• Family: Apidae
• Approximate # species in region: 13
• Common name: cellophane-cuckoo bees

Epeolus are cleptoparasites of cellophane bees (Colletes spp.). They are typically orange-red and black, with cream-white or silvery bands on the abdomen. Females sneak into nests while the host female is out foraging and lay an egg in the wall of a brood cell or in between the double-layered cell lining. Epeolus eggs hatch into scissor-jawed larvae that quickly kill the host egg and develop on the pollen provisions. Many Colletes nests are still undescribed, meaning that relationships between Epeolus and their hosts are often only presumed from frequent co-occurrence of certain Epeolus and Colletes.

Telling Epeolus apart from their close relatives Triepeolus can be tricky in the field – as a general rule, the pseudopygidial area (a flat area in the middle of T5 covered with short, silvery hairs) is shorter in Epeolus than in Triepeolus, but this is often tough to see and judge without very good views and experience. Instead, we find it easier to learn the distinctive color patterns of the few common Epeolus and Triepeolus in our region and know that unfamiliar rare species might be difficult to ID when we first encounter them.

Regional Species List: