Western Bumble Bee
Bombus occidentalis
This record describes Bombus occidentalis (species). Recorded family: Apidae. Recorded order: Hymenoptera.
Identification and Appearance
White tail tip distinctive. Usually but not always with yellow band centered on T3 but this can be lacking or yellow of the metasoma may extend to other terga. Has declined in the Pacific states including California. In the San Francisco Bay Area common until the early 1990s but now absent. Still regularly found in Colorado and elsewhere in the Rocky Mountains and has reappeared recently in small numbers at various sites in the Pacific Northwest. Sympatric with another member of its subgenus, B. franklini of southern Oregon and adjacent northern California, which has not been seen since 2006 and is feared extinct. **Listed as Vulnerable by the IUCN Red List of Threatened Species **
Classification
- Kingdom
- Animalia
- Phylum
- Arthropoda
- Class
- Insecta
- Order
- Hymenoptera (Ants, Bees, Wasps and Sawflies)
- Superfamily
- Trigonaloidea
- Family
- Apidae (Cuckoo, Carpenter, Digger, Bumble, and Honey Bees)
- Subfamily
- Apinae
- Tribe
- Bombini
- Genus
- Bombus (Bumble Bees)
Imported taxonomy record. Source availability varies; see the source references and editorial policy below.
Habitat and Range
Geographic Range
southern Alaska [update: now recognized as a distinct species B. mckayi. See https://www.tandfonline.com/doi/full/10.1080/00222933.2021.1900444], western Canada [but far NW pertains now to B. mckayi], and western USA
Diet and Behavior
Diet: The Hosts section of its Discover Life species page lists known associations based on specimen records and images.
Additional species information
Species notes from the sources
Etymology: Refers to its western distribution
About Flies: the wider group
Order-level background for Hymenoptera, the group containing Bombus occidentalis. Species-specific details appear above.
Group overview
Hymenoptera includes over 150,000 described species of ants, bees, wasps, and sawflies. Earth harbors approximately 20 quadrillion (20×10^15) ants, with a combined biomass of ~12 megatons of dry carbon - exceeding the combined biomass of all wild birds and mammals (PNAS, 2022).
Ecological role of the group
About 35% of the world's food crops depend on animal pollinators. The chocolate industry, valued at over $100 billion, depends on pollinating flies and midges. Ants are the dominant soil engineers in most terrestrial ecosystems, turning more soil than earthworms in many habitats.
Economic and practical significance of the group
Pollinators contribute $235-577 billion worth of annual global food production (FAO). In the U.S., bee pollination alone benefits crops valued at $18 billion annually, and honey bees are responsible for $5.4 billion in agricultural productivity. Between April 2023-2024, 55.1% of managed honey bee colonies were lost. The U.S. bee population dropped from 5 million to 2.5 million.
Recorded sources for this group: FAO, USDA, EPA, PNAS (2022), US Fish & Wildlife Service. Imported estimates may describe particular regions or reporting periods.
Photos of Western Bumble Bee (5)
Photo credits: Contributed by John S. Ascher; Additional contributions by Nathaniel Green
Frequently Asked Questions About Western Bumble Bee
What is Western Bumble Bee?
Western Bumble Bee (Bombus occidentalis) is a species in the family Apidae, within the order Hymenoptera.
How do you identify Western Bumble Bee?
White tail tip distinctive. Usually but not always with yellow band centered on T3 but this can be lacking or yellow of the metasoma may extend to other terga.
Where is Western Bumble Bee found?
Range: southern Alaska [update: now recognized as a distinct species B. mckayi. See https://www.tandfonline.com/doi/full/10.1080/00222933.2021.1900444], western Canada [but far NW pertains now to B. mckayi], and western USA
What does Western Bumble Bee eat?
The diet of the Western Bumble Bee includes The Hosts section of its Discover Life species page lists known associations based on specimen records and images..