24 



other bark and wood-boring insects, which attack the tree a.^ soon as 

 it manifests weakened vitality. 



The two-lined chestnut borer {Agrilus bilineatiM) is another enemy of 

 medium to large white oak and other oak and chestnut trees, which 

 has caused the death of a large amount of this kind of timber through- 

 out the Appalachian region. 



The oak timber worm {Ewpsalis minutd) is one of the most 

 destructive enemies of the wood of living, dying, dead, standing, and 

 felled trees. It causes what is known as pin-hole defects. The loss 

 of the more valuable timber of the largest and best trees caused hy 

 this insect is enormous; indeed it is far beyond the conception of 

 persons who have not given special attention to the subject. The 

 ravages of this insect do not end with living and dead trees, but it 

 continues its work in lumber and squai'e timber from infested logs, 

 and will even attack freshly sawed and closely piled oak lumber. 

 This insect alone furnishes one of the big problems for detailed 

 investigation. 



The Columbian timber beetle {Corthylus columhianus Hopk.) causes 

 one of the commonest defects in white oak lumber and square timber. 

 It attacks and breeds in the sapwood of living trees, and the healed- 

 over wounds cause pin-hole and stained-streak defects. 



A serious trouble has for many years affected the oaks of the 

 northern United States from New York to Minnesota, and has caused 

 the death of a vast amount of timber in lawns, parks, and the forest. 

 This has not been specially investigated, and therefore little or 

 nothing is known regarding the primary cause. 



THE CHESTNUT. 



The living chestnut trees throughout the Appalachian region, and 

 apparently wherever this tree grows, have a most destructive enemy 

 in the chestnut timber worm {Lymexylon serlceimi). This wood-boring 

 worm or grub hatches from eggs deposited in the slightest wound in 

 the bark and surface of the wood, and burrows deep into the heart- 

 wood, causing the wood of nearly every old tree to be perforated 

 with pin-hole defects. It attacks and breeds in dying, dead, and 

 felled trees and stumps, and will continue to work for a time in 

 square timber, telegraph poles, and heavy timber cut from infested 

 trees. It also infests red oak, and often renders worthless parts of 

 the trees which otherwise would make the highest grade timber. 

 The enormous damage to the forest resources of the United States 

 caused by this insect makes it one of primary importance to take up 

 for detailed study and for exhaustive experiments with different 

 methods of reducing the numbers of the pest and preventing losses 

 from its ravages. The giant root-borer and the two-lined chestnut 

 borer also attack chestnut, and in some sections do great harm. 



