus, 0930–0959, 2, 2N, 1P (EGL, JML, AEM, MMM). TULARE COUNTY: Dinuba 5.5 mi S, 7 Sep 75, H. annuus, 1200–1230, 6, 1P, 12N (EGL, JML, AEM, MMM); Tulare, 6 Oct 75, H. annuus, 1600–1629, 2, 1N, 5P (EGL, JML, AEM, MMM).

77. Melissodes (Eumelissodes) appressa LaBerge

This California species is an oligolege of Compositae, especially Gutierrezia, Haplopappus, and Heterotheca (LaBerge, 1961). A nectar-gathering female was taken at flowers of Helianthus annuus at Anaheim, California in August by P. H. Timberlake.

78. Melissodes (Eumelissodes) bidentis Cockerell

The range of this species extends from North Dakota to New York and south to Texas. Flower records include Helianthus annuus, H. maximiliani, and H. tuberosus and related Compositae (Stevens, 1951b). It is apparently an oligolege of Compositae, secondarily associated with Helianthus.

79. Melissodes (Eumelissodes) bimatris LaBerge

LaBerge (1961) reported M. bimatris as an oligolege of Compositae, especially Chrysothamnus. His list of flower records includes Helianthus sp. The bee is known from British Columbia to southern California and east to Colorado and New Mexico. It appears to be secondarily associated with Helianthus.

80. Melissodes (Eumelissodes) boltoniae Robertson

Recorded from Helianthus sp., H. annuus, H. grosseserratus and H. tuberosus (LaBerge, 1961), the species ranges from Minnesota to North Carolina, Florida, and eastern Texas. It is an oligolege of the Compositae that regularly visits the flowers of Helianthus.

81. Melissodes (Eumelissodes) brevipyga LaBerge

Recorded from California, Arizona, and Idaho, the flower list provided by LaBerge (1961) suggests that the species may be an oligolege of Compositae, although it has not previously been reported from Helianthus. For our collection data see Table B. It appears to be secondarily associated with Helianthus.

82. Melissodes (Eumelissodes) confusa Cresson

Melissodes confusa ranges from southern Canada (Alberta, Manitoba, and Saskatchewan) to southern Mexico (Veracruz and Oaxaca). The data of LaBerge (1961) indicate a strong preference for Compositae, but as he emphasized at that time, it had not yet been found on Helianthus.

Only males of this species have been taken by us in our surveys shown in Table C and the following:

ARIZONA.—COCHISE COUNTY: Cochise, 8 Sep 75, H. annuus, 0800–0829, 1 (EGL, JML).

83. Melissodes (Eumelissodes) coreopsis Robertson

This species visits plants of a wide variety of genera of Compositae but appears to have a preference for Helianthus. Cockerell (1923) recorded the female (as M. confusiformis) from H. annuus lenticularis at Wray, Colorado. Of 579 floral records for females tabulated by LaBerge (1961), 211 were from Helianthus, 54 from Gaillardia, 44 from Rudbeckia, 36 from Echinacea, 22 from Grindelia, 15 from Solidago, 38 from Aster, 25 from Coreopsis, 77 females were recorded from other genera of Compositae, and 57 from plants of other families. Species of Helianthus visited include H. annuus, H. grosseserratus, H. maximiliani, H. petiolaris, H. salicifolius, and H. tuberosus. The species ranges from Alberta, North Dakota, and Minnesota to Illinois, Texas, and Arizona. It is an oligolege of the Compositae, primarily associated with Helianthus.

We have taken both sexes in our surveys; most of the females were collecting pollen. Collection data is recorded in Table C and the following:

ARIZONA.—COCHISE COUNTY: Cochise, 8 Sep 75, H. annuus, 0800–0829, 2P (EGL, JML).

84. Melissodes (Eumelissodes) denticulata Smith

This species, which ranges from Quebec west to North Dakota and south to Florida and Texas, is apparently chiefly dependent upon Compositae, especially the genus Vernonia, for pollen and nectar. Graenicher (1930:160) has recorded it on Helianthus debilis (as M. perplexa) and it appears to be a casual polylege of sunflower.

85. Melissodes (Eumelissodes) dentiventris Smith

LaBerge (1961) regards this species as primarily associated with Astereae, especially Aster and only secondarily with Heliantheae, including Helianthus annuus, H. divaricatus, H. grosseserratus, and H. radula. Cockerell (1915c) quoted Rohwer as noting that at Falls Church, Virginia, this species only visits sunflower in the morning, not in the afternoon. Later Cockerell (1917a) recorded both sexes at Helianthus in Virginia and a female at the flowers in Connecticut.

Robertson (1929) found the species, which ranges from southeastern Canada to Georgia, the Gulf states, and Texas, visiting three species of Helianthus in Carlinville, Illinois, including H. annuus (N), H. divaricatus (, P), H. grosseserratus (, P, frequent).

86. Melissodes (Eumelissodes) gelida LaBerge

LaBerge (1961) regarded M. gelida as an oligolege of Compositae with some preference for Helianthus, as indicated by 7 of 20 females and 14 of 55 males bearing flower data in material studied by him. The species ranges from Montana and North Dakota to New Mexico and Texas. Helianthus species visited include H. annuus and H. petiolaris. Possibly M. gelida is primarily associated with Helianthus.

87. Melissodes (Eumelissodes) grindeliae Cockerell

This species, an oligolege of Compositae, secondarily associated with Helianthus, ranges from Minnesota and North Dakota west through Wyoming, Colorado, and New Mexico to California and Washington (LaBerge, 1961).

88. Melissodes (Eumelissodes) humilior Cockerell

This species, although known to visit various Compositae (LaBerge, 1961), has not been recorded from sunflower previously (Table B). It is apparently an oligolege of Compositae, secondarily associated with Helianthus and ranges from western Texas to Arizona and south into Mexico (Chihuahua).

89. Melissodes (Eumelissodes) illata Lovell and Cockerell

An oligolege of Compositae, secondarily associated with Helianthus, it seems to prefer especially species of Solidago and Aster. It has been recorded as a visitor to Helianthus strumosus (LaBerge, 1961), and ranges from Prince Edward Island to Alberta and south to North Carolina (in the mountains) and Illinois.

90. Melissodes (Eumelissodes) limbus LaBerge

Although this species is an oligolege of Compositae, especially Verbesina, Haplopappus, and Baileya, LaBerge (1961) remarked that it had not yet been collected on Helianthus, a genus frequented by most species of the subgenus Eumelissodes. Although we have now taken it on H. annuus, the specimens involved were all males (Table B) and further investigation may establish more precisely its relationship with sunflowers.

91. Melissodes (Eumelissodes) lutulenta LaBerge

According to LaBerge (1961), this species is an oligolege of the Compositae and seems to prefer Chrysothamnus, Grindelia, and Solidago. Included among his flower records are Helianthus sp.; Moldenke and Neff (1974) record it from Helianthus in Contra Costa County, California. The species is primarily an inhabitant of western North America, ranging from British Columbia to Saskatchewan and south to California, Arizona, and Mexico (Guanajuato). It seems to be secondarily associated with Helianthus.

92. Melissodes (Eumelissodes) menuachus Cresson

Recorded from Helianthus sp. (Cockerell, 1906a), H. grosseserratus (N) (Robertson, 1929), and H. annuus, H. petiolaris, and H. grosseserratus (LaBerge, 1961), the species ranges from British Columbia, Alberta, and North Dakota south to Illinois, Texas, California, and into north-central Mexico (Chihuahua and Zacatecas).

We have taken it in a number of principal sample sites (Tables A-E), as well as:

ARIZONA.—COCHISE COUNTY: Cochise, 8 Sep 75, 0830–0859, 1 (EGL, JML).

The species is an oligolege of the Compositae, secondarily associated with Helianthus.

93. Melissodes (Eumelissodes) microsticta Cockerell

This is an oligolege of Compositae that visits Helianthus especially in the Utah-Wyoming areas of its range, which includes British Columbia to Saskatchewan and south to California, Nevada, Utah, and Texas (LaBerge, 1961). It is apparently secondarily associated with Helianthus.

94. Melissodes (Eumelissodes) montana Cresson

This species is an oligolege of Compositae secondarily associated with Helianthus. It has been collected from flowers of Helianthus sp. and H. annuus (LaBerge, 1961). The species ranges from Colorado and Utah south to Mexico (Oaxaca and Baja California).

Both sexes, including pollen-collecting females, have been taken by us in primary sampling sites in New Mexico and Arizona (Tables A-E) as well as additional sites as follows:

ARIZONA.—COCHISE COUNTY: Cochise, 8 Sep 75, H. annuus, 0830–0859, 2P (EGL, JML). SANTA CRUZ COUNTY: Nogales, 17 Sep 74, H. annuus, 1210–1240, 1P (PDH, AEM, MMM), 15 Sep 77, H. annuus, 0930–0959, 1P (EGL, JML); Sonoita, 16 Sep 74, H. annuus, 8, 1 (PDH, AEM, MMM); Sonoita 10 mi E, 7 Sep 77, H. petiolaris, 0830–0859, 1N (EGL, JML).

95. Melissodes (Eumelissodes) nivea Robertson

Regarded by LaBerge (1961) as an oligolege of Compositae, it has been captured at flowers of Helianthus sp., H. annuus, and H. atrorubens and appears to be secondarily associated with sunflowers. The species ranges from New York to North Carolina and west to Mississippi, Kansas, and Minnesota. Robertson (1929) found the species visiting two species of Helianthus in Carlinville, Illinois, including H. divaricatus () and H. grosseserratus (, N).

96. Melissodes (Eumelissodes) pallidisignata Cockerell

LaBerge (1961) reported this species as an oligolege of Compositae depending primarily on the flowers of Chrysothamnus, Grindelia, and Haplopappus. Helianthus is included among his flower records. Thorp and Chemsak (1964) have described the nesting habits and adult behavior in coastal California, where females were gathering pollen from Grindelia stricta and Erigeron glaucus. It appears to be secondarily associated with Helianthus.

97. Melissodes (Eumelissodes) paulula LaBerge

Melissodes paulula is regarded by LaBerge (1961) as an oligolege of Compositae that appears to prefer Gutierrezia, Haplopappus, and Solidago, as borne out by his tabular summary of floral data. Included among his lesser flower records is Helianthus annuus, and Moldenke and Neff (1974) cite a male from this sunflower from Riverside County, California. The species occurs from Washington to southern California but is primarily confined to California. It is evidently secondarily associated with Helianthus.

98. Melissodes (Eumelissodes) perlusa Cockerell

LaBerge (1961) suggests that M. perlusa is probably an oligolege of Compositae. He recorded the species from Helianthus sp., H. annuus, and H. petiolaris. Of 38 collections (58 bees) with flower data examined by him, 23 collections (12 females and 28 males) were made on Helianthus, mostly H. petiolaris. The species ranges from Alberta and Manitoba south to Iowa and Arizona. It appears to be an oligolege of the Compositae possibly associated primarily with Helianthus.

99. Melissodes (Eumelissodes) robustior Cockerell

This is a species of western North America, ranging from Washington and Idaho to southern California and northern Nevada. It is an oligolege of Compositae, primarily associated with Helianthus. Of 148 females included by LaBerge (1961) in his tabulation of flower records, 60 were from Helianthus. Species included were Helianthus annuus, H. bolanderi, H. gracilentus, H. lenticularis, and H. petiolaris. Chemsak and Thorp (1962) have described the sleeping habits of males on fresh flowers of Scabiosa atropurpurea and Cosmos bipinnatus in August and September at Berkeley, California. Females were taking pollen from Cosmos.

This species was collected at H. annuus at one primary sampling site in California (Table K) as well as additional localities as follows:

CALIFORNIA.—FRESNO COUNTY: Parlier, 7 Oct 75, H. annuus, 1400–1429, 2 (EGL, JML, AEM, MMM). IMPERIAL COUNTY: El Centro, 29 Jul 75, H. annuus, 1000–1029, 5 (AEM, MMM); Holtville 3 mi W, 29 Jul 75, H. annuus, 1100–1114, 1 (AEM, MMM). KERN COUNTY: Highway 5 at Old River Road, 10 Sep 75, H. annuus, 1400–1415, 2 (AEM, MMM); Highway 5 and Junction of Copus Road, 10 Sep 75, H. annuus, 3 (AEM, MMM). STANISLAUS COUNTY: Patterson, 27 Jul 77, H. annuus, 0930–0959, 3, 3P (EGL, JML, AEM, MMM).

100. Melissodes (Eumelissodes) rustica (Say)

This species is primarily associated with Solidago, Aster, and Grindelia, but has been reported from Helianthus sp., H. atrorubens, H. divaricatus, H. grosseserratus, H. maximiliani, H. petiolaris, H. radula, and H. tuberosus (LaBerge, 1961). The species ranges from Nova Scotia south to Louisiana, west to Idaho and New Mexico, and south into Mexico. It is an oligolege of the Compositae, secondarily associated with Helianthus.

In Wisconsin, Graenicher (1909) found males visiting flowers of Helianthus strumosus and in Illinois Robertson (1929) found males visiting H. divaricatus, H. grosseserratus, and H. tuberosus. Clement (1973) has described the nesting habits and larva of this species.

101. Melissodes (Eumelissodes) snowii Cresson

LaBerge (1961) regards this species as probably an oligolege of Compositae. Females have been taken most often on Helianthus, including Helianthus sp., H. petiolaris, and H. subrhomboideus. The species ranges over the western part of the Great Plains including Alberta, Manitoba, Colorado, New Mexico, Nebraska, and North Dakota. It seems to be secondarily associated with Helianthus.

