Bombus polaris

Worker bees measure about 10 to 16 mm from the top of the head to the tip of the abdomen.

Adults are large, with long dense hair and dark colouring, features described as adaptations to low Arctic temperatures.

In Canada the species is recorded from Yukon, the Northwest Territories, Nunavut, British Columbia, Alberta, Manitoba, Ontario, Quebec and Newfoundland and Labrador.

Whether the North American Bombus polaris and the Palaearctic Bombus pyrrhopygus are one circumpolar species or two separate species is still debated among taxonomists.

Colonies are small because usually only a single brood of workers is produced before the queen switches to rearing males and new queens.

All the eggs of the first brood are laid together in one cell and the larvae are fed as a group, which shortens the colony cycle in the brief Arctic summer.

At Lake Hazen the first queens were seen on 27 May in 1967 and 14 June in 1968, and adults stayed active until early August when few flowers remained.

At Lake Hazen on Ellesmere Island, 92 of 94 natural nests were found on the surface of the ground rather than underground.

Nests are built on surface sites with the entrance facing the direction of the sun when it is highest in the sky.

Most of the nesting material consists of mosses and liverworts, and the main vascular plant material is dried blades of sedge and cotton grass.

Before workers emerged, queens at Lake Hazen visited only purple saxifrage and Arctic willow flowers; later foragers accepted a wide variety of flowers.

Queens and workers forage for extended periods in the continuous daylight of the Arctic summer and fly close to the ground surface.

The cuckoo bumble bee Bombus hyperboreus is a nest parasite of this species; its queens do not found their own nests but take over Bombus polaris colonies.

The Northwest Territories lists the species with an undetermined general status, noting only a handful of records and that climate change is expected to have a large impact.