The Collaborative International Dictionary of English v.0.48:

Yucca borer \Yuc"ca bor`er\
   (a) A California boring weevil (Yuccaborus frontalis).
   (b) A large mothlike butterfly (Megathymus yuccae) of the
       family Megatimidae, whose larva bores in yucca roots.
       [Webster 1913 Suppl.]