102. Melissodes (Eumelissodes) subagilis Cockerell

Melissodes subagilis is mainly found at Compositae, although LaBerge (1961) does include other families among his flower records. For Helianthus, he lists H. sp., H. annuus, H. maximiliani, and H. petiolaris. It appears to be an oligolege of Compositae, secondarily associated with Helianthus. For records of our collections see Table B and D.

103. Melissodes (Eumelissodes) subillata LaBerge

This species is an oligolege of Compositae and has been recorded from flowers of Helianthus maximiliani and H. petiolaris (LaBerge, 1961). It ranges from Quebec to Saskatchewan and south to Illinois and North Carolina. It appears to be secondarily associated with Helianthus.

104. Melissodes (Eumelissodes) submenuacha Cockerell

LaBerge (1961) regarded this species as probably an oligolege of Compositae. Cockerell (1906b) reported it from Helianthus at Albuquerque, New Mexico, and LaBerge's flower records include a female and male at Helianthus annuus at Las Cruces and Mesilla Park, New Mexico, respectively, and both sexes at H. petiolariṡ at Carrizozo, New Mexico. The range includes Colorado and southeastern Arizona, New Mexico and western Texas. It appears to be an oligolege of Compositae, secondarily associated with Helianthus.

For data from principal sampling sites, see Table B, C, and E. Additional records are as follows:

ARIZONA.—COCHISE COUNTY: Cochise, 8 Sep 75, H. annuus ( flowers), 0800–0829, 4P (EGL, JML). SANTA CRUZ COUNTY: Sonoita, 16 Sept 74, H. annuus, 3 (PDH, AEM, MMM).

NEW MEXICO.—DONA ANA COUNTY: Mesilla Park, 5 Sep 61, H. annuus, (PDH). LINCOLN COUNTY: Carrizozo, 10 Sep 61, H. petiolaris, 2N (PDH).

105. Melissodes (Eumelissodes) tineta LaBerge

An oligolege of Compositae, especially Chrysopsis and Aster, this species has also been taken at flowers of Helianthus maximiliani (LaBerge, 1961). It ranges from Minnesota and Michigan south to Florida and Texas. It appears to be secondarily associated with Helianthus.

106. Melissodes (Eumelissodes) trinodis Robertson

FIGURE 11

LaBerge (1961) regards this species as an oligolege of Compositae primarily associated with Helianthus. His table of floral records supports this conclusion, although he had flower data for only 47 females. Of these, 30 were from species of Helianthus, 13 from Compositae other than Helianthus, and 4 from plants other than Compositae. The species ranges from southeastern Canada and Maine south to Georgia and west to North Dakota and Kansas. Helianthus records include H. annuus, H. atrorubens, H. divaricatus, H. grosseserratus, H. maximiliani, H. mollis, H. salicifolius, and H. tuberosus. Graenicher (1909) recorded the species in Wisconsin from Helianthus giganteus (, P) and H. strumosus (, P) and Robertson (1929) found it visiting five species in Carlinville, Illinois, including H. annuus (, P), H. divaricatus (, P), H. grosseserratus (, P, frequent), H. mollis (P), and H. tuberosus (, N, frequent). The species is parasitized by Triepeolus helianthi (Graenicher, 1905), which is also a frequent visitor to sunflowers.

FIGURE 11.—Distribution of Melissodes (Eumelissodes) trinodis Robertson.

107. Melissodes (Eumelissodes) tristis Cockerell

This is the most polylectic species of the subgenus Eumelissodes, visiting plants of a wide range of families and seeming to prefer flowers of the Leguminosae, Compositae, and Malvaceae. It has been recorded from Helianthus sp., H. annuus, H. ciliaris, and H. petiolaris. The range includes Nebraska to California and south through Texas, New Mexico, and Arizona to southern Mexico (Oaxaca).

Our numerous sunflower records are all based upon nectar seeking individuals of both sexes. It appears to be a casual polylege of Helianthus.

For data from primary survey sites see Table A–E; additional samples are as follows:

ARIZONA.—GRAHAM COUNTY: Franklin, 6 Aug 75, H. annuus, 1130–1159, 1 (EGL, JML). PIMA COUNTY: Rillito, 6 mi W, 27 Jun 74, H. annuus, 0900–0929, 1, 1N (AEM, MMM), 30 Jul 75, H. annuus, 1330–1529, 10 (EGL, JML, AEM, MMM), 2 Aug 75, H. annuus, 0715–0729, 1 (AEM, MMM); Sahuarita, 26 Jun 74, H. annuus, 1200–1229, 22 (AEM, MMM). PINAL COUNTY: Eloy, 30 Jul 75, H. annuus, 1 (AEM, MMM). SANTA CRUZ COUNTY: Sonoita, 16 Aug 74, 3 (PDH, AEM, MMM).

108. Melissodes (Eumelissodes) velutina (Cockerell)

Melissodes velutina females appear to prefer species of Polemoniaceae (LaBerge, 1961) although Compositae are visited by the species including Helianthus gracilentus (by males). The species is limited to central and southern California (LaBerge, 1961), and is considered as a nectar visitor to Helianthus.

109. Melissodes (Eumelissodes) verbesinarum Cockerell

LaBerge (1961) records the known range of M. verbesinarum as from Washington to southern California, east to Nevada and Texas, and south to Jalisco, Mexico. He regards it as an oligolege of Compositae, but Helianthus is not included in his records. Our Helianthus records involve only males (Table B).

110. Melissodes (Eumelissodes) vernoniae Robertson

Although primarily an oligolege of Vernonia (345 of 380 females tabulated by LaBerge (1961) were from plants of this genus), it has been recorded from Helianthus sp. and H. tuberosus. The species ranges from Indiana and North Dakota west to Idaho and south to New Mexico and Texas. It appears to be secondarily associated with Helianthus.

111. Melissodes (Eumelissodes) wheeleri Cockerell

An oligolege of Compositae, especially Gaillardia, Helianthus, and Rudbeckia in that order (LaBerge, 1961), it has been recorded from H. annuus, H. debilis, and H. petiolaris. The range includes Michigan and North Dakota south to Louisiana, Texas, and Arizona. It evidently is secondarily associated with Helianthus.

112. Melissodes (Callimelissodes) coloradensis Cresson

Recorded from Helianthus sp., H. annuus, H. atrorubens, H. divaricatus, H. grosseserratus, H. mollis, H. petiolaris, H. scaberrimus, and H. tuberosus (LaBerge, 1961), this species ranges from Wisconsin to North Carolina and west to Arizona, Utah, and Wyoming. Robertson (1929) found M. coloradensis visiting six species of Helianthus in Carlinville, Illinois, including H. annuus (, P), H. divaricatus (, P, frequent), H. grosseserratus (P), H. rigidus (P), and H. tuberosus (, P, frequent). LaBerge (1961) reports Helianthus serves as the primary source of pollen.

113. Melissodes (Callimelissodes) composita Tucker

This species ranges from Montana south to New Mexico and Arizona. LaBerge (1961) noted a preference for Compositae but his list of flower records did not include Helianthus. Our data indicate this species to be an oligolege of Compositae secondarily associated with Helianthus.

In addition to sunflower pollen collecting data in Table B and D, we have one record as follows:

ARIZONA.—SANTA CRUZ COUNTY: Sonoita, 16 Aug 74, H. annuus, 1N (PDH, AEM, MMM).

Hurd and Linsley (1959) report the species using a common entrance to reach their nests which are made individually from subsoil cracks. They also report that Triepeolus helianthi Robertson may be a parasite of this species as many were found about the nesting site as well as at the same flowers being visited by M. composita.

114. Melissodes (Callimelissodes) glenwoodensis Cockerell

This species ranges from North Dakota to New Mexico and west to Washington and southern California. It has been recorded from Helianthus sp. and H. petiolaris as well as other Compositae (LaBerge, 1961) and appears to be secondarily associated with Helianthus.

115. Melissodes (Callimelissodes) lupina Cresson

Melissodes lupina is a western species ranging from Montana to Washington and south through Colorado, Utah, Nevada, and California to Baja California. LaBerge (1961) regards the species as oligolectic on Compositae and in his summary of flower records Compositae were involved in 225 of 290 collections, including 436 of 499 females and 223 of 288 males. Included in his flower list are Helianthus sp., H. annuus, and H. gracilentus. In California, Moldenke and Neff (1974) have recorded both sexes from H. nuttallii and H. gracilentus. The species is an oligolege of Compositae, secondarily associated with Helianthus.

In addition to the data in principal sampling sites (Table H, J–M), we have taken this species at sunflowers as follows:

CALIFORNIA.—FRESNO COUNTY: Parlier, 7 Sep 75, H. annuus, 1400–1429, 1, 2N (EGL, JML, AEM, MMM). KERN COUNTY: Highway 5 at Copus Road, 10 Aug 75, H. annuus, 1430–1445, 6 (AEM, MMM); Highway 5 and Old River Road, H. annuus, 1400–1415, 5 (AEM, MMM). STANISLAUS COUNTY: Patterson, 27 Jul 77, H. annuus, 0930–0959, 1P (EGL, JML, AEM, MMM). TULARE COUNTY: Dinuba 5.5 mi S, 7 Sep 75, H. annuus, 1200–1230, 3 (EGL, JML, AEM, MMM).

116. Melissodes (Callimelissodes) lustra LaBerge

Recorded by LaBerge (1961) from Helianthus sp. but preferring Gutierrezia, Chrysothamnus, and Haplopappus (Isocoma), in that order, this species occurs in Idaho, Oregon, Nevada, California, and Mexico (Baja California). It appears to be secondarily associated with Helianthus.

117. Melissodes (Callimelissodes) plumosa LaBerge

A male doubtfully referred to this species by LaBerge (1961) was taken on Helianthus petiolaris at Marmarth, North Dakota. It is otherwise known from California, Oregon, and Washington.

118. Melissodes (Callimelissodes) stearnsi Cockerell

This is a Pacific Coast species ranging from Washington to California. Among the flower records provided by LaBerge (1961) are a number of Compositae, including Helianthus sp. and H. annuus. The female has been collected taking pollen from Helianthus annuus in Riverside, California, by P. H. Timberlake in August. It is possibly an oligolege of Compositae, secondarily associated with Helianthus.

Genus Martinapis Cockerell

This genus contains three species, two in North America and one in South America. Both of the North American species are polyleges and only the species treated below has been taken at sunflower.

119. Martinapis (Martinapis) occidentalis Zavortink and LaBerge

According to Zavortink and LaBerge (1976), the females of this species are polylectic and are known to collect pollen from plants in the Compositae, Leguminosae, Solanaceae, and Zygophyllaceae. Among the flower records listed by them is one male from Helianthus niveus.

Genus Anthophora Latreille

Species of this genus are well represented in the Holarctic, Ethiopian, Oriental, and Neotropical Regions. Three subgenera are found in America north of Mexico, of which only Anthophora proper and Micranthophora contain species that visit sunflowers. Although 63 species of the genus Anthophora are present in America north of Mexico, only seven species are known to visit the flowers of Helianthus. Most of these are casual polyleges and the others apparently seek nectar only from these flowers.

120. Anthophora (Anthophora) montana Cresson

Anthophora montana is a southwestern species ranging from Texas to Colorado, New Mexico, and Arizona. The floral relationships of the females are not well known. Linsley and Hurd (1959) observed them taking pollen from Mentzelia pumila in southeastern Arizona as the flowers began to open at about 1540 hrs and continuing until 1912 hrs when a storm caused cessation of all bee activity. At other times of day they were seen taking nectar from Asclepias, Monarda, Helenium, and other flowers in the vicinity. For our collection records on Helianthus annuus, see Table B and C. The species appears to be a casual polylege of Helianthus.

121. Anthophora (Anthophora) smithii Cresson

This is a species ranging from South Dakota and Kansas to Texas, New Mexico, and Arizona. We have taken a single male on sunflower (Table B) and this species is considered to be a nectar visitor to Helianthus.

122. Anthophora (Anthophora) urbana urbana Cresson

A female of this highly polylectic species has been recorded from Helianthus annuus in Stanislaus County and males from H. gracilentus in San Bernardino, Riverside, and San Diego counties, California, by Moldenke and Neff (1974). It ranges from Washington and Idaho to New Mexico, Arizona, California, and northwestern Mexico; Mayer and Johansen (1976) have given an account of its habits. Other subspecies have been named from the coastal southern California islands.

Data from our primary sunflower surveys (Table C and H–M) as well as the following sampling data indicate that this species, although a frequent visitor, does not take pollen from sunflowers.

CALIFORNIA.—CONTRA COSTA COUNTY: Byron, 21 Jul 77, H. annuus, 1100–1129, 2N (EGL, JML, AEM, MMM). INYO COUNTY: Big Pine, 28 Aug 77, H. annuus, 0700–0729, 1N (EGL, JML). KERN COUNTY: Highway 5 at Copus Road, 10 Aug 75, H. annuus, 1430–1445, 1 (AEM, MMM); Wheeler Ridge, 23 Sep 76, H. annuus, 1245, 10 (AEM, MMM). SAN JOAQUIN COUNTY: Manteca 7.5 mi N, 21 Jul 77, H. annuus, 1100–1129, 1N (EGL, JML, AEM, MMM). STANISLAUS COUNTY: Grayson 6.5 mi N, 21 Jul 77, H. annuus, 1130–1159, 1N (EGL, JML, AEM, MMM). TULARE COUNTY: Dinuba 5.5 mi S, 7 Sep 75, H. annuus, 1200–1229, 4 (EGL, JML, AEM, MMM); Tulare, 6 Sep 75, H. annuus, 1600–1629, 2 (EGL, JML, AEM, MMM).

Thus this subspecies visits the flowers of Helianthus for nectar only.

