STATE AGRICULTURAL SOCIETY. 
829 
HESSIAN FLY. EGG-PARASITE. 
notched. Three exceedingly slender abortive veins may be perceived in these wings, as 
follows: One extending from the inner tooth of the apex of the stigmal branch to the hind 
end; another arising in the base of the wing near the rib-vein, meeting the end of the trans¬ 
verse veinlet and continuing from thence nearly parallel with the inner margin its whole 
length till it reaches the edge; a third forking from this latter one near the middle of tho 
wing and joining the hind edge equidistant between the ends of the other two. 
Legs dull pale yellow, or in tho males whitish, with a brown streak on the thighs. Feet 
black at tho tips, five-jointed, tho basal joint longest and the following ones successively 
shorter. 
It is when the Hessian-fly lias completed its growth and 
assumed its flax-seed form that this parasite attacks it. With 
its sting it'pierces the straw to where its victim lies, and punc¬ 
tures its body and inserts an egg therein. The little maggot 
which comes from this egg consumes the larva and then occupies 
the flax-seed shell in its stead, till it has passed through its pupa 
state and become a fly, when it gnaws a small hole through tho 
shell and straw and makes its escape. Two of the holes thus 
made in the straw are seen in fig. B, plate 3, at the mark 
In addition to this species, Mr. Herrick discovered two others 
which destroy the Hessian fly in its flax seed state, and a fourth 
which attacks the eggs. This last is a species of Platygaster, 
and is probably closely like that which we have represented in 
fig. 4 of plate 1. He states that this egg-parasite is abundant 
irt autumn, and when the Hessian fly deposits its eggs upon the 
leaves of the young wheat, this insect searches them out, and 
piercing them with its sting, lays four or five of its own eggs in 
a single egg of the fly. These eggs it is probable do not hatch 
immediately, as the contents of the fly’s egg are obviously insuffi¬ 
cient to feed even one of them to maturity. It is therefore 
necessary that more nutriment should be elaborated for their 
sustenance. And accordingly the larva of the fly comes from 
the egg with these seeds of destruction within it; it grows to 
maturity and passes into its flax-seed state, by which time its 
“intestine foes” having also become fully grown, spin their 
cocoons in a cluster within the flax seed and in due time eat 
their way out, the worm of the Hessian fly having now perished. 
By these different parasites, according to the observations ot 
Mr. Herrick, it is probable that nine tenths of every generation 
of the Hessian fly is destroyed. 
With regard to remedies, it may be observed that, in districts 
where tho Hessian fly is numerous, it is scarcely possible to 
obtain a crop of winter wheat except upon a fertile soil. Such 
a soil enables the plants to elaborate a sufficiency of fluids for 
