204 NEMATUS GALLICOLA. 



On Salix caprea they are somewhat oval, dark 

 shining green, glabrous above, very hairy beneath. On 

 Salix cinerea they are oblong, dark green, like those 

 on 8. caprea, but are smaller and more hairy. 



The eggs are deposited in May in the leaf-buds, and 

 the galls grow with the leaves. The autumnal broods 

 of course lay the eggs in more mature leaves. 



After escaping from the egg the larva is transparent 

 white, with the exception of the head which is very 

 shining and brownish-black. In a short time it 

 assumes a greenish hue on account of the food canal 

 getting filled with food. When full-fed it varies from 

 a quarter to three-eighths of an inch in length. The 

 head is shining brownish-black, with a dark greenish- 

 white semicircle on the face, the mouth light brown, 

 mandibles darker; the body is dull whitish -green 

 throughout, the legs white with brown claws. 



The pupa is white. 



At first the gall is perfectly solid except in the 

 centre, where there is a small free space surrounding the 

 egg, but through the eating of the larva it becomes in 

 course of time converted into a bladder. On the 

 lower side at one end the larva eats out a round hole, 

 from which it casts out the frass, and occasionally it 

 leaves the gall entirely for a short time. The cocoons 

 are spun as a rule in the earth, but when the larvae have 

 been on a willow with rough, broken bark, they are 

 spun in the crevices of the bark, under which the old 

 and new ones may sometimes be found packed together 

 in large quantities. 



This is undoubtedly the commonest saw-fly in this 

 country, and the most widely distributed. 



It is generally distributed over the Continent. 



