Discovery of Social Nests in a Bivoltine, Basically Solitary Halictine Bee, Lasioglossum (Lasioglossum) mutilum (Vachal) (Hymenoptera: Halictidae)

The annual life cycle and sociality of Lasioglossum mutilum were studied in a greenhouse. The results proved that L. mutilum is bivoltine and basically solitary. The oviposition period of the overwintered and first generations commenced from late May to late June, and mid July to late August, respectively. The next overwintering generation appeared after early September. Among the total of 13 nests, one each of semisocial and eusocial colonies was found. These findings are the first authentic records of sociality in the subgenus Lasioglossum. In the semisocial colony, the larger female with developed ovarioles behaved as queen-like, while the smaller one with less developed ovarioles was worker-like.