Source : Webster's Revised Unabridged Dictionary (1913)

Grugru worm \Gru"gru worm"\ (Zo["o]l.)
   The larva or grub of a large South American beetle ({Calandra
   palmarum}), which lives in the pith of palm trees and sugar
   cane. It is eaten by the natives, and esteemed a delicacy.