PEAR AND QUINCE INSECTS 



215 



plants, in this country its 

 inj uries are confined almost 

 (entirely to the pear, cherry 

 and plum. Eggs are fre- 

 quently laid in peach leaves 

 on trees adjoining infested 

 pear and cherry orchards, 

 but the larvae do not seem 

 to thrive on that food 

 plant. 



In the North the small, 

 glossy black, four-winged 

 flies about J inch in length 

 appear on the leaves about 

 the middle of May. The 

 female is provided with a 

 sharp saw-edged ovipositor 



Fig. 197. — Egg-blisters of the pear slug. ^3^ means of which she de- 

 posits her eggs under the epidermis of the leaf. The oviposi- 

 tor is inserted from the under surface of the leaf and then so 

 manipulated as to cut loose a portion of the upper epidermis, 

 forming a kind of blister in 

 which the oval egg is laid 

 (Figs. 197 and 198). The 

 egg hatches in about two 

 weeks and the whitish young 

 larva escapes on the upper 

 side of the leaf through a 

 semicircular cut in the over- 

 lying epidermis. The larvse 

 soon become covered with a 

 brownish sticky slime, which 

 is retained until they are full 

 grown and gives them the 



Fig. 198. — Egg-blister of the pear slug, 

 greatly enlarged. 



