Plateaux-Quénu (2008) reviews the social biology of this boreo-alpine species. Lasioglossum fratellum dig tunnel nests into the soil. The tunnel opens onto a cavity which contains a comb-like cluster of brood cells. Females produced from the previous summer mate and overwinter to initiate nests the following spring. These females only produce one brood per summer. However, the foundress females can live for two years. Thus, a foundress female may rear a daughter in summer who overwinters in the nest so that in the second summer there are two (or more) females in the nest. If there is reproductive division of labor in the nest (the original foundress is a reproductive queen and the daughters serve as her workers) than the nest is eusocial. However, if there is no division of labor (all females reproduce) than the nest is communal.
