512 ECONOMIC ZOOLOGY AND ENTOMOLOGY 



yellow stripes across the thorax and wing covers. Repeated 

 attacks may kill the trees, and it is the safest policy to cut out 

 and burn all infested trees in order that they may not serve as 

 breeding places for new generations that will later attack sound 

 trees. 



The Carpenter -worm (Prionoxystus robinice). The larvae of 

 a large, grayish, night-flying moth have come to be known as 

 "carpenter worms" because they work so readily in the wood 



FIG. 243. Elm leaves curled by elm aphis, Schizoneura ulmi. (Reduced.) 



of many of our shade trees. For some months after hatching 

 the larvae burrow in the sapwood, and when several of them are 

 at work in one tree they may kill it by girdling. As they 

 grow older the larvae bore into the solid wood, making large 

 burrows in which they live for a year or two longer before 

 they change to pupae. As these borers are more apt to be 

 found in trees that have the bark rough or scarred or wounded, 

 care should be taken to keep the bark uninjured. The larvae 



