The females (queens and workers) have black and yellow hairs intermixed on the face and forward part of the thorax and a black patch in the middle of the thorax, while their sides are yellowish.

[3] The species is a common bumblebee found in the western North America from Alaska and British Columbia, and Washington, to northern Idaho, western Montana, and the coastal parts of California.

[2][4] The Sitka bumblebee has experienced mild population declines in parks in California due to competition with the yellow-faced bumblebee (B. vosnesenskii) for nesting sites, such as rodent holes.

[5] The Sitka bumblebee forages on flowering plants from several families, including the Ericaceae, Asteraceae, Saxifragaceae, and Rhamnaceae.

The flight period for the queen is very long, from the end of January to the beginning of December.