Bombus appositus is a species of bumblebee known commonly as the white-shouldered bumblebee.[1] [2] It is native to western North America, including western Canada and the western United States.[1]
This species lives in open habitat, such as meadows and slopes. It nests underground or on the surface. Males congregate to seek mates. It feeds on a variety of plant taxa, including giant hyssops, thistles, gentians, owl's clovers, locoweeds, penstemons, and clovers.[1] It especially favors subalpine larkspur (Delphinium barbeyi) and it serves as one of the plant's main pollinators.[3]
This species has a range from southwestern Canada south to the Cascade Mountains and the Sierra Nevada, and west to central California[4]
This species is a host to Bombus insularis, a species of cuckoo bumblebee.[1]