Bees are flying insects, closely related to wasps and ants. Bees are a monophyletic lineage within the superfamily Apoidea, presently classified by the unranked taxon name Anthophila. There are slightly fewer than 20,000 known species of bee, though many are undescribed and the actual number is probably higher. They are found on every continent except Antarctica, in every habitat on the planet that contains flowering dicotyledons.