318 



SCHOOL ENTOMOLOGY 



the anterior segments are much expanded, concealing the 

 head and legs. There are seven pairs of legs on the abdomen, 

 the usual pair at the tip being wanting, so that it is slightly 

 elevated. The slugs eat off the surface of the leaf until only 

 a network of veins, held together by the brown epidermis of 

 the lower surface, is left. Injured leaves drop and trees are 

 often nearly defoliated, thus seriously injuring the growth 



and fruiting of the 

 tree. The larvae be- 

 come grown in about 

 twenty-five days and 

 are then about one- 

 half an inch long. 

 After the last moult 

 the larva becomes a 

 light orange-yellow 

 color, without the 

 slimy covering, but it 

 almost immediately 

 enters the soil where 

 it forms a small cell 

 and transforms to 

 the pupa. Some of 

 the larvae of each 



generation and all of those of the last generation remain 

 in the soil over winter and transform to pupae the next 

 spring. In the North there are but two generations, the 

 second larvae appearing in August. In the latitude of the 

 District of Columbia, the second generation of larvae are 

 most injurious about the middle of July, and there is 

 probably a third generation later. 



The best means of control is by spraying with arsenate 

 of lead, which quickly destroys the larvae. They may also 



FIG. 232. Illustrating method of oviposi- 

 tion and emergence of the pear slug. 

 (After Marlatt, U. S. Dept. Agr.) 



o, cutting of cell beneath epidermis, showing 

 the tip of the ovipositor; 6, the cell after the egg 

 has been deposited; c, same after escape of the 

 larva all much enlarged. 



