Lasioglossum

The sweat bee genus Lasioglossum is the largest of all bee genera, containing over 1800 species in numerous subgenera worldwide.^[1][2] They are highly variable in size, coloration, and sculpture; among the more unusual variants, some are kleptoparasites, some are nocturnal, and some are oligolectic. Most Lasioglossum species nest in the ground, but some nest in rotten logs.^[3]

Social behaviour among species of Lasioglossum is extraordinarily variable; species are known to exhibit solitary nesting, primitive eusociality, and social parasitism. Colony sizes vary widely, from small colonies of a single queen and four or fewer workers to large colonies of >400 workers and perennial life cycles.^[4]

The genus Lasioglossum can be divided into two informal series based on the strength of the distal veins of the forewing.^[5] The nominate series Lasioglossum (or strong-veined Lasioglossum) is mostly composed of solitary or communal species, even if some species like L. aegyptiellum show signs of division of labour indicative of eusociality.^[1]

The series Hemihalictus (or weak-veined Lasioglossum) includes species with a wide range of sociality.^[6][4] The Hemihalictus series is composed of species which are solitary, communal, primitively eusocial, kleptoparasitic, or socially parasitic.^[1] Eusocial species may have small colonies with only one or a few workers or large colonies with dozens of workers. Large colony sizes occur in L. marginatum, which forms perennial colonies lasting five or six years, with hundreds of workers; this species is the only halictine bee with perennial colonies.^[4]