THE TEN THREDINIDEE. 
169 
saw-fly places its eggs in the very midst of the food, and protects 
them with extraordinary care. It makes a series of slits in the 
stalk of a leaf or in the twig of a shrub with its tiny saw, and 
deposits an egg 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 Tenthredinidce 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 Tenthredinidce 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 Hylotomites , the Tenthredites, and 
the Lydites. 
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 luted) 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 
