14 



POPULAK PAPERS ON ENTOMOLOGY. 



THE RASPBERRY SAW-FLY (Selandria rubi Harris). 



BY WM. SAUNDERS, LONDON, ONT. 



This destructive insect appeared in great force during the past season in many parts 

 of our Province, doing much damage to the foliage of raspberry plants. Although in 

 form and habits the larva of this insect much resembles the currant worm, it is not 

 nearly so well known, nor is it usually so promptly recognized. There are several 

 reasons for this. The raspberrry saw-fly does not appear in such flocks as the currant 

 worm, because the eggs are laid singly and not often near together ; nor is the larva 

 easily detected owing to the fact that in colour it so exactly resembles that of the leaf on 

 which it feeds. 



The eggs are oval, yellowish white and semi-transparent, and are buried beneath the 

 skin of the raspberry leaf near the ribs and'veins, placed there by means of the saw-like 

 apparatus situated at the extremity of the body of the female, by which slits are cut in 

 the tissues of the leaf. The skin covering the egg is so transparent that the movements of 

 the enclosed larva may be observed several days before it is hatched. It escapes through 

 an irregular hole made on one side of the egg. 



The newly-hatched larva is about one-twelfth of an inch long, with a greenish-white 

 head having a black eye-like spot on each side, The body is nearly white and semi- 

 parent and thickly covered with transverse rows of white spines. As it grows older 

 the colour changes to green, and when full grown it measures about three-quarters of an inch 

 in length and appears as shown on the leaf in figure 1. The body then is of a dark green 

 colour, and is thickly set with pale green branching spines. In figure 1 some of the 

 segments of the body are represented, magnified, showing the arrangement of the spines 

 on the back and side. The head is small, of a pale yellowish green colour, with a dark 



brown dot on each side. The eggs are laid near the 

 tips of the growing canes, and the larvae are usually 

 found feeding on the upper surface of the young leaves. 

 When full grown, which is generally from the middle 

 to the end of June, the larva leaves the bush and de- 

 scends to the ground, where it penetrates beneath the 

 surface and constructs a small oval earthy cocoon, 

 mixed with silky and glutinous material. The larva 

 remains unchanged within the cocoon for a consider- 

 LfgjR *^y able period but finally transforms to a chrysalis from 



'" v which the perfect insect is produced the following 



season. 



This is a four-winged fly, shown magnified in 

 figure 2, which appears from about the tenth of May 

 to the beginning of June, or soon after the young leaves 

 of the raspberry begin to appear. The wings, which are transparent with a glossy 

 surface and metallic hue, measure when expanded about half an inch across; the veins 

 are black and there is a streak of black across the front margin, extending more than 





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Fn;. 1. 



