Insects also, at least many of the social ones, emit peculiar noises while engaged in their various employments. If an ear be applied to a wasps or humble-bees nest, or a bee-hive, a hum more or less intense may always be perceived. Were I disposed to play upon your credulity, I might tell you, with Gœdart, that in every humble-bees nest there is a trumpeter, who early in the morning, ascending to its summit, vibrates his wings, and sounding his trumpet for the space of a quarter of an hour, rouses the inhabitants to work! But since Reaumur could never witness this, I shall not insist upon your believing it, though the relater declares that he had heard it with his ears, and seen it with his eyes, and had called many to witness the vibrating and strepent wings of this trumpeter humble-bee[614].—The blue sand-wasp (Ammophila? cyanea), which at all other times is silent, when engaged in building its cells emits a singular but pleasing sound, which may be heard at ten or twelve yards distance[615].
Some insects also are remarkable for a peculiar mode of calling, commanding, or giving an alarm. I have before mentioned the noise made by the neuters or soldiers amongst the white ants, by which they keep the labourers, who answer it by a hiss, upon the alert and to their work[616]. This noise, which is produced by striking any substance with their mandibles, Smeathman describes as a small vibrating sound, rather shriller and quicker than the ticking of a watch. It could be distinguished, he says, at the distance of three or four feet, and continued for a minute at a time with very short intervals. When any one walks in a solitary grove, where the covered ways of these insects abound, they give the alarm by a loud hissing, which is heard at every step[617].—"When house-crickets are out," says Mr. White, "and running about in a room in the night, if surprised by a candle they give two or three shrill notes, as it were for a signal to their followers, that they may escape to their crannies and lurking-holes to avoid danger[618]."
Under this head I shall consider a noise before alluded to[619], which has been a cause of alarm and terror to the superstitious in all ages. You will perceive that I am speaking of the death-watch—so called, because it emits a sound resembling the ticking of a watch, supposed to predict the death of some one of the family in the house in which it is heard. Thus sings the muse of the witty Dean of St. Patrick on this subject:
"..................A wood-worm
That lies in old wood, like a hare in her form:
With teeth or with claws it will bite or will scratch,
And chambermaids christen this worm a death-watch;
Because like a watch it always cries click;
Then woe be to those in the house who are sick!
For, sure as a gun, they will give up the ghost,
If the maggot cries click, when it scratches the post;
But a kettle of scalding hot water injected,
Infallibly cures the timber affected:
The omen is broken, the danger is over,
The maggot will die, and the sick will recover."
To add to the effect of this noise, it is said to be made only when there is a profound silence in an apartment, and every one is still.
Authors were formerly not agreed concerning the insect from which this sound of terror proceeded, some attributing it to a kind of wood-louse, as I lately observed, and others to a spider; but it is a received opinion now, adopted upon satisfactory evidence, that it is produced by some little beetles belonging to the timber-boring genus Anobium. Swammerdam observes, that a small beetle, which he had in his collection, having firmly fixed its fore legs, and put its inflexed head between them, makes a continual noise in old pieces of wood, walls, and ceilings, which is sometimes so loud, that upon hearing it, people have fancied that hobgoblins, ghosts, or fairies were wandering around them[620]. Evidently this was one of the death-watches. Latreille observed Anobium striatum produce the sound in question by a stroke of its mandibles upon the wood, which was answered by a similar noise from within it. But the species whose proceedings have been most noticed by British observers is A. tessellatum. When spring is far advanced, these insects are said to commence their ticking, which is only a call to each other, to which if no answer be returned, the animal repeats it in another place. It is thus produced. Raising itself upon its hind legs, with the body somewhat inclined, it beats its head with great force and agility upon the plane of position; and its strokes are so powerful as to make a considerable impression if they fall upon any substance softer than wood. The general number of distinct strokes in succession is from seven to nine or eleven. They follow each other quickly, and are repeated at uncertain intervals. In old houses, where these insects abound, they may be heard in warm weather during the whole day. The noise exactly resembles that produced by tapping moderately with the nail upon the table; and when familiarized, the insect will answer very readily the tap of the nail[621].
