The
Bombini are a tribe of large bristly
apid bees which feed on
pollen or
nectar. Many species are social, forming nests of up to a few hundred individuals; other species, formerly classified as
Psithyrus cuckoo bees, are
brood parasites of nest-making species. The tribe contains a single living genus,
Bombus, the bumblebees, and some extinct genera such as
Calyptapis and
Oligobombus.