LETTER XXIV.

_ON THE NOISES PRODUCED BY INSECTS._

That insects, though they fill the air with a variety of sounds, have no _voice_, may seem to you a paradox, and you may be tempted to exclaim with the Roman naturalist, What, amidst this incessant diurnal hum of bees; this evening boom of beetles; this nocturnal buz of gnats; this merry chirp of crickets and grasshoppers; this deafening drum of Cicadæ, have insects no voice! If by voice we understand sounds produced by the air expelled from the lungs, which, passing through the larynx, is modified by the tongue, and emitted from the mouth,--it is even so. For no insect, like the larger animals, uses its mouth for utterance of any kind: in this respect they are all perfectly mute; and though incessantly noisy, are everlastingly silent. Of this fact the Stagyrite was not ignorant, since, denying them a voice, he attributes the sounds emitted by insects to another cause. But if we feel disposed to give a larger extent to this word; if we are of opinion that all sounds, however produced, by means of which animals determine those of their own species to certain actions, merit the name of voice; then I will grant that insects have a voice. But, decide this question as we will, we all know that by some means or other, at certain seasons and on various occasions, these little creatures make a great din in the world. I must therefore now bespeak your attention to this department of their history.

In discussing this subject, I shall consider the noises insects emit--during their motions--when they are feeding, or otherwise employed--when they are calling or commanding--or when they are under the influence of the passions; of fear, of anger, of sorrow, joy, or love.

The only kind of _locomotion_ during which these animals produce sounds, is flying: for though the hill-ants (_Formica rufa_), as I formerly observed[600], make a rustling noise with their feet when walking over dry leaves, I know of no other insect the tread of which is accompanied by sound--except indeed the flea, whose steps, a lady assures me, she always hears when it paces over her night-cap, and that it clicks as if it was walking in pattens! That the flight of numbers of insects is attended by a humming or booming is known to almost every one; but that the great majority move through the air in silence, has not perhaps been so often observed. Generally speaking, those that fly with the most force and rapidity, and with wings seemingly motionless, make the most noise; while those that fly gently and leisurely, and visibly fan the air with their wings, yield little or no sound.

Amongst the beetle tribes (_Coleoptera_), none is more noticed, or more celebrated for "wheeling its droning flight," than the common dung-chafer (_Geotrupes stercorarius_) and its affinities. Linné affirms--but the prognostic sometimes fails--that when these insects fly in numbers, it indicates a subsequent fine day[601]. The truth is, they only fly in fine weather. Mr. White has remarked, that in the dusk of the evening beetles begin to buz, and that partridges begin to call exactly at the same time[602]. The common cock chafer, and that which appears at the summer solstice (_Melolontha vulgaris_ and _Amphimalla solstitialis_), when they hover over the summits of trees in numbers, produce a hum somewhat resembling that of bees swarming. Perhaps some insect of this kind may occasion the humming in the air mentioned by Mr. White, and which you and I have often heard in other places. "There is," says he, "a natural occurrence to be met with in the highest part of our down on the hot summer days, which always amuses me much, without giving me any satisfaction with respect to the cause of it;--and that is a loud audible humming of bees in the air, though not one insect is to be seen.--Any person would suppose that a large swarm of bees was in motion, and playing about over his head[603]."

"Resounds the living surface of the ground-- Nor undelightful is the ceaseless hum To him who muses through the woods at noon, Or drowsy shepherd as he lies reclined."

The hotter the weather, the higher insects will soar; and it is not improbable that the sound produced by numbers may be heard, when those that produce it are out of sight.--The burying-beetle (_Necrophorus Vespillo_), whose singular history[604] so much amused you, as well as _Cicindela sylvatica_ of the same order, flies likewise, as I have more than once witnessed, with a considerable hum.

