INSECT DEPREDATIONS IN NOETH AMERICAN FORESTS. 67 



Construction timbers and other woodworlc in new and old build- 

 ings are often so seriously damaged by powder-post beetles, white 

 ants, and other wood-boring insects that the affected material has 

 to be removed and replaced by new, or the entire structure torn down 

 and rebuilt. (Hopkins, 1905a.) 



Construction timbers in bridges and like structures, railroad ties, 

 telephone and telegraph poles, mine props, fence posts, etc., are 

 sometimes seriously injured by wood-boring larva;, termites, black 

 ants, carpenter bees, and powder-post beetles, and sometimes reduced 

 in eificiency from 10 to 100 per cent. 



INSECTS IX THEIR RELATION TO THE REDUCTION OF FUTURE SUPPLIES OF 



TIMBER. 



Insects not only reduce future supplies by killing the mature 

 trees and destroying the wood of timber that is inaccessible for 

 utilization, but through injuries inflicted upon trees during the 

 flowering, fruiting, germinating, seedling, and sapling periods of 

 early growth they prevent normal reproduction and development. 

 (Hopkins, IQOia, 1906e.) 



INTERRELATIONS OF FOREST INSECTS AND FOREST FIRES. 



Investigations conducted by the writer and assistants in all sec- 

 tions of the' country during the past ten years indicate to them 

 quite conclusively that the average percentage of loss of merchant- 

 able 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. (Hopkins, 1906a, pp. 4-5, 19086; p. 345, 1909&, 

 pp. 5, 24 ; Forbes, 1909, pp. 51-52.) 



Losses from forest insects. — The writer estimates (p. 70) that for 

 a ten-year period the average amount of timber in the forests of the 

 entirecountry killed and reduced in value by insects would represent 

 an average loss of $62,500,000 annually." 



It has been estimated (Hopkins, 19056, p. 5; 1908a, p. 162) that 

 the Black Hills beetle killed approximately 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 depredations by a single species of 

 barkbeetle in a single national forest." (See also p. 70.) 



Prof. Lawrence Bruner, state entomologist of Nebraska, at a meet- 

 ing of the Am erican Association of Economic Entomologists, held at 



"Losses from forest flres.-lt has been estimated that " on the average, since 

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



1909, p. 3.) ^ ,, , 



»It has been estimated that the losses of timber from forest flres on all of 

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

 only $165,062 annually. (Cleveland, T., jr., 1908, p. 541.) 



