In full "promethea moth". A large North American saturniid silk moth, Callosamia promethea, the male of which has dark brown wings with pale margins.
Mid 19th century. From scientific Latin promethea, specific name (in Phalaena promethea; D. DruryIllustr. Nat. Hist II. 18), feminine of classical Latin Promēthēus (adjective) of or associated with Prometheus from Promētheus.