Whether the innumerable locust armies, to which I have so often called your attention, make any noise in their flight, I have not been able to ascertain; the mere impulse of the wings of myriads and myriads of these creatures upon the air, must, one would think, produce some sound. In the symbolical locusts mentioned in the Apocalypse[605], this is compared to the sound of chariots rushing to battle: an illustration which the inspired author of that book would scarcely have had recourse to, if the real locusts winged their way in silence.

Amongst the _Hemiptera_, I know only a single species that is of noisy flight; though doubtless, were the attention of entomologists directed to that object, others would be found exhibiting the same peculiarity. The insect I allude to (_Coreus marginatus_) is one of the numerous tribe of bugs; when flying, especially when hovering together in a sunny sheltered spot, they emit a hum as loud as that of the hive-bee.

From the magnitude and strength of their wings, it might be supposed that many _lepidopterous_ insects would not be silent in their flight;--and indeed many of the hawk-moths (_Sphinx_, F.), and some of the larger moths (_Bombyx_, F.), are not so; _Cossus ligniperda_, for instance, is said to emulate the booming of beetles by means of its large stiff wings; whence in Germany it is called the humming-bird (_Brumm-Vogel_).--But the great body of these numerous tribes, even those that fan the air with "sail-broad vans," produce little or no sound by their motion. I must therefore leave them, as well as the _Trichoptera_ and _Neuroptera_, which are equally barren of insects of sounding wing--and proceed to an order, the _Hymenoptera_, in which the insects that compose it are, many of them, of more fame for this property.

The indefatigable hive-bee, as she flies from flower to flower, amuses the observer with her hum, which, though monotonous, pleases by exciting the idea of happy industry, that wiles the toils of labour with a song. When she alights upon a flower, and is engaged in collecting its sweets, her hum ceases; but it is resumed again the moment that she leaves it.--The wasp and hornet also are strenuous hummers; and when they enter our apartments, their hum often brings terror with it. But the most sonorous fliers of this order are the larger humble-bees, whose _bombination_, _booming_, or _bombing_, may be heard from a considerable distance, gradually increasing as the animal approaches you, and when, in its wheeling flight, it rudely passes close to your ear, almost stunning you by its sharp, shrill, and deafening sound. Many genera, however, of this order fly silently.

But the noisiest wings belong to insects of the _dipterous_ order, a majority of which, probably, give notice of their approach by the sound of their trumpets. Most of those, however, that have a slender body,--the gnat genus (_Culex_) excepted,--explore the air in silence. Of this description are the _Tipulariæ_, the _Asilidæ_, the genus _Empis_, and their affinities. The rest are more or less insects of a humming flight; and with respect to many of them, their hum is a sound of terror and dismay to those who hear it. To man, the trumpet of the gnat or mosquito; and to beasts, that of the gad-fly; of various kinds of horse-flies; and of the Ethiopian zimb, as I have before related at large[606], is the signal of intolerable annoyance. Homer, in his _Batrachomyomachia_, long ago celebrated the first of these as a trumpeter--

"For their sonorous trumpets far renown'd, Of battle the dire charge mosquitos sound."

Mr. Pope, in his translation, with his usual inaccuracy, thinking no doubt to improve upon his author, has turned the old bard's gnats into hornets. In Guiana these animals are distinguished by a name still more tremendous, being called the devil's trumpeters[607]. I have observed that early in the spring, before their thirst for blood seizes them, gnats when flying emit no sound. At this moment (Feb. 18) two females are flying about my windows in perfect silence.

