Queen and worker:
Head: Face is black with only a few gray hairs just above the antennae; worker has more gray.
Thorax: Yellow with a black band between wing bases. Yellow continues down thorax sides before wings; rest of sides black.
Wings: Very dark with black veins.
Legs: Legs, hair and fringe on pollen basket entirely black.
Abdomen: The abdomen is yellow on segments 1 to 4 and black on segments 5 and 6.
Male: Hairs are longer than queen and worker.
Head: Face is black with a few yellowish hairs intermixed on top of head (vertex) and some obscure gray on face. Face much blacker-looking than the similar American B. pensylvanicus.
Thorax: Yellow with black band between wing bases. Sides yellow before wings; rest of sides black.
Wings: Lightly tinted – lighter than female.
Legs: Black. Fringe yellow and black mixed on thighs (femora), lower legs have black fringe.
Abdomen: Segments 1 to 5 bright yellow with slight black stripe between segments. 6 and 7 black entirely black.
Similar Species: Northern Amber Bombus borealis has much more yellow on entire face. The American Bombus pensylvanicus has no yellow on lower half of thorax.
Size: Queen 19 to 21 mm; Worker 14.5 to 17.5 mm; Male 11 to 20 mm.
Flight Time: Mid-May to early October.
Habitat: Meadows, roadsides and in open areas.
Food: Adults and larvae feed on flower nectar and pollen.
Life Cycle: In the fall newly mated females hibernate in litter until the next spring. They can be aggressive if their nest is disturbed. Sometimes queens will try to take over other nests. Workers will cover the invading queen with honey to push her out of the nest. Queens lay an average of 20 eggs a day for about 4 months. Workers hatch in 3 weeks and live for a month. Large workers forage, smaller workers are nurses to larvae. Nest size is between 100 to 200 bees. Towards the end of the season workers may lay unfertilized eggs but these are usually consumed by the queen, then the workers retaliate by consuming the next generation of eggs laid by the queen (Goulson 2003). In some colonies the second brood is all male and the third brood is female. Workers of the later broods become progressively larger.
Comments: Essex County – Ojibway Prairies. Canadian National Collections (CNC) have specimens from Point Pelee, Pelee Island and Kingsville. Also in Tilbury and Colchester.