GNATS, MIDGES, AND MOSQUITOES 225 



mind that not every small, long-legged, fragile fly is a 

 gnat in the sense in which the word is here used, i.e., 

 a blood-sucking gnat, we may now proceed to con- 

 sider first what sort of being a blood-sucking gnat or 

 mosquito really is, referring afterwards to those which 

 seem to be more correctly called midges. The photo- 

 graphs shown in Plate III. will give a pretty good 

 idea of the general form of a gnat. A small head, a 

 considerable portion of which is occupied by the com- 

 pound eyes, is attached by means of a short neck to a 

 huge globular thorax, so disproportionately large as to 

 give the insect, when viewed sideways, a hump -backed 

 appearance. Behind this the trunk is completed by a 

 long, slender, cylindrical abdomen. A long, straight, 

 beak-like appendage, carrying the mouth organs, points 

 forward from the head, and a pair of more or less tufted, 

 thread-like antennae form an elegant head-gear, counter- 

 balancing this above. From the upper part of the 

 thorax spreads at each side a single membranous wing, 

 exquisitely delicate, and gracefully fringed along its 

 hinder edge ; the place of the customary second pair is 

 taken by the " poisers," long knobbed stalks, as already 

 described in the other division of flies, but propor- 

 tionately much larger than in those. From the under 

 surface of the thorax start the three pairs of inordinately 

 long legs, upon which, when at rest, the body is, as it 

 were, slung up off the ground as if on springs. Though 

 the legs consist only of the ordinary parts, yet the 

 divisions seem at first sight to be more numerous than 

 usual, by reason of the great proportionate length of 

 some of the parts, and particularly of the tarsi, or feet, 

 which in the hind pair constitute more than half the 

 entire length of the leg, the leg itself becoming nearly 

 three times as long as the abdomen. The insect is 



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