21 



that measures may be taken, by introducing or encouraging its natural 

 enemies or by girdled trap trees, to prevent its multiplication and 

 future destructive invasions. 



Recent investigations in California, Oregon, Washington, and Idaho, 

 by the writer, under the auspices of the Division of Entomology, 

 United States Department of Agriculture," revealed the fact that the 

 western 3'ellow pine, Jeti'ery pine, sugar pine, mountain or silver pine, 

 shore pine, and lodgepole pine has each its peculiar insect enemies, 

 some of which are very destructive. Many of the finest examples of 

 yellow pine were found to be dead or dying from the ravages of the 

 western pine destroyer {DeiidrodonnH Tyrevleoniis Lee.) from northern 

 California to northern and western Idaho. The mountain pine in 

 northern Idaho and western Montana suffered severely from the ravages 

 of the mountain pine destroyer {Dendroetonus numtlcola Hopk. MSS.). 

 The 3^ellow pine has also suffered greatly in Idaho and eastern Wash- 

 ington from the larvfe of a white butterfly {Neoplmma ■menapia Feld.), 

 which defoliates the trees over large areas. 



Recent (September, 1901) investigations in the Black Hills forest 

 reservation revealed the fact that a vast amount of the best timber 

 on man}' thousands of acres has died within the past six or seven 

 years and is yet dying from the ravages of the pine-destroying beetle 

 of the Black Hills {I)e))d/'<>ct(}n.i(.s jHniderosa' Hopk. MSS.). 



It is also reported that the pine is dying in other sections of the 

 Rocky Mountain region, from Idaho to Arizona, evidently because of 

 the ravages of bark lieetles. 



It is evident from observations made in the Black Hills reservation 

 and in the forests of Idaho, W^ashington, and Oregon that the death of 

 the pine timber over many extensive areas, supposed to have resulted 

 from fires, was primaril}^ due to the work of tree-destroying insects. 

 Even the meager knowledge we have been al>]e to acquire during 

 hurried investigations in the forest and from ol)servations along the 

 routes of travel through the Rocky Mountain region, the Pacific slope, 

 and the Northwest makes it very plain that the destruction of pine 

 timber, due primarily to the ravages of insects, has been progressing 

 during the past half century at a I'ate far beyond that conceived by 

 the casual observer or even by those who are making a study of the 

 forests and forest conditions of those regions. Indeed, the extensive 

 ravages of insects on the pines of the United States furnish a problem 

 whose great importance and magnitude would justify the expenditure of 

 large sums of money for detailed investigation by specially trained forest 

 entomologists. 



THE SPRUCES. 



The spruces of this country are also inhabited by many hundreds 

 of species of insects. 



«Bul. No. 21 (11. s.), Division of Entomology, U. S. Department of Agriculture. 



