PINE BARK-BEETLES. 



721 



Occurring under the bark of the piue in Alaska, Canada, and Virginia, a bark-borer 

 closely allied to Xylehorus, witri the prothoras strongly punctured, not roughened in 

 front ; length, AA""^ (0.17 inch). (Le Conte.) 



50. The boring dendroctonus. 



Dendroctovus terebrans (Olivier). 



Order Coleoptera ; family Scolytid^. 



Perforating larger holes in the bark than any of the preceding bark-beetles, and 

 mining curved galleries in every direction in the inner layers of the bark, and slightly 

 grooving the outer surface of the wood, a cylindrical light chestnut red or yellowish 

 fox-colored beetle 0.23 to 0.33 long, bluntly rounded at each end, thinly clothed with 

 yellowish hairs, its thorax narrowed anteriorly and with coarsish shallow punctures 

 and a slightly raised line along the middle, at least on the posterior half, a faint black- 

 ish line along the middle of the upper part of the head, and its wing-covers rough, 

 with rather shallow furrows, in which are coarse indistinct punctures. Appearing 

 abroad early in May, numerous in pine forests, and in lum- 

 ber and mill yards. Its larvje common under the thick 

 bark of pine logs and stumps ; a yellowish-white footless 

 grub thinly clothed with yellowish hairs, and divided into 

 thirteen segments, its head polished and horny, of a tawny 

 yellow color, with the mouth black, and the neck having 

 on each side, above, a large polished spot tinged with 

 tawny yellow. (Harris's Treatise, page 75.) 



With this account, taken from Harris, our 

 own observations .igree. The cells are smaller 

 than those of Pissodes strobi. We have found 

 the larvae and immature beetles in abundance 

 in Brunswick, Me., in the middle of March. The 

 burrrows are very irregular, winding about under 

 the bark, while the very irregular cells are from 

 half an inch to an inch long, and nearly a quarter 

 of an inch wide, and surrounded with the white woody chips made by the 

 larva before pupating. 



Le Conte states that in this species the prothorax is very densely and 

 coarsely punctured ; the hairs of the elytra not being very long. It 

 has been collected in Canada, Georgia, Oregon, and California, as well 

 as the pine woods of New England and northern New York. " The 

 specimens from the Pacific slope are larger, and the punctures of the 

 prothorax are rather smaller. and more dense, but these differences do 

 not seem to me worthy of specific distinction. Some specimens from 

 New Hampshire and Canada have the prothorax more sparsely punct- 

 ured, almost as in the next species (i>. similis), from which they are 

 only distinguished by the shorter hairs of the elytra. Length 5.2 to 

 S^^ (.2 to 3.2 inch). 



51. The red polygraphus. • 



Polygraphus rufipennis Kirby. 



Boring irregular galleries under the bark of the pitch pine, somewhat like those of 

 Tomicus ^iwi, but much lees regular and twice as wide and deep, a reddish browu 

 bark-borer. 



5 ENT 46 



Fig. 250. — Dendroctonus tere- 

 brans. — Smith and Miss 

 Sullivan del. 



