222 THE STUDY OF INSECTS. 



the burrow made by the larva. When ready to change to 

 an adult, the pupa works its way partially out from its bur- 

 row. This is accomplished by means of backward-project- 

 ing, saw-like teeth, there being one or two rows of these on 

 each abdominal segment. After the moths have emerged 

 the empty pupa-skins can be found projecting from the 

 deserted burrows. 



The Carpenter-moths are of medium or large size. Our 

 more common species are of a pepper-and-salt color, due to 

 strongly contrasting dark and light scales. The antennae 

 are usually pectinate in both sexes, but in some species those 

 of the female are simple ; the ocelli are wanting ; and the 

 mouth-parts are obsolete. 



The structure of the wings is shown in Figure 255 

 There are two anal veins in the fore wing, and three in the 

 hind wings. The base of vein V is preserved, and is forked 

 within the discal cell. In the fore wings, the branches of 

 vein III anastomose so as to form an accessory cell. The 

 frenulum is rudimentary in most of our genera (Fig. 255), 

 but is strongly developed in others. 



Our most common species is the Locust-tree Carpenter- 



FIG. z^.Prionoxystus robinia. 



moth, Prionoxystus robinia (Pri-on-ox-ys'tus ro-bin'i-ae). 

 Figure 256 represents the female natural size. The male is 

 but little more than half as large as the female. It is much 



