About Bombus appositus Cresson, 1879
Bombus appositus is a bumblebee species commonly known as the white-shouldered bumblebee. It is native to western North America, occurring in western Canada and the western United States. Its range extends from southwestern Canada south to the Cascade Mountains and the Sierra Nevada, and west to central California. This species inhabits open habitats including meadows and slopes. It nests either underground or on the ground surface. Males of the species congregate to search for mates. It feeds on a wide range of plant types, including giant hyssops, thistles, gentians, owl's clovers, locoweeds, penstemons, and clovers. It particularly favors subalpine larkspur, Delphinium barbeyi, and acts as one of the main pollinators for this plant. The cuckoo bumblebee species Bombus insularis uses this bumblebee as a host.
