228 DISEASES OF INSECTS. 
site attached to it, which keeps it in check. The only 
other Dipterous insects that I have seen mentioned as 
affording pabulum to an Ichneumon, are — one of the 
aphidivorous flies mentioned by De Geer, who does not 
note the species, to the larva of which the Ichneumon 
commits only a single egg, producing a grub that intirely 
devours its interior*; — and two described by Scopoli 
one, the larva of n.jly frequenting hemp ; and the other, 
which feeds on a Boletus^ that of a gnat b . 
The Lepidoptera, however, is the Order over the larvae 
of which the Ichneumons reign with undisputed sway ; 
attacking all indiscriminately, from the minute one that 
forms its labyrinth within the thickness of a leaf, to the 
giant caterpillar of the hawk-moth. The most useful of 
all, however, the silkworm, appears at least with us, ex- 
empted from this scourge. De Geer, out of fifteen larvae 
that were mining between the two cuticles of a rose-leaf, 
belonging to the first tribe here alluded to, found that 
fourteen were destroyed by one of these parasites, only 
one coming forth to display itself in all its brilliancy and 
miniature magnificence . One of the most useful to us 
is that which destroys the clothes-moth, which the same 
writer also traced d . Another, equally serviceable, takes 
up its abode in the caterpillar that ravages our cabbages 
tion was printed, Say's account of the Hessian Fly has been met 
with, where he distinguishes it by the above name. {Journal of the 
Acad, of Nat. Sciences of Philadelphia 181 7-) The Ichneumon he 
calls Ceraphron Destructor. 
a De Geer, i. 605. This, as before observed, is not the J. Mus- 
carum of Linne ; but it ought to have that name, and the other in- 
stead to be named, I. Coccinellcc. 
b Ent. Cam. 700, 761. 
" De Geer i. 587. 
d Ibid. ii. 876. 
