Bombus bimaculatus

Two-spotted Bumblebee
Bombus bimaculatus


Two-spotted Bumblebee Bombus bimaculatus worker
Two-spotted Bumblebee Bombus bimaculatus worker on Blazingstar, Jul 19, 2004 Wheatley, Ontario.
Two-spotted Bumblebee Bombus bimaculatus queen
Two-spotted Bumblebee Bombus bimaculatus queen on Spring Beauty Apr 18, 2004 Wheatley Provincial Park, Wheatley, Ontario.

Identification: Main ID: Abdomen segment 1 yellow, segment 2 yellow at centre, sides straight. All three (worker, queen and male) have yellow on top of head.

Queen and Worker:
Head: Hair black with triangular patch of yellow hairs on top of head (vertex).
Thorax: All yellow with a small, central black shiny spot between wings.
Wings: Wing knobs black. Wings lightly tinted, veins brownish-black.
Legs: Legs and spurs black. Fringe mostly black, with a few pail hairs on thigh. Pollen basket hairs long and black. Feet reddish-black.
Abdomen: Segment 1 is yellow. Segment 2 is yellow only in central 2/3 on segment, side edges of the yellow are straight up and down unlike the Brown-belted B. griseocollis which has curved sides.


Two-spotted Bumblebee Bombus bimaculatus male
Two-spotted Bumblebee Bombus bimaculatus male on Purple Coneflower Aug 01, 2005 Wheatley, Ontario.

Head: Hair yellow around antenna and top of head, with a line of yellow hairs across back of head.
Antenna: Long antenna.
Thorax: Yellow with small patch of short, black hairs between the wings.
Wings: Wing knobs with yellowish-hyaline along outer margin. Wings lightly tinted, veins dark.
Legs: Legs black, spurs reddish. Fringe yellow on thighs, dark gray on lower legs, hind tibia (shin) with very long hairs. Underside of hind shin is reddish.
Abdomen: Abdominal segments can vary. 1 is yellow. 2 is yellow in center, but laterally wider than Queen. 3 to 6 are usually black, but sometimes have yellow on segments 4 or 5. Underside has some yellow stripes.

Similar Species: The Brown-belted Bombus griseocollis has the brownish-yellow sides of segment 2 curving out and up to base of segment.

Size: Queen 17 to 22 mm. Worker 11 to 16 mm. Male 14 to 14.5 mm.

Flight Time: Mid-April to August. Males from July to mid-August.

Habitat: Woodlands and forest edges.

Food: Pollen and flower nectar for both the adult and larvae.

Life Cycle: Mated queens overwinter in the soil and emerge from hibernation in very early spring. Prefers to nest above ground and has been recorded nesting as high as three meters. Queen collects pollen and lays eggs on top. She feeds larvae daily by storing pollen in old cocoons or cells. Workers emerge about 21 days after the eggs are laid and take over the duties of pollen and nectar collection as well as colony defence. The size of the workers increases with each new brood.

Comments: Essex County along Lake Erie shoreline and Pelee Island per Colla 2005 maps. All Ontario.
Parasitized by Thick-headed Fly Physocephala tibialis.