The Eucerini (often called longhorn bees or long-horned bees) are the most diverse tribe in the family Apidae, with over 32 genera worldwide that were previously classified as members of the family Anthophoridae. All species are solitary, though many nest in large aggregations, and large "sleeping" aggregations of males are found occasionally. Most genera are distinctive in the unusually long male antennae from which the tribe derives its name (eucer- means true horned). They are most diverse in the Western Hemisphere.
The classification within the tribe is rather chaotic, as many of the genera are small and poorly characterized, with the bulk of species (about 500) in only five genera. This is a group in serious need of a thorough taxonomic overhaul, and the fusion of many genera would likely result (a revision in 2000 eliminated seven genera, another in 2018 eliminated six more).[1]