INSECT DEl'HKDATIONS IN NOimi A.MKUICAN FORESTS. 71 



loss because of tlie impossibility of iitilizalioii ; but in some cases a 

 iri'oater or less percenta<re can be. and in some cases is. utilized witliin 

 the period in which it is of sullicicnt value to yield :i pro(itai)le icturn 

 on the cost of logging and manufacture, althoii^di its value is greatly 

 reduced. 



Redurtion in the Xdfion'.s ircdff/i. — AVhen we consider the forest 

 resources both in merchantable timber and young growth as an im- 

 portant asset of the Nation's wealth; as representing a given value 

 to the people for direct utilization: as a cover to the soil for |)rotec- 

 tion of the land from erosion: as protection of heatlwater streams and 

 of game: ami a> contributing to the ;esthetic value of health and 

 pleasure resorts, it Avt)uld be diflicult indeed to estimate the amount 

 or jH'reentage of loss of timber or the reduction in the land values, in 

 each case, chargeable to insects. It is plain, however, that in the 

 aggregate it is considerably greater than when estimated on stumpage 

 values alone. 



lii'ducfion ill rasli rcrerh/c. — AVhen we consider the problem from 

 the standpoint of direct utilization we can estimate the annual loss 

 on a basis of mill values; but here again we meet with conij)lications, 

 since much of the damaged material is left standing or is discarded 

 in the woods or at the mill without measurement. Therefore we are 

 left to judge from our observations and knowledge of the general 

 conditions as regards dead and (hunaged timl)er found in the forests 

 of the country, and the infui'ination from lumbermen in different sec- 

 tions, as to the percentage of loss from defective timl)er. On this 

 basis we can estimate that the amount of insect-killed and danuiged 

 timber left in the woods, plus the reduction in value of that utilized, 

 to be chai'ge(l to insects is not far from an equivalent of 10 per cent 

 of the value of the annual output of forest jiroducts of all kinds, in 

 the rough. The total \alue of the forest |)ro(luct- of the Tnited 

 States in r.»07 i- given as ii;i."JSO.OO().000: the losses from insect depre- 

 dations would therefore rejiresent an annual loss in a cash value of 

 more than $I0().()()().00(). (Hopkins. 1805r, V.)04a.) 



R('(h(rfioii i/i nthic of fnishrti <iik1 i(nn inrrcial inndncts. — \\ hen 

 we consider the aggregate loss to the manufacturers of tiie finished 

 products, to the trade, and to the consumer from insect injuries to 

 the wood, it is evident that it amounts to many millions of dollars in 

 addition to the estimated loss of crude products, or at least W \wv 

 cent of tlu' mill value. 



METHODS OF PREVENTION AND CONTROL. 



The residts of extensive investigations and of piaciical applications 

 of the knowledg(> gained duiMUg recent years have demonstrated that 

 some of the most destructive insect enemies of American forests and 

 of the manufactured and utilizeil products can Ix' controlled, and 



