ENTOMOLOGY 317 



zation, but through injuries inflicted upon trees during the flower- 

 ing, fruiting, germinating, seedling, and sapling periods of early 

 growth they prevent normal reproduction and development. 



INTERRELATIONS OP FOREST INSECTS AND FOREST FIRES. 



Losses from Forest Insects. The writer estimates that for a ten- 

 year period the average amount of timber in the forests of the entire 

 country killed and reduced in value by insects would represent an 

 average loss of $62,500,000 annually. 



Insect-Killed Timber as Fuel for Fires. It has often happened 

 that after insects have killed the timber over extensive areas the 

 standing and fallen dead trees furnished fuel for great forest fires 

 which have not only destroyed or charred the dead timber but killed 

 the living timber and reproduction and swept on into adjacent areas 

 of healthy timber. Indeed, abundant evidence has been found dur- 

 ing recent investigations to indicate that some of the vast denuded 

 areas in the Rocky Mountains and other sections of the country are 

 primarily due to widespread devastation by insects, and that subse- 

 quent fires destroyed the timber and prevented reproduction. 



It is also evident that a considerable percentage of dead timber, 

 and especially that found in coniferous forest regions, which has gen- 

 erally been believed to have been fire-killed is a result of primary 

 attack by insects. This has been demonstrated in many cases by the 

 pitch-marked galleries of the destructive barkbeetles on the surface 

 of the wood of the old dead trees which had escaped subsequent fires. 



INTERRELATION OF FOREST INSECTS AND FOREST FUNGI. 



Decay Following Injury by Insects. It is well known that the 

 burrows 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 decay are thus far 

 more rapid than would otherwise be possible. 



SUMMARY OF INSECT DAMAGES. 



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 

 by insects; and the damage from decay resulting from insect injuries 

 to the wood, have all been more or less continuous for centuries and 

 are still going on in the forest and woodland areas of this country. 



While these depredations are not always evident or important in 

 all forests or localities, yet almost every year, somewhere in the 

 forests of the country, there are widespread depredations. In every 

 forest and woodland there is an ever present but inconspicuous army 

 of insects which require the bark, wood, foliage, and seeds of the 

 various tree species for their breeding places or food. Thus, the ac- 

 cumulated but inconspicuous injuries wrought during the period re- 

 quired for the growth of a tree to commercial size go far toward re- 

 ducing the average annual increment below the point of profitable 

 investments. 



The accumulated damage to crude, finished, and utilized prod- 

 ucts reduces the profits of the manufacturer, increases the price of 



