The Glow-Worm and Other Beetles Part 19

Let us try the influence of danger. With what natural enemy shall I confront the big Scarites, motionless on his back? I know none. Let us then create a make-believe a.s.sailant. The Flies put me on the track of one.

I have spoken of their importunity during my investigations in the hot season. If I do not employ a bell-gla.s.s or keep an a.s.siduous watch, rarely does the shrewish Dipteron fail to alight upon my patient and explore him with her proboscis. We will let her have her way this time.

Hardly has the Fly grazed this apparent corpse with her legs, when the Scarites' tarsi quiver as though twitched by a slight electric shock.

If the visitor be merely pa.s.sing, matters go no farther; but, if she persist, particularly near the Beetle's mouth, moist with saliva and disgorged secretions of food, the tormented Scarites promptly kicks, turns over and makes off.

Perhaps he did not think it opportune to prolong his fraud in the face of so contemptible an enemy. He resumes his activity because he has recognized the absence of danger. Then let us call in another interloper, one of formidable size and strength. I happen to have handy a Great Capricorn, with powerful claws and mandibles. That the long-horned insect is a peaceful creature I am well aware; but the Scarites does not know it; on the sands of the sh.o.r.e he has never encountered such a colossus as this, who is capable of impressing less timid creatures than he. Fear of the unknown will merely aggravate the situation.

Guided by the tip of my straw, the Capricorn sets his foot upon the prostrate insect. The Scarites' tarsi begin to quiver immediately. If the contact be prolonged or multiplied, or if it become aggressive, the dead insect gets on its legs again and scuttles off, just as the t.i.tillations of the Fly have already shown me. When danger is imminent and all the more to be dreaded because its nature is unknown, the trick of the simulation of death disappears and flight takes its place.

The following experiment is not without value. I take some hard substance and knock the foot of the table on which the insect is lying on its back. The shock is very slight, not enough to shake the table perceptibly. The whole thing is limited to the inner vibrations of a resilient body which has received a blow. But it is quite enough to disturb the insect's immobility. At each tap the tarsi are flexed and quiver for a moment.

Lastly, let us try the effect of light. So far, the patient has been treated in the shade of my cabinet, away from the direct sunlight. The sun is s.h.i.+ning full upon the window. What will the motionless insect do if I carry it thither, from my table to the window, into the bright light? That we can find out in a moment. Under the direct rays of the sun, the Scarites immediately turns over and moves off.

This is enough. Patient, persecuted creature, you have half-betrayed your insect. When the Fly tickles you, drains your moist lip, treats you as a corpse whose juices she would like to suck; when the huge Capricorn appears to your horrified gaze and puts a foot on your belly, as though to take possession of his prey; when the table quivers, that is to say, when, for you, the ground shakes, undermined perhaps by some invader of your burrow; when a bright light surrounds you, favouring the designs of your enemies and imperilling your safety as an insect that loves the dark, then, in truth, it would be wiser not to move, if really your chief resource, when danger threatens you, is to simulate death.

On the contrary, at those critical moments, you give a start; you move, you resume your normal att.i.tude, you run away. Your fraud is discovered; or, to put it more plainly, there is no trick. Your inertia is not simulated; it is real. It is a condition of temporary torpor into which you are plunged by your delicate nervous organization. A mere nothing makes you fall into it; a mere nothing withdraws you from it, above all a bath of light, that sovran stimulus of activity.

In respect of prolonged immobility as the result of emotion, I find a rival of the Giant Scarites in a large black Buprestis, with a flour-speckled corselet, a lover of the blackthorn, the hawthorn and the apricot-tree. His name is _Capnodis tenebrionis_, LIN. At times I see him, with his legs closely folded and his antennae lowered, prolonging his motionless posture upon his back for more than an hour.

At other times the insect is bent upon escaping, apparently influenced by atmospheric conditions of which I do not know the secret. One or two minutes' immobility is as much as I can then obtain.

Let me recapitulate: in my various subjects the att.i.tude of death is of very variable duration, governed as it is by a host of unsuspected circ.u.mstances. Let us take advantage of favourable opportunities, which are fairly frequent. I subject the Cloudy Buprestis to the different tests undergone by the Giant Scarites. The results are the same. When you have seen the first, you have seen the second. There is no need to linger over them.

