60 SOME INSECTS INJURIOUS TO FORESTS. 



and Arizona, and still anotlier has contributed greatly to the de- 

 struction of the larch throughout the northeastern United States and 

 southeastern Canada. (Hopkins, 1000/v, pp. 49, 53, and 77.) 



The hickory harkheetle. — Within the past ten years the hickory 

 oarkbeetle {Scolytvs qvadrispinoHus Say) has caused the destruction 

 of an enormous amount of hickory timber throughout the northern 

 tier of States from Wisconsin to Vermont and southward through 

 the eastern Atlantic States and into the Southern States as far as 

 central Georgia. (Hopkins, 1904/>, pp. 314-317.) 



The larch loorrn. — There are also many examples of widespread 

 depredations chargeable to insects which defoliate the trees, thus 

 contributing to their death. Notable among these are the depreda- 

 tions by the larch worm {Nematvs crichsonii Hartig), which, during 

 several extensive outbreaks since 1880, has killed from 50 to 100 per 

 cent of the mature larch over vast areas in the northeastern United 

 States and southeastern Canada. It is evident that the amount of 

 merchantable-sized timber that has died as the result of defoliation by 

 this insect will aggregate many billions of feet. (Packard, 1890, 

 pp. 879-890; Pinchot, 1899; Hopkins, 1908«.) 



Insect Injuries to the Wood of Living Trees. 



It has been determined that insects of a certain class attack the 

 wood and bark of living timber and that, while they do not con- 

 tribute materially to the death of the trees or give much external 

 evidence of their presence, they jDroduce wounds in the bark and 

 wormhole and pinhole defects in the wood which result in a depre- 

 ciation in commercial value amounting to from 5 to 50 per cent. 

 These defects in the wood are not detected until after the trees have 

 been felled and the logs transported to the mill and converted into 

 lumber. Thus to the actual damage to the lumber is added the 

 expense of logging and manufacture of the defective, low-grade ma- 

 terial, much of which must be discarded as worthless culls. (Hop- 

 kins, 1894a, 1894Z>, 1904Z>, 1905«, l*^m\h.) 



TJie oah timher vorni. — One of the most destructive of the class of 

 depredators just mentioned is the oak timber worm {Eupsalis minuta 

 Dru.). It enters the wood of the trunks of living trees through 

 Avounds in the bark and at (he base of broken or dead branches aiul 

 extends its " pinhole " burrows in all directions through the solid 

 heartwood. The losses occasioned by this insect in the hardwood 

 forests of the eastern United States are enormous and usually affect 

 the wood of the finest examples of old trees. (Hopkins, 1894(7, 

 1904/v.) 



The chestnut t'nnher iroi-rn. — The chestnut throughout its range is 

 damaged in a like manner by the chestnut timber Avorm {Ly))iexyl()n 

 sericeum Harr.). »Practically every tree of merchantable size is 



