640 A CHAPTER ON FLIES. 
passed. No one has traced the transformations of this fly 
in this country, but we copy from Bouché’s work on the 
transformations of insects, the rather rude figures of the 
larva (Fig. 2), and puparium (a) of the Musca domestica 
of Europe, which is supposed to be our species. Bouche 
states that the larva is cylindrical, rounded posteriorly, 
Fig. 2. smooth and shining, fleshy, and yellowish white, 
and is four lines long. The puparium is dar! 
reddish brown, and three lines in length. It re- 
mains in the pupa state from eight to fourteen 
days. In Europe it is preyed upon by minute 
ichneumon flies (Chalcids). The flesh-fly, Musca 
Cesar, or the Bluebottle-fly, feeds upon decay- 
ing animal matter. Its larva (Pl. 13, fig. 6) is 
long cylindrical, the head being pointed, and the 
body conical, the posterior end being squarely 
docked. The larva of an allied form which feeds on offal, 
ete., transforms into a flattened puparium (Pl. 13, fig. 5), 
provided with long scattered hairs. The Hovse-fly disap- 
pears in autumn, ‘at the approach of cold weather, though a 
few individuals pass through the winter, hibernating in 
houses, and when the rooms are heated may often þe seen 
flying on the windows. Other species fly early in March, 
on warm days, having hibernated under leaves, and the bark 
of trees, moss, ete. An allied species, the M. vomitoria, 
is the Meat-fly. Closely allied are the parasitic species of 
Tachina, which live within the bodies of caterpillars and 
other insects, and are among the most beneficial of insects, 
as they prey on thousands of injurious caterpillars. Another 
fly of this Muscid group, the Idia Bigoti, according tO 
Coquerel and Mondiere, produces in the natives of Senegal, : 
hard, red, fluctuating tumors, in which the larva resides. 
Many of the smaller Muscids mine leaves, running galler- 
ies within the leaf, or burrow in seeds or under the bark of 
plants. We have often noticed blister-like swellings 0? the 
bark of the willow, which are occasioned by a cylindrical 
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