332 THE LIVING ANIMALS OF THE WORLD 
TWO-WINGED INSECTS, OR FLIES 
BY W. F. KIRBY, F.LS. 
Tuts 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 meta- 
morphoses 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 
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seep CaN Maury eal [smprna wings, or only mere rudiments of wings, are to be 
CICADA AND PUPE met with. The Gnats, Daddy-long-legs, and House- 
Noted for the loud drumming sound produced by the males flies are among the commonest representatives of this 
order. 
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 antenne, 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 antennz, 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 pupz resembling flax-seeds. The maggots attack the 
stalk, feeding on the sap till the stalk cracks and bends over. This is an Ry at cae 
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 Xi 
popular categories. In England any of these troublesome insects are ~t 
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 
“onat”’ Anglicised. 
Gnats breed in standing water, fresh or otherwise, but seem to prefer | Photo by W, P. Dando, F.Z.S. 
rain-water, for they are very numerous about small pools and water-butts. BROWN MOSQUITO 
Consequently they were formerly far more abundant in England than at bon. 
present, when the fens were still undrained, and when every house had by Ce gees 
