INSECT ENEMIES OF WESTERN FORESTS li 
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 
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FIGURE 5.—Cone beetle damage: A, Sugar pine cone and cone beetle, the latter xX 7 
(drawings by Edmonston). 8B, 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. 
136650°—38 
2 
