Bombus is one of more than 250 species in the genus, part of the Apidae, a family of bees. This genus is the only extant group in the Bombini tribe, although several related extinct genera (e.g., Calyptapis) are known from fossils. They are found primarily at high altitudes or latitudes in the Northern Hemisphere, although they are also found in South America, where several lowland tropical species have been identified.