INSECTS AFFECTING PARK AND WOODLAND TREES 



387 



Description. The beetle varies from a light brown to a black. It is 

 quite small, being al^put 3 32 inch long and with a rather stout form. The 

 head is thickly and finely punctured and nearly concealed by the overhang- 

 ing prothorax. The mouth parts are tipped with black and the concolorous, 

 coarsely granulated eyes are divided, the two portions being connected by 

 a smooth strip of chitin. The prothorax is much narrowed in front, thickly 

 and finely punctured and the wing covers or elytra are rough, finely 

 punctured and almost striate. The structure of the antennae is shown on 

 plate 67, figure 8, and that of the tibia in figure 85^ . 



The white pupa is about the same size as the beetle, rather stout 

 and with a tapering abdomen terminated by a pair of fleshy spinelike 

 processes. 



The brown headed, white grubs or larvae are about ^ inch long 

 when full grown. The mouth parts and adjacent sutures are a dark brown 

 and the body is usually somewhat curved. 



Life history. The life history of this borer in West Virginia has been 



given by Dr Hopkins as follows : 



The adults emerge in May or June and are attracted to stumps, trunks 

 and tops of recently fallen trees and those that are weakened by the attack 

 of insects, such as the destructive pine bark beetle, Dendroctonus 

 frontalis Zimm., or diseases of any kinds. The beetles commence to 

 excavate entrance galleries through the outer bark, and their presence is 

 indicated by the fine brownish borings in the crevices of the bark. This 

 entrance is extended to the outer surface of the inner soft bark where the 



central chamber is excavated. In the meantime, the 

 female, which appears to do the greater part of the 

 work, is joined by a male who stations himself in the 

 outer gallery to keep out enemies and objectionable 

 visitors and to render assistance in expelling the bor- 

 ings. The female excavates a gallery from one edge 

 of the central chamber through the inner bark of the 

 wood and then in the inner layer of the bark, usually 

 at right angles to the bark fibers, and for a distance 

 Fig. 86 Polygraph us rufi- of one or two inches. Small notches are made along 

 m^I^J^S^^?' the sides of the brood gallery, in each of which pearly 



white eggs are deposited. One to three other females 

 are admitted to this central chamber by the male and from it extend similar 



