Agapostemon

Distinguished from other metallic green bees in the tribe Augochlorini by subtle morphological characters requiring close examination; Augochlorini members are typically brighter metallic green and lack the distinct sexual dimorphism in abdominal patterning seen in Agapostemon. Males of Agapostemon are readily identified by their yellow-and-black banded abdomens contrasting with metallic green thoraces. Females carrying pollen on hind leg scopae can be distinguished from similar-looking cuckoo wasps (Chrysididae), which do not collect pollen and exhibit quick, jerky movements rather than the deliberate flight of bees.

Small to medium-sized bees with striking metallic coloration. Head and thorax are typically bright metallic green or blue. Females of most species have wholly metallic green or blue abdomens, though some (such as A. virescens) have black abdomens with bands of white hairs. Males generally have yellow-and-black striped abdomens on a metallic or black background. Females possess scopae (pollen-collecting hairs) on the hind legs. Males have only the head and thorax metallic green, with the abdomen distinctly banded.

Ground-nesting bees found in diverse open habitats. Favor loamy soils with sparse vegetation for nest construction. Some species form dense nesting aggregations in suitable soil conditions. Found in gardens, meadows, prairies, and other open sunny areas with exposed ground for nesting.

Western Hemisphere from southern Canada (Alberta, Saskatchewan) through the United States, Mexico, Central America, and South America to Argentina. Individual species have more restricted ranges; for example, A. angelicus is native to the Texas high plains, while A. fasciatus ranges into the southern Prairies Ecozone of Canada.

In cool temperate regions, one generation per year with females active in early summer and males plus pre-diapausing females active in late summer. Only mated females survive winter; unmated females apparently cannot enter diapause. Males frequently observed in large numbers flying around shrubs with large flowers in late summer.

All species nest in the ground, excavating burrows with individual brood cells. In communal species such as A. virescens, multiple females share a common nest entrance but construct separate brood cell tunnels beneath, with each female provisioning her own cells with pollen and nectar. No reproductive division of labor exists in communal nests—unlike eusocial bees, all females reproduce. Nests may contain more than 100 brood cells. Communal nesting appears to provide defense against kleptoparasitic Nomada cuckoo bees.

Flight patterns resemble those of bumble bees and honey bees, with foraging distance influenced by flower density; bees favor high-density flower patches. Males perch on leaves and stems to watch for passing females. Guard bees have been observed at communal nest entrances, emerging to inspect surroundings for threats. Unlike many halictid sweat bees, not attracted to human perspiration.

Generalist pollinators of diverse flowering plants. Agapostemon angelicus has been documented as a specialized pollinator of cotton and has been proposed as a managed alternative to honey bees for crop pollination. Communal nesting behavior may reduce parasitism by cuckoo bees, potentially stabilizing local pollinator populations.

A. angelicus studied as a potential managed pollinator for cotton production, capable of replacing honey bees in some agricultural contexts. Commonly observed in gardens and pollinator plantings, contributing to urban pollination services. Some species proposed as candidates for state bee designation due to public recognition and ecological importance.

• Augochlorini (Augochlora, Augochlorella, Augochloropsis)Also metallic green halictid bees, but typically brighter green; require microscopic examination to distinguish; lack distinct male abdominal banding; some species nest in rotten wood rather than soil
• Chrysididae (cuckoo wasps)Superficially similar metallic coloration, but wasps do not collect pollen, exhibit rapid jerky movements, and are seldom found on flowers
• LasioglossumOther halictid sweat bees, but generally smaller, less vividly metallic, and many species attracted to human sweat

• pollinator
• ground-nesting
• metallic coloration
• communal nesting
• Halictidae
• Western Hemisphere

• BugGuide
• Wikipedia
• GBIF taxonomy match
• iNaturalist taxon
• NCBI Taxonomy
• Catalogue of Life
• California Has No State Bee--Yet! | Bug Squad
• The Native Bees in the UC Davis Bee Haven | Bug Squad
• National Pollinator Week: Visit the UC Davis Bee Garden | Bug Squad
• Going Native: Do You Know the Native Bees of California? | Bug Squad
• Sweet times for sweat bees: Sweat bees, Halictus ligatus and Agapostemon virescens — Bug of the Week
• Bug Eric: Metallica
• Phylogeny of the bee genus Agapostemon (Hymenoptera: Halictidae)
• Agapostemon fasciatus Crawford (Hymenoptera, Halictidae), a valid North American bee species ranging into southern Canada