army worm

/AA1 R M IY0 W ER1 M/
noun
  1. 1

    The larva of any of the Spodoptera and Mythimna genera of noctuid moths, which typically feed in large, destructive groups.

Source: https://en.wiktionary.org/wiki/army%20worm, https://en.wiktionary.org/wiki/armyworm