20 SOME INSECTS INJURIOUS TO FORESTS. 



EARLY HISTORY OF THE SPECIES. 



LeConte, in 1876, described the species under the name Dendroc- 

 tonus hrevicomis from a single specimen collected in middle California. 

 Dietz, 1890, considered D. hrevicomis the same as the southeastern 

 species, D. frontalis Zinim. Hopkins, 1899, concluded that it was 

 distinct from D. frontalis, and therefore that the old name should be 

 retained. 



It appears that previous to 1899 nothing had been recorded in 

 regard to the habits and life history of this insect, and that, therefore, 



the earliest records were made in 1899 

 by Hopkins, who found it associated 

 with dying sugar ])ine and western yel- 

 low pine at McCloud, Cal., on April 21, 

 1899, and the next day at Grants Pass, 

 Oregon, with several hundred pine trees 

 which had evidently died from its attack. 

 On May 20, also, at Buckeye (near Spo- 

 kane), Wash., many trees were found 



Fig. 9.— The western piue-destroying i • i i • ' i i i • i 



barkbeetle ( rjendroctonus breviconm: whlch WCrC dyUlg, Or had died, as CVl- 

 Larva. Line below represents natural dcUCed by the abuudaUCe of the insects 



ong origina . and the cxteiit of their work, and ouJuue 



6, at Cedar Mountain, Idaho, Doctor Hopkins found it in the bark of 

 pine trees which had been defoliated the previous year by the cater- 

 pillars of the pine butterfly {NeopTiasia menapia Feld.). He found 

 also that this beetle was quite intimately associated with the destruc- 

 tion of a large amount of timber only partly defoliated by the cater- 

 pillars. 



Under his discussion of the ])rincipal scolytid enemies of the forests 

 ill the Northwest, Doctor Hopkins refers to this species as follows:" 



Dendroctonus hrevicomis Lee. was found to be a most destructive enemy of tlu> yellow pine 

 {Pinus pomlerom) in northern California, southern and eastern Oregon, northeastern 

 Washington, and western Iflaho. A large amount of some of the finest timber in all of 

 these localities had died witiiin the past seven or eight years, evidently as a direct result of 

 attacks by this bark beetle. It was atso found to attack and prevent the recovery of trees 

 injured by defoliating insects and other causes. Its habits and the character of its galleries 

 appear to be identical with those of Dendroctonus frontalis, which is noted for its destruction 

 of vast ciuantitios of pine and spruce t imber in West Virginia and adjoining States between 

 1890 and 1S93. It i.s killing the western yellow pine just as D. frontalis commenced to kill 

 the eastern yellow pine {Pinus echinata) before it spread to all the other pines and spruce. 

 Therefore, just as D. frontalis has proven to be the most destructive enemy of eastern 

 conifers, the western representative of this species will doubtless prove to be, untler similarly 

 favorable conditions, e(|ually as destructive to the western forests in which the conifers 

 predominate. 



Among the most important features observed regarding the habits of this beetle was the 

 fact that it is attracted to trees girdled by settlers and farmers in the process of clearing land, 

 and that in the bark of such trees it breeds and multiplies in sufficient numbers to enable it 



a Bui. 21, n. s., Div. Ent., U. S. Dept. Agric, 1899. 



