2 INSECTS WHICH KILL FOREST TREES. 



this barkbeetle has been more or less active in the Southern States 

 from Virginia to Texas, and in some localities and during certain 

 years it has killed a large amount of timber. Records of extensive 

 destruction of timber in the Southern States are found dating back 

 to the early part of the nineteenth century. This species may be 

 considered one of the most dangerous insect enemies of southeastern 

 conifers and, therefore, a constant menace to the pine forests of the 

 Southern States. 



The eastern spruce heetle. — During the period between 1818 and 

 1900 there were several outbreaks of the eastern spruce beetle in the 

 spruce forests of New York, New England, and southeastern Canada. 

 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 man}^ 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 heetle. — The Engelmann spruce beetle, 

 with habits similar to the eastern spruce beetle, has from time to time 

 during the past fifty j'ears caused widespread devastations in the 

 Rocky Mountain region to forests of Engelmann spruce, in some sec- 

 tions killing from 75 to 90 per cent of the timber of merchantable size. 



The Black Hills heetle. — 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, Avhere during the past 

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

 forest has been killed by the Black Hills beetle. It is estimated that 

 more than a billion feet of timber have been destroj'ed 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 Rocky 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. 



The mountain pine heetle and the western pine heetle. — 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 and the weste*rn pine beetle, and, as a direct consequence, 

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

 ern 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. 

 Through many sections of 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. 



[Cir. 125] 