The queen bee has long been celebrated for a peculiar sound, producing the most extraordinary effects upon her subjects. Sometimes, just before bees swarm,—instead of the great hum usually heard, and even in the night,—if the ear be placed close to the mouth of the hive, a sharp clear sound may be distinguished, which appears to be produced by the vibration of the wings of a single bee. This, it has been pretended, is the harangue of the new queen to her subjects, to inspire them with courage to achieve the foundation of a new empire. But Butler gives to it a different interpretation. He asserts, that the candidate for the new throne is then with earnest entreaties, lamentations, and groans, supplicating the queen-mother of the hive to grant her permission to lead the intended colony;—that this is continued, before she can obtain her consent, for two days; when the old queen relenting gives her fiat in a fuller and stronger tone. That should the former presume to imitate the tones of the sovereign, this being the signal of revolt, she would be executed on the spot, with all whom she had seduced from their loyalty[622].—But it is time to leave fables: I shall therefore next relate to you what really takes place. You have heard how the bees detain their young queens till they are fit to lead a swarm.—I then mentioned the attitude and sound that strike the former motionless[623]. When she emits this authoritative sound, reclining her thorax against a comb, the queen stands with her wings crossed upon her back, which, without being uncrossed or further expanded, are kept in constant vibration. The tone thus produced is a very distinct kind of clicking, composed of many notes in the same key, which follow each other rapidly. This sound the queens emit before they are permitted to leave their cells; but it does not then seem to affect the bees. But when once they are liberated from confinement and assume the above attitude, its effects upon them are very remarkable. As soon as the sound was heard, Huber tells us, bees that had been employed in plucking, biting, and chasing a queen about, hung down their heads and remained altogether motionless; and whenever she had recourse to this attitude and sound, they operated upon them in the same manner. The writer just mentioned observed differences both with regard to the succession and intensity of the notes and tones of this royal song; and, as he justly remarks, there may be still finer shades which, escaping our organs, may be distinctly perceived by the bees[624]. He seems however to doubt by what means this sound is produced. Reasoning analogically, the motion of the wings should occasion it. We have seen that they are in constant motion when it is uttered. Probably the intensity of the tones and their succession are regulated by the intensity of the vibrations of the wings. Reaumur remarks, that the different tones of the bees, whether more or less grave or acute, are produced by the strokes, more or less rapid, of their wings against the air, and that perhaps their different angles of inclination may vary the sound. The friction of their bases likewise against the sides of the cavity in which they are inserted, as in the case of the fly lately mentioned, or against the base-covers (Tegulæ), may produce or modulate their sounds, a bee whose wings are eradicated being perfectly mute[625]. This last assertion, however, is contradicted by John Hunter, who affirms that bees produce a noise independent of their wings, emitting a shrill and peevish sound though they are cut off, and the legs held fast[626]. Yet it does not appear from his experiment that the wings were eradicated. And if they were only cut off, the friction of their base might cause the sound. I have before noticed the remarkable fact, that the queens educated according to M. Schirach's method are absolutely mute; on which account the bees keep no guard around their cells, nor retain them an instant in them after their transformation[627].
The passions, also, which urge us to various exclamations, elicit from insects occasionally certain sounds. Fear, anger, sorrow, joy, or love and desire, they express in particular instances by particular noises. I shall begin with those which they emit when under any alarm. One larva only is recorded as uttering a cry of alarm, and it produces a perfect insect remarkable for the same faculty: I allude to Acherontia Atropos. Its caterpillar, if disturbed at all, draws back rapidly, making at the same time a rather loud noise, which has been compared to the crack of an electric spark[628].—You would scarcely think that any quiescent pupæ could show their fears by a sound,—yet in one instance this appears to be the case. De Geer having made a small incision in the cocoon of a moth, which included that of its parasite Ichneumon (I. Cantator, De G.), the insect concealed within the latter uttered a little cry, similar to the chirping of a small grasshopper, continuing it for a long time together. The sound was produced by the friction of its body against the elastic substance of its own cocoon, and was easily imitated by rubbing a knife against its surface[629].
But to come to perfect insects. Many beetles when taken show their alarm by the emission of a shrill, sibilant, or creaking sound—which some compare to the chirping of young birds—produced by rubbing their elytra with the extremity of their abdomen. This is the case with the dung-chafers (Geotrupes vernalis, stercorarius, and Copris lunaris); with the carrion-chafer (Trox sabulosus); and others of the lamellicorn beetles. The burying-beetle (Necrophorus Vespillo), Lema melanopa and merdigera, and Hygrobia Hermanni, and many other Coleoptera, produce a similar noise by the same means. When this noise is made, the movement of the abdomen may be perceived; and if a pin is introduced under the elytra it ceases. Long after many of these insects are dead the noise may be caused by pressure. Rösel found this with respect to the Scarabæidæ[630], and I have repeated the experiment with success upon Necrophorus Vespillo. The capricorn tribes (Prionus, Lamia, Cerambyx, &c.) emit under alarm an acute or creaking sound—which Lister calls querulous, and Dumeril compares to the braying of an ass[631]—by the friction of the thorax, which they alternately elevate and depress, against the neck, and sometimes against the base of the elytra[632]. On account of this, Prionus coriarius, is called the fiddler in Germany[633]. Two other coleopterous genera, Cychrus and Clytus, make their cry of Noli me tangere by rubbing their thorax against the base of the elytra. Pimelia, another beetle, does the same by the friction of its legs against each other[634]. And, doubtless, many more Coleoptera, if observed, would be found to express their fears by similar means.