''Bombus sitkensis'', the Sitka bumblebee, is a species of

bumblebee A bumblebee (or bumble bee, bumble-bee, or humble-bee) is any of over 250 species in the genus ''Bombus'', part of Apidae, one of the bee families. This genus is the only extant group in the tribe Bombini, though a few extinct related gener ...

common in western North America from

Alaska Alaska ( ; russian: Аляска, Alyaska; ale, Alax̂sxax̂; ; ems, Alas'kaaq; Yup'ik: ''Alaskaq''; tli, Anáaski) is a state located in the Western United States on the northwest extremity of North America. A semi-exclave of the U.S., ...

California California is a U.S. state, state in the Western United States, located along the West Coast of the United States, Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the List of states and territori ...

Description

The Sitka bumblebee has an oblong head with a medium-length

proboscis A proboscis () is an elongated appendage from the head of an animal, either a vertebrate or an invertebrate. In invertebrates, the term usually refers to tubular mouthparts used for feeding and sucking. In vertebrates, a proboscis is an elong ...

. The females (queens and workers) have black and yellow hairs intermixed on the face and forward part of the

thorax The thorax or chest is a part of the anatomy of humans, mammals, and other tetrapod animals located between the neck and the abdomen. In insects, crustaceans, and the extinct trilobites, the thorax is one of the three main divisions of the cre ...

and a black patch in the middle of the thorax, while their sides are yellowish.

Terga A ''tergum'' (Latin for "the back"; plural ''terga'', associated adjective tergal) is the dorsal ('upper') portion of an arthropod segment other than the head. The anterior edge is called the 'base' and posterior edge is called the 'apex' or 'ma ...

(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. 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, and terga 3 to 5 yellow on the anterior part, black on the posterior. The tail (terga 6 to 7) is brownish-red.

Distribution

The species is a common bumblebee found in the western North America from

and

British Columbia British Columbia (commonly abbreviated as BC) is the westernmost province of Canada, situated between the Pacific Ocean and the Rocky Mountains. It has a diverse geography, with rugged landscapes that include rocky coastlines, sandy beaches, ...

, and

Washington Washington commonly refers to: * Washington (state), United States * Washington, D.C., the capital of the United States ** A metonym for the federal government of the United States ** Washington metropolitan area, the metropolitan area centered on ...

, to northern

Idaho Idaho ( ) is a state in the Pacific Northwest region of the Western United States. To the north, it shares a small portion of the Canada–United States border with the province of British Columbia. It borders the states of Montana and Wyom ...

, western

Montana Montana () is a state in the Mountain West division of the Western United States. It is bordered by Idaho to the west, North Dakota and South Dakota to the east, Wyoming to the south, and the Canadian provinces of Alberta, British Columbi ...

, and the coastal parts of

. The Sitka bumblebee has experienced mild population declines in parks in California due to competition with the

yellow-faced bumblebee ''Bombus vosnesenskii'', the yellow-faced bumblebee, is a species of bumblebee native to the west coast of North America, where it is distributed from British Columbia to Baja California. It is the most abundant species of bee in this range, and ...

(''B. vosnesenskii'') for nesting sites, such as rodent holes.

Ecology

The Sitka bumblebee forages on flowering plants from several families, including the Ericaceae,

Asteraceae The family Asteraceae, alternatively Compositae, consists of over 32,000 known species of flowering plants in over 1,900 genera within the order Asterales. Commonly referred to as the aster, daisy, composite, or sunflower family, Compositae w ...

, Saxifragaceae, and

Rhamnaceae The Rhamnaceae are a large family of flowering plants, mostly trees, shrubs, and some vines, commonly called the buckthorn family. Rhamnaceae is included in the order Rosales. The family contains about 55 genera and 950 species. The Rhamnaceae h ...

. 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.

References

{{Taxonbar, from=Q2143140 Bumblebees Hymenoptera of North America Insects of Canada Insects of the United States Fauna of Alaska Fauna of California Fauna of the Northwestern United States Natural history of British Columbia Natural history of Oregon Natural history of Washington (state) Insects described in 1848

Description

Distribution

Ecology

See also

References