Bombus sitkensis

Bombus sitkensis, the Sitka bumblebee, is a species of bumblebee common in western North America from Alaska to California.

Bombus sitkensis
Conservation status
Least Concern  (IUCN 3.1)
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Insecta
Order:	Hymenoptera
Family:	Apidae
Genus:	Bombus
Subgenus:	Pyrobombus
Species:	B. sitkensis
Binomial name
Bombus sitkensis Nylander, 1848[1]

Description

The Sitka bumblebee has an oblong head with a medium-length proboscis. 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.[2] Terga (abdominal segments) 1 and 2 are yellow, and 3 and 4 black, the latter with a yellow posterior rim. The two last terga are brownish-red.[3] The male has the face and forward parts of the thorax yellow, and only the posterior parts are darker (black and yellow intermixed). On the abdomen terga 1 and 2 are yellow,[2] and terga 3 to 5 yellow on the anterior part, black on the posterior. The tail (terga 6 to 7) is brownish-red.[3]

Distribution

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]

Ecology

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. The first workers emerge in early March, while males appear in early April. Both the latter castes have disappeared by the end of September.[4]

See also

• List of bumblebee species

References

1. Hatfield, R., et al. 2015. Bombus sitkensis. The IUCN Red List of Threatened Species. Downloaded on 10 March 2016.
2. Koch, J.; J. Strange & P. Williams (2012). "Bumble Bees of the Western United States" (PDF, 7.56 MB). The Xerces Society. Retrieved 30 January 2013.
3. McFrederick, Q. S. "Guide to the Bombus of San Francisco" (PDF). San Francisco State University. Retrieved 1 February 2013.
4. Thorp, R. W.; et al. (February 1983). "Bumble Bees and Cuckoo Bumble Bees of California" (PDF (6,94 MB)). Bulletin of the California Insect Survey. University of California Press. 23: 42–43. ISBN 0520096452. Retrieved 27 July 2011.
5. McFrederick, Q. S.; LeBuhn, G. (2006-05-01). "Are urban parks refuges for bumble bees Bombus spp. (Hymenoptera: Apidae)?". Biological Conservation. 129 (3): 372–382. doi:10.1016/j.biocon.2005.11.004.