The Collaborative International Dictionary of English v.0.48:

Polyphagous \Po*lyph"a*gous\, a. [L. polyphagus, Gr. ?; poly`s
   much, many + ? to eat: cf. F. polyphage.]
   Eating, or subsisting on, many kinds of food; as, polyphagous
   animals.
   [1913 Webster]