123. Anthophora (Anthophora) walshii Cresson

This species, usually associated with Cassia, has been recorded taking nectar from Helianthus grosseserratus in Illinois by Robertson (1929) and at flowers of H. petiolaris in North Dakota by Stevens (1951b). The species has been recorded from Massachusetts, Wisconsin, Illinois, Iowa, Nebraska, Kansas, Colorado, Texas, and doubtfully from Arizona.

124. Anthophora (Micranthophora) curta Provancher

This species ranges from Colorado and Texas to California and Baja California, Mexico. Moldenke and Neff (1974) regard the females as pollen specific to Compositae. They record one female and 9 males from Helianthus gracilentus in San Diego County, California, males from H. annuus and H. sp. in Riverside County. Two subspecies have been recognized, A. c. curta and A. c. melanops Cockerell, but the character given for the latter by Cockerell does not hold up in our material.

Records from major survey sites are presented in Table A, B, H, and K. In addition it was taken at sunflower as follows:

CALIFORNIA.—SAN DIEGO COUNTY: Highway 8 at Laguna Junction, 13 Jun 74, H. annuus, 1300–1415, 2, 3N, 1P (AEM, MMM).

It appears to be a casual polylege of Helianthus.

125. Anthophora (Micranthophora) maculifrons Cresson

Cockerell (1898a) recorded this species from Helianthus annuus in New Mexico. The range extends westward to Nevada and Baja California. Moldenke and Neff (1974) record pollen-bearing females from Chrysothamnus and regard it as an oligolege of this genus of plants. More likely it is an oligolege of Compositae but too few records are available to judge. It appears to be a casual polylege of Helianthus.

126. Anthophora (Micranthophora) peritomae Cockerell

Cockerell (1907b) has recorded the female of this species from Helianthus annuus at Las Cruces, New Mexico. The known occurrence also includes Wyoming, Colorado, and Utah. In this last state, Torchio (1971) has reported females storing pollen from Grindelia squarrosa. It appears to be a casual polylege of Helianthus.

Genus Xeromelecta Linsley

Two species of this American genus of cleptoparasitic bees have been taken at sunflowers as detailed below.

127. Xeromelecta (Melectomorpha) californica (Cresson)

This cleptoparasite was recorded from Helianthus lenticularis at Orange, California, by Cockerell (1916a) and from H. sp. in Nebraska by Swenk (1907). Timberlake made the following collections:

CALIFORNIA.—ORANGE COUNTY: Anaheim, 14 Aug 25, H. annuus, 1 (P. H. Timberlake). RIVERSIDE COUNTY: Idyllwild 13 mi N, San Jacinto Mountains, 23 Jul 63, H. petiolaris, 3, 2 (P. H. Timberlake). The Gavilan, 4 Jun 50, H. gracilentus, 1 (P. H. Timberlake).

The species ranges widely through central and western North America where it has been associated with the nests of many species of Anthophora and has a wide variety of floral hosts. In our surveys it was frequently found at sunflowers along with one of its hosts, Anthophora urbana. For collection data at major sites see Tables I and J. It was collected as follows:

CALIFORNIA.—KERN COUNTY: Wheeler Ridge, 23 Sep 76, H. annuus, 1245, 1 (AEM, MMM). SAN DIEGO COUNTY: Highway 8 at Laguna Junction, 13 Jun 74, H. gracilentus, 1300–1415, 3 (AEM, MMM).

128. Xeromelecta (Melectomorpha) interrupta (Cresson)

A cleptoparasitic bee ranging from the Central and Rocky Mountain states to Arizona, New Mexico, and Texas and south into north central Mexico (Hurd, 1953). Hurd and Linsley (1975) have recorded it from flowers of Larrea tridentata. Our sunflower collections appear in Table B and C.

Genus Centris Fabricius

Most of the species included in this genus occur in the Neotropical Region, but a number of these (22) either occur in America north of Mexico or extend into the United States from Mexico or Central America. Only two of these have been taken at sunflowers, which they visit only for nectar.

129. Centris (Paracentris) atripes Mocsary

A polylectic species ranging widely from the southwestern United States (Texas to southern California) to Central America (Costa Rica). It has not been previously recorded from Helianthus. In addition to collections at a principal sampling site (Table C), we have taken it as follows:

ARIZONA.—SANTA CRUZ COUNTY: Nogales, 15 Sep 77, H. annuus, 0900–0929, 1 (EGL, JML).

130. Centris (Paracentris) caesalpiniae Cockerell

Centris caesalpiniae is a desert species that occurs in Texas, New Mexico, Arizona, and northern Mexico (Chihuahua). It has not been recorded previously from Helianthus, but a single male is listed from H. annuus in Table C.

Genus Ceratina Latreille

These bees are found on all continents and many of the islands. Thirteen of the 21 species known from America north of Mexico have been taken at flowers of Helianthus including the successfully adventive C. dallatorreana from the western Palaearctic, which visits these flowers for nectar only. Otherwise all of our native species are casual polyleges of this plant, except C. tejonensis, which appears to seek nectar only.

131. Ceratina (Zadontomerus) acantha Provancher

Ceratina acantha is a highly polylectic species ranging from British Columbia and Idaho to Utah, Nevada, California, and Baja California Norte, Mexico. Daly (1973) lists the species from Helianthus sp. and Moldenke and Neff (1974) record it from H. gracilentus. It appears to be a casual polylege of Helianthus.

132. Ceratina (Zadontomerus) apacheorum Daly

This is a southwestern species ranging from New Mexico to Nevada and southern California. Daly (1973) provides numerous flower records, including many from Compositae, but it has apparently not been recorded previously from Helianthus. The single collection in our sunflower survey was as follows:

CALIFORNIA.—SAN DIEGO COUNTY: Highway 8 at Laguna Junction, 13 Jun 74, H. annuus, 1300–1415, 2 (AEM, MMM).

It is apparently a casual polylege of Helianthus.

133. Ceratina (Zadontomerus) calcarata Robertson

Among the flowers in the long list of hosts for males of this bee provided by Daly (1973) is Helianthus sp. It ranges throughout most of the eastern United States east of the Rocky Mountains. It may be a casual polylege of Helianthus.

134. Ceratina (Zadontomerus) dupla Say

Ceratina dupla is a highly polylectic species ranging from Quebec to Florida, west to Manitoba, and south to Texas, Louisiana, and Mississippi. Among the many floral records provided by Robertson (1929) is Helianthus annuus (P), H. divaricatus (, P), and H. strumosus (N). Graenicher (1909) lists it from H. strumosus (P). Daly (1973) also records a male from Helianthus. It appears to be a casual polylege of Helianthus.

135. Ceratina (Zadontomerus) micheneri Daly

Ceratina micheneri is presently known from California and Oregon. Among the flower visits recorded by Daly (1973) are a male and two females at Helianthus from Westwood Hills, Los Angeles County, California, in February. It may be a casual polylege of Helianthus.

136. Ceratina (Zadontomerus) nanula Cockerell

This is a western species ranging from British Columbia to Montana and southward to California, Arizona, New Mexico, and northern Mexico. Among the flower records listed by Daly (1973) for females is Helianthus petiolaris; for males, Helianthus sp. It appears to be a casual polylege of Helianthus.

137. Ceratina (Zadontomerus) neomexicana Cockerell

A western species occurring from Texas to California, Colorado, and Idaho, C. neomexicana is apparently polylectic. Daly (1973) lists a female from flowers of Helianthus petiolaris at Artesia, Moffat County, Colorado, in July. It appears to be a casual polylege of Helianthus.

138. Ceratina (Zadontomerus) pacifica Smith

Daly (1973) records a series of four females and one male captured on Helianthus petiolaris in Colorado by C. D. Michener and a female taken on H. sp. in Utah by G. E. Bohart. The species is polylectic and widespread in Western North America (British Columbia to California, east to Idaho and Wyoming south to Arizona). It has been taken once on H. annuus. It evidently is a casual polylege of Helianthus.

139. Ceratina (Zadontomerus) punctigena Cockerell

A California species for which Daly (1973) lists many flower records including Helianthus occidentalis and H. gracilentus. It appears to be a casual polylege of Helianthus.

140. Ceratina (Zadontomerus) shinnersi Daly

Thus far this species is known only from Texas. Daly (1973) lists a female from Helianthus annuus 6 miles north of Raymondville, Willacy County, in April and a male from H. annuus 25 mi E. of McKinney, Collin County, in August. It evidently is a casual polylege of Helianthus.

141. Ceratina (Zadontomerus) strenua Smith

Females of this widespread species of Eastern North America (New York to Georgia and west to Wisconsin, Missouri, Kansas, Oklahoma, and Texas) visit a large range of flowers, including Helianthus (Daly, 1973). It appears to be a casual polylege of Helianthus.

142. Ceratina (Zadontomerus) tejonensis Cresson

This is a Pacific Coastal species occurring in California and Oregon. The females are apparently polylectic. Daly (1973) has listed a male at flowers of Helianthus gracilentus at Mt. Santiago, Orange County, California, in September.

143. Ceratina (Euceratina) dallatorreana Friese

This species is a native of the Mediterranean Region and is adventive in California, where it reproduces by thelytokous parthenogenesis (Daly, 1966, 1973). Our single capture of a nectar gathering female is reported in Table M.

Genus Xylocopa Latreille

This is a very large genus of carpenter bees that is especially well represented in the tropical and subtropical regions of both the Old and New Worlds. A few species occur or extend into the warm temperate regions of both the northern and southern hemispheres and, insofar as is known, all the species are polyleges, many visiting the flowers of both native and introduced plants. There are about 100 species in the Western Hemisphere and prior to this study only a single species, X. mordax Smith of the West Indies, had been taken at the flowers of Helianthus, apparently seeking nectar (Hurd, 1978). Even though there are nine species of Xylocopa present in America north of Mexico and some of them very abundant in areas where sunflowers grow, only the two subspecies of X. californica listed below have been found at these flowers, each on a single occasion questing for nectar.

Since this study was completed, one of us (PDH) had an opportunity to observe the Old World X. (Koptortosoma) pubescens Spinola visiting flowers of an ornamental sunflower (Helianthus annuus) growing under introduced conditions in the home garden of Dr. Dan Gerling in Tel-Aviv, Israel. Although during the period of these observations (20 July–7 August 1978) there were a number of competing sources of pollen and nectar (e.g., Carica, Cleome, and Luffa) in that garden, not to mention other nearby sources, both sexes of this carpenter bee were commonly observed sipping nectar from these sunflowers and occasionally the females collected pollen, especially in the morning before 0900 hrs.

On 16 September 1978 and again two days later, males of X. virginica texana Cresson (one in each instance) were observed (Hurd) taking nectar from flowers of H. annuus in Austin, Texas. No females were seen at these flowers during the month and, although females of two other carpenter bees (X. micans Lepeletier and X. tabaniformis parkinsoniae Cockerell) collected pollen from flowers of Solanum elaeagnifolium and S. rostratum growing among and adjacent to H. annuus, they did not visit the sunflowers.

144. Xylocopa (Xylocopoides) californica Cresson

Three subspecies of X. californica occur within the range of Helianthus, but only two of these have been taken at these flowers. For X. c. arizonensis Cresson, which ranges across the deserts of southwestern United States (western Texas to Utah, Nevada, and southern California) south into Mexico (Hurd, 1955, 1961), we record:

NEW MEXICO.—HIDALGO COUNTY: Rodeo, 2 Sep 73, H. annuus, 1130–1459, 2N (EGL, JML).

Subspecies X. c. diamesa, which occurs in the Peninsular Ranges of cismontane southern California northward through the Central Coast Ranges into Monterrey County, California, and southward into the Peninsular Ranges of northwestern Baja California (Hurd, 1954), has been taken as follows:

CALIFORNIA.—LOS ANGELES COUNTY: Gorman, 29 Aug 76, H. annuus, 0800–0830, 1N (AEM, MMM).

The nominate subspecies, which occurs in the North Coast ranges and Sierra Nevada Mountains of California and the southern Cascade Mountains of Oregon (Hurd and Moure, 1963; Hurd, 1978), visits many kinds of flowers for nectar and pollen, but has not been found at those of Helianthus.

Smith and Whitford (1978) have recently discussed the factors affecting the nesting success of X. c. arizonensis including pollen sources utilized by this subspecies in Arizona, New Mexico, and Mexico (Chihuahua).

Family APIDAE

Members of this family are present throughout much of the world from the high Arctic latitudes to or near the southern limits of the major land masses of the Southern Hemisphere. In America north of Mexico there are 47 species most conspicuously represented by the introduced European honeybee, Apis mellifera, and many native species of bumblebees (Bombus and Psithyrus).

Twenty-five species of this family have been associated with the flowers of Helianthus in America north of Mexico. All except four species of the social parasitic genus Psithyrus are pollen-collecting species and are either casual polyleges (15 species) or regular polyleges (6 species) of sunflowers.

Genus Bombus Latreille

This is a widespread genus that occurs on both the North and South American continents and Eurasia (including Japan and Taiwan, the Philippine Islands, and Indonesia east to Java) and is adventive in New Zealand. Almost half of the species present in America north of Mexico have been found at the flowers of Helianthus and doubtless additional species will be found to visit these flowers. Of the 20 species thus far taken at sunflowers most are casual polyleges (14 species), although a surprising number (6 species) are regular polyleges of that plant. At times their numbers become so large as to interfere or even dislodge other anthophilous visitors of sunflowers.

1. Bombus (Bombus) affinis Cresson

Fye and Medler (1954) have reported workers of this species at flowers of Helianthus in Wisconsin and Graenicher (1909) records workers taking pollen from flowers of H. giganteus in the same state. The species occurs from Quebec and Ontario south to Georgia and west to the Dakotas and is evidently a casual polylege of Helianthus.