After this short account of insects that give notice when they are upon the wing by the sounds that precede them, I must inquire by what means these sounds are produced. Ordinarily, except perhaps in the case of the gnat, they seem perfectly independent of the will of the animal; and in almost every instance, the sole instruments that cause the noise of flying insects are their wings, or some parts near to them, which, by their friction against the trunk, occasion a vibration--as the fingers upon the strings of a guitar--yielding a sound more or less acute in proportion to the rapidity of their flight--the action of the air perhaps upon these organs giving it some modifications. Whether, in the beetles that fly with noise, the elytra contribute more or less to produce it, seems not to have been clearly ascertained: yet, since they fly with force as well as velocity, the action of the air may cause some motion in them, enough to occasion friction. With respect to _Diptera_, Latreille contends that the noise of flies on the wing cannot be the result of friction, because their wings are then expanded; but though to us flies seem to sail through the air without moving these organs, yet they are doubtless all the while in motion, though too rapid for the eye to perceive it. When the aphidivorous flies are hovering, the vertical play of their wings, though very rapid, is easily seen; but when they fly off it is no longer visible. Repeated experiments have been tried to ascertain the cause of sound in this tribe, but it should seem with different results. De Geer, whose observations were made upon one of the flies just mentioned, appears to have proved that, in the insect he examined, the sounds were produced by the friction of the root or base of the wings against the sides of the cavity in which they are inserted. To be convinced of this, he affirms, the observer has nothing to do but to hold each wing with the finger and thumb, and stretching them out, taking care not to hurt the animal, in opposite directions, thus to prevent their motion,--and immediately all sound will cease. For further satisfaction he made the following experiment. He first cut off the wings of one of these flies very near the base; but finding that it still continued to buz as before, he thought that the winglets and poisers, which he remarked were in a constant vibration, might occasion the sound. Upon this, cutting both off, he examined the mutilated fly with a microscope, and found that the remaining fragments of the wings were in constant motion all the time that the buzzing continued; but that upon pulling them up by the roots all sound ceased[608]. Shelver's experiments, noticed in my last letter, go to prove, with respect to the insects that he examined, that the winglets are more particularly concerned with the buzzing. Upon cutting off the wings of a fly--but he does not state that he pulled them up by the roots--he found the sound continued. He next cut off the poisers--the buzzing went on. This experiment was repeated eighteen times with the same result. Lastly, when he took off the winglets, either wholly or partially, the buzzing ceased. This, however, if correct, can only be a cause of this noise in the insects that have winglets. Numbers have them not. He next, therefore, cut off the poisers of a crane-fly (_Tipula crocata_), and found that it buzzed when it moved the wing. He cut off half the latter, yet still the sound continued; but when he had cut off the whole of these organs the sound entirely ceased[609].

Aristophanes in his _Clouds_, deriding Socrates, introduces Chærephon as asking that philosopher whether gnats made their buz with their mouth or their tail[610]. Upon which Mouffet very gravely observes, that the sound of one of these insects approaching is much more acute than that of one retiring; from whence he very sapiently concludes, that not the tail but the mouth must be their organ of sound[611]. But after all, the friction of the base of the wings against the thorax seems to be the sole cause of the alarming buz of the gnat as well as that of other _Diptera_. The warmer the weather, the greater is their thirst for blood, the more forcible their flight, the motion of their wings more rapid, and the sound produced by that motion more intense. In the night--but perhaps this may arise from the universal stillness that then reigns--their hum appears louder than in the day: whence its tones may seem to be modified by the will of the animal.

Sounds also are sometimes emitted by insects when they are _feeding_ or otherwise _employed_. The action of the jaws of a large number of cockchafers produces a noise resembling the sawing of timber; that of the locusts has been compared to the crackling of a flame of fire driven by the wind; indeed the collision at the same instant of myriads of millions of their powerful jaws must be attended by a considerable sound. The timber-borers also--the _Buprestes_; the stag-horn beetles; and particularly the capricorn-beetles--the mandibles of whose larvæ resemble a pair of mill-stones[612]--most probably do not feed in silence. A little wood-louse (_Atropos pulsatoria_)--which on that account has been confounded with the death-watch--is said also, when so engaged, to emit a ticking noise.--Certain two-winged flies seen in spring, distinguished by a very long proboscis (_Bombylius_), hum all the time that they suck the honey from the flowers; as do also many hawk-moths, particularly that called from this circumstance the humming-bird (_Macroglossa Stellatarum_), which, while it hovers over them, unfolding its long tongue, pilfers their sweets without interrupting its song.--The giant cock-roach (_Blatta gigantea_), which abounds in old timber houses in the warmer parts of the world, makes a noise when the family are asleep like a pretty smart rapping with the knuckles--three or four sometimes appearing to answer each other.--On this account in the West Indies it is called the _Drummer_; and they sometimes beat such a reveille, that only good sleepers can rest for them[613]. As the animals of this genus generally come forth in the night for the purpose of feeding, this noise is probably connected with that subject.

