THE BEETLES: COLEOPTERA 53 



to trees. The larvae dig tunnels and burrows in the bark 

 and wood, frequently causing the death of trees and greatly 

 injuring the wood for use as lumber (Fig. 37). 



Definition of Coleoptera (Gr. koleos, "sheath"; pteron, 

 "wing"). The insects which we have considered in this 

 chapter agree in possessing biting mouth parts and hardened 

 sheaths to cover the posterior wings. The wing covers, or 

 elytra, meet in a straight line down the middle of the back. 

 These insects are termed beetles or Coleop'tera. The Cole- 

 optera undergo complete metamorphosis, — the life history 

 comprising the egg, an active larva or grub, a resting pupal 

 stage, and the winged adult. 