2. Bombus (Bombus) terricola Kirby

Two subspecies are currently recognized. The nominate subspecies occurs from Nova Scotia to Florida and westward to South Dakota, Montana, and British Columbia. Workers have been recorded from Helianthus in Wisconsin by Fye and Medler (1954); Graenicher (1909) reports workers collecting pollen from flowers of H. strumosus in the same state. The western subspecies, B. terricola occidentalis Greene, ranges from Alaska to northern California, Nevada, and South Dakota and southward into Arizona and New Mexico. Milliron (1971) gives a number of flower records but sunflower is not included. Our record is based on the form named nigroscutatus by Franklin, which is regarded as a synonym of occidentalis by Milliron:

CALIFORNIA.—CONTRA COSTA COUNTY: Antioch, 20 Oct 75, H. annuus, 0900–0930, 4, 1N (EGL, JML).

This species appears to be a casual polylege of Helianthus.

3. Bombus (Fraternobombus) fraternus (Smith)

Bombus fraternus, a species of eastern and central United States (New Jersey to Florida and west to North Dakota, South Dakota, Nebraska, Colorado, and New Mexico) was reported (as B. Scutellaris Cresson) from flowers of Helianthus grosseserratus and H. divaricatus in Illinois by Robertson (1894, 1898) and later by him (Robertson, 1929) from flowers of H. divaricatus (P), H. grosseserratus (, ) and H. rigidus (N). LaBerge and Webb (1962), in their list of flowers visited in Nebraska, included H. annuus, H. grosseserratus, H. petiolaris, and H. rigidus. The species appears to be a regular polylege of Helianthus.

4. Bombus (Bombias) nevadensis Cresson

Bombus nevadensis auricomus (Robertson) was recorded from flowers of Helianthus grosseserratus and H. tuberosus in Illinois by Robertson (1929). According to LaBerge and Webb (1962), this subspecies, which occurs from Ontario to Florida and west to Texas, Oklahoma, Colorado, Wyoming, Montana, and southwestern Canada (Saskatchewan, Alberta, and British Columbia), has been collected often in Nebraska from sunflowers, including Helianthus annuus, H. grosseserratus, H. maximiliani, H. petiolaris, and H. rigidus.

The nominate subspecies is found from Alaska south to California, Arizona, and New Mexico and east to Wisconsin; it has also been reported from Mexico (Hidalgo). Moldenke and Neff (1974) list four workers of the nominate subspecies from Helianthus in California.

The species appears to be a regular polylege of Helianthus.

5. Bombus (Separatobombus) griseocollis (Degeer)

This species, which ranges across Canada and most of the United States, is regarded by LaBerge and Webb (1962) as having some preference for sunflowers in Nebraska. Among their list of flowers visited are Helianthus annuus, H. grosseserratus, H. maximiliani, H. petiolaris, and H. rigidus. Earlier, under the name Bombus separatus Cresson, Robertson (1894, 1929) had recorded it from H. annuus, H. divaricatus, H. grosseserratus, H. rigidus, H. strumosus, and H. tuberosus in Illinois and Graenicher (1909) reported workers gathering pollen from flowers of H. giganteus and H. strumosus in Wisconsin. Moldenke and Neff (1974) list 2 queens, 25 workers, and 43 males from Helianthus sp. in California. The species appears to be a regular polylege of Helianthus.

6. Bombus (Separatobombus) morrisoni Cresson

This is a western species ranging from British Columbia to California and east to South Dakota, Nebraska, Colorado, and New Mexico. Titus (1902) first recorded it from Helianthus annuus in Colorado. Our collection data appear in Table B and we have also taken it as follows:

CALIFORNIA.—INYO COUNTY: Big Pine, 28 Aug 77, H. annuus, 0630–0829, 1, 40P, 10N (EGL, JML).

It evidently is a regular polylege of Helianthus.

7. Bombus (Crotchiibombus) crotchii Cresson

Bombus crotchii occurs in California and Baja California, Mexico. Moldenke and Neff (1974) have recorded 6 males at flowers of Helianthus, of which the species may be a casual polylege.

8. Bombus (Cullumanobombus) rufocinctus Cresson

Workers and males of B. rufocinctus were reported at flowers of Helianthus in Wisconsin by Fye and Medler (1954). Possibly this species is a casual polylege of Helianthus. It ranges across southern Canada (Nova Scotia, New Brunswick, and Quebec to British Columbia), across the United States (Maine, Vermont, New York, Michigan, Illinois, Kansas, New Mexico, Arizona, and California), and southward into Mexico (Distrito Federal, Hidalgo, Mexico, Michoacan, Morelos, and Sonora).

9. Bombus (Pyrobombus) bimaculatus Cresson

This species, which ranges through most of eastern North America (Ontario and Maine south to Florida and west to Illinois, Kansas, Oklahoma, and Mississippi), has been recorded from Helianthus in Nebraska by LaBerge and Webb (1962) and in Wisconsin by Medler and Carney (1963). Robertson (1929) found males visiting the flowers of H. annuus in Carlinville, Illinois. It appears to be a casual polylege of Helianthus.

10. Bombus (Pyrobombus) centralis Cresson

Cockerell (1919) reported a worker from Helianthus in Colorado (as B. juxtus Cresson). Moldenke and Neff (1974) listed four workers and five males from Helianthus sp. without reference to locality. Graenicher (1909) recorded workers gathering pollen from flowers of H. strumosus in Wisconsin. The species ranges from Wisconsin to British Columbia and south to California, Arizona, and New Mexico. It is apparently a casual polylege of Helianthus.

11. Bombus (Pyrobombus) huntii Greene

This is a western North American species listed by Moldenke and Neff (1974) from Helianthus sp. in California. Clements and Long (1923) report it from flowers of H. petiolaris in Colorado. The species occurs from British Columbia and Alberta south to California, Nevada, Utah, and New Mexico. It may be a casual polylege of Helianthus.

12. Bombus (Pyrobombus) impatiens Cresson

A species of eastern North America (Ontario and Maine, south to Florida and west to Michigan, Illinois, Kansas, and Mississippi), B. impatiens has been recorded from Helianthus annuus and H. grosseserratus in Illinois by Robertson (1929). It appears to be a casual polylege of Helianthus.

13. Bombus (Pyrobombus) ternarius Say

Fye and Medler (1954) have recorded workers of B. ternarius from Helianthus in Wisconsin and Graenicher (1909) found workers collecting pollen from flowers of H. strumosus in the same state. The species ranges from Yukon east to Nova Scotia and south to Georgia, Michigan, Kansas, Montana, and British Columbia. It appears to be a casual polylege of Helianthus.

14. Bombus (Pyrobombus) vagans vagans Smith

This nominate subspecies ranges from British Columbia east to Nova Scotia and south to Georgia, Tennessee, South Dakota, Montana, Idaho, and Washington. Workers have been recorded by Graenicher (1909) collecting pollen from flowers of Helianthus giganteus and H. strumosus in Wisconsin where Fye and Medler (1954) also listed it from H. sp.; Robertson (1929) recorded nectar seeking males at flowers of H. annuus, H. grosseserratus, and H. tuberosus in Illinois. With relatively few records of floral visitation available for Nebraska, LaBerge and Webb (1962) could not draw conclusions about floral preferences, but did include H. annuus in their list of flowers visited. Workers of this subspecies were recorded (as B. consimilis Cresson) from flowers of Helianthus in Virginia and Connecticut by Cockerell (1917a). It appears to be a casual polylege of Helianthus.

15. Bombus (Subterraneobombus) appositus Cresson

Moldenke and Neff (1974) record a worker of this species from Helianthus sp. without indication of locality. The species ranges from British Columbia east to Saskatchewan and south to New Mexico, Arizona, and California. It may be a casual polylege of Helianthus.

16. Bombus (Subterraneobombus) borealis Kirby

A queen of B. borealis was recorded from Helianthus in Wisconsin by Fye and Medler (1954). The species ranges across southern Canada from Nova Scotia to Alberta and occurs in the northern United States from Maine to New Jersey and west to North Dakota and South Dakota. It may be a casual polylege of Helianthus.

17. Bombus (Fervidobombus) californicus Smith

One queen and two workers of this western North American species have been listed from Helianthus sp. without locality reference by Moldenke and Neff (1974). The species ranges from British Columbia and Alberta in Canada south to California, Arizona, and New Mexico in the United States, and into Mexico (Baja California Norte and Sonora). It is possibly a casual polylege of Helianthus.

18. Bombus (Fervidobombus) fervidus fervidus (Fabricius)

The nominate subspecies occurs from Quebec and New Brunswick south to Georgia and west to British Columbia, Washington, Oregon, California and into Mexico (Chihuahua). LaBerge and Webb (1962) list the flowers from which this widespread bumblebee has been collected in Nebraska. Included is Helianthus sp., but their records do not indicate that sunflower was a preferred host. Cockerell (1919) recorded the species from H. annuus zonatus at Falls Church, Virginia, and Moldenke and Neff (1974) from H. sp. in California. It appears to be a casual polylege of Helianthus.

19. Bombus (Fervidobombus) pennsylvanicus pennsylvanicus (Degeer)

This subspecies was recorded at flowers of Helianthus by Swenk (1907) and from H. annuus zonatus by Cockerell (1917a). Under the name Bombus americanorum this bee has been reported at flowers of Helianthus annuus, H. grosseserratus, H. mollis, H. rigidus, H. tuberosus, and H. divaricatus in Illinois (Robertson, 1894, 1898, 1929), at H. annuus lenticularis in Nebraska (Cockerell 1923). LaBerge and Webb (1962) report that in Nebraska it has been most often collected on sunflowers, including H. annuus, H. grosseserratus, H. maximiliani, H. petiolaris, and H. rigidus. It has also been recorded from sunflowers by Cockerell (1907b) and others. Graenicher (1909) reports nectar-seeking males and workers collecting pollen from flowers of H. giganteus and H. strumosus in Wisconsin. This subspecies was one of the commonest bees at flowers of H. annuus in Austin, Texas, during September 1978. Most workers were seeking nectar as were males and queens, but a few queens and workers occasionally were observed collecting pollen. The principal competing pollen sources were Solanum elaeagnifolium and S. rostratum which provided nearly all of the pollen collected by this subspecies during these observations. It is evidently a regular polylege of Helianthus and ranges from Quebec and Ontario, south to Florida, west to Minnesota, South Dakota, Nebraska, Colorado and New Mexico, and southward into Mexico and possibly Central America.

20. Bombus (Fervidobombus) pennsylvanicus sonorus Say

PLATE 5

This subspecies is a frequent visitor to sunflowers in the southwestern United States (Texas west to California) and northwestern Mexico. It was first recorded from this plant in New Mexico by Cockerell and Porter (1899). At times we have found it so numerous at sunflower in Arizona, especially males, as to preclude sampling for other bees. In almost all collections from the southern part of that state this bee was undersampled. It is a regular polylege of Helianthus.

Collection records for this subspecies at principal sampling sites may be found in Table A–E, G, and I–M. In addition it has been taken at sunflowers as follows:

ARIZONA.—COCHISE COUNTY: Cochise, 8 Sep 75, H. annuus, 0830–0859, 2N (EGL, JML); St. David 1.5 mi W, 3 Sep 61, H. annuus, 1P (PDH). GRAHAM COUNTY: Franklin, 6 Aug 74, H. annuus, 0830–0859, 2N (EGL, JML). SANTA CRUZ COUNTY: Nogales, 15 Sep 77, H. annuus, 0700–0759, 1, 45P (EGL, JML), Patagonia 6 mi N, 7 Sep 77, H. annuus, 0730–0759, 1, 4P, 2N (EGL, JML).

CALIFORNIA.—CONTRA COSTA COUNTY: Antioch, 21 Sep 75, H. annuus, 0900–0930, 4N (EGL, JML). FRESNO COUNTY: Parlier, 7 Oct 75, H. annuus, 1400–1429, 2 (EGL, JML, AEM, MMM). INYO COUNTY: Big Pine, 28 Aug 77, H. annuus, 0630–0659, 1P (EGL, JML). LOS ANGELES COUNTY: Calabasas, 29 Sep 75, H. annuus, 0915–0929, 1N (AEM, MMM). ORANGE COUNTY: Newport Beach, 27 Aug 76, H. annuus, 1400–1429, 5P, 15N (AEM, MMM). STANISLAUS COUNTY: Ceres, 27 Jul 77, H. annuus, 0800–0829, 1P (EGL, JML, AEM, MMM); Modesto, 3 Oct 75, H. annuus, 0745–0814, 8, 2N (EGL, JML, AEM, MMM). TULARE COUNTY: Dinuba 5.5 mi S, 7 Oct 75, H. annuus, 1200–1229, 4, (EGL, JML, AEM, MMM).

Genus Psithyrus Lepeletier

Included in this genus are social parasites that live in the nests of the pollen-collecting bumblebees. Four of the six Nearctic species have been taken sipping nectar at the flowers of Helianthus, often in company with the species in whose nests they live.

21. Psithyrus ashtoni (Cresson)

This species, which occurs across southern Canada (Prince Edward Island west to Saskatchewan) and much of the more northern parts of the eastern United States (North Dakota, Minnesota, Wisconsin, Michigan, Ohio, West Virginia, and Virginia), is a social parasite of Bombus affinis and B. terricola, both of which are casual polyleges of Helianthus. It has been recorded at the flowers of Helianthus in Wisconsin by Medler and Carney (1963).

