The Collaborative International Dictionary of English v.0.48:

Phytophagous \Phy*toph"a*gous\, a. [Phyto- + Gr. fagei^n to
   eat.] (Zool.)
   Feeding on plants; herbivorous; as, a phytophagous animal.
   [1913 Webster]

WordNet (r) 3.0 (2006):

phytophagous
    adj 1: (of animals) feeding on plants [syn: plant-eating(a),
           phytophagic, phytophagous, phytophilous]