THE GENUS DENDKOCTONUS. 6 
experiments with trap trees. He also spent the season of 1906 in 
the Black Hills to complete the investigations on the Black Hills 
beetle and the season of 1907 in the national forests of southern New 
Mexico and Arizona in general field work. 
Mr. Burke spent three seasons (1903, 1904, and 1905) in western 
and northwestern Washington in general forest insect investigations, 
and made observations on the Sitka spruce beetle (No. 17) and the 
Douglas fir beetle (No. 13). He also made special trips to Idaho and 
South Dakota in 1904 to determine certain facts relating to the west- 
ern pine beetle (No. 1) in Idaho and the Black Hills beetle (No. 10) in 
South Dakota. In 1906 he spent the greater part of the season in 
the Yosemite National Park, under instructions to make special 
studies of the mountain pine beetle (No. 9), the western pine beetle 
(No. 1), and the red turpentine beetle (No. 23), and in 1907 he made 
observations on the southwestern pine beetle (No. 2), the Black Hills 
beetle (No. 10), and other species in the forests of Utah. 
Mr. Fiske gave special attention to the investigation of the south- 
ern pine beetle (No. 4) and its work, experiments with trap trees, 
etc., during his general investigations of forest insects in the South 
Atlantic and Gulf States during the seasons of 1903, 1904, 1905, 
and 1906, and studied the seasonal history and habits of the black 
turpentine beetle (No. 22) and the red turpentine beetle (No. 23) — 
the latter in the mountains of North Carolina. In the fall of 1906 
he made observations on the eastern larch beetle (No. 12) and the 
redwinged pine beetle (No. 18) in northwestern Michigan, and in the 
spring of 1907 he made observations on species 4 and 22 in Texas 
and on species 2, 3, 5, 8, 13, 15, and 23 in southern New Mexico. 
This field work by the writer and his assistants has resulted in 
the accumulation of a mass of material in specimens and notes 
which has served as a basis for the preparation of this part of the 
bulletin. 
Considerable material has also been received from officials of the 
Forest Service, together with information in regard to the location and 
extent of depredations, and from owners of private forests and other 
correspondents in different sections of the country who have notified 
us of troubles affecting the timber and have responded to our requests 
for specimens and detailed information in regard to the character and 
extent of the depredations. 
DESTRUCTION CAUSED BY THE BEETLES. 
The results of our investigations have clearly shown that some of 
the species of this genus of beetles are the most destructive enemies 
of the coniferous forest trees of North America. As examples, we 
have only to cite the well-known depredations by the eastern spruce 
beetle (No. 14) in the northeastern United States and New Bruns- 
