INSECT ENEMIES OF WESTERN FORESTS 



143 



Figure 64. — The red turpentine beetle (Dendroctonus valens) : A, Adults; 

 B, pupa; C, larva (all natural size) ; D, base of infested tree showing 

 characteristic work. 



ing a cavity ranging from a few square inches to a square foot or 

 more in area, between the bark and wood. These chambers are 

 often filled with a resinous liquid that apparently has no injurious 

 effect on the developing broods. Transformation to the adult stage 

 occurs within pupal cells constructed in the boring dust of the 

 brood chamber or in short mines along its margin. 



There may be one or more generations annually, depending on 

 locality and season. In the more southern range of the beetle it 

 can be found in all stages of development at nearly any season of 

 the year. The heaviest attacks occur in midsummer, and the winter 

 is passed as larvae, new adults, and parent adults, in trees and 

 stumps attacked the previous season. 



Though this beetle is seldom of serious importance in commer- 

 cial timber stands, should control measures become necessary, the 

 broods can be destroyed by removing the bark from fresh stumps 

 and from the base of infested trees. For the protection of indi- 

 vidual park or shade trees, the damage can be halted by cutting 

 out the attacking beetles with a knife or chisel as soon as pitch 

 exudations indicate their presence. Successful control also has 

 been obtained by injecting carbon disulfide into the galleries. 



Pine Engraver Beetles 



Smaller species of bark beetles, which work in the trunks and 

 larger branches of pines and construct egg galleries that radiate 

 from a central nuptial chamber and form distinctive patterns, are 



