INSECT DEPREDATIONS IN NORTH AMERICAN FORESTS. 63 



CONIFEROUS TBEES. 



Sfru'i/ff'ft. — Olio of tlio most strikiiij; examples of tlio dostructioii or 

 (letoi-ioratioii of tlio wood of dyinj^ and (load timber, familiar to all 

 liimi)onii('ii. is (he injury to fire-killed and storm-felled pine, fir, 

 spruce, eto., caused by borin<^ larva' known as '' sawyers." These 

 borers hatch from eggs deposited by the adult beetles in the l)ark of 

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

 enter the solid wood and extend their large l)urrows deep into the 

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

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

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

 cent. The short leaf, 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 

 throe months after the storm. (AYebb, 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, 1905f/. p. 385; Webb. 1909.) 



Amhvosia hectles. — Wood-boring insects of another class, known as 

 timber beetles or ambrosia beetles, cause pinhole defects, principally 

 in the sai)wood, although some of them extend their l)urrows 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 jiroducos 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. 1894^/, 1895r, 18986, 

 1904//, 1905//.) 



Pinhole borers in cj/press. — An oxauiplo of the dostruct i\"e work 

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

 in the (lulf States, where these trees are deadened i)y the lumbermen 

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

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