22. Psithyrus citrinus (Smith)

Under the name Psithyrus laboriosus (Fabricius) (see Mitchell, 1962, for synonymy), Medler and Carney (1963) have recorded females of this species at Helianthus in Wisconsin. Earlier, Graenicher (1909) reported the male at H. strumosus from the same state. It is known to be a social parasite in the nests of Bombus impatiens, B. nevadensis auricomus, and B. vagans, all of which visit the flowers of Helianthus. It also occasionally attempts to invade hives of the common honeybee, Apis mellifera (Hurd, 1979). The species ranges from Prince Edward Island and New Brunswick south to Florida and Alabama and west to South Dakota and North Dakota.

23. Psithyrus insularis (Smith)

A widespread North American species listed from Helianthus sp. in California by Moldenke and Neff (1974), the species ranges from Canada south to California, Arizona, New Mexico, Nebraska, New York, and New Hampshire. It is known to live as a social parasite in the nests of many species of Bombus (Hurd, 1979), including a number of those that also visit flowers of Helianthus.

24. Psithyrus variabilis (Cresson)

This is a primarily eastern North American species that is parasitic on Bombus pennsylvanicus (Frison, 1916, 1921). Robertson (1929) recorded it from H. annuus (, ) and H. grosseserratus (, , frequent) in Illinois and LaBerge and Webb (1962) included among the flowers visited by this bee in Nebraska, Helianthus annuus, H. grosseserratus, H. petiolaris, and H. rigidus. The species ranges from Ohio south to Florida and west to North Dakota, South Dakota, Nebraska, Oklahoma, Texas, New Mexico, and Mexico.

Genus Apis Linnaeus

This genus, which is native to Eurasia and Africa, is well established in the Western Hemisphere, having been originally introduced into both North and South America from Europe. While there is much variation evident in the introduced species owing to hybridization of the several introduced races or strains, only one species is represented.

25. Apis mellifera Linnaeus

PLATE 5

Honeybees, as the most universally distributed and polylectic of pollinators of agricultural and ornamental crops, as well as entomophilous plants in general, are obviously of special interest to students of sunflower pollination. We have devoted a section to the conflicting information on the role of honeybees in the pollination of commercial sunflowers in the introductory section of this paper (page 19). The data presented here relate to its role in the pollination of wild sunflowers. Unfortunately, it is no more clear-cut or definitive than the data regarding the role of honeybees in the pollination of commercial varieties of sunflower in the United States. This is obviously a subject for more intensive investigation.

Perhaps the strongest statement regarding the role of the honeybee is that of Robertson (1922) in a special situation, at his home in Carlinville, Illinois. He reported that of 153 individuals taken in his yard on H. annuus in 1917, Apis showed 40.5 percent and of 467 individuals taken on H. annuus and H. divaricatus, it showed 14.1 percent. Although this can hardly be considered a typical “wild” environment for these species, it is nevertheless significant. Later, he provided summary statistics over the years (Robertson, 1929) for seven local species near Carlinville as follows: H. annuus (collections made from cultivated sunflower between 11 July and 6 September yielded 434 specimens of insect visitors, of which 65 were honeybees), H. divaricatus (honeybees were present among 53 species of bees collected between 22 July and 10 September—numbers were not given; on 27 August, of 10 species of bees represented by 35 individuals, only one was a honeybee). At H. grosseserratus, however, among 72 species of visitors observed between 27 August and 15 October, honeybees were “abundant.” On H. rigidus, H. mollis, H. scaberrimus, and H. tuberosus during the summer months he found no honeybees.

In his extensive surveys of Wisconsin bees, Graenicher (1909) reported (without numerical data) worker honeybees taking pollen from H. giganteus and nectar and pollen from H. strumosus. In his list of sunflower bees at Sterling, Colorado, Cockerell (1911) included no honeybees, at Falls Church, Virginia (Cockerell, 1917a) only one worker, and no Apis at Colebrook, Connecticut.

In Orange County, California, Cockerell (1916a) found no honeybees visiting the flowers of Helianthus lenticularis, although seven species of native bees were collected and honeybees were present in the vicinity. During a series of surveys of bees and other visitors to Helianthus annuus (both wild and commercial varieties) in the central and lower San Joaquin Valley and Delta region of California (particularly Contra Costa, San Joaquin, Stanislaus, Merced, and Madera counties) in the last week of July 1977, we were impressed with the relatively small numbers of honeybees at the flowers in comparison with such native species as Diadasia enavata, Svastra obliqua, and Melissodes agilis (e.g., see Tables I, J, L, M). These last three species were busily taking nectar and pollen, sometimes in incredibly large numbers, yet in half-hour spot samples in a number of localities and all-day samples at three wild sunflower sites involving four collectors, not a single pollen-collecting honeybee was captured or seen. The nectar-gatherers were few, even when a large stand of H. annuus in excellent bloom and producing an abundance of pollen and nectar attracting other species of bees was growing within 50 yards of an apiary comprising approximately 25 colonies. Even when taking nectar, the honeybees frequently did not enter the flower head but rested on the large peripheral ray florets and probed the nectar bearing florets from the outside.

The sampling of commercial sunflowers was superficial and largely limited to the periphery of the fields due to the density of the planting, the size of the flowers and the drooping heads, so the relatively small number of honeybees observed in these plantings may have been quite misleading. Large nesting sites, however, of Svastra obliqua and Diadasia enavata on the edge of one commercial field from which the females were actively returning with heavy loads of pollen left no doubt that these species can be an important factor in sunflower seed production.

Data from collections at primary survey sites are presented in Tables G, I, J, L, and M. In addition we have taken honeybees at sunflowers as follows:

ARIZONA.—COCHISE COUNTY: Cochise, 8 Sep 75, H. annuus, 0800–0859, 1P, 5N (EGL, JML). PIMA COUNTY: Rillito, 5 mi W, 27 Jun 74, H. annuus, 0900–0929, 1P (AEM, MMM), 30 Jul 75, H. annuus, 1315–1329, 1N (AEM, MMM). SANTA CRUZ COUNTY: Nogales, 15 Sep 77, H. annuus, 0830–0859, 2P, 2N, 1600–1629, 1P (EGL, JML).

CALIFORNIA.—CONTRA COSTA COUNTY: Antioch, 20 Oct 75, H. annuus, 0900–0930, 2N (EGL, JML); Byron 4 mi E, 21 Jul 77, H. annuus, 0800–0829, 1N (EGL, JML, AEM, MMM). IMPERIAL COUNTY: Holtville 3 mi W, 29 Jul 75, H. annuus, 1100–1114, 1N (AEM, MMM). INYO COUNTY: Big Pine, 28 Aug 77, H. annuus, 0630–0759, 5P, 3N (EGL, JML). MERCED COUNTY: Atwater, 23 Jul 77, H. annuus, 1200–1229, 1P, 2N (EGL, JML, AEM, MMM). RIVERSIDE COUNTY: Coachella, 8 Jun 76, H. annuus, 0900–0929, 1N (EGL, JML). SAN DIEGO COUNTY: Highway 8 at Laguna Junction, 13 Jun 74, H. annuus, 1300–1415, 1N (AEM, MMM). SAN JOAQUIN COUNTY: Manteca 7.5 mi N, 27 Jul 77, H. annuus, 1100–1129, 3P, 2N (EGL, JML, AEM, MMM); Victoria Island, 0.5 mi E of Old River, 0930–0959, H. annuus (commercial sunflower), 0930–0959, 1P, 1N (EGL, JML, AEM, MMM). STANISLAUS COUNTY: Modesto, 3 Oct 75, H. annuus, 0745–0815, 1P, 2N (EGL, JML); Modesto 10 mi S, 27 Jul 77, H. annuus, 0800–0829, 2P (EGL, JML).

TEXAS.—TRAVIS COUNTY: Austin, 18 Sep 78, H. annuus, 0900–1730, 17P, 33N (PDH).

Appendix

Tables

(For explanation of format, see “Sampling Procedures” in text)

TABLE A.5v —Silver City, 8 km NW, Grant County, New Mexico, 1798 m elevation; half-hour samples of principal species of bees visiting Helianthus petiolaris, 11–12 September 1974 (sky broken with scattered clouds, rain in late afternoon; collectors: E. G. and J. M. Linsley)

TABLE B.—Animals, Hidalgo County, New Mexico, 1341 m elevation; half-hour samples of principal species of bees visiting Helianthus annuus, 4–5 September 1974 (sky clear throughout morning, scattered clouds in afternoon; collectors: E. G. and J. M. Linsley)

TABLE C.—Rodeo, Hidalgo County, New Mexico; half-hour samples of principal species of bees visiting Helianthus annuus, 2–4 September 1973 (sunrise, 0505; sunset, 1820; sky clear with scattered clouds; collectors: E. G. and J. M. Linsley)

TABLE D.—Double Adobe, Cochise County, Arizona; half-hour samples of principal species of bees visiting Helianthus annuus on various dates in 1974 and 1975 (collectors: P. D. Hurd, Jr., A. E. and M. M. Michelbacher, E. G. and J. M. Linsley)

TABLE E.—Benson, Cochise County, Arizona, 1091 m elevation; half-hour samples of principal species of bees visiting Helianthus annuus, 14 September 1974 (sky broken, scattered clouds beginnig about 1100, rain at about 1430; collectors: E. G. and J. M. Linsley)

TABLE F.—Indio, Riverside County, California; half-hour samples of principal species of bees visiting Helianthus, annus, 18 September 1977 (pollen essentially all removed by bees by midmorning, small amount available at midafternoon; collectors: E. G. and J. M. Linsley)

TABLE G.—Bishop, Inyo County, California, 1292 m elevation; half-hour samples of principal species of bees visiting Helianthus annuus, 27 August 1977 (sunrise, 0610; clear in morning, cloudy in afternoon, particularly over Sierra Nevada Mountains in the west; collectors: E. G. and J. M. Linsley)

TABLE H.—Corcoran, Kings County, California; half-hour samples of principal species of bees visiting Helianthus annuus, 6 October 1975 (cool breeze in early morning after heavy rain previous evening, sky clear at sunrise but clouds forming by 0930, broken sky and cool breeze until early afternoon, gusty wind and clouds about 1300 and dust storm approaching by late 1400, all activity over; collectors: E. G. and J. M. Linsley and A. E. and M. M. Michelbacher)

TABLE I.—Madera, Madera County, California; half-hour samples of principal species of bees visiting Helianthus annuus, 24 July 1977 (sunrise, 0512; sky clear; collectors: E. G. and J. M. Linsley, A. E. and M. M. Michelbacher)

TABLE J.—Madera, Madera County, California; half-hour samples of principal species of bees visiting Helianthus annuus, 21 September 1977 (sunrise behind clouds, 0600; anthesis beginning 0705; collectors: E. G. and J. M. Linsley)

TABLE K.—Madera, Madera County, California; half-hour samples of principal species of bees visiting Helianthus annuus, 5 October 1975 (cool morning after cool night, sun generally bright; sunrise, 0540; very little pollen available until after 0700; first bee checking flowers for pollen and/or nectar at 0656; first bee gathering pollen at 0715; collectors: E. G. and J. M. Linsley, A. E. and M. M. Michelbacher)

TABLE L.—Merced, Merced County, California; half-hour samples of principal species of bees visiting Helianthus annuus, 4 October 1975 (sunrise, 0605; sunset, 1738; thin clouds in sky but sun generally bright; honey bees searching flowers at 0650 but no new nectar or pollen yet available; first Melissodes with pollen at 0715; pollen visibly becoming available by 0730, more so at 0800; collectors: E. G. and J. M. Linsley)

TABLE M.—Escalon, San Joaquin County, California; half-hour samples of principal species of bees visiting Helianthus annuus, 22 July 1977 (sunrise, 0510; sky clear, slight breeze in afternoon; collectors: E. G. and J. M. Linsley, A. E. and M. M. Michelbacher)

TABLE N.—Pollen relationships of the oligoleges primarily associated with the North American species of Helianthus (species of bees and sunflowers are arranged phylogenetically)

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1909.   Some Anthidiine Bees. Entomological News, 20:261–262.

1910.   The North American Bees of the Genus Nomia. Proceedings of the United States National Museum, 38:289–298.

1911.   Records of Bees. Canadian Entomologist, 43:389–391.

1912.   The Red Sunflower. Popular Science Monthly, 80:373–382.

1914a. New and Little-known Bees. Entomologist, 47:114–119.

1914b. Bees Visiting Helianthus. Canadian Entomologist, 46:409–415.

1914c. Suppression and Loss of Characters in Sunflowers. Science, new series, 40:283–285.

1914d. The Entomology of Helianthus. Entomologist, 47:191–196.

1915a. Characters of Helianthus. Torreya, 15:11–16.

1915b. Sunflower Insects. Canadian Entomologist, 47:280–282.

1915c. Notes on Some Bees from Virginia. Proceedings of the Entomological Society of Washington, 7:3–5.

1916a. Sunflower Insects in California and South Africa. Canadian Entomologist, 48:76–79.

1916b. Descriptions and Records of Bees, LXXI. Annals and Magazine of Natural History, series 8, 17:277–287.

1917a. Sunflower Insects in Virginia and Connecticut. Canadian Entomologist, 49:212.

1917b. Some Sunflower Insects. Journal of Economic Entomology, 10:561–562.

1918.   The Story of the Red Sunflower. American Museum Journal, 18:39–47.

1919.   The Bees of Peaceful Valley, Colorado. Journal of the New York Entomological Society, 27:298–300.

1922.   Bees of the Genus Perdita from the Western States. American Museum Novitates, 33:1–15.

1923.   A Bee-collecting Trip across the Plains. Entomological News, 34:45–50.

1929.   Hybrid Sunflowers. American Naturalist, 63:470–475.

1936.   Records of Western Bees. American Museum Novitates, 831:1–6.

1938.   Recollections of a Naturalist, X: The Red Sunflower. Bios, 9:117–124.

Cockerell, T.D.A., and Wilmatte Porter

1899.   Contributions from the New Mexico Biological Station, VII: Observations on Bees, with Descriptions of New Genera and Species. Annals and Magazine of Natural History, series 7, 4:403–421.