I will only mention the promptness with which the Buprestis, lying motionless in the shade, recovers his activity when I carry him away from my table into the broad sunlight of the window. After a few seconds of this bath of heat and light, the insect half-opens his wing-cases, using them as levers, and turns over, ready to take flight if my hand did not instantly snap him up. He is a pa.s.sionate lover of the light, a devotee of the sun, intoxicating himself in its rays upon the bark of his blackthorn-trees on the hottest afternoons.

This love of tropical temperature suggests the following question: what would happen if I were to chill the creature in its immobile posture? I foresee a more prolonged inertia. The chill, of course, must not be great, for it would be followed by the lethargy into which insects capable of surviving the winter fall when benumbed by the cold.

On the contrary, the Buprestis must as far as possible retain his full vitality. The lowering of the temperature must be gentle, very moderate and such that the insect, under similar climatic conditions, would retain his powers of action in ordinary life. I have a convenient refrigerator at my disposal. It is the water of my well, whose temperature, in summer, is nearly twenty-two degrees Fahrenheit below that of the surrounding air.

The Buprestis, in whom I have just produced inertia by means of a few taps, is installed on his back in a little flask which I seal hermetically and immerse in a bucket full of this cold water. To keep the bath as cool as at first, I gradually renew it, taking care not to shake the flask in which the patient is lying, in his att.i.tude of death.

The result rewards my pains. After five hours under water, the insect is still motionless. Five hours, I say, five long hours; and I might certainly say longer, if my exhausted patience had not put an end to the experiment. But this is enough to banish any idea of fraud on the insect's part. Here, beyond a doubt, the insect is not shamming dead.

He is actually somnolent, deprived of the power of movement by an internal disturbance which my teasing produced at the outset and which is prolonged beyond its usual limits by the surrounding coolness.

I try the effect of a slight decrease in temperature upon the Giant Scarites by subjecting him to a similar sojourn in the cold water of the well. The result does not respond to the hopes which the Buprestis gave me. I do not succeed in obtaining more than fifty minutes'

inertia. I have often obtained as long periods of immobility without resorting to the refrigerating artifice.

It might have been foreseen. The Buprestis, a lover of the burning suns.h.i.+ne, is affected by the cold bath in a different degree from the Scarites, who prowls about by night and spends his day in the bas.e.m.e.nt. A fall of a few degrees in temperature takes the chilly insect by surprise and has no effect upon the one accustomed to the coolness underground.

Other experiments on these lines tell me nothing more. I see the inert condition persisting sometimes for a longer, sometimes for a shorter period, according as the insect seeks the sunlight or avoids it. Let us change our method.

I evaporate a few drops of sulphuric ether in a gla.s.s jar and put in a Stercoraceous Geotrupes and a specimen of _Buprestis tenebrionis_, at the same time. In a few moments both subjects are motionless, anaesthetized by the etheric vapour. I take them out quickly and lay them on their backs in the open air.

Their att.i.tude is exactly that which they would have a.s.sumed under the influence of a shock or any other cause of alarm. The Buprestis has his legs symmetrically folded against his chest and belly; the Geotrupes has his outspread, stretched in disorder, rigid and as though attacked by catalepsy. You could not tell if they were dead or alive.

They are not dead. In a minute or two, the Geotrupes' tarsi twitch, the palpi quiver, the antennae wave gently to and fro. Then the fore-legs move; and a quarter of an hour has not elapsed before the other legs are struggling. The activity of the insect made motionless by the concussion of a shock would reawaken in precisely the same fas.h.i.+on.

As for the Buprestis, he is in a state of inertia so profound that at first I really believe him to be dead. He recovers during the night; and next day I find him in possession of his usual activity. The ether experiment, which I took care to stop at the moment when it produced the desired effect, has not been fatal to him; but it has had much more serious consequences for him than for the Geotrupes. The insect more sensitive to the alarm due to concussion or to a fall of temperature is also the more sensitive to the action of ether.

Thus the enormous difference which I observe in these two insects, with regard to the inertia provoked by a shock or by handling them in one's fingers, is explained by nice differences of impressionability.

Whereas the Buprestis remains motionless for nearly an hour, the Geotrupes is struggling violently after a minute or two. And even then I rarely attain this limit.

