STATES OF INSECTS. (Larva.) 225 
in a palisade, in an oval ring around its body, connect- 
ing them by a slight tissue of silk, which forces them to 
bend into a sort of roof at the top: and under this curi- 
ously-formed cocoon assumes its state of pupa*. Some 
larvze make so much hair and so little silk enter into the 
composition of their cocoons, that on the first inspec- 
tion they would be pronounced wholly composed of it”; 
others, thickening the interior of their cocoon with hair, 
line the whole with a viscid matter like varnish °¢. 
The larve of some saw-flies are remarkable for inclo- 
sing themselves in a double cocoon, in which the inner is 
not, as in the silk-worm, &c. connected with the outer, 
but perfectly distinct from it. Some species, as Hylotoma 
Rosa, which have but a small stock of silk, compose the 
outer cocoon of thick silken cords crossing at right an- 
gles, and forming an oval net; which at the same time 
that it protects them effectually from the ants, which are 
always ready to attack them, demands much less silk 
than a covering of a closer texture. But the tender 
nymph itself requires to be inclosed in a case of a softer 
and more delicate substance ; and accordingly the inner 
cocoon is composed of fine silk, woven so closely that 
the threads are scarcely perceptible under a microscope‘. 
Reaumur mentions a hymenopterous larva belonging to 
Latreille’s Fossores (Sphex, L.) which thickened its cocoon 
with the legs, wings, and other relics of the flies which it 
had devoured *: trophies—like the drinking-cups of some 
savages, made of the skulls of their enemies, or the skull 
pyramid near Ispahan—of its powers of devastation. 
It is a general rule, that those larvee which spin co- 
* Reaum. i. 524. > Bonnet ii. 297. © Tbid. ix. 18]. 
4 Reaum. y. 102. © Ibid. iv. 269, 
VOL. III. Q 
