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Suckley’s Cuckoo Bumble Bee is a medium-sized bumble bee with a black head. The upper segment of the hind leg has a convex, densely hairy outer surface and lacks a pollen basket. Suckley’s Cuckoo Bumble Bee looks similar to the Gypsy Cuckoo Bumble Bee, but its thorax is mostly yellow on the sides. There are prominent triangular ridges on the underside of the last segment of the abdomen.

Length: Females, 1.5 to 2.5 cm (0.59 to 0.98 in); Males, 1.5 to 2.2 cm (0.59 to 0.87 in)

Report Suckley's Cuckoo Bumble Bee sightings to

Check out the Field Guide to Bumble Bees of the Northwest Territories 

Range map information

Suckley’s Cuckoo Bumble Bee was historically widespread in western North America with scattered populations in the east. 

Suckley’s Cuckoo Bumble Bee is a ‘social parasite.’ Like other cuckoo bumble bees, they do not collect pollen or establish their own colonies. Instead, they take advantage of the nests and workers of other ‘host’ bumble bees. Potential host species found in the NWT include McKay's  Bumble Bee, Yellow-banded Bumble Bee and Cryptic Bumble Bee.

Suckley’s Cuckoo Bumble Bees require host bumble bee nests, which are typically underground in abandoned rodent burrows. Females probably overwinter in soil, mulch or rotting logs. The bees visit flowers for nectar, such as aster, thistle and goldenrod.

Bumble bees have a type of genetic sex determination that makes them very prone to extinction when population sizes are small.


Cuckoo bumble bees are naturally less abundant than other bumble bees because they do not produce workers.

Populations of the host species for Suckley's Cuckoo Bumble Bee have declined in Canada. Therefore, Suckley’s Cuckoo Bumble Bee populations have probably declined also. Population size and trend in the NWT are unknown.

Potential threats in the Northwest Territories include: declines in the populations of host species, such as McKay's Bumble Bee and Yellow-banded Bumble Bee; introduction of exotic bumble bee species for pollination, which can spread diseases to native bees; and use of pesticides and herbicides. At high densities, imported honey bees can outcompete native bumble bees for pollen.

In 2019, the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) assessed Suckley's Cuckoo Bumble Bee as Threatened in Canada.

Dehcho Gwich'in Inuvialuit North Slave / Tłı̨chǫ Sahtú South Slave