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.

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.

The merry inhabitant of our dwellings, the house-cricket (_Gryllus domesticus_), though it is often heard by day, is most noisy in the night. As soon as it grows dusk, its shrill note increases till it becomes quite an annoyance, and interrupts conversation. When the male sings, he elevates the elytra so as to form an acute angle with the body, and then rubs them against each other by a horizontal and very brisk motion[650]. The learned Scaliger is said to have been particularly delighted with the chirping of these animals, and was accustomed to keep them in a box for his amusement. We are told that they have been sold in Africa at a high price, and employed to procure sleep[651]. If they could be used to supply the place of laudanum, and lull the restlessness of busy thought in this country, the exchange would be beneficial. Like many other noisy persons, crickets like to hear nobody louder than themselves. Ledelius relates that a woman, who had tried in vain every method she could think of to banish them from her house, at last got rid of them by the noise made by drums and trumpets, which she had procured to entertain her guests at a wedding. They instantly forsook the house, and she heard of them no more[652].

The field-cricket (_Gryllus campestris_) makes a shrilling noise--still more sonorous than that of the house-cricket--which may be heard at a great distance. Mouffet tells us, that their sound may be imitated by rubbing their elytra, after they are taken off, against each other[653]. "Sounds," says Mr. White, "do not always give us pleasure according to their sweetness and melody; nor do harsh sounds always displease.--Thus the shrilling of the field-cricket, though sharp and stridulous, yet marvellously delights some hearers, filling their minds with a train of summer ideas of every thing that is rural, verdurous, and joyous." One of these crickets when confined in a paper cage and set in the sun, and supplied with plants moistened with water--for if they are not wetted it will die--will feed, and thrive, and become so merry and loud, as to be irksome in the same room where a person is sitting[654].

Having never seen a female of that extraordinary animal the mole-cricket (_Gryllotalpa vulgaris_), I cannot say what difference obtains in the reticulation of the elytra of the two sexes. The male varies in this respect from the other male crickets, for they have no circular area, nor do the nervures run so irregularly; the areolets, however, toward their base are large, with very tense membrane. The base itself also is scarcely at all elevated. Circumstances these, which demonstrate the propriety of considering them distinct from the other crickets. This creature is not however mute. Where they abound they may be heard about the middle of April singing their love-ditty in a low, dull, jarring, uninterrupted note, not unlike that of the goat-sucker (_Caprimulgus europæus_), but more inward[655]. I remember once tracing one by its shrilling to the very hole, under a stone, in the bank of my canal, in which it was concealed.

Another tribe of grasshoppers (_Acrida_, _Pterophylla_, &c.[656])--the females of which are distinguished by their long ensiform ovipositor--like the crickets, make their noise by the friction of the base of their elytra. And the chirping they thus produce is long, and seldom interrupted, which distinguishes it from that of the common grasshoppers (_Locusta_). What is remarkable, the grasshopper lark (_Sylvia locustella_), which preys upon them, makes a similar noise. Professor Lichtenstein in the _Linnean Transactions_ has called the attention of naturalists to the eye-like area in the right wing of the males of this genus[657]; but he seems not to have been aware that De Geer had noticed it before him as a sexual character; who also, with good reason, supposes it to assist these animals in the sounds they produce. Speaking of _Acrida viridissima_--common with us--he says, "In our male grasshoppers, in that part of the right elytrum which is folded horizontally over the trunk, there is a round plate made of very fine transparent membrane, resembling a little mirror or piece of talc, of the tension of a drum. This membrane is surrounded by a strong and prominent nervure, and is concealed under the fold of the left elytrum, which has also several prominent nervures answering to the margin of the membrane or ocellus. There is," he further remarks, "every reason to believe that the brisk movement with which the grasshopper rubs these nervures against each other, produces a vibration in the membrane augmenting the sound. The males in question sing continually in the hedges and trees during the months of July and August, especially towards sun-set and part of the night. When any one approaches they immediately cease their song[658]."

