ENEMIES OF THE HESSIAN FLY. 
587 
egg is hatched a little maggot, which devours the pupa of 
the Hessian fly, and then changes to a chrysalis within the 
shell of the latter, through which it finally eats its way, 
after being transformed to a fly. This last change takes 
place both in the autumn and in the following spring. Some 
of the females of this or of a closely allied species come 
forth from the shells of the Hessian fly, without wings, or 
with only very short and imperfect wings, in which form 
they somewhat resemble minute ants. 
Two more parasites, which Mr. Herrick has not yet 
described, also destroy the Hessian fly, while the latter is 
in the flax-seed or pupa state. Mr. Hemck says, that the 
egg-parasite of the Hessian fly is a species of Platygaster^ 
that it is YQVj abundant in the autumn, when it lays its 
own ecfors, four or five tosether, in a sinMe ess of the Hes- 
sian fly. This, it appears, does not prevent the latter from 
hatching, but the maggot of the Hessian fly is unable to 
go through its transformations, and dies after taking the 
flax-seed form. Meanwhile its intestine foes are hatched, 
come to their growth, spin themselves little brownish co¬ 
coons within the skin of their victim, and, in due time, are 
changed to winged insects, and eat their way out. Such 
are some of the natural means, proAuded by a benevolent 
ProAudence, to check the ra\’ages of the destructiA’e Hessian 
fly. If Ave are humiliated by the reflection, that the Author 
of the uniA^erse should haA'e made eA^en small and feeble 
insects the instruments of His poAA’er, and that He should 
occasionally permit them to become the scourges of our race, 
ought Ave not to admire His wisdom in the formation of 
the still more humble agents that are appomted to arrest 
the Avork of destruction ? 
The Avheat crops in England and Scotland often suffer 
seA^erely from the depredations of the maggots of a ver}^ 
small gnat, called the A\’heat-fly, or the Ceeidomyia Tritiei 
of Mr. Kirby. This insect seems to have been lonor known 
in England, as appears fi'om the folloAving extract from a 
