The song consists of a Gri-i-i, Gri-i-i, a slow, gentle note, rendered more expressive by a slight tremor. Hearing it, one divines the extreme tenuity and the amplitude of the vibrating membranes. If the insect is not in any way disturbed as it sits in the low foliage, the note does not vary, but at the least noise the performer becomes a ventriloquist. First of all you hear it there, close by, in front of you, and the next moment you hear it over there, twenty yards away; the double note decreased in volume by the distance.
You go forward. Nothing is there. The sound proceeds again from its original point. But no—it is not there; it is to the left now—unless it is to the right—or behind.... Complete confusion! It is impossible to detect, by means of the ear, the direction from which the chirp really comes. Much patience and many precautions will be required before you can capture the insect by the light of the lantern. A few specimens caught under these conditions and placed in a cage have taught me the little I know concerning the musician who so perfectly deceives our ears.
The wing-covers are both formed of a dry, broad membrane, diaphanous and as fine as the white skin on the outside of an onion, which is capable of vibrating over its whole area. Their shape is that of the segment of a circle, cut away at the upper end. 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.
THE ITALIAN CRICKET.