INTERNAL ANATOMY /OF INSECTS. 133 
mur with regard to the larva of Crioceris merdigera, 
which forms its cocoon with a kind of froth produced 
from the mouth?. 
il. Varnish or Gum. The eggs of various insects, when 
they leave the oviduct, are covered with a kind of var- 
nish or gum by which they adhere to the substances 
that the young larvee are to feed upon, or are placed in a 
proper position for their hatching in an appropriate sta- 
tion. Several instances of this have been already men- 
tioned®; I shall therefore not enlarge further upon the 
subject. With regard to the secretion itself, little has 
been recorded except its colour, which has been before 
noticed. Some Lepidoptera also, as we learn from 
Reaumur and Bonnet‘, use a varnish in the construction 
of their cocoons. _ 
iv. Jelly or Gluten. ‘This secretion is particularly con- 
spicuous in the Trzchoptera and some Diptera, serving 
as a bed or nidus for those eggs that are committed to 
the water,—upon which I have nothing to add to what 
has been before said?. Under this head also may be 
noticed the fluid, secreted in peculiar vesicles, that lubri- 
cates the oviduct and the passages of the sexual or- 
gans°. 
v. Oils. Oily substances are sometimes produced by 
insects. ‘The common oil-beetle (Meloe Proscarabaus) 
when touched sends forth a drop of this kind of fluid, of 
an orange colour, from each joint of its legs f: something 
similar I have observed in Coccinella bipunctata: Ray 
2 Reaum. ii. 230. > Vor. III. p. 78—. 
© Reaum. iii. 215. Bonnet ix. 182. 4 Vor. III. p. 68— 
© Marcel de Serres Mem. du Mus. 1819. 133, 141. 
‘ De Geer, v. 6. 
