The Collaborative International Dictionary of English v.0.48:

Promethea \Pro*me"the*a\, n. [NL. See Prometheus.] (Zool.)
   A large American bombycid moth (Callosamia promethea). Its
   larva feeds on the sassafras, wild cherry, and other trees,
   and suspends its cocoon from a branch by a silken band.
   [1913 Webster]