INSECT DEPREDATIONS IN NORTH AMERICAN FORESTS. 63 



CONIFKBOUS TKEES. 



Sawyers. — One of the most striking examples of the destruction or 

 deterioration of the wood of dying and dead timber, familiar to all 

 lumbermen, is the injury to fire-killed and storm-felled pine, fir, 

 spruce, etc., caused by boring larvae Imown as "sawyers." These 

 borers hatch from eggs deposited by the adult beetles in the bark of 

 the dying trees, and after feeding on the inner bark for a time they 

 enter the solid wood and extend their large burrows deep into the 

 heartwood. Fire-killed white pine is especially liable to this injury, 

 and is often so seriously damaged within three or four months dur- 

 ing the warm season as to reduce the value of the timber 30 to 50 per 

 cent. The shortleaf, loblolly, and longleaf pines of the Southern 

 States are damaged to a somewhat less extent, but instances are 

 known in which more than one billion feet of storm-felled timber 

 within limited areas were reduced in value 25 to 35 per cent within 

 three months after the storm. (Webb, 1909.) The fire-killed and 

 insect-killed sugar pine, silver pine, and yellow pine of the western for- 

 ests are also damaged in a similar manner and the value of the prod- 

 uct greatly reduced within a few months after the trees die. The 

 aggregate losses from this secondary source in the coniferous forests 

 of the entire country contribute largely to the annual waste of mil- 

 lions of dollars' worth of forest products which otherwise might be 

 utilized. (Hopkins, 1905a, p. 385; Webb, 1909.) 



Ambrosia beetles. — Wood-boring insects of another class, known as 

 timber beetles or ambrosia beetles, cause pinhole defects, principally 

 in the sapwood, although some of them extend their burrows into the 

 heartwood. These insects make their attack in the early stage of the 

 declining or dying of the tree, or before the sapwood has materially 

 changed from the normal healthy condition, and often in such num- 

 bers as to perforate every square inch of wood. Thus the wood is 

 not only rendered defective on account of the presence of pinholes, 

 but the holes give entrance to a wood-staining fungus which causes a 

 rapid discoloration and produces still further deterioration of the 

 product. 



The sapwood of trees dying from the attack of other insects or 

 from fire, storm, or other causes is often reduced in value 50 per cent 

 or more, and in some cases the value of the heartwood is reduced in a 

 like manner from 5 to 10 per cent. (Hopkins, 1894a, 18956-, 1898&, 

 1904a, 1905a.) 



Pinhole borers in cypress. — An example of the destructive work 

 of insects which attack dying and dead trees is found in the cypress 

 in the Gulf States, where these trees are deadened by the lumbermen 

 and left standing several months, or until the timber is sufficiently 

 dry to be floated. Upon investigation it was found that trees dead- 



