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



Figure 108. — Trees infested by the western pine beetle are burned after the 

 bark has been partially peeled. 



leaves the forest free from the fire hazard of fallen logs and 

 piles of brush. This method also permits the control work to start 

 before the close of the fire season in the fall since the piles can 

 be prepared and the burning can be done at a later date. Since 

 the burning of decked logs throws out terrific heat, the size of the 

 piles should be adjusted to the space available, so that neighbor- 

 ing living trees will not be injured. If this precaution is not 

 taken, the scorched trees may draw in additional infestation and 

 more or less nullify the effects of the control work. 



The Oil-Burning Method 



Recent control technique has developed an economical method 

 of killing bark beetles in thin-bark trees, such as lodgepole pine, 

 by spraying the bark with fuel oil, firing it, and letting the bark 

 be scorched deeply enough so that the beetles will be killed by the 

 heat. The trees may be either felled and burned or burned in a 

 standing position. 



A fuel oil is used that has a high caloric content and burns 



