INSECTS INJURIOUS TO RASPBERRY AND BLACKBERRY 413 



Injury has been observed in New York, Canada, Michigan, 

 Pennsylvania, and recently it has become a serious pest in Wash- 

 ington, so that it is undoubtedly much more widely distributed 

 than the records indicate. The parent fly, shown in Fig. 347, is 

 grayish-black, much resembling the house-fly, but slightly smaller. 

 Life History. The flies appear in April and deposit their eggs 

 as soon as the shoots are well above ground, continuing until early 

 June. The white egg (Fig. 

 347, c) is elongate, about one- 

 fifteenth inch long, and is laid 

 in the axil of a young leaf at 

 the tip of a shoot (Fig. 347, d). 

 The egg hatches in a few days, 

 and the little maggot burrows 

 into the pith of the shoot, leav- 

 ing a conspicuous entrance 

 hole, which becomes blackish. 

 It tunnels downward, making 

 a small tortuous channel, and 



after boring for a few days 



FIG. 348. Gall-like swelling one living 



about half way down the shoot, blackberry canes caused by the rasp- 

 it works its way out to just berr y cane-maggot. (After Lawrence.) 



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

 so as to girdle it completely, 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 nearly to 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 

 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 