The last description of singers that I shall notice amongst the _Locustina_, and which includes the migratory locust, are those that are more commonly denominated grasshoppers. To this genus belong the little chirpers that we hear in every sunny bank, and which make vocal every heath. They begin their song--which is a short chirp regularly interrupted, in which it differs from that of the _Acridæ_--long before sun-rise. 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[659], 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 Tettigoniæ, they have also a tympanum or drum. De Geer, who examined the insects he describes 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 abdomen," 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 semi-lunar, 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[660]." This description, which was taken from the migratory locust (_L. migratoria_), answers tolerably 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 Cicadæ, 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 _Grillo_--in cages, which they name _Grilleria_, for the sake of their song[661].

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 _Cicadiadæ_, including the genera _Fulgora_, _Cicada_, _Tettix_, and _Tettigonia_[662]. The _Fulgoræ_ appear to be night-singers, while the _Cicadæ_ sing usually in the day. The great lantern-fly (_Fulgora laternaria_), from its noise in the evening--nearly resembling the sound of a cymbal, or razor-grinder when at work--is called _Scare-sleep_ by the Dutch in Guiana. It begins regularly at sun-set[663]. Perhaps an insect mentioned by Ligon as making a great noise in the night in Barbadoes, may belong to this tribe. "There is a kind of animal in the woods," says he, "that I never saw, which lie all day in holes and hollow trees, and as soon as the sun is down begin their tunes, which are neither singing nor crying, but the shrillest voices I ever heard: nothing can be so nearly resembled to it as the mouths of a pack of small beagles at a distance; and so lively and chirping the noise is, as nothing can be more delightful to the ears, if there were not too much of it; for the music hath no intermission till morning, and then all is husht[664]."

The species of the other genus, _Cicada_, called by the ancient Greeks--by whom they were often kept in cages for the sake of their song--_Tettix_, seem to have been the favourites of every Grecian bard from Homer and Hesiod to Anacreon and Theocritus. Supposed to be perfectly harmless, and to live only upon the dew, they were addressed by the most endearing epithets, and were regarded as all but divine. One bard entreats the shepherds to spare the innoxious Tettix, that nightingale of the Nymphs, and to make those mischievous birds the thrush and blackbird their prey. Sweet prophet of the summer, says Anacreon, addressing this insect, the Muses love thee, Phœbus himself loves thee, and has given thee a shrill song; old age does not wear thee out; thou art wise, earth-born, musical, impassive, without blood; thou art almost like a god[665]. So attached were the Athenians to these insects, that they were accustomed to fasten golden images of them in their hair, implying at the same time a boast that they themselves, as well as the Cicadæ, were _Terræ filii_. They were regarded indeed by all as the happiest as well as the most innocent of animals--not, we will suppose, for the reason given by the saucy Rhodian Xenarchus, when he says,

"Happy the Cicadas' lives, Since they all have voiceless wives."

