ORDER VII 
TWO-WINGED INSECTS, OR FLIES—(DIPTERA). 
THE insects of this order, as their Greek name imports, 
are creatures with two wings, which we commonly call 
flies. They are generally small, and we find among them 
some so diminutive that they can be seen only with a mag- 
nifying glass. Their bodies are divided into a head, tho- 
rax, and hind body or abdomen, which are connected to- 
gether by a thin filament. The head consists of two large 
eyes, with an addition in some species of three small ones, 
and two short antennz, very near together; below these 
are found, in some species, a soft proboscis, as in the house- 
fly ; in others a hard, pointed sucking-tube, as in the mos- 
quito; and in others simply a mouth. On the under side 
of the thorax are fastened three pair of feet, and on the 
opposite side one pair of thin, transparent wings, by the 
vibration of which they produce a humming sound when 
flying. ‘The hind body consists of ten ringlets. 
These insects are for the most part oviparous, only a few” 
species being viviparous. ‘Their maggots are white, of a 
spindle form, and without feet, but some of them have mi- 
nute fleshy warts which answer the purpose of feet, and 
upon which they are able to move; they have two respira- 
tory organs on the neck, and two on the hind body. Many 
of these larve live in the water, but the greatest part of 
them live in dirt, dung-hills, cheese, spoiled meat, fruits, 
etc. After a time the skin of these maggots becomes hard 
and brown, and thus they are transformed into a pupa, 
which in many species has the form of a barrel, from which 
afterward the perfect fly issues. 
