CHERRIES ENEMIES. 



149 



Cui'tis). The damage done by the larva of this sawfly to the leaves of the cherry and 

 other fruit trees is sometimes considerable, the larva being repulsive in appearance. 

 The slug- worms (larvse) are sluggish in their habits, but very voracious, feeding on the 

 upper surface of the leaves, consuming the soft parts, leaving only the lower skin of 

 the leaf, veins, and midrib, the whole leaf turning brown and ultimately falling. The 

 devastating nature of slug-worms is shown in the engraving. 



The sawfly is one-fifth of nn inch long, black, shining, and hairy, wings transparent, 

 with a smoky band across the middle. The 

 insects appear in July, and sham death when 

 alarmed. The female deposits eggs on the 

 upper surface of the leaves in a slit made by 

 her ovipositor, each separately; these are 

 oval, and hatch in a few days, the egg having 

 an elastic shell, increasing in size before 

 hatching. The larvee are at first very small, 

 and soon become coated with a thick slime 

 of blackish brown, which emits an unpleasant 

 smell. In a month or five weeks the larva 

 attains full size, about half an inch long, up 

 to which it is greenish yellow with a black 

 head ; behind that is a sort of hump, and 

 from the head, where it is largest, tapers 

 sharply to the tail. The slug- worm has ten 

 pairs of feet, and glides slowly over the 



and expanse of \vuigs, lines on left. 2, Larva (slug- 



feeding with the tail a little elevated. worm) slightly enlarged. 3, Cocoon. Upper part of 



Fig. 48. SLUG-WORM OF CHERKY AXD PEAR SAWFLY 

 (SELAXDKIA ATRA) INFESTING CHERRY SHOOT. 



References : 1, Sawfly magnified ; natural length 



, , , i cherry shoot shows slug-worms destroying the leaves, 



At the last mOUlt the larV8e become yellow, 80 we akening them that they form wood-buds only 



caterpillar like, and shortly afterwards quit in their axils; liaffected leaves at the lower part of 



the shoot, with fruit buds. 



the leaves, having preyed on them from the 



middle of August until October, descend to and enter the ground, where they spin an 

 oval cocoon, coated on the outside with earth, from which the sawfly emerges in the 

 July following. 



The attacks of slug-worms may be lessened by shaking the trees on which the saw- 

 flies are found in the morning and evening during July over a sheet placed on the 

 ground, the insects dropping when disturbed; they should be promptly destroyed. 