Cockerell, W. P.

1941.   The Red Sunflower Garden of 1941. 3 pages. [Booklet issued by Burpee's Seed Company.]

Crawford, J. C.

1902.   Notes and Descriptions of Bees. Canadian Entomologist, 34:234–240.

1915.   Descriptions of New Hymenoptera, No. 9. Proceedings of the United States National Museum, 48:577–586, 11 figures.

Cross, Earle A.

1958.   A Revision of the Bees of the Subgenus Epinomia in the New World (Hymenoptera: Halictidae). University of Kansas Science Bulletin, 38:1261–1301, 4 figures.

Cross, Earle A., and George E. Bohart

1960.   The Biology of Nomia (Epinomia) triangulifera with Comparative Notes on Other Species of Nomia. University of Kansas Science Bulletin, 41:761–792, figures 1–16.

Custer, Clarence P.

1928.   On the Nesting Habits of Melissodes Latr. (Hymenop.). Canadian Entomologist, 60:28–31, 2 figures.

1929a. Habits of Perdita zebrata with Description of Larva. Canadian Entomologist, 61:49–51.

1929b. Notes on Cocoons and Parasites of Melissodes obliqua and Nests of Perdita opuntiae (Hymenoptera: Apoidea). Psyche, 36:293–295.

Custer, C. P., and C. H. Hicks

1927.   Nesting Habits of Some Anthidiine Bees. Biological Bulletin, 52:258–277.

Daly, Howell V.

1966.   Biological Studies on Ceratina dallatorreana, an Alien Bee in California Which Reproduces by Parthenogenesis (Hymenoptera: Apoidea). Annals of the Entomological Society of America, 59:1138–1154.

1973.   Bees of the Genus Ceratina in America North of Mexico (Hymenoptera: Apoidea). University of California Publications in Entomology, 74:1–113, 2 plates.

Donovan, Barry J.

1977.   A Revision of North American Bees of the Subgenus Cnemidandrena (Hymenoptera: Andrenidae). University of California Publications in Entomology, 81:1–107, 130 figures, 17 maps.

Dyer, Judith G., and Alvin F. Shinn

1978.   Pollen Collected by Calliopsis andreniformis Smith in North America (Hymenoptera: Andrenidae). Journal of the Kansas Entomological Society, 51:787–795, 23 figures, 2 tables.

Essig, E. O.

1926.   Insects of Western North America. 1035 pages, 766 figures. New York: Macmillan.

Faegri, K., and L. van der Pijl

1966.   The Principles of Pollination Ecology. ix + 248 pages. Pergamon Press.

Fischer, Roland L.

1950.   Kansas Bees of the Genus Agapostemon Guerin (Hymenoptera: Halictidae). Journal of the Kansas Entomological Society, 23:76–78.

1951.   Observations on the Nesting Habits of Some Megachilid Bees. Journal of the Kansas Entomological Society, 24:46–50.

Free, J. B.

1964.   The Behaviour of Honeybees on Sunflower (Helianthus annuus L.). Journal of Applied Ecology, 1:19–27, 1 plate, 5 tables.

1966.   The Foraging Behaviour of Bees and Its Effect on the Isolation and Speciation of Plants. In Reproductive Biology and Taxonomy of Vascular Plants, pages 76–91. Pergamon Press.

1970.   Insect Pollination of Crops. xi + 544 pages. London and New York: Academic Press.

Free, J. B., and J. Simpson

1964.   The Pollination Requirements of Sunflowers (Helianthus annuus L.). Empire Journal of Experimental Agriculture, 32:340–342, 2 tables.

Frison, T. H.

1916.   Note on the Habits of Psithyrus variabilis Cress. Bulletin of the Brooklyn Entomological Society, 11:46–47.

1921.   Psithyrus laboriosus Fabr. in the Nests of Bumblebees (Hym.). Canadian Entomologist, 53:100–101.

Furgala, Basil

1954.   Honeybees Increase Seed Yields of Cultivated Sunflowers. Gleanings in Bee Culture, 82:532–534.

1970.   Sunflower Pollination—A Neglected Research Problem Area in the Indispensable Pollinators, Report of the Ninth Pollination Conference, Hot Springs, Arkansas, October 12–15, 1970. Agricultural Extension Service, University of Arkansas, MP-127: 37–42.

Fye, R. E., and J. T. Medler

1954.   Spring Emergence and Floral Hosts of Wisconsin Bumblebees. Wisconsin Academy of Sciences, Arts and Letters, 43:75–82.

Gage, Earle W.

1963.   Sunflowers—A Profitable Farm Crop. Organic Gardening, 10:42–45.

Gagné, Raymond J.

1972.   A New Species of Contarinia (Diptera: Cecidomyiidae) from Helianthus annuus L. (Compositae) in North America. Entomological News, 83:279–281, 7 figures.

Graenicher, S.

1905.   Some Observations on the Life History and Habits of Parasitic Bees. Bulletin of the Wisconsin Natural History Society, 3:153–167.

1909.   Wisconsin Flowers and Their Pollinators. Bulletin of the Wisconsin Natural History Society, 7:19–77.

1910a. Wisconsin Bees—New and Little-known Species. Canadian Entomologist, 42:101–104.

1910b. Bees of Northwestern Wisconsin. Bulletin of the Public Museum of Milwaukee, 1:221–249.

1914.   Wisconsin Bees of the Genus Perdita, Geographical Distribution and Relations to Flowers. Canadian Entomologist, 46:51–57.

1927.   Bees of the Genus Halictus from Miami, Florida. Psyche, 34:203–208.

1930.   Bee-Fauna and Vegetation of the Miami Region of Florida. Annals of the Entomological Society of America, 23:153–174.

1935.   Bee-Fauna and Vegetation of Wisconsin. Annals of the Entomological Society of America, 28:285–310.

Grant, Verne

1950.   The Flower Constancy of Bees. Botanical Review, 16:379–398.

Grigarick, A. A., and L. A. Stange

1968.   The Pollen-collecting Bees of the Anthidiini of California (Hymenoptera: Megachilidae). Bulletin of the California Insect Survey, 9:1–113, 227 figures.

Guynn, Godfrey, and Elbert R. Jaycox

1973.   Observations on Sunflower Pollination in Illinois. American Bee Journal, 113:168–169, 3 figures.

Heiser, Charles B., Jr.

1947.   Hybridization between the Sunflower Species Helianthus annuus and H. petiolaris. Evoluation, 1:249–262.

1949.   Studies in the Evolution of the Sunflower Species Helianthus annuus and H. bolanderi. University of California Publications in Botany, 23:157–196, plates 30–39.

1951a. Hybridization in the Annual Sunflowers: Helianthus annus × H. argophyllus. American Naturalist, 85: 64–72.

1951b. Hybridization in the Annual Sunflowers: Helianthus annuus × H. debilis var. cucumerifolius. Evolution, 5:42–51.

1951c. The Sunflower among the North American Indians. Proceedings of the American Philosophical Society, 95:432–448.

1954.   Variation and Subspeciation in the Common Sunflower, Helianthus annuus. American Midland Naturalist, 51:287–305.

1955.   The Origin and Development of the Cultivated Sunflower. American Biology Teacher, 17:161–167.

1961.   Evolution in Sunflowers. American Journal of Botany, 48:547.

1965.   Sunflowers, Weeds, and Cultivated Plants. In H. G. Baker and G. L. Stebbins, The Genetics of Colonizing Species, pages 391–398. London and New York: Academic Press.

1976.   The Sunflower. xxvi + 198 pages, illustrated. Norman: University of Oklahoma Press.

Heiser, Charles B., Dale Smith, Sarah B. Clevenger, and William C. Martin, Jr.

1969.   The North American Sunflowers (Helianthus). Memoirs of the Torrey Botanical Club, 22:1–218, illustrated.

Hicks, Charles H.

1926.   Nesting Habits and Parasites of Certain Bees of Boulder County, Colorado. University of Colorado Studies, series A, 15:217–252.

1929.   On the Nesting Habits of Callanthidium illustre (Cresson). Canadian Entomologist, 61:1–8.

Hurd, Paul D., Jr.

1953.   Notes on the Melectine Bees of Mexico (Hymenoptera: Apoidea). Journal of the Kansas Entomological Society, 26:35–37, 1 figure.

1954.   A Polytypic Interpretation of the California Carpenter Bee Xylocopa californica with the Description of a New Subspecies and Notes on a Possible Polytopic Form. Pan-Pacific Entomologist, 30:199–200, 1 map.

1955.   The Carpenter Bees of California. Bulletin of the California Insect Survey, 4:35–72, plates 3–6, 4 maps.

1958.   American Bees of the Genus Dioxys Lepeletier and Serville (Hymenoptera: Megachilidae). University of California Publications in Entomology, 14:275–302, 28 figures, 4 maps.

1961.   A Synopsis of the Carpenter Bees Belonging to the Subgenus Xylocopoides Michener. Transactions of the American Entomological Society, 87:247–257, 9 figures.

1970.   A New, Narrowly Polylectic, Autumnal Species of Dialictus from the Flowers of Jepsonia heterandra, an Endemic California Saxifrage. Pan-Pacific Entomologist, 46:209–212.

1978.   An Annotated Catalog of the Carpenter Bees (Genus Xylocopa Latreille) of the Western Hemisphere (Hymenoptera: Anthophoridae). vi + 106 pages, 1 frontispiece. Washington: Smithsonian Institution Press.

1979.   Superfamily Apoidea. In Karl V. Krombein et al., Catalog of Hymenoptera in America North of Mexico, 2: 1741–2209. Washington: Smithsonian Institution Press.

Hurd, Paul D., Jr., and E. Gorton Linsley

1959.   Observations on the Nest-Site Behavior of Melissodes composita Tucker and Its Parasites, with Notes on the Communal Use of Nest Entrances (Hymenoptera: Apoidea). Entomological News, 70:141–146.

1964.   The Squash and Gourd Bees—Genera Peponapis Robertson and Xenoglossa Smith—Inhabiting America North of Mexico (Hymenoptera: Apoidea). Hilgardia, 35:375–477, 1 frontispiece, 18 figures, 2 tables.

1972.   Parasitic Bees of the Genus Holcopasites Ashmead (Hymenoptera: Apoidea). Smithsonian Contributions to Zoology, 114: 41 pages, 16 figures, 1 table.

1975.   The Principal Larrea Bees of the Southwestern United States (Hymenoptera: Apoidea). Smithsonian Contributions to Zoology, 193: 74 pages, 18 figures, 15 tables.

1976.   The Bee Family Oxaeidae with a Revision of the North American Species (Hymenoptera: Apoidea). Smithsonian Contributions to Zoology, 220: 75 pages, 68 figures, 3 plates, 3 maps, 2 tables.

Hurd, Paul D., Jr., and Charles D. Michener

1955.   The Megachiline Bees of California (Hymenoptera: Megachilidae). Bulletin of the California Insect Survey, 3:1–247, 141 figures.

Hurd, Paul D., Jr., and J. S. Moure

1963.   A Classification of the Large Carpenter Bees (Xylocopini) (Hymenoptera: Apoidea). University of California Publications in Entomology, 29: vi + 365 pages, 1 frontispiece, 244 figures.

Hurt, E. F.

1948.   Sunflowers for Food, Fodder and Fertility. 175 pages. London: Faber and Faber Ltd.

Johnson, S. A.

1904.   Nests of Anthidium illustre Cresson. Entomological News, 15:284.

Kapil, R. P., J. R. Chaudhary, and K. L. Jain

1975.   Biology and Utilization of Insect Pollinators for Crop Production (AZ-Ent-118). In Second Annual Report, 1974–75, Department of Zoology, Haryana Agricultural University, Hissar, India, [pages 246–247.]

Katzarov, G.

1971.   Determination of Economic Effect of Sunflower Pollination by Bees on the Basis of Experiments Conducted in Dobrudgea District. In [Transactions of] XXIIIrd International Apicultural Congress, Moscow. Apimondia, 1971:510–512.

Kikuchi, T.

1963.   Studies on the Co-action among Insects Visiting Flowers, III: Dominance Relationships among Flower-visiting Flies, Bees and Butterflies. The Science Reports of Tôhoku University, series 4 (Biology), 29:1–8.

Knerer, Gerhard, and C. E. Atwood

1962.   An Annotated Checklist of the Non-parasitic Halictidae (Hymenoptera) of Ontario. Proceedings of the Entomological Society of Ontario, 92:160–176.

Knoll, F.

1926.   Insekten und Blumen. Abhandlungen der Zoologisch-botanische Gesellschaft, Wien, 12:1–646.

Knowles, P. F., and W. H. Lange

1954.   The Sunflower Moth. California Agriculture, 8(4): 11–12.

Krombein, Karl V.

1967.   Trap-nesting Wasps and Bees: Life Histories, Nests, and Associates. vi + 570 pages, 29 plates. Washington: Smithsonian Institution Press.

Kucinsky, K. J., and W. S. Eisenmenger

1944.   Sunflowers as a Crop. Massachusetts Agricultural Experiment Station Bulletin, 415:1–8, illustrated.

Kurennoi, N. M.

1957.   [Experiment on Increasing the Effectiveness of Sunflower Pollination by Bees.] Pchelovodstvo, 34(9):42–48. [In Russian.]

Kushnir, L. G.

1960.   [Economic Estimation of Sunflower Pollination with the Help of Bees and by Hand.] Pchelovodstvo, 37(1):22–25. [In Russian.]

