Synonyms and other taxonomic changes
Bombus edwardsii var russulus Frison, 1927
Red tail tip separated by black from pale hairs on T1 and T2 (at least mediobasally) in combination with some admixture of black hairs on the anterior scutum is distinctive. Males have a distinctive patch of dense hairs on basal segments of their flagellum (only visible from certain angles) and this is useful for separating them from frigidus. Also, in mixtus males the red tail tip is separated from yellow basal tergal segments. In mixtus the apicolateral corners of T2 are often black whereas in frigidus all of T2 is yellow.
western North America. Records mapped in the Williams et al. guide from the eastern United States are unprecedented and surely all erroneous. a report in the text from Maritime NB, not represented in the maps, is questionable at best.
includes mountain meadows
The Hosts section of its Discover Life species page
lists known associations based on specimen records and images.
Widely distributed and common in western mountains