(X 300.) by a nervure and traversed by two A, With " bladder," b, longitudinal nervures, or the nervuration protruded; B, retracted, may be altogether degenerated.
The forewings have at least a single longitudinal nervure - often two - reaching from base to tip of the wing.
There is no ovipositor, and the wings are either without nervures or have only a single degraded longitudinal nervure which does not reach to the tip. While the Terebrantia are (After H.
The hind-wings, when developed, are characteristic in form, possessing a sub-costal nervure with which the reduced radial nervure usually becomes associated.
At this fold the median nervure stops and is joined by a cross nervure to the radial, which can be distinguished throughout its length from the subcostal.
The generalized arrangement of the wing-nervure and the nature of the larva, which is less unlike the adult than in other beetles, distinguish this tribe as primitive, although the perfect insects are, in the more dominant families, distinctly specialized.
Close to a transverse fold near the base of the wing, the median nervure divides into branches which extend to the wing-margin; there is a second transverse fold near the tip of the wing, and cross nervures are altogether wanting.
3, Then comes the radial - usually 4 the most important nervure of the wing - typically with five branches, and the median with four.
From another hinder trunk arise the two-branched cubital nervure and three separate anal nervures.
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.
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.
All the wings are of firm, glassy texture, and very complex in their neuration; a remarkable and unique feature is that a branch of the radius (the radial sector) crosses the median nervure, while, by the development of multitudinous cross-nervules, the wing-area becomes divided into an immense number of small areolets.
The other wing consists of a rigid nervure in front and behind of thin parchment which supports fine rods of steel.
During the vigorous depression of the wing, the nervure has the power of remaining rigid, whereas the flexible portion, being pushed in an upward direction on account of the resistance it experiences from the air, assumes an oblique position which causes the upper surface of the wing to look forwards."