LaBerge, Wallace E.

1956a. A Revision of Bees of the Genus Melissodes in North and Central America, Part I (Hymenoptera, Apidae). University of Kansas Science Bulletin, 37:911–1194, 129 figures, 19 maps, 6 tables.

1956b. A Revision of Bees of the Genus Melissodes in North and Central America, Part II (Hymenoptera, Apidae). University of Kansas Science Bulletin, 38:533–578, 13 figures, 1 table.

1958.   Notes on the North and Central American Bees of the Genus Svastra Holmberg (Hymenoptera: Apidae). Journal of the Kansas Entomological Society, 31: 266–273.

1961.   A Revision of the Bees of the Genus Melissodes in North and Central America, Part III (Hymenoptera, Apidae). University of Kansas Science Bulletin, 42:283–663, 125 figures, 37 maps, 18 tables.

1963.   New Species and Records of Little-known Species of Melissodes from North America (Hymenoptera: Anthophoridae). Bulletin of the University of Nebraska State Museum, 4:227–242.

1967.   A Revision of the Bees of the Genus Andrena of the Western Hemisphere, Part I: Callandrena (Hymenoptera: Andrenidae). Bulletin of the University of Nebraska State Museum, 7:1–298, 340 figures.

1969.   A Revision of the Bees of the Genus Andrena of the Western Hemisphere, Part II: Plastandrena, Aporandrena, Charitandrena. Transactions of the American Entomological Society, 95:1–47, 38 figures, 2 tables.

LaBerge, Wallace E., and D. W. Ribble

1975.   A Revision of Bees of the Genus Andrena of the Western Hemisphere, Part VII: Subgenus Euandrena. Transactions of the American Entomological Society, 101:371–466, 74 figures.

LaBerge, Wallace E., and Morgan C. Webb

1962.   The Bumblebees of Nebraska. Nebraska Agricultural Experiment Station, Research Bulletin, 205:1–37, 12 figures.

Leclercq, P.

1970.   Sunflower Hybrids Using Male Sterility. In Proceedings of the Fourth International Sunflower Conference, June 23–25, 1970, Memphis, Tennessee, pages 123–126.

Lehman, W. F., F. E. Robinson, P. F. Knowles, and R. A. Flock

1973.   Sunflowers in the Desert Valley Areas of Southern California. California Agriculture, 27(8):12–14.

Levin, Marshall D., and George D. Butler, Jr.

1966.   Bees Associated with Safflower in South Central Arizona. Journal of Economic Entomology, 59:654–657, 1 figure, 3 tables.

Linsley, E. Gorton

1958.   Ecology of Solitary Bees. Hilgardia, 27:534–559.

1978.   Temporal Patterns of Flower Visitation by Solitary Bees, with Particular Reference to the Southwestern United States. Journal of the Kansas Entomological Society, 51:531–546.

Linsley, E. Gorton, and Paul D. Hurd, Jr.

1959.   Ethological Observations on Some Bees of Southeastern Arizona and New Mexico (Hymenoptera: Apoidea). Entomological News, 70:63–68.

Linsley, E. Gorton, and J. W. MacSwain

1957.   The Nesting Habits, Flower Relationships, and Parasites of Some North American Species of Diadasia (Hymenoptera: Anthophoridae). Wasmann Journal of Biology, 15:199–235, 2 plates, 1 table.

1958.   The Significance of Floral Constancy among Bees of the Genus Diadasia (Hymenoptera: Anthophoridae). Evolution, 12:219–223, 1 table.

Litte, Marcia

1977.   Aspects of the Social Biology of the Bee Halictus ligatus in New York State. Insectes Sociaux, 24:9–36, 6 tables.

Long, Robert W.

1955.   Hybridization in Perennial Sunflowers. American Journal of Botany, 42:769–777.

1959.   Natural and Artificial Hybrids of Helianthus maximiliani × H. grosseserratus. American Journal of Botany, 46:687–692.

1960.   Biosystematics of Two Perennial Species of Helianthus (Compositae), I: Crossing Relationships and Transplant Studies. American Journal of Botany, 47:729–735.

Lutz, Frank E.

1919.   Unpublished data. Archives, Department of Entomology, American Museum of Natural History.

Matthews, R. W.

1965.   The Biology of Heriades carinata Cresson. Contributions from the American Entomological Institute, 1:1–33.

Mayer, D. F., and C. A. Johansen

1976.   Biological Observations on Anthophora urbana Cresson (Hymenoptera: Anthophoridae). Pan-Pacific Entomologist, 52:120–125, 3 figures, 1 table.

McGregor, S. E.

1976.   Insect Pollination of Cultivated Crop Plants. United States Department of Agriculture Handbook, 496: viii + 411 pages, 196 figures.

MacSwain, J. W., P. H. Raven, and R. W. Thorp

1973.   Comparative Behavior of Bees and Onagraceae, IV: Clarkia Bees of the Western United States. University of California Publications in Entomology, 70: 1–80, 10 figures, 3 plates, 18 tables.

Medler, J. T.

1958a. A Note on Megachile inermis Prov. in Trap-Nests in Wisconsin. Canadian Entomologist, 90:325–327.

1958b. Parasitism of Bees in Trap-Nests by Leucospis affinis Say. Entomological News, 66:21–24.

1961.   A Note on Hoplitis producta in Wisconsin. Canadian Entomologist, 93:571–573.

1964.   A Note on Megachile (Sayapis) pugnata pugnata Say in Trap-Nests in Wisconsin. Canadian Entomologist, 96:918–921.

1965.   A Note on Megachile mendica Cresson in Trap-Nests in Wisconsin. Proceedings of the Entomological Society of Washington, 67:113–116.

1966.   A Resin Bee Using Trap-Nests in Wisconsin with a Note on Other Resin Bees. Entomological News, 77:228–230.

Medler, J. T., and D. W. Carney

1963.   Bumblebees of Wisconsin (Hymenoptera: Apidae). University of Wisconsin Research Bulletin, 240:1–47.

Medler, J. T., and T. W. Koerber

1958.   Biology of Megachile relativa Cresson (Hymenoptera, Megachilidae) in Trap-Nests in Wisconsin. Annals of the Entomological Society of America, 51:337–344, 3 figures, 4 tables.

Medler, J. T., and J. F. Lussenhop

1968.   Leafcutter Bees of Wisconsin (Hymenoptera: Megachilidae). University of Wisconsin, College of Agriculture and Life Sciences Research Bulletin, 274:1–80, 136 figures.

Mel'nichenko, A. N.

1976      [1972]. Role of Insect Pollinators in Increasing Yields of Agricultural Plants. In R. B. Kozin, Pollination of Entomophilous Agricultural Crops by Bees, pages 1–14. New Delhi: Amerind Publishing Company Limited. [Originally in Russian, 1972; translated into English and published in 1976 for Agriculture Research Service, United States Department of Agriculture and United States National Science Foundation.]

Metcalf, C. L., and W. P. Flint

1962.   Destructive and Useful Insects: Their Habits and Control. Fourth edition, revised by R. L. Metcalf, xvi + 1087 pages, illustrated. New York: McGraw Hill. Michener, Charles D.

1947.   Bees of a Limited Area in Southern Mississippi. American Midland Naturalist, 38:443–455.

1949.   Records and Descriptions of American Megachilid Bees. Journal of the Kansas Entomological Society, 22:41–59.

1953.   The Biology of a Leafcutter Bee (Megachile brevis) and Its Associates. University of Kansas Science Bulletin, 35:1659–1748, 31 figures, 9 tables.

1955.   Some Biological Observations on Hoplitis pilosifrons and Stelis lateralis (Hymenoptera, Megachilidae). Journal of the Kansas Entomological Society, 28:81–87, 3 figures.

1978.   The Parasitic Groups of Halictidae (Hymenoptera, Apoidea). University of Kansas Science Bulletin, 51:291–339, 72 figures, 3 tables.

Michener, Charles D., and F. D. Bennett

1977.   Geographical Variation in Nesting Biology and Social Organization of Halictus ligatus. University of Kansas Science Bulletin, 51:233–260, 18 figures, 4 tables.

Milliron, H. E.

1971.   A Monograph of the Western Hemisphere Bumblebees (Hymenoptera: Apidae; Bombinae), I: The Genera Bombus and Megabombus Subgenus Bombias. Memoirs of the Entomological Society of Canada, 82: iii + 80 pages, 3 figures, 11 plates, 6 maps.

Mitchell, Theodore B.

1934.   A Revision of the Genus Megachile in the Nearctic Region, Part I: Classification and Descriptions of New Species. Transactions of the American Entomological Society, 59: 295–361, plates 20, 21.

1935.   A Revision of the Genus Megachile in the Nearctic Region, Part III: Taxonomy of Subgenera Anthemois and Delomegachile (Hymenoptera: Megachilidae). Transactions of the American Entomological Society, 61:155–205, plates 8, 9.

1936.   A Revision of the Genus Megachile in the Nearctic Region, Part IV: Taxonomy of Subgenera Xanthosarus, Phaenosarus and Derotropis (Hymenoptera: Megachilidae). Transactions of the American Entomological Society, 62:117–166, plates 9–11.

1937a. A Revision of the Genus Megachile in the Nearctic Region, Part V: Taxonomy of Subgenus Xeromegachile (Hymenoptera: Megachilidae). Transactions of the American Entomological Society, 62:323–382, plates 22–26.

1937b. A Revision of the Genus Megachile in the Nearctic Region, Part VI: Taxonomy of Subgenera Argyropile, Leptorachis, Pseudocentron, Acentron and Melanosarus (Hymenoptera: Megachilidae). Transactions of the American Entomological Society, 63:45–83, plates 5, 6.

1960.   Bees of the Eastern United States, Volume I. North Carolina Agricultural Experiment Station Technical Bulletin, 141:1–538, 134 figures, 16 tables.

1962.   Bees of the Eastern United States, Volume II. North Carolina Agricultural Experiment Station Technical Bulletin, 152:1–557, 134 figures, 18 tables.

1973.   A Subgeneric Revision of the Bees of the Genus Coelioxys of the Western Hemisphere. Contributions from the Department of Entomology, North Carolina State University, 1973: 129 pages, 1 frontispiece, 61 figures.

Moldenke, A. R., and J. L. Neff

1974.   The Bees of California: A Catalogue with Special Reference to Pollination and Ecological Research. Origin and Structure of Ecosystems (IBP) Technical Reports, 74-1 to 74-6. University of California, Santa Cruz.

Muma, M. H., R. N. Lyness, C. E. Claasen, and A. Hoffman

1950.   Control Tests on Sunflower Insects in Nebraska. Journal of Economic Entomology, 43:477–480.

Ordway, Ellen

1966a. Systematics of the Genus Augochlorella (Hymenoptera, Halictidae). University of Kansas Science Bulletin, 56:509–624, 92 figures, 3 tables.

1966b. The Bionomics of Augochlorella striata and A. persimilis in Eastern Kansas. Journal of the Kansas Entomological Society, 39:270–313, 30 figures, 11 tables.

Palmer-Jones, T., and I. W. Forster

1975.   Observations on the Pollination of Sunflowers. New Zealand Journal of Experimental Agriculture, 3:95–97.

Parker, F. D., and R. M. Bohart

1966.   Host-Parasite Associations in Some Twig-nesting Hymenoptera from Western North America. Pan-Pacific Entomologist, 42:91–98.

Pearson, Jay Frederick Wesley

1933.   Studies on the Ecological Relationships of Bees in the Chicago Region. Ecological Monographs, 3:373–441, 1 figure, 22 tables.

Phillips, R. L., N. M. Randolph, and G. L. Teetes

1973.   Seasonal Abundance and Nature of Damage of Insects Attacking Cultivated Sunflowers. Texas Agricultural Experiment Station Miscellaneous Publications, 1116:1–7.

Posey, M. H.

1969.   Sunflower—A Literature Survey, January 1960–June 1967. United States Department of Agriculture, National Agriculture Library, List, 95:1–133.

Putt, E. D.

1940.   Observations on Morphological Characters and Flowering Process in the Sunflower (Helianthus annuus L.). Scientific Agriculture, 21:167–179.

Putt, E. D., and C. B. Heiser

1964.   Better Hybird Sunflowers May Result from Sterility. Crops and Soils, 16:18.

Radaeva, E. N.

1954.   [Bee Pollination Increases the Yield of Sunflower Seeds (Helianthus annuus L.).] Pchelovodstvo, 2:33–38. [In Russian.]

Radoev, L.

1954.   [Study on the Role of Honeybee and Wild Insects in Sunflower Pollination.] Spisanie na Nauchno-issle-dovatelskite Instituti pri Ministerstvata na Zemedelete Igorite, Sofiya, 4:3–16. [In Romanian.]

Rajamokan, N.

1976.   Pest Complex of Sunflower—A Bibliography. Pans, 22:546–563.

Randolph, N. M., G. L. Teetes, and M. C. Baxter

1972.   Life Cycle of the Sunflower Moth under Laboratory Conditions. Annals of the Entomological Society of America, 65:1161–1164.

Rangarajan, A. V., N. R. Mahadevan, and S. Iyemperumal

1974.   Note on the Time of Visit of Pollinating HoneyBees to Sunflower. Indian Journal of Agricultural Science, 44:66–67.

Rashad, S., and R. L. Parker

1958.   Major Pollen Sources in the Manhattan, Kansas, Area, and the Influence of Weather Factors upon Pollen Collection by Honeybees. Proceedings of the Tenth International Congress of Entomology, 4:1037–1046.

Ribble, David W.

1965.   A Revision of the Banded Subgenera of Nomia in America (Hymenoptera: Halictidae). University of Kansas Science Bulletin, 45:277–359, 32 figures.

