140 MISC. PUBLICATION 273, U.S. DEPT. OF AGRICULTURE 



Figure 62. — Light-colored treetops show severe damage by the Black Hills 

 beetle to ponderosa pine in the Kaibab National Forest, Ariz. 



and peeling the bark, (2) decking trees into piles and burning 

 them, or (3) spraying felled or standing trees with toxic pene- 

 trating oils. This work usually is done late in the spring or in the 

 summer until mid-July. Peeling becomes ineffective as soon as 

 new callow adults have formed. Burning can be carried on later, 

 but should be halted on the approach of fire weather. Spraying 

 standing trees with a mixture of 6 parts of fuel oil and 1 part of 

 orthodichlorobenzene was the method used in 1948 on a large 

 control project in the Black Hills of South Dakota. 



The Jeffrey pine beetle (Dendroctonus jeffreyi Hopk.) is an 

 aggressive and at times very destructive enemy of Jeffrey pine in 

 California. Although it often attacks apparently healthy growth, 

 it seems to prefer trees that are retarded in growth by drought 

 or defoliation. It rarely attacks felled trees, so does not breed in 

 slash or windfalls to any extent. It confines its attacks to Jeffrey 

 pine, and its distribution is therefore limited to that of its host 

 tree (99). 



The work of this beetle (fig. 63) is very similar to that of the 

 mountain pine beetle. Reddish pitch tubes form at the mouth of 

 the entrance holes, which are usually in crevices of the bark. There 

 is usually a slight turn at the bottom of the egg gallery, which 

 then proceeds up the tree in nearly a straight line following the 

 grain of the wood. These galleries are usually 2 or 3 feet in length 

 and are packed with boring dust. The eggs are placed in niches 

 along the sides of the galleries, and the larvae work out from the 

 egg gallery across the grain of the wood. The pupal cells are 

 formed in the inner bark and are exposed to view when the bark is 

 removed. The adults are black and about % inch long, and similar 

 to, but considerably larger than the mountain pine beetle. 



