The Collaborative International Dictionary of English v.0.48:
fall webworm \fall webworm\, n. (Zool.) The larva of any moth of the genus Hyphantria, which spins a web around the foliage on which it feeds. [PJC]WordNet (r) 3.0 (2006):
fall webworm n 1: a variety of webworm [syn: fall webworm, Hyphantria cunea]