palmerworm \palm"erworm`\, n. zool.
   a 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.
   b 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.
       1913 webster
see also:
ypsolophus pometellus