Source : Webster's Revised Unabridged Dictionary (1913)

Wireworm \Wire"worm`\, n. (Zo["o]l.)
   (a) One of the larv[ae] of various species of snapping
       beetles, or elaters; -- so called from their slenderness
       and the uncommon hardness of the integument. Wireworms
       are sometimes very destructive to the roots of plants.
       Called also {wire grub}.
   (b) A galleyworm.

Source : WordNet®

wireworm
     n : wormlike larva of various elaterid beetles; feeds on roots
         of many crop plants