3 



The pear slug is an insect vvliich is easily distributed with the soil 

 about the plants which it infests, and it has been so carried about the 

 M'orld until it has made its way into practically every civilized countr}-. 

 It is known at least to occur throughout Europe and America and in 

 many of the British colonies. The slugs have been found on a great 

 many different plants, Reaumur recording them on the plum and cherry, 

 and especially pear, but also on the oak, and a recent catalogue by 

 Dalla Torre indicates their occurrence on over thirty different plants in 

 Europe. Certain stone fruits and the pear, particularly the latter, are 

 their especial favorites. 



LIFE HISTORY AND HABITS. 



The parent fly may be seen on the pear or other trees which serve 

 as food for the larvae very early in the spring. In Washington, D. C, 

 the present season they were 

 observed on the newly-ex- 

 panded leaves by the middle 

 of April actively engaged in 

 laying their eggs. In the lat- 

 itude of Boston and northward 

 the flies do not appear much 

 before the middle of May, and 

 the egg-laying is chiefly during 

 the latter part of May and first 

 of June. Judging from our 

 experience here many of the 

 eggs laid by the flies which 

 appear in April perish during 

 the cold wet weather which 

 often characterizes this month. 

 This was notably the case the 

 present season, few, if any, of the eggs first deposited producting larva^. 



But one egg is deposited in a place, and it is always inserted from 

 the under side of the leaf. The ovipositor is thrust obliquely through 

 the leaf to the upper epidermis, but not piercing' the latter, and shows 

 there distinctly through the transparent ui)per skin of the leaf, as rep- 

 resented in the accompanying illustration ((ig. 2), while the insect 

 otherwise is completely hidden. The saw-like instrument, when brought 

 into the position noted, is moved rapidly with a swinging lateral motion 

 from side to side, cutting the upper epidermis free so as to form an 

 irregular cell or pocket of peculiar flattened ovoid outline. The egg is 

 quickly passed down between the y)lates of tin; ovipositor and dropped 

 into the pocket thus made, the time occUipied being a little over one 

 minute for the entire operation. 



Fig. 2.— Pear slug, illustrating method of ovipositioii 

 and emergence of larva: a. putting of cell beneath 

 epidermis, with ovipositor; b, same after egg has 

 been deposited ; r, same after escai)e of larva— en- 

 larged (original). 



