This specious genus is notoriously challenging to even the most accomplished bee researchers. Active through the whole season in every habitat, these are some of the most frequently encountered bees. While a few species are distinctive, the vast majority are impossible to identify past sub-genus level from photos. Included in this genus are obligate social species, cleptoparasites, flower specialists, log nesting, and ground nesting species. The host to most species of Blood Bees (Sphecodes).
Genus-level ID
Species-level ID
Though species-level ID is very challenging, many individuals can be quickly assigned to a subgenus, or group of subgenera. The following 3 categories split out relatively well.
Small and shiny (subgenus Dialictius) – The most diverse and hardest subgenus to ID.
Large with white hair bands (primarily subgenus Lasioglossum) – More similar to Furrow Bees (genus Halictus) than other Lasioglossum.
Variable size, all black (several subgenera) – Roughly a dozen species, including two uncommon flower specialists.
Field Identifiable Lasioglossum

Viereck's Sweat Bee
Lasioglossum viereckiRugose-chested Sweat Bee
Lasioglossum pectorale
Ground Cherry Sweat Bee
Lasioglossum pectinatum
Evening Primrose Sweat Bee
Lasioglossum oenotherae
Bristle Sweat Bee
Lasioglossum imitatum
Hairy Sweat Bee Species Group
Complex Lasioglossum pilosumEpaulette Sweat Bee Species Group
Complex Tegulare groupQuebec Sweat Bee
Lasioglossum quebecensePhotos with dark gray background are courtesy of Margarita Miklasevskaja at PCYU with funding from NSERC-CANPOLIN.