If the Grecian _Tettix_ or _Cicada_ had been distinguished by a harsh and deafening note, like those of some other countries, it would hardly have been an object of such affection. That it was not, is clearly proved by the connexion which was supposed to exist between it and music. Thus the sound of this insect and of the harp were called by one and the same name[666]. A Cicada sitting upon a harp was a usual emblem of the science of music, which was thus accounted for:--When two rival musicians, Eunomus and Ariston, were contending upon that instrument, a Cicada flying to the former and sitting upon his harp, supplied the place of a broken string, and so secured to him the victory[667]. To excel this animal in singing seems to have been the highest commendation of a singer; and even the eloquence of Plato was not thought to suffer by a comparison with it[668]. At Surinam the noise of the _Cicada Tibicen_ is still supposed so much to resemble the sound of a harp or lyre, that they are called there harpers (_Lierman_)[669]. Whether the Grecian Cicadæ maintain at present their ancient character for music, travellers do not tell us.

Those of other countries, however, have been held in less estimation for their powers of song; or rather have been execrated for the deafening din that they produce. Virgil accuses those of Italy of bursting the very shrubs with their noise[670]; and Sir J. E. Smith observes that this species, which is very common, makes a most disagreeable dull chirping[671]. Another, _Cicada septendecim_--which fortunately, as its name imports, appears only once in seventeen years--makes such a continual din from morning to evening that people cannot hear each other speak. They appear in Pennsylvania in incredible numbers in the middle of May[672].--"In the hotter months of summer," says Dr. Shaw, "especially from midday to the middle of the afternoon, the Cicada, τεττιξ, or grasshopper, as we falsely translate it, is perpetually stunning our ears with its most excessively shrill and ungrateful noise. It is in this respect the most troublesome and impertinent of insects, perching upon a twig and squalling sometimes two or three hours without ceasing; thereby too often disturbing the studies, or short repose that is frequently indulged, in these hot climates, at those hours. The τεττιξ of the Greeks must have had a quite different voice, more soft surely and melodious; otherwise the fine orators of Homer, who are compared to it, can be looked upon no better than loud loquacious scolds[673]."--An insect of this tribe, and I am told a very noisy one, has been found by Mr. Daniel Bydder, before mentioned, in the New Forest, Hampshire. Previously to this it was not thought that any of these insect musicians were natives of the British Isles.--Captain Hancock informs me that the Brazilian Cicadæ sing so loud as to be heard at the distance of a mile. This is as if a man of ordinary stature, supposing his powers of voice increased in the ratio of his size, could be heard all over the world. So that Stentor himself becomes a mute when compared with these insects.

