Half-black bumble bee (Bombus vagans) is a common, small, colonial, ground-nesting bumble bee. It is found in shady forests wooded areas, urban parks, wetlands, and gardens from June to August and possibly later. The nests are annual—only mated queens overwinter, emerging from hibernation in May. They build nests mostly underground but sometimes on the surface of the ground or in hollow trees.
As the common name suggests, this bumble bee is half black. The head, thorax, and first two abdominal segments are yellow. The rest of the abdomen is black. Other identifying features of this species are a small, round, black spot on the thorax; the top of the lateral simple eyes in line with the top of the compound eyes; and the area on the face corresponding to the cheek longer than wide.