498 NOISES OF INSECTS. 
produces similar sounds. A still farther proof that these notched neryureg 
or files are the main agents in producing the sounds, is afforded by the 
facts that their notches are more distinct in newly disclosed specimens, 
especially of Acrida viridissima, than in older individuals, in which they 
have been partially obliterated by use; and that the sounds, as M, 
Goureau has remarked, may be readily produced in the dead insect by 
gently rubbing the bases of the elytra together, which could not happen if 
the rushing of the air from the spiracles had any effect in producing 
them.* 
The last description of singers that Ishall notice amongst the Locustina, 
and which includes the migratory locust, are those that are more com- 
monly denominated grasshoppers. To this genus belong the little chirpers 
that we hear in every sunny bank, and which make yocal every heath. 
They begin their song—which is a short chirp regularly interrupted, in 
which it differs from that of the Acride—long before sunrise. In the heat 
of the day it is intermitted, and resumed in the evening. This sound is 
thus produced :— Applying its posterior shank to the thigh, the animal 
rubs it briskly against the elytrum?, doing this alternately with the right 
and left legs, which causes the regular breaks in the sound. . But this is 
not their whole apparatus of song — since, like the Tettigoniz, they have 
also a tympanum or drum, De Geer, who examined the insects he de- 
scribes with the eye of an anatomist, seems to be the only entomologist that 
has noticed this organ. “On each side of the first segment of the ab-! 
domen,” says he, “immediately above the origin of the posterior thighs, 
there is a considerable and deep aperture of rather an oval form, which is 
partly closed by an irregular flat plate or operculum of a hard substance, 
but covered by a wrinkled flexible membrane. The opening left by this 
operculum is semilunar, and at the bottom of the cavity is a white pellicle 
of considerable tension, and shining like a little mirror, On that side of 
the aperture which is towards the head there is a little oval hole, into 
which the point of a pin may be introduced without resistance. When 
the pellicle is removed, a large cavity appears. In my opinion this aperture, 
cavity, and above all the membrane in tension, contribute much to produce 
and augment the sound emitted by the grasshopper.” * This description, 
which was taken from the migratory locust (L. migratoria), answers tole- 
rably well to the tympanum of our common grasshoppers; only in them 
the aperture seems to be rather semicircular, and the wrinkled plate — 
which has no marginal hairs —is clearly a continuation of the substance of 
the segment. This apparatus so much resembles the drum of the Cicada, 
that there can be little doubt as to its use. The vibrations caused by the 
friction of the thighs and elytra striking upon this drum are reverberated 
by it, and so intenseness is given to the sound. In Spain, we are told 
that people of fashion keep these animals — called there Gril/o— in cages, 
which they name Grilleria, for the sake of their song. 
I shall conclude this diatribe upon the noises of insects with a tribe that 
have long been celebrated for their musical powers: I mean the Cicadiade, 
a Burmeister, Manual of Entom. 470, Goureau, ubi supra. Newport, ubi supra, 
2 De Geer, iii. 470, 5 Ibid. 471. t. xxiii. f, 2, 3. 
4 Goureau (op. cit.) and Miller (Burmeister, Manual, 672.) regard this drum as an 
auditory organ, but probably without sufficient grounds, 
5 Osbeck’s Voy, i. 71, 
