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Western Bumble Bee

Bombus occidentalis

RareInsect & Arthropod
Illustration of Western Bumble Bee (Bombus occidentalis)

The Western Bumble Bee was once among the most abundant bumble bees in the western United States but suffered a catastrophic population collapse in the late 1990s following commercial rearing for greenhouse tomato pollination, which spread a fungal pathogen. It is now federally proposed for endangered listing. It has yellow-and-black banding with a distinctive white tail.

Habitat
Mountain meadows, open forests, and subalpine grasslands of the West
Diet
Adults: pollen and nectar from diverse wildflowers
How common
Rare

Best time to see a Western Bumble Bee

The best time to see a Western Bumble Bee is July–August, when about 69% of U.S. sightings happen, based on 1,602 research-grade iNaturalist observations.

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