808 
ANNUAL REPORT OF NEW YORK 
MIDGE. PARASITES. GENERAL YIEW OF THEM. 
like the tunica arachnoides of the human brain, a mere film aa 
thin as a spider’s web. Eventually, the insect by gently writhing 
ruptures this film at its anterior end and gradually crowds it off 
downward to the lower end of the vescicle, carrying the minute 
black jaws of the larva with it. It there remains, becoming dry 
and torn into shreds which flake and fall off by the continued 
motions of the insect. At the same time, from the remainder of 
the surface not occupied by this vescicle, a still more slight and 
delicate film, appearing as though the worm had been wet in milk 
which had dried upon it, forming an exceedingly thin pellicle or 
scurf, becomes separated by the same motions of the insect and 
diops ofl in minute scales scarcely to be perceived with a magni- 
fying glass. And now the insect has acquired its perfect pupa 
form, the moulting which occurs in this change being, not a 
throwing off of an entire skin like that which the larva often 
parts with when it is done feeding, and that which the pupa 
always leaves when it changes to a fly, but only a slight scurf-like 
exfoliation from the surface —so slight that in a small delicate 
species like the wheat midge it is doubtful whether any indica- 
tions of it can be perceived. 
Its Parasites and other natural destroyers. 
In its native haunts on the eastern continent the wheat midge 
appears to be preyed upon by several other insects. Earwigs 
devour the larvae, and the ravenous two-winged flies of the genus 
Empis seize and carry them away to suck out their juices. But 
by far the most important and serviceable of these destroyers are 
its parasitic foes. These are small four-winged flies having some 
resemblance to little winged ants, and are at a glance distin¬ 
guished from the yellow flies of the midge by their black color. 
Their young subsist within and destroy the larvae and eggs of the 
midge. And these insects increase or diminish in numbers in the 
same ratio with the supply of food which they are able to find 
for their young. Hence, when the midge chances to become 
numerous these parasites also rapidly multiply and thus immedi¬ 
ately quell and subdue it, reducing it back within the'sphere it 
was designed to occupy in the domain of nature; the same as the 
Hessian fly, once so frightfully destructive to our wheat crops 
here in America, has become subdued by its parasites, whereby 
it is seldom noticed now, or known to be present in our country, 
