368 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1941 



Experiment Station. In an area of over 75,000 square miles a large 

 percentage of the pine and spruce was killed. A few years later, 

 around 1900, the eastern spruce beetle {D. piceaperda Hopk.) was 

 responsible for extensive depredations in the forests of Maine. Here 

 again Hopkins (1901), collaborating with Austin Gary (1900) of 

 the Forest Service, made a study of the conditions. Just prior to and 

 during the Maine outbreak, 1895-1905, the Black Hills beetle {D. 

 ponderosae Hopk.), which was not laiown to science at this time, 

 destroyed more than a billion feet of timber in the Black Hills 

 National Forest in South Dakota (Hopkins, 1902). This outbreak 

 crystallized the realization that more technical knowledge was needed 

 concerning these destructive bark beetles, and resulted in a small 

 appropriation of $5,800 for the Bureau of Entomology for forest 

 insect investigations and an allotment of $2,700 in 1906 for the control 

 of this outbreak. 



WESTERN BARK BEETLES 



Recent outbreaks of bark beetles have been even more widespread 

 and spectacular. To quote from a recent unpublished report of 

 F. P. Keen, in charge of our Portland, Oreg., laboratory : 



The ponderosa pine forests of the Pacific States have suffered a continuous 

 and serious drain from western pine beetle attack for the past 20 years or 

 more, while in the Rocliy Mountain region sporadic outbreaks of the Black 

 Hills beetle have taken a heavy toll of this species of pine in many local 

 areas. Most spectacular of all has been the destruction of lodgepole pine for- 

 ests in the northern Rocky Mountain region and local areas in the Cascades 

 from uncontrolled outbreaks of the mountain pine beetle. Sugar pine [pi. 2, 

 fig. 1; pi. 4], western white pine, and other si)ecies of pine are from time to 

 time also seriously damaged by pine beetles. 



Records from annual surveys in the Klamath region of southern Oregon 

 and northeastern California show that on an area of 4,300,000 acres 5,273,000,000 

 board feet of ponderosa pine timber, representing 17.5 percent of the stand, 

 was killed during the 20-year period 1921 to 1940 inclusive. This, of course, is 

 not all a direct loss, as some of it was offset by growth. In portions of this 

 region from 60 to 90 percent of the stand was destroyed. The western pine 

 beetle {Dendroctonus hrevicomis Lee.) was a major factor in this mortality. 

 [PI. 2, fig. 2.] 



An outbreak of the Black Hills beetle (Dendroctonus ponderosae Sopk.) on 

 the Kaibab Forest of northern Arizona between 1917 and 1926 is a good example 

 of the potential destructiveness of this species. During this outbreak it was 

 estimated that 300,000,000 board feet of timber, representing 12 percent of 

 the stand, was killed. In the heaviest centers of infestation, on areas 1,000 acres 

 or more in extent, all trees down to those 2 inches in diameter were killed. 

 Large openings in the forest, with remains of fallen snags showing the markings 

 of beetle galleries, attest the fact that similar outbreaks have occurred in the 

 past and may occur from time to time In the future. 



Outbreaks of the mountain pine beetle (Dendroctonus monticolae Hopk.) in 

 lodgepole pine forests as described by Evenden [1940] are the most devastating 



