 The genus Bombus , the only one extant in the tribe Bombini , comprises over 250 species ; for an overview of the differences between bumblebees and other bees and wasps , see characteristics of common wasps and bees . The genus has been divided variously into up to 49 subgenera , a degree of complexity criticised by Williams ( 2008 ) . The cuckoo bumblebees Psithyrus have sometimes been treated as a separate genus but are now considered to be part of Bombus , in one or more subgenera . Williams identifies 15 subgenera that are seen to be monophyletic , fewer in number , diagnosable from morphology , and at least roughly correspond to behavioural and ecological groupings : Examples of Bombus species include Bombus atratus , Bombus dahlbomii , Bombus fervidus , Bombus lapidarius , Bombus ruderatus , and Bombus rupestris . 
