INSECT ENEMIES OF WESTERN FORESTS 



17 



they overwinter. Most moths have one generation annually, and the 

 adults emerge the following spring, but a few may retard their 

 emergence and appear the second or third season. Thus in the event 



Figure 5. — Cone beetle daiaage : .1 , Sugar pine cone and cone beetle, the latter X 7 

 (drawings by Edmonston). B, Pitch tubes on the stem, indicating cone beetle attack. 

 C, Knobcone pine cones riddled by cone beetles : a, Cone showing pitch tube at point 

 of attack near stem and exit hole near center ; c, cone showing larval excavations and 

 adult beetle. 



that one or two cone crops fail, the species is still able to survive. 

 No methods have been devised for the control of these insects, nor 

 would control be economically justifiable under present forest con- 

 ditions. 



18064.' 



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