132 



APPLIED ENTOMOLOGY 



out the borings and castings, often called "sawdust" which shows the 

 location of the burrows. After hibernating during the winter the borer 

 (Fig. 124) resumes its work the following spring, still feeding on the sap- 

 wood, and if the tree is small or if several borers are present, girdling may 

 result. After a second winter in hibernation the borer turns its atten- 

 tion to the heart-wood, boring into this, and finally as it approaches full 

 growth, working its way out toward the surface, being now about three- 

 quarters of an inch long. After a third winter of rest the larva pupates 

 in its tunnel in the spring, having previously carried the tunnel out to the 

 bark, and the adult beetle emerges after about 3 weeks. One generation 



Fig. 124. — Round-headed Apple-tree Borer {Saperda Candida Fab.) : back and side 

 views of adult beetle on bark and exit hole; full-grown larvse (borers). (After Rumsey 

 and Brookn.) 



accordingly requires 3 years in which to complete its life history but 

 this comes in parts of 4 calendar years. In the southern part of its 

 range this is shortened to 2 years and in intermediate regions some may 

 require 2, and some 3 years. 



Small trees suffer most severely by the attacks of this pest, a single 

 borer often entirely girdling a tree : larger ones are weakened and become 

 unhealthy and if strongly infested may also be killed. 



Control. — Various methods of control have some value. "Worming" 

 the trees, i.e., cutting out the young borers early in the fall is a good 

 practice if it is thoroughly done and if the cutting is carried on carefully. 

 Litter should be carefully scraped away from the trunk to expose any 

 sawdust present, and from this the burrows can be located and the dead 

 bark cut out and the borer killed, either in place under the bark or by 

 running a flexible wire into its burrow if it has gone deeper into the tree. 

 In cases where the borer cannot be reached by the wire, a little carbon 



