INSECTS INJURIOUS TO RASPBERRY AND BLACKBERRY 



maggot burrows into the pith of the shoot, leaving a conspicuous 

 entrance hole, which becomes blackish. It tunnels downward, 

 making a small tortuous channel, and after boring for a few days 

 about half way down the shoot, it works its way out to just 

 beneath the bark and tunnels around the shoot, often in a spiral, 

 so as to completely girdle it, and usually eats a small hole through 

 the bark at this point. The maggot continues to feed on the 

 pith at this point so as to nearly sever the shoot, the tip of which 

 soon wilts and droops, turning a deep blue color. On blackberry 

 shoots, however, the bark is so thick that although the tip droops 



FIG. 339. Gall-like swelling on living blackberry canes caused by the rasp- 

 berry cane-maggot. (After Lawrence.) 



for a few days, it usually revives and the girdling forms a circular, 

 gall-like swelling, though even blackberries are often killed. 

 Affected shoots usually branch from below the girdled point, 

 making a bushy growth. Lawrence states that later in the 

 season lateral shoots are also attacked. He also observes that 

 maggots never develop in living . canes. The maggot continues 

 to burrow downward in the pith and becomes full grown in June, 

 When it pupates at the lower end of the burrow. The puparia 

 are to be found in the lower part of the affected stalk in June 

 and July, but the adult flies do not emerge until the next spring. 

 Control. As soon as the young tips are seen to droop they 



