INSECT DEPKEDATIONS IN NORTH AMEEICAN FORESTS. 71 



loss because of the impossibility of utilization; but in some cases a 

 greater or less percentage can be, and in some cases is, utilized within 

 the period in which it is of sufficient value to yield a profitable return 

 on the cost of logging and manufacture, although its value is greatly 

 reduced. 



Reduction in the Nation^s wealth. — When 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 protec- 

 tion of the land from erosion ; as protection of headwater streams and 

 of game; and as contributing to the aesthetic value of health and 

 pleasure resorts, it would be difficult indeed to estimate the amount 

 or percentage 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. 



Reduction in cash revenue. — ^When we consider tike 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 complications, 

 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 damaged timber found in the forests 

 of the country, and the information from lumbermen in different sec- 

 tions, as to ihe percentage of loss from defective timber. On this 

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

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

 to be charged to insects is not far from an equivalent of 10 per cent 

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

 the rough. The total value of the forest products of the United 

 States in 1907 is given as $1,280,000,000 ; the losses from insect depre- 

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

 more than $100,000,000. (Hopkins, 1895c, 1904a.) 

 ' Reduction in value of -finished and commercial products.— When 

 we consider the aggregate loss to the manufacturers of the 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 3 per 

 cent of the mill value. 



METHODS OF PBEVENTION AND CONTROL. 



The results of extensive investigations and of practical applications 

 of the knowledge gained during recent years have demonstrated that 

 some of the most destructive insect enemies of American forests and 

 of the manufactured and utilized products can be controlled, and 



