The Saw -Flies 



Fig. 48. — Pear Slug : 8, last 

 moulted larval skin; b, larva 

 after casting last skin — 

 somewhat enlarged. 

 (After Marlatt.) 



of the female is moved rapidly with a swinging lateral motion 

 from side to side, forming an irregular cell or pocket of an oval 

 outline. The egg is quickly passed down between the plates of 

 the ovipositor, and dropped into the 

 pocket thus made, the time occupy- 

 ing little more than a minute for the 

 operation. A single saw-fly usually 

 deposits only one egg in the same leaf, 

 and after laying the egg she goes around 

 to the upper side of the leaf and ex- 

 amines it carefully, rests awhile, and 

 then flies to another leaf and repeats 

 the operation. The egg is oval, slightly 

 flattened on one side, and remains in the 

 leaf about two weeks. It increases in 

 size apparently by absorbing the plant 

 juices. 



The young larva on hatching makes 

 a semi-circular cut through the upper surface and crawls on the 

 top of the leaf. At first it is nearly white in color, with a yellow- 

 ish brown head. Almost 

 immediately a slimy, 

 olive-colored liquid be- 

 gins to exude over the 

 whole body ; the head 

 appears black under the 

 slime, and the body be- 

 comes dark. The an- 

 terior segments of the 

 thorax swell out and the 

 head is retracted, so that 

 the little larva appears 

 club-shaped. It begins 

 feeding on the upper 

 surface of the leaf, eating 

 out small holes the size 

 of a pinhead. This work 

 continues and increases as the larva grows until the leaf becomes 

 entirely skeletonized. Full size is reached in less than a month. 

 The larva casts its skin four times, and usually eats its cast skin 



77 





Fig. 49.- 



-Pear Slug, illustrating method of ovi- 

 position and emergence of larva, a, cutting 

 of cell beneath epidermis, with ovipositor; 



b, same after egg has beeen deposited ; 



c, same after escape of larva-enlarged. 



(After Marlatt.) 



