INSECTS INJURIOUS TO RASPBERRY AND BLACKBERRY 463 



through the pith of the stems, the burrows winding from side 

 to side and frequently penetrating the side of the stem, where 

 openings are made every few inches, through which long strings 

 of excrement are cast out. By fall they have bored to the base 

 of the cane, in which they hibernate over winter. The full- 

 grow^ larva is about one inch long, of a dull yellow color, with 

 a small dark-brown head. The body is quite cylindrical and 





FIG. 331. Egg of the rasp- 

 berry cane-borer, showing 

 girdling of cane. (Photo 

 by Headlee.) 



FIG. 332. Young grubs and exit hole 

 of the raspberry cane-borer. (Photo 

 by Headlee.) 



the segments constricted as shown in Fig. 330. The pupal stage is 

 passed in the burrow during the spring. Although it has been gen- 

 erally assumed that the life cycle is passed in a single year, there is 

 some reason for believing that two years may be required. The 

 eggs are usually laid only in the young tips, but Comstock and 

 Slingerland found larvae somewhat over half grown which had made 

 burrows only two inches long in old canes in late July, and Professor 

 Webster has secured larvae over half grown in early June. Possibly, 



