90 THE SCOLYTID BEETLES. 



collections and through correspondence, are Piedmont and Keystone, 

 Wyo.; Pokegama, Ashland, and Washington National Forest (Port- 

 land), Oregon; Columbia Falls, Lewis and Clarke National Forest, 

 Saltese, Missoula, Medicine Bow National Forest, Lolo National 

 Forest (Iron Mountain) , and Big Four, Mont. ; Coeur d'Alene National 

 Forest and Weiser National Forest, Idaho. It is represented in the 

 forest-insect collection of the Bureau of Entomology by more than 

 500 specimens, including all stages and work. 



BIBLIOGRAPHY. 



Hopkins, 18996 (under Dendroctonus n. sp.), pp. 15, 26; Hopkins, 19016, p. 67; 

 Hopkins, 1902c, p. 21; Hopkins, 1903a, pp. 59-60; Hopkins, 1904 (under " mountain 

 pine Dendroctonus"), pp. 19, 42, 45; Hopkins, 1905, p. 1; Webb,1906,p. 22; Hopkins, 

 1909, pp. 105-109. 



No. 10. THE BLACK HILLS BEETLE. 



(Dendroctonus ponderosse Hopk. Figs. 51-59.) 



The Black Hills beetle is a stout, black, cylindrical barkbeetle, 

 4 to 7 mm. in length, with head broad and without frontal groove, 

 but with slight longitudinal impression above or behind the middle; 

 the prothorax short, broad, and punctured, the sides narrowed and 

 slightly constricted toward the head; the elytra with moderately 

 coarse rugosities between the rows of punctures, which are usually 

 distinct on the sides, and the declivity, which bears a few long hairs, 

 slightly impressed each side of the middle line, the impressed striae 

 narrow, and the interspaces broad and roughened with sparsely 

 placed, coarse granules. (See fig. 51.) The adult beetles attack 

 living and sometimes injured and felled, yellow pine, lodgepole pine, 

 limber pine, Mexican white pine, white spruce, and Engelmann 

 spruce from the Black Hills, South Dakota, to southern Arizona, 

 and westward into Utah, and are very destructive. The parent 

 beetles excavate long, nearly straight, longitudinal egg galleries 

 (fig. 52) through the inner living bark and groove the surface 

 of the wood on the main trunk (figs. 53, 54). The eggs are placed 

 at quite regular intervals, or more often arranged in groups of four 

 or five along the sides. The short, broad larval mines and trans- 

 formation cells are exposed in the inner bark and mark the surface of 

 the wood; the short, whitish, grublike larvae (fig. 51) transform to 

 pupae (fig. 51), usually exposed in the inner bark, and the broods 

 usually work independently of other species and occupy exclusively 

 the greater part of the bark on the main trunks of the trees. The 

 attack causes pitch tubes (figs. 55, 56) on the trunk of the infested 

 trees in the summer and fall, and the leaves fade and turn yellow 

 and red the following season during the period from May to August. 