1968.   Revisions of Two Subgenera of Andrena: Micrandrena Ashmead and Derandrena, New Subgenus (Hymenoptera: Apoidea). Bulletin of the Nebraska State Museum, 8:237–394, 121 figures, 14 maps.

Roberts, Radclyffe B.

1969.   Biology of the Bee Genus Agapostemon (Hymenoptera: Halictidae). University of Kansas Science Bulletin, 48:689–719, 21 figures.

1972a. Revision of the Bee Genus Agapostemon (Hymenoptera: Halictidae). University of Kansas Science Bulletin, 49:437–590, 228 figures.

1972b. Pollination for Flower Seed Production. In R. R. Robinson, editor, Oregon Insect Control Handbook, pages 264–268. Corvallis: Extension Service, Oregon State University.

1973a. Bees of Northwestern America: Agapostemon (Hymenoptera: Halictidae). Oregon State University Agricultural Experiment Station Technical Bulletin, 125:1–23, 23 figures.

1973b. Bees of Northwestern America: Halictus (Hymenoptera: Halictidae). Oregon State University Agricultural Experiment Station Technical Bulletin, 126:1–34, 35 figures.

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1894.   Flowers and Insects—Rosaceae and Compositae. Transactions of the Academy of Sciences of St. Louis, 6: 435–480, 4 tables.

1898.   Flowers and Insects, XVIII. Botanical Gazette, 25: 229–245.

1922.   The Sunflower and Its Insect Visitors. Ecology, 3: 17–21, 1 table.

1929.   Flowers and Insects. 221 pages. Carlinville, Illinois.

Robinson, R. G., F. K. Johnson, and O. C. Soine

1967.   The Sunflower Crop in Minnesota. Minnesota Agricultural Extension Service Bulletin, 299:1–11, illustrated.

Rogers, C. E.

1977a. Laboratory Biology of a Lace Bug of Sunflower. Journal of Ecomonic Entomology, 70:144–145.

1977b. Cerambycid Pests of Sunflower: Distribution and Behavior in the Southern Plains. Environmental Entomology, 6:833–838.

1978.   Sunflower Moth: Feeding Behavior of the Larva. Environmental Entomology, 7:763–765, 1 figure, 2 tables.

Rogers, C. E., and T. E. Thompson

1978.   Resistance in Wild Helianthus to the Sunflower Beetle. Journal of Economic Entomology, 71: 622–623.

Rogers, C. E., T. E. Thompson, and R. J. Gagné

1979.   Cecidomyiidae of Helianthus: Taxonomy, Hosts and Distribution. Annals of the Entomological Society of America, 72:109–113, 3 figures, 1 table.

Rogers, C. E., T. E. Thompson, and M. B. Stoetzel

1978.   Aphids of Sunflower: Distribution and Hosts in North America (Homoptera: Aphididae). Proceedings of the Entomological Society of Washington, 80:508–513, 2 tables

Rozen, Jerome G., Jr.

1958.   Monographic Study of the Genus Nomadopsis Ashmead (Hymenoptera: Andrenidae). University of California Publications in Entomology, 15:1–202, 218 figures, 17 maps.

1959.   A New Species of Nomadopsis and Notes on Some Previously Described Ones (Hymenoptera, Andrenidae). Proceedings of the Entomological Society of Washington, 61:255–259, 5 figures.

1963.   Notes on the Biology of Nomadopsis, with Descriptions of Four New Species (Apoidea, Andrenidae). American Museum Novitates, 2142:1–17, 20 figures, 2 tables.

1964.   The Biology of Svastra obliqua obliqua (Say), with a Taxonomic Description of Its Larvae (Apoidea: Anthophoridae). American Museum Novitates, 2170: 1–13, 15 figures.

1967.   Review of the Biology of Panurgine Bees, with Observations on North American Forms (Hymenoptera, Andrenidae). American Museum Novitates, 2297:1–44, 18 figures, 2 tables.

1973.   Biology Notes on the Bee Andrena accepta Viereck (Hymenoptera, Andrenidae). Journal of the New York Entomological Society, 81:54–61, 10 figures.

1977.   Immature Stages of and Ethological Observations on the Cleptoparasitic Bee Tribe Nomadini (Apoidea, Anthophoridae). American Museum Novitates, 2638:1–16, 27 figures.

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1933.   [The Role of the Bees in the Cross-Pollination of the Sunflower.] Akademia Nauk SSSR Doklady, 6: 304–305. [In Russian.]

Ruppolt, W. von

1961.   Extrafloralen Nektarien und Ihre Demonstration in der Schule. Zeitschrift fur Praxis Naturwisschaften, 1961:147–150.

Rust, Richard W.

1974.   The Systematics and Biology of the Genus Osmia, Subgenera Osmia, Chalcosmia, and Cephalosmia (Hymenoptera: Megachilidae). Wasmann Journal of Biology, 32:1–93, 45 figures.

Salaman, Redcliffe N.

1940.   Why “Jerusalem” Artichoke? Journal of the Royal Horticultural Society, 65:338–348, 376–383.

Satherwait, A. F.

1946.   Sunflower Seed Weevils and Their Control. Journal of Economic Entomology, 39:787–794.

1948.   Important Sunflower Insects and Their Insect Enemies. Journal of Economic Entomology, 41:725–731.

Satherwait, A. F., and R. B. Swain

1946.   The Sunflower Moth and Some of Its Natural Enemies. Journal of Economic Entomology, 39:575–580.

Schacht, Henry

1979.   Farm Reporter: California's Sunflower Seeds. San Francisco Chronicle, 4 January 1979.

Schelotto, B., and N. L. Pereyras

1971.   An Evaluation of the Economic Significance of Pollinating Sunflower with Bees. Ciencia y Abejas, 1:7–25.

Schulz, J. T.

1973.   Damage to Cultivated Sunflower by Contarinia schulzi. Journal of Economic Entomology, 66:282, 1 figure.

1978.   Insect Pests. In Jack F. Carter, editor, Sunflower Science and Technology. Agronomy, 19:169–223.

Schwarz, Herbert F.

1926.   North American Dianthidium, Anthidiellum, and Paranthidium. American Museum Novitates, 226:1–25.

Seiss, C. F.

1897.   Hemiptera on Sunflower. Entomological News, 8:67.

Shanks, Sandra S.

1977 [1978]. A Revision of the Cleptoparasitic Bee Genus Neolarra (Hymenoptera: Anthophoridae). Wasmann Journal of Biology, 35(2):212–246, 27 figures, 1 table. [Date on title page is 1977; actually published 1978].

Shinn, Alvin F.

1965.   Descriptions of Three New Species of the Bee Genus Calliopsis (Hymenoptera, Andrenidae). American Museum Novitates, 2211:1–19, 12 figures.

1967.   A Revision of the Bee Genus Calliopsis and the Biology and Ecology of C. andreniformis (Hymenoptera, Andrenidae). University of Kansas Science Bulletin, 46:753–936, 156 figures, 9 tables.

Shinners, Lloyd H.

1956.   Wind a Factor in Floral Ecology and Morphology. Southwestern Naturalist, 1:88–89.

Smith, Walter E., and Walter G. Whitford

1978.   Factors Affecting the Nesting Success of the Large Carpenter Bee, Xylocopa californica arizonensis. Environmental Entomology, 7:614–616, 1 figure, 3 tables.

Snelling, Roy R.

1962.   Notes on the Distribution of Some Southwestern Megachilids, with Descriptions of Three New Forms (Hymenoptera: Apoidea). Pan-Pacific Entomologist, 37:225–234, 2 figures.

1975.   Range Extension of Two Heteranthidium, with Description of H. cordaticeps Male (Hymenoptera: Megachilidae). Proceedings of the Entomological Society of Washington, 77:87–90, 1 figure.

Springensgut, W.

1935.   Physiologische und Okologische Untersuchungen über Nektarien und die Sie besuchenden Insekten. Sitzungsbericht Abhandlungen Naturforsch der Gesellschaft zu Rostock, series 3, 5:31–111.

Stage, Gerald I.

1966.   Biology and Systematics of the American Species of the Genus Hesperapis Cockerell. 461 pages. Ph.D. dissertation, University of California, Berkeley.

Stephen, W. P.

1954.   A Revision of the Bee Genus Colletes in America North of Mexico (Hymenoptera, Colletidae). University of Kansas Science Bulletin, 36:149–527, 87 figures, 8 maps.

Stevens, O. A.

1919.   The Panurgine Bees of North Dakota and a New Epeolus (Hym.). Canadian Entomologist, 51:205–210.

1921.   Further Notes on Evening Flowers, Panurgine and Halictine Bees. Canadian Entomologist, 53:65–69.

1949a. Native Bees. North Dakota Agricultural Experiment Station Bimonthly Bulletin, 12:14–22. [Andrena.]

1949b. Native Bees. North Dakota Agricultural Experiment Station Bimonthly Bulletin, 11:130–135. [Leaf-cutter bees.]

1949c. Native Bees. North Dakota Agricultural Experiment Station Bimonthly Bulletin, 11:210–215. [Mason bees.]

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1951a. Native Bees. North Dakota Agricultural Experiment Station Bimonthly Bulletin, 13:199–205. [Wasp bees.]

1951b. Native Bees. North Dakota Agricultural Experiment Station Bimonthly Bulletin, 14:27–31. [Pollen-collecting Anthophoridae.]

1951c. Native Bees. North Dakota Agricultural Experiment Station Bimonthly Bulletin, 14:59–64. [Halictidae.]

Swenk, Myron H.

1907.   The Bees of Nebraska, III. Entomological News, 18: 293–300.

1914.   Studies of North American Bees. University of Nebraska Studies, 14:1–36.

Swenk, Myron H., and T.D.A. Cockerell

1907a. The Bees of Nebraska, I. Entomological News, 18: 51–58.

1907b. The Bees of Nebraska, II. Entomological News, 18: 178–187.

Talley, L. D., B.J.C. Brummett, and E. E. Burns

1970.   Utilization of Sunflower in Human Food Products. In Proceedings of the Fourth International Sunflower Conference, June 23–25, 1970, Memphis Tennessee, pages 110–113.

Teetes, G. L., and N. M. Randolph

1969.   Some New Host Plants of the Sunflower Moth in Texas. Journal of Economic Entomology, 62:264–265, 1 table.

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1970b. Ecology and Control of the Sunflower Moth, Homoeosoma electellum, in Texas. In Proceedings of the Fourth International Sunflower Conference, June 23–25, 1970, Memphis, Tennessee, pages 184–186.

Thorp, R. W., and J.A. Chemsak

1964.   Biological Observations on Melissodes (Eumelissodes) pallidisignata (Hymenoptera: Anthophoridae). Pan-Pacific Entomologist, 40:75–83, 2 figures.

Timberlake, P. H.

1940.   New Species of Bees of the Genus Diadasia from California (Hymenoptera, Apoidea). Bulletin of the Brooklyn Entomological Society, 35:22–30.

1943.   Bees of the Genus Colletes Chiefly from Colorado. Bulletin of the American Museum of Natural History, 81: 385–410, 6 figures.

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1951.   New and Little-known Bees of the Family Andrenidae from California. Proceedings of the United States National Museum, 101:373–414.

1953.   Bees of the Genus Perdita in the Collection of the University of Kansas. University of Kansas Science Bulletin, 35:961–985.

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1955.   Notes on the Species of Psaenythia of North America. Bollettino del Laboratorio di Zoologia Generale e Agraria “Filippo Silvestri,” Portici, 33:398–409.

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1958.   A Revisionai Study of the Bees of the Genus Perdila F. Smith, with Special Reference to the Fauna of the Pacific Coast (Hymenoptera, Apoidea), Part III. University of California Publications in Entomology, 14:303–410, plates 4–15.

1960.   A Revisionai Study of the Bees of the Genus Perdita F. Smith, with Special Reference to the Fauna of the Pacific Coast (Hymenoptera, Apoidea), Part IV. University of California Publications in Entomology, 17:1–156, plates 1–17.

1964.   A Revisionai Study of the Bees of the Genus Perdita F. Smith, with Special Reference to the Fauna of the Pacific Coast (Hymenoptera, Apoidea), Part VI. University of California Publications in Entomology, 28:175–388, 22 plates, 77 figures.

1967.   New Species of Pseudopanurgus from Arizona. American Museum Novitates, 2298:1–23.

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1969b. A Contribution to the Systematics of North America Species of Synhalonia (Hymenoptera, Apoidea). University of California Publications in Entomology, 57: 1–76, 80 figures.

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1902.   Colorado Bombidae. Canadian Entomologist, 34:37–44.

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1970.   Economics of Producing Sunflowers for Oil in the United States. In Proceedings of the Fourth International Sunflower Conference, June 23–25, 1970, Memphis, Tennessee, pages 23–24.

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1914.   New North American Bees of the Genus Andrena. Proceedings of the United States National Museum, 48: 1–58.

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1936.   Observations on Sunflower Insects in Kansas. Journal of the Kansas Entomological Society, 9:16–25.

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1976.   Bees of the Genus Martinapis in North America. Wasmann Journal of Biology, 34:119–145, 2 figures, 2 tables.

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Plates

PLATE 1.—Nomia (Dieunomia) heteropoda Say, female (above); Megachile (Argyropile) parallela Smith, female (below).

PLATE 2.—Diadasia enavata (Cresson): female (above); male (below).

PLATE 3.—Svastra (Epimelissodes) obliqua (Say): female (above); male (below).

PLATE 4.—Melissodes (Eumelissodes) agilis Cresson: female (above); male (below).

PLATE 5.—Bombus (Fervidobombus) pennsylvanicus sonorus Say, worker (above). Apis mellifera Linnaeus, worker (below).

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