TWO-WINGED INSECTS, OR FLIES.
BY W. F. KIRBY, F.L.S.
This order of insects is probably one of the most numerous in individuals, though it may be that, when we know more of the insect population of the world, we shall find that it is outnumbered in species by the Beetles or the order to which the Bees and Ants belong. It differs from all other orders in possessing only two wings instead of four, which is the usual number in insects. The metamorphoses are complete, and the mouth is furnished with a proboscis for imbibing liquid food. Hind wings are represented in many species by a pair of organs called "poisers," resembling a knob at the end of a stick, and other species have two small additional lobes attached to the wing, called "winglets "; but there is no such thing as a really developed hind wing in any insect belonging to the group. They are always two-winged flies, except in the case of a few aberrant species, such as the Fleas, in which no wings, or only mere rudiments of wings, are to be met with. The Gnats, Daddy-long-legs, and House-flies are among the commonest representatives of this order.
Photo by C. N. Mavroyeni] [Smyrna.
CICADA AND PUPÆ.
Noted for the loud drumming sound produced by the males.
The first section of the group includes the Gnats and the Daddy-long-legs, or Crane-Flies, the members of which may be distinguished by having moderately long antennæ, composed of more than six joints, and never terminating in a bristle. They are all vegetable-feeders, with the exception of the females of gnats and sand-flies, which are furnished with a lancet-like arrangement for sucking the blood of warm-blooded animals.
The Gall-flies, Wheat-midges, etc., have rather long, jointed antennæ, which are not feathered, though sometimes tufted on the sides, and their maggots produce small galls on various trees and plants, or distort and otherwise injure them. They resemble small gnats, and there are two particularly destructive species which attack corn in England and elsewhere,—the Wheat-midge, an orange-yellow fly with black eyes, which produces little yellowish or reddish maggots which injure the growing grain in the ear; and the Hessian Fly, which is brown, and produces semi-transparent maggots, which afterwards grow darker, and when full grown become pupæ resembling flax-seeds. The maggots attack the stalk, feeding on the sap till the stalk cracks and bends over. This is an infallible sign of their presence, and of the mischief they are doing.
Among the best-known insects of this group are the Gnats, or Mosquitoes, of which there are many genera and species. There is no difference, however, to permit of their being classified in two separate popular categories. In England any of these troublesome insects are called Gnats; out of England they are termed Mosquitoes, if we are tormented by them, even though they may belong to the same species as the English ones—for "mosquito" is merely the Spanish word for "gnat" Anglicised.