598 
DIPTERA. 
transformations. Moreover, the pupa is entirely naked, not 
being enclosed either in a cocoon or in the puparium formed 
of this outer skin of the larva, and it has its limbs and wings 
free or unconfined. The pupa state lasts but a short time, 
a week or two at most, and probably, in many cases, only 
a few days. Under the most favorable circumstances, the 
pupa works its way to the surface, before liberating the 
included fly ; and when the insect has taken wing, its empty 
pupa-skin will be seen sticking out of the ground. In other 
cases, the fly issues from its pupa-skin in the earth, and 
comes to the surface with flabby wings, which soon expand 
and dry on exposure to the air. This last change occurs 
mostly during the months of June and July, when great 
numbers of the flies have been seen, apparently coming from 
the ground, in fields where grain was raised the year before. 
Some persons have stated that the insects are transformed 
to flies in the ears of the grain, having probably mistaken 
the cast-skins of the maggots found therein for the shells 
of the chrysalis or pupa. 
Several cases of the efficacy of fumigation in preventing 
the depredations of these insects are recorded in our agricul- 
tural papers.* For this purpose brimstone has been used, 
in the proportion of one pound to every bushel of seed sown. 
Strips of woollen cloth, dipped in melted brimstone, and 
fastened to sticks in different parts of the field, and particu- 
larly on the windward side, are set on fire, for several 
evenings in succession, at the time when the grain is in 
blossom ; the smoke and fumes thus penetrate the standing 
grain, and prove very offensive or destructive to the flies, 
which are laying their eggs. A thick smoke from heaps 
of burning weeds, sprinkled with brimstone, around the 
sides of the field, has also been recommended. Lime or 
ashes, strown over the grain when in blossom, has, in some 
cases, appeared to protect the crop ; and the Rev. Henry 
Colman, the Commissioner for the Agricultural Survey of 
* Among others, see The Cultivator, Vol. V. p. 130. 
