INSECT DEPREDATIONS IN NORTH AMERICAN FORESTS. 59 



This species caused the death of a very large percentage of the ma- 

 ture spruce over an area of thousands of square miles. In the aggre- 

 gate many billions of feet of the best timber were destroyed. The 

 larger areas of this dead timber furnished fuel for devastating for- 

 est fires, with the result that in most cases there was a total loss. 



The Engelmann spruce beetle. — Another barkbeetle {Dendrocto- 

 nus engelmanni Hopk.), similar in habits to piceaperda, has from 

 time to time during the past fifty years caused widespread devasta- 

 tions in the Rocky Mountains region to forests of Engelmann spruce, 

 in some sections killing from 75 to 90 per cent of the timber of mer- 

 chantable size. (Hopkins, 1908a, p. 161 ; 19096, pp. 12&-132.) 



The Black Hills beetle. — One of the most striking examples of the 

 destructive powers of an insect enemy of forest trees is found in the 

 Black Hills National Forest of South Dakota, where during the past 

 ten years a large percentage of the merchantable timber of the entire 

 forest has been killed by the Black Hills beetle (Dendroctonus pon- 

 derosoe Hopk.). It is estimated that more than a biUion feet of 

 timber have been destroyed in this forest as the direct result of the 

 work of this beetle. This destructive enemy of the western pine is 

 distributed throughout the forests of the middle and southern Eocky 

 Mountains region, where, within recent years, it has been found that 

 in areas of greater or less extent from 10 to 80 per cent of the trees 

 have been killed by it. (Hopkins, 1902a, 1903&, 1905&, 1908a, and 

 19096, pp. 90-101.) 



The mountain pine beetle and the tvestern pine beetle. — ^The sugar 

 pine, silver pine, western yellow pine, and lodgepole pine of the 

 region north of Colorado and Utah, westward to the Cascades, and 

 southward through the Sierra Nevadas are attacked by the mountain 

 pine beetle {Dendroctonus monticolce Hopk.) and the western pine 

 beetle {Dendroctonus brevicomis Lee), and, as a direct consequence, 

 billions of feet of the timber have died. In one locality in north- 

 eastern Oregon it is estimated that 90 to 95 per cent of the timber in a 

 dense stand of lodgepole pine covering an area of 100,000 acres has 

 been killed within the past three years by the mountain pine beetle. 

 Throughout the sugar-pine districts of Oregon and California, as the 

 result of attacks by this same destructive barkbeetle, a considerable 

 percentage of the largest and best trees is dead. (Webb, 1906 ; Hop- 

 kins, 1908a, 1909&, pp. 80-90.) 



The Douglas fir beetle.— The Douglas fir throughout the region 

 of the Eocky Mountains from southern New Mexico to British Co- 

 lumbia has suffered severely from the ravages of the Douglas fir 

 beetle {Dendroctonus pseudotsugce Hopk.), with the result that a 

 large percentage of dead timber is found, much of which will be a 

 total loss. (Hopkins, 19096, pp. 106-114.) 



Three other species of beetles, having destructive habits similar 

 to those above mentioned, depredate on the. pines of New Mexico 



