174 MISC. PUBLICATION 273, U.S. DEPT. OF AGRICULTURE 



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Figure 80. — The roundheaded fir borer ( Tetropium abietis) : A, Adult, X 3; 

 B, detail of adult head, side view, X 4; C, larva, X 2; D, dorsal view of 

 last abdominal segments of larvae, X 2; E, pupa, X 2; F, cocoon of para- 

 sitized larva in pupal cell, natural size; G, ichneumon parasite, natural 

 size. (Drawing by Edmonston.) 



later stages of larval development they may enter the wood to 

 pupate, or they may pupate in the bark. 



The ponderosa pine bark borer (Acanthocinus spectabilis Lee.) 

 (fig. 81), in the larval stage is the large white grub so commonly 

 found in ponderosa pines killed by the western pine beetle, and is 

 sometimes mistakenly supposed to be the insect responsible for the 

 death of the trees. It also occurs in other pines. These insects are 

 more beneficial than otherwise, in that they rob the bark beetles 

 of their food. The adults are large, speckled, gray beetles with ex- 

 tremely long feelers, and the female has a long, hornlike ovipositor 

 extending from the end of the abdomen. 



Acanthocinus obliqmis Lee. is a smaller gray species with wavy 

 markings on the wing covers. Its larvae feed under the drier bark 

 at the tops of pines and spruces throughout the Western States. 



The poplar borer (Saperda calcarata Say) (69), a reddish-brown 

 beetle with dense gray pubescence, breeds in felled and weakened 



