THE GENUS DENDROCTONUS. 
87 
lightning, broken, or felled by storms, landslides, etc., or injured by 
fire. Unfavorable conditions for attacks on living timber will be 
found in areas of vigorous young to matured growth under some 
system of forest management which provides for the utilization of 
the old timber and especially that injured by storm, lightning, fire, etc. 
Fig. 49.— The mountain pine beetle: Tops of the trees shown in figure 48. (Original.) 
METHODS OF CONTROL. 
Whenever it is positively determined that this species is killing 
the timber and that the bark of living or dying trees contains living 
broods, the principal groups of infested trees should be located and 
marked during September, and then during the period beginning in 
October and ending in the following July the infested bark should be 
removed from the main trunk. The simple removal of the bark, 