In what respect has the Geotrupes, to defend itself, less need of the stratagem of simulated death than the Black Buprestis, well protected by his ma.s.sive build and his armour, which is so hard that it resists the point of a pin and even of a needle? We should be perplexed by the same question in respect of a mult.i.tude of insects, some of which remain motionless while others do not; and we could not possibly foresee what would happen from the genus of the subject, its form, or its way of living.

_Buprestis tenebrionis_, for example, exhibits a persistent inertia.

Will it be the same, because of similarity of structure, with other members of the same group? Not at all. My chance finds provide me with the Brilliant Buprestis (_B. rutilans_, FAB.), and the Nine-spotted Buprestis (_Ptosima novemmaculata_, FAB.). The first resists all my attempts. The splendid creature grips my fingers, grips my tweezers and insists on getting up the moment that I lay it on its back. The second readily becomes immobile; but how brief is its att.i.tude of death! Four or five minutes at most.

A Melasoma-beetle, _Omocrates abbreviatus_, OLIV., whom I frequently discover under the broken stones on the neighbouring hills, continues motionless for over an hour. He rivals the Scarites. We must not forget to add that very often the awakening takes place within a few minutes.

Can he owe his long period of inertia to the fact that he is one of the Tenebrionidae, or Darkling Beetles? By no means, for here in the same group is _Pimelia bipunctata_, who turns a somersault on his round back and finds his feet the moment he has turned over; here is a Cellar-beetle (_Blaps similis_, LATR.), who, unable to turn with his flat back, his big belly and his welded wing-cases,[1] struggles desperately after a minute or two of inertia.

[Footnote 1: The Cellar-beetle is one of the wingless Beetles.--_Translator's Note_.]

The short-legged Beetles, trotting along with tiny steps, ought, one would think, to make up in cunning, more fully than the others, for their incapacity for rapid flight. The facts do not correspond with this apparently well-founded forecast. I have consulted the genera Chrysomela,[2] Blatta,[3] Silpha, Cleonus,[4] Bolboceras,[5] Cetonia, Hoplia, Coccinella,[6] and so on. A few minutes or a few seconds are nearly always long enough for the return to activity. Several of them even obstinately refuse to sham death.

[Footnote 2: Golden-apple Beetles.--_Translator's Note_.]

[Footnote 3: Blackbeetles or c.o.c.kroaches.--_Translator's Note_.]

[Footnote 4: A genus of Weevils.--_Translator's Note_.]

[Footnote 5: A mushroom-eating Beetle. Cf. _The Life of the Fly_: chap. xviii.--_Translator's Note_.]

[Footnote 6: Ladybirds.--_Translator's Note_.]

As much must be said of the Beetles well-equipped for pedestrian escape. Some remain motionless for a few seconds; others, more numerous still, behave in an ungovernable fas.h.i.+on. In short, there is no guide to tell us in advance:

"This one will readily a.s.sume the posture of a dead insect; this one will hesitate; that one will refuse."

There is nothing but shadowy probabilities, until experiment has given its verdict. From this muddle shall we draw a conclusion which will set our minds at rest? I hope so.

CHAPTER XV SUICIDE OR HYPNOSIS?

You do not imitate the unfamiliar; you do not counterfeit a thing of which you know nothing: that is obvious. The simulation of death, therefore, implies a certain knowledge of death.

Well, has the insect, or rather, has any kind of animal, a presentiment that its life cannot last for ever? Does the perturbing problem of an end occur to its dense brain? I have a.s.sociated a great deal with animals, I have lived on intimate terms with them and I have never observed anything to justify me in saying yes. The animal, with its humbler destiny, is spared that apprehension of the hour of death which const.i.tutes at once our torment and our greatness.

Like the child still in the limbo of unconsciousness, it enjoys the present without taking thought of the future; free from the bitterness of a prospective ending, it lives in the blissful calm of ignorance.

It is ours alone to foresee the briefness of our days; it is ours alone anxiously to question the grave regarding the last sleep.

Moreover, this glimpse of the inevitable destruction calls for a certain maturity of mind and, for that reason, is rather late in developing. I had a touching example of it this very week.

A pretty little Kitten, the joy of all the household, after languidly dragging itself about for a couple of days, died in the night. Next morning the children found it lying stark in its basket. General affliction. Anna, especially, a little girl of four, considered with a pensive glance the little friend with which she had so often played.

She petted it, called it, offered it a drop of milk in a cup: