ORDER VII. 



TWO-WINGED INSECTS, OK 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 antennce, 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 arc for the most part oviparous, only a few 

 species being viviparous. Their maggots arc 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 larva? 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. 



