The Collaborative International Dictionary of English v.0.48:

lymantriid \lymantriid\ n.
   A dull-colored moth whose larvae have tufts of hair on the
   body and feed on the leaves of many deciduous trees.

   Syn: tussock moth.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

lymantriid
    n 1: dull-colored moth whose larvae have tufts of hair on the
         body and feed on the leaves of many deciduous trees [syn:
         lymantriid, tussock moth]