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



to use two or more methods, even on a single project, because of 

 differences in exposure or site conditions, the size of trees in- 

 fested, or the height of the infestation in the trunk. 



Some of the methods that have been of greatest usefulness are 

 described below. 



Since most of the destructive bark beetles confine their attacks 

 to a few species of trees, control can be carried out by treating 

 just the affected host trees. 



The Fell-Peel-Burn Method 



The fell-peel-burn method is one of the oldest for bark-beetle 

 control, yet one which is still used in the suppression of outbreaks 

 of the western pine beetle and related species, the larvae of which 

 burrow into the outer bark and are not exposed when the bark 

 is peeled from the tree. 



In this method the infested trees are first felled (fig. 107), 

 either up or down hill but away from new growth or heavy 

 patches of brush — never across the slope of the hill, if this can 

 be avoided, since a broad flame is more difficult to control than 

 a narrow one. Then the bark is peeled from the top half of the 

 fallen trunk for as far as the infestation extends, piled along 

 the sides, and set on fire (fig. 108) . The flames creep under the 

 log and scorch the unpeeled bark. If it is desired to dispose of 

 the brush at the same time, the limbs and top are cut off and 

 piled back over the trunk. If this would make too large and dan- 

 gerous a fire, this material can be left out and burned at a 

 later time or spread on the ground to decay. As a fire precaution, 

 a fire line is constructed by scraping away all the litter and duff 

 down to the mineral soil for a width of about 3 feet and com- 

 pletely encircling the tree. In treating a tree infested with the 

 western pine beetle it is desirable to leave the stump and the duff 

 around it unburned in order to protect the beneficial clerids in 

 their pupal cells, which are usually concentrated around the base 

 of the tree. 



The fire should be allowed to consume the infested bark, but 

 should not be so large as to make it difficult to control. In wet 

 weather pitch will have to be supplied to burn the bark suffi- 

 ciently, while in dry weather all tops, limbs, and even needles 

 will have to be thrown outside the fire line, to keep the fire from 

 becoming dangerously large. In wet weather the burning should 

 be with the wind and uphill, to create enough draft to consume 

 the bark. In dry weather this should never be done, but the burn- 

 ing should be downhill and against the wind, so the fire can be 

 controlled. Burning, if done by experienced men, can be handled 

 without injury to the forest. Ordinarily the fire is not hot enough 

 to burn the logs, and if at all accessible they can be used for 

 lumber if taken out within a year or two. 



The Fell-Deck-Burn Method 



The fell-deck-burn method is one of the most economical control 

 methods and is particularly useful in the control of bark beetles 