You feel very curious, doubtless, to know by what means these little animals are enabled to emit such prodigious sounds. I have lately mentioned to you the drum of certain grasshoppers; this, however, appears to be an organ of a very simple structure; but since it is essential to the economy of the Cicadæ that their males should so much exceed all other insects in the loudness of their tones, they are furnished with a much more complex, and indeed most wonderful, apparatus, which I shall now describe. If you look at the underside of the body of a male, the first thing that will strike you is a pair of large plates of an irregular form--in some semi-oval, in others triangular, in others again a segment of a circle of greater or less diameter--covering the anterior part of the belly, and fixed to the trunk between the abdomen and the hind legs[674]. These are the drum-covers or opercula, from beneath which the sound issues. At the base of the posterior legs, just above each operculum, there is a small pointed triangular process (_pessellum_)[675], the object of which, as Reaumur supposes, is to prevent them from being too much elevated. When an operculum is removed, beneath it you will find on the exterior side a hollow cavity, with a mouth somewhat linear, which seems to open into the interior of the abdomen[676]: next to this, on the inner side, is another large cavity of an irregular shape, the bottom of which is divided into three portions; of these the posterior is lined obliquely with a beautiful membrane, which is very tense--in some species semi-opake, and in others transparent--and reflects all the colours of the rainbow. This mirror is not the real organ of sound, but is supposed to modulate it[677]. The middle portion is occupied by a plate of a horny substance, placed horizontally and forming the bottom of the cavity. On its inner side this plate terminates in a carina or elevated ridge, common to both drums[678]. Between the plate and the after-breast (_postpectus_) another membrane, folded transversely, fills an oblique, oblong, or semi-lunar cavity[679]. In some species I have seen this membrane in tension--probably the insect can stretch or relax it at its pleasure. But even all this apparatus is insufficient to produce the sound of these animals;--one still more important and curious yet remains to be described. This organ can only be discovered by dissection. A portion of the first and second segments being removed from that side of the back of the abdomen which answers to the drums, two bundles of muscles meeting each other in an acute angle, attached to a place opposite to the point of the mucro of the first ventral segment of the abdomen, will appear[680]. In Reaumur's specimens these bundles of muscles seem to have been cylindrical; but in one I dissected (_Cicada capensis_) they were tubiform, the end to which the true drum is attached being dilated[681]. These bundles consist of a prodigious number of muscular fibres applied to each other, but easily separable. Whilst Reaumur was examining one of these, pulling it from its place with a pin, he let it go again, and immediately, though the animal had been long dead, the usual sound was emitted. On each side of the drum-cavities, when the opercula are removed, another cavity of a lunulate shape, opening into the interior of the abdomen, is observable[682]. In this is the true drum, the principal organ of sound, and its aperture is to the Cicada what our larynx is to us. If these creatures are unable themselves to modulate their sounds, here are parts enough to do it for them: for the mirrors, the membranes, and the central portions, with their cavities, all assist in it. In the cavity last described, if you remove the lateral part of the first dorsal segment of the abdomen, you will discover a semi-opaque and nearly semicircular concavo-convex membrane with transverse folds--this is the drum[683]. Each bundle of muscles, before mentioned, is terminated by a tendinous plate nearly circular, from which issue several little tendons that, forming a thread, pass through an aperture in the horny piece that supports the drum, and are attached to its under or concave surface. Thus the bundle of muscles being alternately and briskly relaxed and contracted, will by its play draw in and let out the drum: so that its convex surface being thus rendered concave when pulled in, when let out a sound will be produced by the effort to recover its convexity; which, striking upon the mirror and other membranes before it escapes from under the operculum, will be modulated and augmented by them[684]. I should imagine that the muscular bundles are extended and contracted by the alternate approach and recession of the trunk and abdomen to and from each other.

And now, my friend, what adorable wisdom, what consummate art and skill are displayed in the admirable contrivance and complex structure of this wonderful, this unparalleled apparatus! The GREAT CREATOR has placed in these insects an organ for producing and emitting sounds, which in the intricacy of its construction seems to resemble that which he has given to man, and the larger animals, for receiving them. Here is a _cochlea_; a _meatus_; and, as it should seem, more than one _tympanum_.

I am, &c.

FOOTNOTES:

[600] See above, p. 98.

[601] _Syst. Nat._ 550. 42.

[602] _Nat. Hist._ ii. 254.

[603] White, _Nat. Hist._ ii. 256.

[604] VOL. I. 352--.

[605] Rev. ix. 9.

[606] VOL. I. 113. 146--.

[607] Stedman's _Surinam_, i. 24.

[608] De Geer, vi. 13.

[609] Wiedemann's _Archiv._ ii. 210. 217.

[610] _Act._ i. _Sc._ 2.

[611] Mouffet, 81.

[612] _Linn. Trans._ v. 255. _t._ xii. _f._ 7. b.

[613] Drury's _Insects_, iii. Preface.

[614] Lister's _Gœdart_, 244--. Compare Reaum. vi. 30.

[615] Bingley, _Animal Biogr._ iii. 1st Ed. 335.

[616] See above, p. 41.

[617] _Philos. Trans._ 1781. 48. 38.

[618] _Nat. Hist._ ii. 262.

[619] VOL. I. p. 36.

[620] _Bibl. Nat._ Ed. Hill, i. 125.

[621] Shaw's _Nat. Misc._ iii. 104. _Phil. Trans._ xxxiii. 159. Compare Dumeril _Traité Element_. ii. 91. n. 694.

[622] Reaum. v. 615. Butler's _Female Monarchy_, c. v. § 4.

