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TaxonomyBrowse
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Subgenus Bombus

Western Bumblebee? - Bombus occidentalis - female Bombus sp female on Senecio - Bombus occidentalis - female Bombus franklini M - Bombus franklini - male Black Bumble Bee with a little yellow - Bombus occidentalis Is this Bombus terricola? - Bombus terricola Bombus occidentalis? - Bombus occidentalis Bombus - Bombus terricola Possible Western Bumblebee ? - Bombus occidentalis
Classification
Kingdom Animalia (Animals)
Phylum Arthropoda (Arthropods)
Subphylum Hexapoda (Hexapods)
Class Insecta (Insects)
Order Hymenoptera (Ants, Bees, Wasps and Sawflies)
No Taxon (Aculeata - Ants, Bees and Stinging Wasps)
No Taxon (Anthophila (Apoidea) - Bees)
Family Apidae (Cuckoo, Carpenter, Digger, Bumble, and Honey Bees)
Subfamily Apinae (Honey, Bumble, Long-horned, Orchid, and Digger Bees)
Tribe Bombini (Bumble Bees)
Genus Bombus (Bumble Bees)
No Taxon Subgenus Bombus
Numbers
6 spp. (of which 2 non-native) in our area, 12 spp. total(1)
Identification
Head and malar space short. Midleg with rounded angle.
Range
A holarctic group; in our area B. terricola is widespread in Canada and the northeastern USA, B. occidentalis is in western Canada and the western half of the USA, B. franklini has a very narrow historic range in southern Oregon and northern California (with no records since 2006), and B. affinis occurs in the e. half of the US and adjacent southeastern Canada; B. cryptarum is found in Alaska and western Canada(1)
Habitat
Forest-edge, mountain meadow, and grassland(2)
Life Cycle
Nests underground; colonies can be large(2)
Remarks
Abrupt and severe declines of bumble bee species in this subgenus were widely reported soon after development of the commercial bumble bee industry and detection of high rates of parasitism in managed colonies. These abrupt losses occurred in the absence of any apparent loss or modification of habitats and are unlikely to be due to pesticides as other bumble bee species, e.g. members of subgenus Pyrobombus, remain abundant at the same sites.

Of greatest concern is loss of Bombus franklini, narrowly endemic to southern Oregon and northern California and not seen since 2006 despite resurveys by bombus specialist Robbin Thorp. Loss of B. affinis from much of its range, in eastern North America, is also very troubling.

A neglected aspect of these declines is loss of the cuckoo bumble bees B. ashtoni and B. suckleyi. These depend on Bombus (Bombus) as hosts and have also severely declined as evidenced by lack of any photos of live individuals on Bugguide.

Recent attention given to local pathogen spillover from particular greenhouses has diverted attention away from the possibility of a broad-scale epizootic.