Circular No. 129. Issued November 25, 1910. 



United States Department of Agriculture, 



BUREAU OF ENTOMOLOGY. 

 L. O. HOWARD, Entomologist and Chief of Bureau. 



INSECTS IN THEIR RELATION TO THE REDUCTION OF 

 FUTURE SUPPLIES OF TIMBER, AND GENERAL PRIN- 

 CIPLES OF CONTROL.'^ 



By A. D. Hopkins, 

 In Charge of Forest Inseet Investigations. 



Insects not only reduce future supplies of timber by killing the ma- 

 ture trees and destroying the wood of timber that is inaccessible for 

 utilization, but through injuries inflicted upon trees during the flow- 

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

 growth they prevent normal reproduction and development. 



INTERRELATIONS OF FOREST INSECTS AND FOREST FIRES. 



Investigations conducted by the writer and assistants in all sections 

 of the country during the past ten years indicate to them quite con- 

 clusivel}^ that the average percentage of loss of merchantable timber 

 in the forests of the entire country to be charged to insects during a 

 five or ten year period is infinitely greater than most people realize. 



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 $02,500,000 annually.^ 



It has been estimated that the Black Hills beetle killed approxi- 

 mately 1,000,000,000 feet B. M. of timber during a period of ten years, 

 which at $2.50 per thousand would amount to an average of $250,000 

 annually. This is merely one example of very destructive depreda- 

 tions by a single species of barkbeetle in a single National Forest.*^ 



<* Revised extracts from Bulletin No. 58, Part V, Bureau of Entomology, 

 United States Department of Agricultui'e. 



* Losses from forest fires. — It has been estimated that " on the average, since 

 1870, forest fires have yearly cost $50,000,000 in timber." (Cleveland, T., jr.. 

 Circular 1G7, Forest Service, United States Department of Agriculture, p. 3.) 



<^ It has been estimated that the losses of timber from forest fires on all of 

 the National Forests of the United States from 1905 to 1908, inclusive, average 

 only $105,002 annually. (Cleveland, T., jr.. Yearbook United States Department 

 of Agriculture for 1908, p. 541.) 



