DIPTERA. — MUSCID&. 569 
manner, in which the larve are developed, sometimes to the number 
of 20,000. (De Geer, Mém. tom. vi. pl. 3. fig. 5—18.; Réaumur, Mém. 
tom. iv. pl. 29.) It is upon animal matter, as well as upon other sub- 
stances in a state of decomposition, that these young larva are depo- 
sited. Bouché has described the larve of several species. Those of 
the genus Cynomyia have only been found on the dead bodies of 
dogs. 

Stomoxys and the immediately allied genera (which, although 
ordinarily arranged with the Conopide, are in all respects, except the 
mouth (jig. 132. 8. head and geniculated mouth of Siphona), most 
closely allied to the typical Muscide) frequent our apartments, and 
are remarkable for their habit of piercing our flesh, even if covered by 
clothes, for the purpose of sucking the blood. The larva of St. cal- 
citrans, observed by Bouché, lives in horse-dung, and closely resembles 
that of Musca domestica. 
The species of the subgenera Lucilia (Musca Ceesar, the blue-bottle 
fly) and Calliphora (Musca vomitoria, the meat-fly, &c.) have the in- 
stinct to deposit their eggs (well known under the name of fly-blows) 
upon meat and other dead animal matter.* The larve are soon 
hatched, and are of an elongated conical form, pointed to the head, 
which is furnished with two fleshy horns, and the mouth is furnished 
with one or two corneous hooks; the hind part of the body is trun- 
cated, and furnished with a pair of spiracles in Lucilia, and with three 
pairs in Calliphora. When the period of transformation is arrived, 
these larvae descend into the ground, where they assume the pupa 
state, enclosed in their own larva skin, which is hard, short, and desti- 
* Numerous instances have been recorded of these and nied species depositing 
their eggs in the wounds of persons incautiously sleeping in the open air. (See 
Kirby and Spence. ) 
