80 THE SCOLYTID BEETLES. 



Anterior coxae approximate or subcontiguous. Abdominal sternites 

 with ends of sutures 4, 5, and 6 strongly recurved. Body cylindrical, 

 subelongate to stout, ranging in color from reddish and brown to 

 deep black. Head prominent and large, with distinct epistomal proc- 

 ess at anterior margin of front. Eyes transversely placed and 

 oblong-oval to oblong-ovate. Antennal insertion in front of ventral 

 end of eye. Pronotum with sides nearly parallel to narrowed and 

 constricted toward head, one-fourth to one-third broader than long. 

 Elytra with base elevated and rugose, remaining surface rugose, with 

 punctured striae and the declivity convex to subconvex. 



Pupa (figs. 37, 38). — The pupa is of the general size of the adult, and 

 is distinguished by its broad prominent head, and the form of the pro- 

 thorax. The sculpture and armature vary with the age of the specimen. 

 In the preimaginal stage the granules and spines become more obscure. 



Larva (text fig. 39; PL VIII).— The body of a matured larva 

 of a given species is somewhat longer than the adult or pupa, and 

 is cylindrical, deeply wrinkled, legless, and with a few long hairs on 

 each segment, becoming longer on the posterior ones. The head 

 is moderately large, shining, yellowish, and with a few hairs on the 

 scutellar lobes. Front distinct; antennae present, but obscure; eye 

 spots not present. The thoracic segments are larger and more prom- 

 inent in some species than in others. Abdominal segments 1 to 9 are 

 of about equal width and length; 10 is represented by the anal lobe. 



Egg. — Short, oval to oblong-oval, pearly white and shining, and 

 apparently without sculpture and specific characters, except in rela- 

 tive size, corresponding with the size of adult representatives of the 

 species. 



Galleries. — The primary or egg galleries are excavated in the inner 

 bark and sometimes mark or groove the wood and vary in their course 

 in the bark of the' tree from transverse and winding to longitudinal 

 and straight, and normally are of the single unbranched type. 



Distribution (PL II). — Eastern continent: Central and northern 

 Europe, from Denmark into Siberia. Western continent : Guatemala, 

 northward through the United States into Alaska and Labrador. 



Host trees.— Pinus, Picea, Pseudotsuga, Larix, and Abies, the latter 

 rarely, if at all. 



BIBLIOGRAPHY AND SYNONYMY OF GENUS. 



Erichson, 1836, pp. 52-53, original description, to include D . inicans (Kug.) (type), D. 

 terebrans (Oliv.) (cotype), Myelophilus piniperda (L.), Myelophilus minor (Hartig), and 

 Carphoborus minimus (Fab.). Eichhoff, 1864, pp. 26-27, PI. I, figs. 5, 6, 7, tibia, maxilla, 

 labium, revised description to include the single European species, D. micans (Kug.). 

 Lacordaire, 1866, pp. 360-361, revision to include D. micans (Kug.) and D. terebrans 

 (Oliv.). Zimmerman, 1868, pp. 148-149, revision to include Carphoborus bifurcus Eich. , 

 D. terebrans (Oliv.), and D. frontalis Zimm. Le Conte, 1868, pp. 172-173, revision to 

 include i). terebrans Lac, D. obesus (Mann.), D. rufipennis (Kirby), D. punctatus Lee, 



