This is one of the medium-sized (7-9mm)  Lasioglossum with a predominantly black body. The females possess a subtle sharply-angled propodeum (rear thoracic section), which is a useful starting point when separating it from other similar species. The abdomen has subtle narrow grey bands. Males are primarily black and possess unusually long antennae. It is usually best to check both sexes under a microscope. It is one of the more likely species to be found in upland areas and habitats featuring acidic soils, although it can be found in lowland areas over neutral soils too. After Lasioglossum albipes and L. calceatum it is the third most frequently-recorded species of its genus in Ireland and is listed as Least Concern.

Distribution in Ireland: Widespread and locally common throughout.

Flight period: Females fly between March-September, whilst males emerge in June and persist until late August.

Habitat: A variety of habitats may be utilised, but more frequent in heaths, bogland margins, scrub, acidic woodland edges, brownfield land and upland pasture.

Flowers visited: Dandelions, Tormentil, Ragwort, hawkweeds and others. The females are polylectic.

Personal records: I have observed this species in good numbers along the Bloody Bridge trail in the Mourne Mountains and Drumkeeragh Forest (both Co. Down). I have also found it at Killard Point along soft-rock cliffs in the same county and at a brownfield site in Armagh, Co. Armagh. I have also observed it in coastal machair, dunes and dry heath in Co. Donegal. It appears to nest singly or in small aggregations, in gravelly heathy soil, clay banks and soft-rock cliffs. It is a possible host of the blood bees Sphecodes hyalinatus and Sphecodes ferruginatus.