62 SOME INSECTS INJURIOUS TO FORESTS. 



percentage of this injury to the pine in the States north and west of 

 the Gulf States and in the Middle and South Atlantic States is 

 caused by the red turpentine beetle {Dendroctonus valens Lee.) and 

 in the Southern States by the black turpentine beetle {Dendroctonus 

 terebrans Oliv.). These beetles attack the healthy living bark at and 

 toward the base of the trunks of medium to large trees and kill areas 

 varying in size from 1 to 10 square feet. These dead areas are sub- 

 sequently burned oif by surface fires and are then generally referred 

 to as fire-wounds. The further damage to the exposed wood by 

 successive fires, decay, and insects often results in a total loss of the 

 best portion of the tree, or a reduction in value of the lower section 

 of the trunk of from 10 to 50 per cent. (Hopkins, 1904ff, 1909&.) 

 These and similar Avounds in the bark of trees, including those caused 

 by lightning and by the uncovering and exposure of the wood in tur- 

 pentining, offer favorable conditions for the attack of the turpentine 

 borer (Buprestis aprieans Hbst.), the work of which, together with 

 that of two or three others with similar habits, is very extensive, and 

 causes losses amounting to from 10 to 50 per cent of the value of the 

 wood of the best part of the trees thus affected. (Hopkins 1904^.) 



The white pine weevil. — The abnormal development of white pine 

 trees as the result of succesive attacks on the terminals of the sap- 

 lings and young trees by the white pine weevil {Pissodes sti'ohi Peck) 

 is an element of loss of considerable importance, especially in mixed 

 stands and in open pure stands of this timber. The value of such 

 trees is reduced from 20 to 50 per cent below those of normal develop- 

 ment, and there is an additional loss from the effect of their spread- 

 ing branches or crowns in the suppression or crowding out of trees 

 which would otherwise occupy the space thus usurped. (Hopkins, 

 190C)f-, 190Tt/.) 



There are many other examples of insects which damage the wood 

 and bark of living trees, but those mentioned should be sufficient to 

 demonstrate the importance of insects in this relation. 



Insect Injuries to the Wood of Dyinc and Dead Trees. 



Timber dying from insect attack and other causes, including fire, 

 disease, storms, etc., is attacked by certain wood-boring insects which 

 extend their burrows through the sound sapwood and heartwood, 

 and thus contribute to the rapid deterioration and decay of a com- 

 modity which otherwise would be available commercially during 

 periods of from one to twenty years or more after the death of the 

 trees, depending on the species of trees and on the character of the 

 product desired. This loss often amounts to from 25 to 100 per cent 

 during the period in which the dead timber would otherwise be 

 almost as valuable as if living. (Hopkins, 189-1«, 1901g^, 1904ff, 1905« ; 

 Webb, 1909.) 



