INSECTS AND REDUCED TIMBER SUPPLY. 3 



This happens when the fire burns the timber while it is infested, thus 

 effectually destroying the broods of the insects. It is perfectly plain 

 that the dying and dead foliage of the beetle-infested trees and the 

 dead bark on the trunks would contribute to the spreading of crown 

 fires and thus the bark on the entire infested trunks would be suffi- 

 cientlj' scorched to kill the insects. Therefore, complete fire control 

 may easily contribute to more extended depredations by insects on the 

 living timber, thus increasing, rather than diminishing, the need for 

 insect control. However, the setting of fires or permitting them to 

 burn for the purpose of combating insects should never be undertaken 

 or permitted. 



Durability of insect -hilled timher. — Some of the matured larch 

 trees which evidently died as a result of defoliation by the larch 

 worm between 1881 and 1885. and which had escaped subsequent 

 depredations by fire and wood-boring insects, were found by the 

 writer in 1908 to be standing and sound enough to be utilized for 

 railroad ties and many other purposes. Under similar conditions the 

 heartwood of red spruce and white pine in the East, of Engelmann 

 spruce in the Rocky Mountains, and of Douglas fir in the Northwest 

 coast region have been found by the writer to be sound enough for 

 profitable utilization for pulp wood, lumber, fuel, and other pur- 

 poses from twenty to thirty years after it had been killed by insects 

 or fire. Thus it is shown that timber killed b}" insects and fire would 

 be available for utilization for many years were it not for injuries 

 through the secondary attacks of wood-boring insects and the de- 

 struction of insect-killed timber by forest fires. 



IXTERRELATIOX OF FOREST INSECTS AND FOREST FUNGI. 



Decay following injury hy insects. — It is well known that the bur- 

 rows in the bark and wood of living and dead trees and in the crude 

 and finished products often contribute to the entrance of bark and 

 wood decaying fungi. Deterioration and deca}' are thus far more 

 rapid than would otherwise be possible. It is also known that trees 

 injured and dying from primary attack by parasitic fungi are attrac- 

 tive to certain insects which breed in the bark and wood of sicklj' and 

 dying trees, and that certain other complicated troubles affecting for- 

 est trees are the result of an intimate interrelation and interdepend- 

 ence of insects and fungi. There can be no doubt, however, that cer- 

 tain species and groups of both insects and fungi are independently 

 capable of attacking and killing perfectly vigorous and healthy trees. 



SUMMARY AND ESTIMATES RELATING TO CHARACTER AND EXTENT OF 



INSECT DAMAGE. 



The killing of trees by insects; the damage by them to the wood 

 of living, dying, and dead timber: the destruction of insect-killed 

 timber by subsequent forest fires; the damage to fire-killed timber 



[Cir. 129] 



