This segment is bent at a right angle along a strong longitudinal nervure, and descends on the outer side in a flap which encloses the insect's flank when in the attitude of repose.
The right wing-cover overlaps the left.

Its inner edge carries, on the under side, near the base, a callosity from which five radiating nervures proceed; two of them upwards and two downwards, while the fifth runs approximately at right angles to these.

This last nervure, which is of a slightly reddish hue, is the fundamental element of the musical device; it is, in short, the bow, the fiddlestick, as is proved by the fine notches which run across it.

The rest of the wing-cover shows a few more nervures of less importance, which hold the membrane stretched tight, but do not form part of the friction apparatus.
The left or lower wing-cover is of similar structure, with the difference that the bow, the callosity, and the nervures occupy the upper face.

It will be found that the two bows--that is, the toothed or indented nervures--cross one another obliquely.
When the note has its full volume, the wing-covers are well raised above the body like a wide gauzy sail, only touching along the internal edges.
The two bows, the toothed nervures, engage obliquely one with the other, and their mutual friction causes the sonorous vibration of the two stretched membranes.
[Illustration: THE ITALIAN CRICKET.] The sound can be modified accordingly as the strokes of each bow bear upon the callosity, which is itself serrated or wrinkled, or on one of the four smooth radiating nervures.