212 DISEASES OF INSECTS, 
indeed of other internal parasites, is chiefly the epzploon 
or fat of the larva, but they never touch any vital organ ; 
so that it continues to feed, and probably more voraci- 
ously, grow, cast its skin, and often it changes to a chry- 
salis, although at the same time inhabited by an army of 
these little devourers. 
Ichneumons, as far as has been at present ascertained, 
are parasitic upon other insects chiefly in their three first 
states, a solitary instance only having been observed of 
their inhabiting an zmago; but from their first exclusion 
as eggs from the ovary till their assumption of that state 
they give them no rest. I shall therefore first treat of 
those that infest the eggs; next those appropriated to 
larve; and lastly those that devour pupe. 
Vallisnieri appears to have been the first naturalist who 
discovered that Ichneumons were appropriated to the 
eggs of other insects. He observed one proceed from those 
of the emperor-moth (Saturnia pavonia): finding two holes 
in each egg, one larger than the other, he conjectured 
that one was made when it entered, and the other when 
it emerged. In this case the egg of the Ichneumon must 
be fixed on the outside of the egg it was to feed upon; 
though some appear to pierce it with their ovipositor, 
and consequently introduce their egg within: for he says 
afterwards; “ I have seen with my own eyes a certain 
kind of wild flies deposit their eggs upon other eggs, and 
bore and pierce others with an aculeus—by which they 
have introduced the egg*.” Count Zinanni, a corre- 
spondent of Reaumur’s, saw an Ichneumon pierce the 
for it to ¢. xxx. f. 19, 20 of that author; whereas the Ichneumon 
that preys upon the aphidtvorous flies does net jump, and is figured 
by De Geer 6095. t. xxxiy. f. 26-29. ‘The jumping one feeds on the 
Jarva of a Coccinella. . * Vallisnieri Lettere, &c. 80. 
