The western bumble bee was historically very common throughout the western United States and Canada. However, in the last 20 years it has declined by more than 90%. Disease is the probable cause.
Western Bumble Bee Making a Comeback - Bug Squad - ANR Blogs
How Many Bumble Bees Have You Seen This Year? - Bug Squad - ANR Blogs
The American bumblebee is on the decline, Bumble Bee
Contenido reciente Servicio de Extensión de OSU
The Bumblebee's Plight: Why It Is Disappearing in the U.S. - WSJ
Western bumble bee population declines sharply
Nearly 40% decline in honey bee population last winter
News of the Wild
Western bumble bee population declines sharply
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