[623] See above, p. 147.

[624] Huber, i. 260. ii. 292--.

[625] Reaum. v. 617.

[626] _Philos. Trans._ 1792.

[627] Huber, i. 292--.

[628] Fuessl. _Archiv._ 8. 10.

[629] De Geer, vii. 594.

[630] Rösel, II. 208.

[631] Rai. _Hist. Ins._ 384. Dumeril, _Trait. Element._ ii. 100. n. 17.

[632] De Geer, v. 58. 69. Rösel, II. iii. 5.

[633] Rösel, ibid.

[634] Latr. _Hist. Nat._ x. 264.

[635] De Geer, iii. 289.

[636] _Hist. Ins._ 56.

[637] VOL. I. 34.

[638] _Naturforscher_ Stk. xxi. 77.

[639] III. 16.

[640] Reaum. ii. 290--.

[641] _Nouv. Obs._ ii. 300, note *.

[642] In _Philos. Trans._ 1792.

[643] Schirach, 73--.

[644] i. 226--.

[645] Aristot. _Hist. Anim._ l. v. c. 30. Plin. _Hist. Nat._ l. xi. c. 26.

[646] Oliv. _Entomol._ i. Pref. ix.

[647] Sparrman, _Voy._ i. 312.

[648] PLATE XXIX. FIG. 13.

[649] Compare De Geer, iii. 512.

[650] De Geer, iii. 517. See also White, _Nat. Hist._ ii. 76;--and Rai. _Hist. Ins._ 63.

[651] Mouffet, 136.

[652] Goldsmith's _Animat. Nat._ vi. 28.

[653] _Ins. Theatr._ 134.

[654] _Nat. Hist._ ii. 73.

[655] _Nat. Hist._ ii. 81.

[656] See Kirby in _Zool. Journ._ p. iv. 429--.

[657] _Linn. Trans._ iv. 51--.

[658] De Greer, iii. 429.

[659] Ibid. 470.

[660] De Geer, iii. 471. _t._ xxiii. _f._ 2. 3.

[661] Osbeck's _Voy._ i. 71.

[662] _Zoolog. Journ._ n. iv. 429--.

[663] Stedman's _Surinam_, ii. 37.

[664] _Hist. of Barbadoes_, 65.

[665] _Epigramm. Delect._ 45. 234.

[666] Gr. τερετισμα.

[667] Mouffet, _Theatr._ 130.

[668] Ἡδνεπους Πλατων, και τεττιξιν ισολαλος.

[669] Merian _Surinam_. 49.

[670] Et cantu querulæ rumpent arbusta cicadæ. _Georg._ iii. 328.

[671] Smith's _Tour_, iii. 95.

[672] Collinson in _Philos. Trans._ 1763. Stoll, _Cigales_, 26.

[673] _Travels_, 2d Ed. 186.

[674] PLATE VIII. FIG. 18. _c._ †. Reaum. v. _t._ xvi. _f._ 5. u u.

[675] PLATE VIII. FIG. 18. _q´´´_. Reaum. _ubi supra_, _t._ xvi. _f._ 11. _b._

[676] Reaum. ibid. _f._ 3. _l l._

[677] Ibid. _ubi supra_, _f._ 3. m m.

[678] Ibid. _q. q. c._

[679] Ibid. _n. n._

[680] Reaum. _ubi supr._ _f._ 6. _f f._

[681] Ibid. _f._ 9. _f f._ PLATE VIII. FIG. 19. C´´.

[682] Reaum. _f._ 3. _l._

[683] Ibid. _f._ 6. _t t. f._ 9.

[684] PLATE VIII. FIG. 19. The figure given in this plate does not show the drums clearly; but the principal object of it was to exhibit the bundles of muscles, which are of a different form from those in Reaumur's figures; they are represented at _C´´. C´´._ in connection with the drums. The mirror is the part directly beneath these bundles.