BeeSpotter

Bombus bimaculatus

Bombus bimaculatus

Bombus bimaculatus (the two-spotted bumble bee)

Bombus bimaculatus. La Salle County, Illinois, 6 July.

Status in Illinois

Common.

Technical description (from Medler and Carney 1963)

Queen: Face black, vertex with a triangular patch of yellow hairs; sometimes a few black hairs intermixed. Thorax entirely yellow except for a small area on the disc, which is smooth and shining, and bordered by scattered black hairs; pleura with yellow hairs to bases of the legs. Abdominal tergite 1 yellow, tergite 2 with yellow on the middle part, edges black with a few yellow hairs laterally; middle of apical margin slightly incised with black. Venter black, legs with a sprinkling of yellow hairs.
Worker: Resembling the queen in the markings; the females exhibit no variation.
Male: Face bearing a considerable admixture of yellow and black hairs; vertex yellow. Resembling females in all markings, but the yellow on tergite 2 more extensive and with considerable yellow hairs on the lateral margins, thus leaving 2 spots or patches of black hairs on the tergite. Venter with many yellow hairs, but some black hairs on the basal sternites; legs each bearing considerable yellow hairs. VARIATION: May have tergite 2 almost entirely yellow. Also, males commonlyhave tergite 5, and rarely tergites 5 and 6, mostly yellow.

Diagnosis

Habits

The queen of Bombus bimaculatus appears fairly early in the spring. Nesting usually occurs underground but has been observed at or even well above the surface.

Flight periods

Medler and Carney (1963) reported the following as earliest recorded appearance dates in Wisconsin: Queens: April 21; workers: June 5; males: July 10.

Main flower preferences

Queens: willow and plum; workers: red clover, mint; males: mint, sweet clover.

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