590 
DIPTERA. 
It is somewhat remarkable that the true nature of this 
covering of the maggot should not have been ascertained 
by English naturalists. Mr. Kirby, as before stated, sup- 
posed it to be a thin membrane, formed by the insect for 
the protection of its body from the cold of winter. Ac - 
cording to Professor Henslow’s account, the larvae “spin 
themselves up in a very thin and transparent web, which 
is often attached to a sound grain, or to the inside of one 
of the chaff-scales.”* Mr. Curtis observed on the backs 
of some of the shrivelled grains “ a long narrow filmy sac, 
on opening which a bright orange granulated maggot came 
out alive ; and when shut up in a tin box, many volunta- 
rily left their cases and wandered about.”! Having care- 
fully watched the insect during the moulting period, I am 
convinced that what these gentlemen called a “ membrane,” 
“ web,” or “ sac,” is really the loosened outer skin of the 
maggot, which is subsequently thrown off in the ears of the 
wheat, or is cast upon the surface of the ground. 
After shedding its skin, the maggot recovers its activity, 
and writhes about as at first, but takes no food. It is 
shorter, somewhat flattened, and more obtuse than before, 
and is of a deeper yellow color, with an oblong greenish 
spot in the middle of the body. Within two or three days 
after moulting, the maggots either descend of their own 
accord, or are shaken out of the ears by the wind, and 
fall to the ground. They do not let themselves down by 
threads, for they are not able to spin. Nearly all of them 
disappear before the middle of August ; and they are very 
rarely found in the grain at the time of harvest. Mrs. 
Gage stated, in one of her letters, that she had not ob- 
served “ how and when the insects issue from the grain,” 
but that it was “ apparent they go in company,” and “ per- 
haps they crawl out upon the heads during a rain, and 
are washed down to the ground, where they remain through 
* Journal of the Royal Agricultural Society of England, Vol. II. p- 22. 
t Ibid., Vol. VI. p. 145. 
