Bombus bimaculatus is one of the most abundant and commonly observed bumble bees in Minnesota. New queens (gynes) either establish a nest belowground, often in abandoned rodent or small mammal burrows, or aboveground, under leaf litter or plant debris. The gynes emerge from hibernation in early spring, prior to the emergence of the similar-looking species, Bombus impatiens (common eastern bumble bee). Males and workers are abundant in early summer, and males and new gynes begin mating at the end of June/early July. 

​

The thorax has long light yellow hairs with a distinct central black spot. The first abdominal segment or tergite (T1) has yellow hairs, the second segment or tergite (T2) has a W-shaped or two-lobed yellow marking. This marking on T2 is reduced on queens/gynes and can be difficult to see when obscured by the wings. For females, the remaining tergites have black hairs. Some males can also have additional yellow hairs T4. Males and females have yellow hairs on the vertex (back of the head or "neck"). Females have dark wings and dark hairs on the face; males have medium-brown or tea-colored wings and yellow hairs on the face.