In the other orders the examples of cries of terror are much less numerous. A bug (Cimex subapterus, De G.) when taken emits a sharp sound, probably with its rostrum, by moving its head up and down[635]. Ray makes a similar remark with respect to another bug (Reduvius personatus), the cry of which he compares to the chirping of a grasshopper[636]. Mutilla europæa, a hymenopterous insect, makes a sibilant chirping, as I once observed at Southwold, where it abounds; but how produced I cannot say. The most remarkable noise, however, proceeding from insects under alarm, is that emitted by the death's-head hawk-moth, and for which it has long been celebrated. The Lepidoptera, though some of them, as we have seen, produce a sound when they fly, at other times are usually mute insects: but this alarmist—for so it may be called, from the terrors which it has occasioned to the superstitious[637]—when it walks, and more particularly when it is confined, or taken into the hand, sends forth a strong and sharp cry, resembling that of a mouse, but more plaintive, and even lamentable, which it continues as long as it is held. This cry does not appear to be produced by the wings; for when they, as well as the thorax and abdomen, are held down, the cries of the insect become still louder. Schrœter says that the animal, when it utters its cry, rubs its tongue against its head[638]; and Rösel, that it produces it by the friction of the thorax and abdomen[639]. But Reaumur found, after the most attentive examination, that the cry came from the mouth, or rather from the tongue; and he thought that it was produced by the friction of the palpi against that organ. When, by means of a pin, he unfolded the spiral tongue, the cry ceased; but as soon as it was rolled up again between the palpi it was renewed. He next prevented the palpi from touching it, and the sound also ceased; and upon removing only one of them, though it continued, it became much more feeble[640]. Huber, however, denies that it is produced by the friction of the tongue and palpi[641]: but as he has not stated his reasons for this opinion, I think his assertion that he has ascertained this cannot be allowed to countervail Reaumur's experiments.
I must next say a few words upon the angry chidings of our little creatures; for their anger sometimes vents itself in sounds. I have often been amused with hearing the indignant tones of a humble-bee while lying upon its back. When I held my finger to it, it kicked and scolded with all its might. Hive-bees when irritated emit a shrill and peevish sound, continuing even when they are held under water, which John Hunter says vibrates at the point of contact with the air-holes at the root of their wings[642]. This sound is particularly sharp and angry when they fly at an intruder. The same sounds, or very similar ones, tell us when a wasp is offended, and we may expect to be stung;—but this passion of anger in insects is so nearly connected with their fear, that I need not enlarge further upon it.
Concerning their shouts of joy and cries of sorrow I have little to record: that pleasure or pain makes a difference in the tones of vocal insects is not improbable; but our auditory organs are not fine enough to catch all their different modulations. When Schirach had once smoked a hive to oblige the bees to retire to the top of it, the queen with some of the rest flew away. Upon this, those that remained in the hive sent forth a most plaintive sound, as if they were all deploring their loss; when their sovereign was restored to them, these lugubrious sounds were succeeded by an agreeable humming, which announced their joy at the event[643]. Huber relates, that once when all the worker-brood was removed from a hive, and only male brood left, the bees appeared in a state of extreme despondency. Assembled in clusters upon the combs, they lost all their activity. The queen dropped her eggs at random; and instead of the usual active hum, a dead silence reigned in the hive[644].
But love is the soul of song with those that may be esteemed the most musical insects, the grasshopper tribes (Gryllina and Locustina), and the long celebrated Cicada. You would suppose, perhaps, that the ladies would bear their share in these amatory strains. But here you would be mistaken—female insects are too intent upon their business, too coy and reserved to tell their love even to the winds.—The males alone
"Formosam resonare docent Amaryllida sylvas."
With respect to the Cicadæ, this was observed by Aristotle; and Pliny, as usual, has retailed it after him[645]. The observation also holds good with respect to the Gryllina, &c., and other insects, probably, whose love is musical. Olivier however has noticed an exception to this doctrine; for he relates, that in a species of beetle (Moluris striata), the female has a round granulated spot in the middle of the second segment of the abdomen, by striking which against any hard substance, she produces a rather loud sound, and that the male, obedient to this call, soon attends her, and they pair[646].
As I have nothing to communicate to you with respect to the love-songs of other insects, my further observations will be confined to the tribes lately mentioned, the Gryllina, &c. and the Cicadæ.
No sound is to me more agreeable than the chirping of most of the Gryllina, Locustina, &c.; it gives life to solitude, and always conveys to my mind the idea of a perfectly happy being. As these creatures are now very properly divided into several genera, I shall say a few words upon the song of such as are known to be vocal, separately.
The remarkable genus Pneumora—whose pellucid abdomen is blown up like a bladder, on which account they are called Blaazops by the Dutch colonists at the Cape—in the evening, for they are silent in the day, make a tremulous and tolerably loud noise, which is sometimes heard on every side[647]. The species of this genus have a much greater claim to the name of Fiddlers, than the insect lately mentioned, since their sound is produced by passing the hind-legs over a number of short transverse elevated ridges on the abdomen, which may be called their fiddle-strings[648].
The cricket tribe are a very noisy race, and their chirping is caused by the friction of the bases of their elytra against each other. For this purpose there is something peculiar in their structure, which I shall describe to you. The elytra of both sexes are divided longitudinally into two portions; a vertical or lateral one, which covers the sides; and a horizontal or dorsal one, which covers the back. In the female both these portions resemble each other in their nervures; which running obliquely in two directions, by their intersection form numerous small lozenge-shaped or rhomboidal meshes or areolets. The elytra also of these have no elevation at their base. In the males the vertical portion does not materially differ from that of the females; but in the horizontal the base of each elytrum is elevated so as to form a cavity underneath. The nervures also, which are stronger and more prominent, run here and there very irregularly with various inflexions, describing curves, spirals, and other figures difficult and tedious to describe, and producing a variety of areolets of different size and shape, but generally larger than those of the female: particularly towards the extremity of the wing you may observe a space nearly circular, surrounded by one nervure, and divided into two areolets by another[649]. The friction of the nervures of the upper or convex surface of the base of the left-hand elytrum—which is the undermost—against those of the lower or concave surface of the base of the right-hand—which is the uppermost one—will communicate vibrations to the areas of membrane, more or less intense in proportion to the rapidity of the friction, and thus produce the sound for which these creatures are noted.