The hind-wings, when developed, are characteristic in form, possessing a sub-costal nervure with which the reduced radial nervure usually becomes associated.
Along the costa runs a costal nervure.
This is followed s s, by a sub-costal which some times shows two main branches.
2, sub-costal; 3, radial; 4, median; 5, cubital; 6, 7, 8, anal nervures.
(3) The fact that the costal or marginal vein runs completely round the wing.
Discoidal; 10, sub-costal; 6.
The main median nervure, and usually also the sub-costal become united with the radial, while the branches of radial, median and cubital nervures pursuing a transverse or recurrent course across the wing, divide its area into a number of areolets or " cells," that are of importance in classification.
They resemble the Orthoptera more nearly than do any other group of the Linnean Neuroptera, having the anal area of the hind-wings folding fanwise beneath the costal area and the whole hind-wing covered by the forewing when the insect is at rest, though the forewing is not firmer in texture than the hind-wing, as is the case in the Orthoptera.
The feelers are long and simple, and the wings are very narrow, each with a sub-costal, a radial, a median and a cubital nervure; the branches of the median and the cubital, however, as well as the anal nervures, are vestigial, and there are a few short cross-bars between After Marlatt, Ent.
The hindwings have a firm costal area, and a more delicate anal area which folds fanwise, so that they are completely covered by the forewings when the insect rests.