GNAT, Ciao!, a genus of dipterous insects, having the wings laid flat on the back when at rest: the antennae thread-like, 14-jointed, feathery in the male, and hairy in the female; the mouth furnished with a long projecting proboscis, adapted for piercing the skin of animals and sucking their blood. They are said to feed also on vegetable juices. The species are numerous, and almost all parts of the world, particularly in marshy regions; and some of them, under the name of mosquitoes (q.v.), are known in many countries as most annoying pests. An irritating fluid, injected through the pro boscis, makes their punctures painful, and The proboscis of a gnat is an extremely interesting mi. roscopical object. It is a membranous cylindrical tube, clothed with minute, feather-like scales, and terminated by two lips„ which, when closed, form a kind of knob, and by six t,liarp bristles or very small lancets. The female gnats have the most powerful proboscis, and are the principal bloodsuckers. Some persons are much more liable to the assaults of gnats than others. The flight of gnats is very swift, and the extremely rapid vibration of their wings causes the loud and sharp buzzing sound, which so often prevents sleep when even one of these insects has found its way into a bedroom on a summer night. The eggs of gnats are deposited on the surface of shallow stagnant water, placed side by side, united by an unctuous matter, and fastened to the bottom by a thread, which prevents their floating away. They are
soon hatched; indeed, a single summer sees several generations of gnats. The larvae are to be seen in immense numbers in stagnant waters; they are of an elongated worm like form; are destitute of feet, but swim and dive by means of fin-like organs; they feed on insects, and also on vegetable substances; and often suspend themselves at the surface of the water, head downwards,• for the purpose of respiration, by means of radi ating bristles attached to a long spiracle or tube at the caudal extremity of the body, by which air is admitted to the trachece or air-tubes. The pupa; also inhabit water, and are Active; they remain almost constantly at the surface of the water, with the body tecurved; and the respiratory. openings of the air-tubes are now in the thorax.—The COMMON GNAT (U. p4)iens) is of very wide geographic distribution. It is about three lines in length, brown, with whitish rings on the abdomen, the wings unspotted. It so abounds in some of the fenny parts of England, that beds are occasionally surrounded with gauze curtains, as in India on account of mosquitoes,—A number of genera, allied to cuter, are united by many entomologists into a family called culicicice.