THE GENUS DENDROCTONUS. 



101 



Forest, Colorado; Fredonia, Ariz.; Kanab, Escalante, Provo, Aqua- 

 rius National Forest, Utah, and at Keystone, Wyo. It is repre- 

 sented in the forest-insect collection of the Bureau of Entomology by 

 more than 10,000 specimens. 



BIBLIOGRAPHY. 



Hopkins, 19026, p. 10; Hopkins, 1902c, p. 21; Hopkins, 1903a, p. 59; Hopkins, 19036, 

 pp. 275-282; Hopkins, 1904, pp. 41, 43, 44; Hopkins, 1905, pp. 1-24; Hopkins, 1906 ; 

 p. 4; Hopkins, 1907, p. 162; Hopkins, 1909, pp. 109-114. 



No. 11. THE JEFFREY PINE BEETLE. 



(Dendroctonus jeff'reyi Hopk. Figs. 60, 61.) 



The Jeffrey pine beetle is a stout, 

 black, cylindrical barkbeetle 6 to 

 8 mm. in length; the head broad, 

 convex, with faint grooves behind 

 and usually in front of the mid- 

 dle; the prothorax stout, broad, 

 shining, the sides suddenly nar- 

 rowed toward the head and the 

 punctures fine; the elytra with mod- 

 erately coarse rugosities between 

 the rows of punctures, which are 

 distinct on sides, the declivity with 

 a few long hairs, the striae on 

 grooves narrow, and the interven- 

 ing spaces broad and roughened with 

 coarse granules. (See fig. 60.) It 

 attacks living and dying Jeffrey pine 

 and yellow pine, in the Yosemite 

 National Park and San Bernardino 

 County, California. It excavates 

 long, nearly straight, egg galleries 

 through the inner bark, and grooves 

 the surface of the wood; the larval mines extend from the sides, 

 exposed in the inner bark. The stout, whitish, grublike larvae trans- 

 form to pupae and adults in cells at the end of the burrows, and the 

 broods occupy the bark on the main trunk. The infested trees are 

 indicated by pitch tubes on the trunks in the summer and fall, and 

 during the following May to August by the fading and yellowish 

 foliage. 



Fig. 60.— The Jeffrey pine beetle (Dendroctonus 

 jeffreyi): Adult. Greatly enlarged. (Au- 

 thor's illustration.) 



