THE TENTHREDINIDM. 1 69 



saw-fly places its eggs in the very midst of the food, and protects 

 them with extraordinary care. It makes a scries of shts in the 

 stalk of a leaf or in the twig of a shrub with its tiny saw, and 

 deposits an a^^ at the very bottom of the cut, covering the opening 

 with a secretion that hardens and keeps out the wet and the air. 

 Some saw-flies only attack the petioles of leaves; others like 

 sawing the hard twigs of trees ; and each species has its particular 

 method of egg-laying and wood-sawing, and each chooses a parti- 

 cular plant. Some large TcntJircdinidce only carry a very delicate 

 and small saw, for the eggs are to be laid in the very tissues of the 

 leaves, which must not be torn or pierced through ; and others, 

 that are small in size, have great saws which are strong and 

 double-toothed, for they have to cut into hard tissues ; so that 

 with a little trouble the naturalist can tell what sort of a saw a 

 tenthredinate insect must have, by observing the habits of the fly ; 

 and he can satisfy himself, on the other hand, when he sees the 

 saw, concerning the peculiar habits of its possessor. 



All the TcnthrcdinidcB are closely allied by their structural 

 peculiarities ; and some external characters have caused them to 

 be grouped in two great tribes, which contain many genera. 



The tribe, the species of which have short and stout bodies, 

 contains the greatest number of saw-flies, and it is subdivided into 

 four groups — the Cimbicides, the Hylotomitcs, the TcntJwcdites, and 

 the Lyditcs. 



The Cimbicides are the largest of the saw-flies. They have 

 thick bodies, and their antennae are swollen at the end so as to 

 resemble a club, and have never more than eight joints. Their 

 flight is heavy, and they make a great buzzing. Their larvae have 

 a peculiar tough-looking skin, and have no less than nine pairs 

 of membranous legs. The common German species, the yellow 

 Cimbex {Cimbex lufed) is a large form, and may be considered 

 to be the representative insect of the genus. 



The difference between the males and females of this saw-fly 

 is so great that many naturalists considered them to belong to 

 separate species. The male is rather long in shape, and has large 

 legs, its colour is brown, and the insect is marked with a bright 

 yellow spot on the first segment of the abdomen. The female, on 

 the contrary, is plump and rounded in figure, and has a yellow 



