70 SOME IISrSECTS INJURIOUS TO FOEESTS. 



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 incon- 

 spicuous army of insects which require the bark, wood, foliage, and 

 seeds of the various tree species for their breeding places or food. 

 Thus, the accumulated but inconspicuous injuries wrought during 

 the period required for the growth of a tree to commercial size go 

 far toward reducing the average annual increment below the point 

 of profitable investments. 



The accumulated damage to crude, finished, and utilized products 

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

 higher grades to the consumer, and results in an increased drain on 

 the natural resources. 



In any attempt to estimate in dollars or feet, hoard measure^ the 

 extent of losses or waste of timber supplies caused by insects there 

 are many conflicting factors which contribute to the difficulty of ar- 

 riving at accurate conclusions. The published information concern- 

 ing the amount in board feet of standing timber in the country is 

 admittedly only an estimate, as are also the published data relating 

 to average stumpage value. The published statistics relating to the 

 amount and value of forest products are of course more accurate, but 

 until more complete data can be furnished by the forest experts on 

 the various complicated phases of forest statistics, any figures given 

 by the forest entomologist relating to the value of timber and com- 

 mercial products destroyed or reduced in value by insects must be 

 considered on the same basis as the other estimates, and as the best 

 that can be presented on available evidence. 



Standing tirriber killed and damaged hy insects. — ^When we con- 

 sider the amount of standing merchantable timber killed by insects 

 and the amount of standing timber, living, dying, and dead, which 

 has been reduced in quantity and value through their agency during 

 a ten-year period, we would estimate that such timber represents an 

 equivalent of more than 10 per cent of the quantity and stumpage 

 value of the total stand of merchantable timber in the United States 

 at any given time."* A certain percentage of such timber is a total 



" The estimate of the area and stand of the present forests of the United 

 States, as given in Circular 166 of the Forest Service, page 6, is two trillion 

 five hundred billion feet (2,500,000,000,000) board measure. The average 

 stumpage value has been given as .$2.50 per one thousand feet b. m., maliing a 

 total value of the standing merchantable timber of $6,250,000,000. Ten per 

 cent of this amount would be .$625,000,000, as the amount to be charged to in- 

 sects for a 10-year period, or an average of $62,500,000 annually. As an ex- 

 ample, it has been estimated that over 1,000,000,000 feet b. m. of timber was 

 killed by the Black Hills beetle in the Black Hills National Forest within a 

 period of ten years. This, at $2.50 per one thousand feet stumpage, would be 

 an average of $250,000 annually in a single forest of 1,294,440 acres. 



