Coelioxys

by Hartmut Wisch

Coelioxys- cuckoo bee (family Megachilidae)
by Lisa Schonberg and Mace Vaughan (Xerces Society) and Gretchen LeBuhn (SFSU)

Genus summary: Coelioxys is a genus found throughout the world. There are about 40 species in America north of Mexico (Hurd 1979, Michener 2000) and about 13 are known from New York State (Danforth & Magnacca 2002).

Nesting habits: All species in the genus Coelioxys are clepto-parasites on leaf-cutter bees in the genus Megachile. They are one of the commonest genera of clepto-parasitic bees (Mcihener 2000). Clepto-parasitic bees are commonly referred to as “cuckoo bees.” Clepto-parasites do not collect pollen or provide for their own young; they instead deposit their eggs in the nests of other bees. Coelioxys females deposit their eggs on the food masses of Megachile brood cells while the host is off foraging. Upon hatching, the Coelioxys larvae kill the Megachile larvae and then consume their pollen balls (O’Toole & Raw 1999).

Diagnostic characteristics: Coelioxys are between 0.2 to 0.8 inches long. They closely resemble stout wasps, are heavily armored, and the tip of their abdomens narrow to a sharp point. They are black, but the legs and abdomen may be red or bluish (Michener 2000). They fly quietly, slowly and low to the ground. They are not hairy since they do not carry pollen.
Similar taxa: Coelioyxs is similar to the large leaf-cutter bees that they parasitize, Megachile. Coelioxyx can be distinguished by the hairs on the eyes (Michener 2000), and because their bodies are not hairy like Megachile. Coelioyxs also has a more tapered abdomen.

Known conservation concerns:
Interesting fact:
Additional resources: Baker (1975)

Guide to eastern Coelioxys females at Discover Life
Guide to eastern Coelioxys males at Discover Life