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BC Conservation Data Centre: Species Summary

Bombus occidentalis
Western Bumble Bee

Scientific Name: Bombus occidentalis Greene, 1858
Scientific Name Synonyms: Bombus (Bombus) occidentalis
English Name: Western Bumble Bee
Classification / Taxonomy
Scientific Name - Concept Reference: Williams, P. H., M. J. F. Brown, J. C. Carolan, J. An, D. Goulson, A. M. Aytekin, L. R. Best, A. M. Byvaltsev, B. Cederberg, R. Dawson, J. Huang, M. Ito, A. Monfared, R. H. Raina, P. Schmid-Hempel, C. S. Sheffield, P. ima, and Z. Xie. 2012. Unveiling cryptic species of the bumblebee subgenus Bombus s. str. worldwide with COI barcodes (Hymenoptera: Apidae). Systematics and Biodiversity 10(1):21-56.
Classification Level: Species
Taxonomy Comments: July 28, 2021 - Bombus occidentalis is split north and south. BC has both species, B. mckayi and B. occidentalis. Yukon and NWT only have B. mckayi, to my knowledge. Prairies only have B. occidentalis (Williams 2021).

Species Group: Invertebrate Animal
Species Code: HY-BOMOCC
Kingdom Phylum Class Order Family
Animalia Arthropoda Insecta Hymenoptera Apidae
Conservation Status / Legal Designation
Global Status: G3 (Apr 2018)
Provincial Status: S4 (Feb 2023)
BC List: Yellow
Provincial FRPA list:   
Provincial Wildlife Act:
COSEWIC Status: Threatened (May 2014)
COSEWIC Comments: ssp. mckayi SC
ssp. occidentalis T
SARA Schedule:
General Status Canada:
Ecology & Life History
General Description:
Global Reproduction Comments: Usually nests underground; males patrol in circuits in search of mates. It is a known host to Bombus suckleyi and possibly other species (Williams et al. 2014).
Migration Characteristics:
(Global / Provincial)
    Local Migrant:
    Distant Migrant:
    Within Borders Migrant:
Y / N
N / N
N / N
na / N
(Type / Subtype / Dependence)
Anthropogenic / Roadside/Ditch / Facultative - frequent use
Anthropogenic / Urban/Suburban / Facultative - frequent use
Forest / Deciduous/Broadleaf Forest / Facultative - frequent use
Forest / Mixed Forest (deciduous/coniferous mix) / Facultative - frequent use
Grassland/Shrub / Grassland / Facultative - frequent use
Grassland/Shrub / Meadow / Facultative - frequent use
Global Habitat Comments: Found in a range of habitats, including mixed woodlands, farmlands, urban areas, montane meadows and into the western edge of the prairie grasslands (COSEWIC 2014b).
Food Habits:
Global Food Habits Comments: A short-tongued species; food plants include Ceanothus, Centaurea, Chrysothamnus, Cirsium, Geranium, Grindellia, Lupinus, Melilotus, Monardella, Rubus, Solidago, and Trifolium (Williams et al. 2014).
Global Phenology:
Provincial Phenology:
(1st half of month/
2nd half of month)
Colonial Breeder: Y
Length(cm)/width(cm)/Weight(g): / /
Elevation (m) (min / max): Global: 
Global Range Comment: This species occurs in Canada and the USA from southern British Columbia to central California, northern Arizona and northern New Mexico and east into southern Saskatchewan and northwestern Great Plains (COSEWIC 2014b, Williams et al. 2014, Sheffield et al. 2016).

The historical range extent of this species is estimated at 4,515,999 km▓, and the extent of current (2008-2017) observations is 3,717,234 km▓. Controlling for larger historical sample size, the range of this species has declined by an estimated 14%. For the purposes of this analysis, when specimen records did not include a subspecies determination, following Sheffield et al. 2016, if the specimen was collected at > 57║ latitude, it was assumed to be B. mckayi (formerly considered a subspecies of B. occidentalis); if it was found < 55║ latitude, it was assigned to species B. occidentalis.
Authors / Contributors
Global Information Author:
Last Updated:
Provincial Information Author:
Last Updated:
References and Related Literature
COSEWIC. 2014b. COSEWIC assessment and status report on the Western Bumble Bee Bombus occidentalis, occidentalis subspecies (Bombus occidentalis occidentalis) and the mckayi subspecies (Bombus occidentalis mckayi) in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. xii + 52 pp. (

Please visit the website Conservation Status Ranks for definitions of the data fields used in this summary report.

Suggested Citation:

B.C. Conservation Data Centre. Species Summary: Bombus occidentalis. B.C. Minist. of Environment. Available: (accessed Sep 29, 2023).