342 



Pear and Cherry Sawfly. 



leaves, but also with the growth and health of the larvae. It 

 is generally found that the larvae or caterpillars do not cause 

 serious harm in wet seasons. 



Life History. 



The sawfly itself is harmless. It is not quite a quarter of 

 an inch in length, having a wing expanse of rather more 

 . than half an inch. Its body is blackish, with a yellowish 

 tinge through the middle part ; its wings are hyaline or 

 glassy, with dark lines or bands running through them. The 

 fly usually makes its appearance early in June, and in the 

 first or second week of this month the female makes a curved 

 abrasion in the upper surface of the leaf, with the aid of her 

 peculiar saw-like apparatus which resembles that of the 

 gooseberry sawfly [Nematus ribesii), and many other sawflies. 

 In this abrasion an egg is deposited ; this can be easily seen 

 on the leaf, as a slight, round excrescence is formed, in the 

 centre of which there is a transparent skin or film covering 

 the whitish egg". The number of eggs upon one leaf often 

 amounts to twentyor even more, but as a rule not more than 

 five or six larvae are seen upon one leaf. 



The larva, which is hatched in about twelve days, is at first 

 white ; in a day or two it becomes green, and soon afterwards 

 an olive-green slime exudes from and covers its body. This 

 exudation is evidently designed to protect the insect from the 

 influences of weather, to which it is fully exposed upon the 

 upper surface of the leaf. The larva is particularly ugly at 

 this period of its life, being dark green and slimy, while its 

 head and the upper part of its body are much broader than 

 the lower part, which tapers towards the end. At this stage 

 it very much resembles a malformed slug or a tadpole. It 

 has seven pairs of "sucker" feet on its abdomen, three pairs 

 of distinct feet upon the thorax, and a pair of very rudimen- 

 tary " sucker" feet at the end of its body. But with all these 

 feet it moves very slowly, being slug-like in its movements. 

 When it is full grown it is close upon half an inch in length, 

 and at about the end of a month, after several moults or 



