126 INTERNAL ANATOMY OF INSECTS. 
caterpillars of Lcpidoptcra they are of the former de- 
scription, and every grain wears some resemblance to an 
insect's egg : as the passage in many of these consists of 
six fleshy parts separated by channels, so the excrement 
represents six little prisms separated by six channels a . 
The Aphides all secrete a fluid excrement as sweet as 
honey, of which the ants are so fond b , which is ejected 
not only at the anal passage, but, in many, by two little 
siphonets also above it-. A semi-fluid excrement is pro- 
duced by some species of Ckcrmes, as that which inhabits 
the Box, which often comes from the animal in long con- 
voluted strings resembling vermicelli. Reaumur says its 
taste is agreeable, much more so than that of manna d . 
Under this head should be included the abundant spume 
with which the larva of Cercopis spumaria envelopes it- 
self e . 
I am, &c. 
a Reaum. i. 143. /. v./. 9. " Vol. IT. p. 88~. 
c De Gcer iii. 26. d Reaum. iii. 357. t. xxix./ G— 10. 
e Vol. II. p. 225. 
