salt-marsh caterpillar

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. The larva of a common tiger moth (Estigmene acrea) that feeds destructively on various grasses.

GNU Webster's 1913

1. adj. (Zoöl.) an American bombycid moth (Spilosoma acræa which is very destructive to the salt-marsh grasses and to other crops. Called also woolly bear. See Illust. under Moth, Pupa, and Woolly bear, under Woolly.