A bumblebee is a member of the genus Bombus, part of Apidae, one of the bee families. This genus is the only extant group in the tribe Bombini, though a few extinct related genera are known from fossils. Over 250 species of bumblebee are known. They are found primarily in higher altitudes or latitudes in the Northern Hemisphere, although they are also found in South America where a few lowland tropical species have been identified. European bumblebees have also been introduced to New Zealand and Tasmania. The brood parasitic or cuckoo bumblebees have sometimes been classified as a subgenus or genus, Psithyrus, but are now usually treated as members of Bombus.