The Collaborative International Dictionary
Ypsolophus pometellus
Palmerworm \Palm"er*worm`\, n. (Zo["o]l.)
Any hairy caterpillar which appears in great numbers, devouring herbage, and wandering about like a palmer. The name is applied also to other voracious insects.
--Joel. i. 4.In America, the larva of any one of several moths, which destroys the foliage of fruit and forest trees, esp. the larva of Ypsolophus pometellus, which sometimes appears in vast numbers.