19 



CHARACTERISTIC FEATURES OF THE LIVING, DYING, AND DEAD 

 TREES INFESTED AND KILLED BY THE BEETLE. 



The characteristic features which are of importance to the forester 

 and lumberman in identifying the presence and the work of the pine- 

 destroying beetle are as follows: 



BORINGS AND PITCH TUBES. 



The first indication of attack is the red dust or borings lodged in the 

 loose bark and fallen around the base of the tree. The next and more 

 conspicuous evidence is the presence of numerous small masses of pitch 

 or so-called pitch tubes on the outer bark at the mouth of the entrance 

 burrows. (PI. VII., figs. 1, 3, 4.) If the pitch is fresh and mixed 

 with reddish and white borings, it- indicates a recent attack and the 

 presence of the living beetles in the bark. If, however, the pitch is 

 dry and hardened, without traces of fresh borings or the presence of 

 living beetles, and the tree is living, it indicates an abandoned attack 

 and that the tree will recover. 



APPEARANCE OF THE LEAVES; 



The leaves of trees d}dng from attack by the beetle present first a 

 pale-yellow appearance in the tops and tips of the branches, followed 

 by a general yellowing of all the leaves, thus presenting from a long 

 distance a marked contrast to the dark, healthy green of the surround- 

 ing living foliage. If the bark is stripped off and examined when the 

 trees are in this condition, all stages from eggs to fully -developed 

 broods will usually be found, together with numerous other secondary 

 enemies of the trees and enemies of the insects. The leaves do not 

 fall from the twigs for possibly two or three years after the trees 

 die and the broods of beetles emerge, but they soon change from yel- 

 low to red, and thus become even more conspicuous. The normal 

 length of time the leaves remain on the twigs has not been determined, 

 but the greater number evidently fall during the second or third year, 

 leaving the twigs almost bare, with the exception of a few leaves on the 

 tips which may adhere for a much longer time. 



APPEARANCE OF THE TREES THAT HAVE BEEN DEAD THREE YEARS OR 



MORE. 



Little opportunity was had to obtain information on the character- 

 istic appearance at different stages of deterioration, but it would appear 

 from such observations and general comparisons as could be made that 

 the twigs and some of the branches commence to fall within three or 

 four years, and that after the fourth year rapid decay sets in, and the 

 tops commence to break off. 



