DIPTERA. 447 



DIPTERA. 



Gnats and Flies. — Maooots, and their Transformations. — Gall-Gnats. 

 Hessian Fly. Wheat-Fly. — Remarks upon and Descriptions of some 

 OTHER Dipterous Insects. — Radish-Fly. — Two-winged Gall-Flies, and 

 Fruit-Flies. — Conclusion. 



Under the name of Diptera, signifying two-winged, are 

 included all the insects that have only two wings, and are 

 provided with two little knobbed threads in the place of hind 

 wings, and a mouth formed for sucking or lapping. 



Various kinds of gnats and of flies are therefore the insects 

 belonging to this order. The proboscis or sucker, wherewith 

 they take their food, is placed under the head, and sometimes 

 can be drawn up and concealed, partly or wholly, within the 

 cavity of the mouth. It consists of a long gutter, usually 

 ending with two fleshy lips, and enclosing, in the channel on 

 its upper side, several fine bristles, from two to six in number, 

 which are sometimes as sharp as needles, and are then capable 

 of inflicting severe punctures. These piercing bristles really 

 take the place of the jaws of biting insects, and hence the 

 wounds made therewith, by gnats and mosquitos, are very 

 properly called bites. The saliva of these insects flowing into 

 the wounds, renders them more painful, and is the cause of 

 the inflammation and itching that follow. The grooved sheath 

 of the proboscis is usually very large and fleshy in the flies 

 that only lap or sip their food. Two small, jointed feelers are 

 commonly found attached to the base of the proboscis. Gnats 

 and flies have softer bodies than most other winged insects. 

 The head is large, and fastened to the thorax by a very slender 

 neck. The eyes, especially in the males, are large, and occupy 

 the whole of the sides of the head. The antennae, in gnats 

 and mosquitos, are rather long, slender, and many-jointed; in 

 flies, they are short, consisting of only two or three thick 

 joints, the last of which often bears a little bristle or delicate 



