THE SIMULATION OF DEATH
The first insect that we will put to the question is that audacious
disemboweller, the savage Scarites. To provoke his state of inertia is
a very simple matter: I handle him for a moment, rolling him between
my fingers; better still, I drop him on the table, twice or thrice in
succession, from a small height. When the shock due to the fall has
been administered and, if need be, repeated, I turn the insect on its
back.
This is enough: the prostrate Beetle no longer stirs, lies as though
dead. The legs are folded on the belly, the antennae extended like the
arms of a cross, the pincers open. A watch beside me tells me the
exact minute of the beginning and the end of the experiment. Nothing
remains but to wait and especially to arm one's self with patience,
for the insect's immobility lasts long enough to become tedious to the
observer watching for something to happen.
The duration of the lifeless posture varies greatly on the same day,
under the same atmospheric conditions and with the same subject,
though I cannot fathom the causes which shorten or lengthen it. How to
investigate the external influences, so numerous and often so slight,
which intervene in such a case; above all, how to scrutinize the
insect's private impressions: these are impenetrable mysteries. Let us
confine ourselves to recording the results.
Immobility continues fairly often for as long as fifty minutes; in
certain cases, even, it lasts more than an hour. The most frequent
length of time averages twenty minutes. If nothing disturbs the
Beetle, if I cover him with a glass shade, protecting him from the
Flies, who are importunate visitors in the hot weather prevailing at
the time of my experiment, the inertia is complete: not a quiver of
the tarsi, nor of the palpi, nor of the antennae. Here indeed is a
simulacrum of death, with all its inertia.
At last the apparently deceased comes back to life. The tarsi quiver,
those of the fore-legs first; the palpi and the antennae move slowly
to and fro: this is the prelude to the awakening. Now the legs begin
to kick. The insect bends slightly at its pinched waist; it buttresses
itself on its head and back; it turns over. There it goes, jogging
away, ready to become an apparent corpse once more if I renew my shock
tactics.
Let us repeat the experiment immediately. The newly resuscitated
Beetle is for a second time lying motionless on his back. He prolongs
his make-believe of death longer than he did at first. When he wakes
up, I renew the test a third, a fourth, a fifth time, with no
intervals of repose. The duration of the motionless condition
increases each time. To quote the figures, the five consecutive
experiments, from the first to the last, have continued respectively
for 17, 20, 25, 33 and 50 minutes. Starting with a quarter of an hour,
the attitude of death ends by lasting nearly a whole hour.
Without being constant, similar facts recur repeatedly in my
experiments, the duration, of course, varying. They tell us that as a
general rule the Scarites lengthens the period of his lifeless posture
the oftener the experiment is repeated. Is this a matter of practice,
or is it an increase of cunning employed in the hope of finally tiring
a too persistent enemy? It would be premature to draw conclusions: the
cross-examination of the insect has not yet been thorough enough.
Let us wait. Besides, we need not imagine that it is possible to go on
like this until our patience is exhausted. Sooner or later, flurried
by my pestering, the Scarites refuses to sham dead. Scarcely is he
laid on his back after a fall, when he turns over and takes to his
heels, as though he judged a stratagem which succeeded so
indifferently to be henceforth useless.
If we were to stop here, it would certainly seem that the insect, a
cunning hoaxer, seeks, as a means of defence, to cheat those who
attack him. He counterfeits death; he repeats the process, becoming
more persistent in his fraud in proportion as the aggression is
repeated; he abandons his trickery when he deems it futile. But
hitherto we have subjected him only to a friendly
examination-in-chief. The time has come to put a string of searching
questions and to trick the trickster if there be really any deception.
The Beetle under experiment is lying on the table. He feels beneath
him a hard body which gives him no chance of digging. As he cannot
hope to take refuge underground, an easy task for his nimble and
vigorous tools, the Scarites lies low in his death-like pose, keeping
it up, if need be, for an hour. If he were reclining on the sand, the
loose soil with which he is so familiar, would he not regain his
activity more rapidly, would he not at least betray by a few twitches
his desire to escape into the basement?
I was expecting to see him do so; and I was mistaken. Whether I place
him on wood, glass, sand or garden mould, the Beetle in no way
modifies his tactics. On a surface readily excavated he continues his
immobility as long as on an unassailable surface.
This indifference to the nature of the support half opens the door to
doubt; what follows opens it wide. The patient is on the table before
me and I watch him closely. With his gleaming eyes, overshadowed by
his antennae, he also sees me; he watches me; he observes me, if I may
so express myself. What can be the visual impression of the insect
when face to face with that monstrosity, man? How does the pigmy
measure the enormous monument that is the human body? Seen from the
depths of the infinitely little, the immense perhaps is nothing.
We will not go so far as that; we will admit that the insect watches
me, recognizes me as his persecutor. So long as I am here, he will
suspect me and refuse to budge. If he does decide to do so, it will be
after he has exhausted my patience. Let us therefore move away. Then,
since any trickery will be needless, he will hasten to take to his
legs again and make off.
I move ten paces farther from him, to the other end of the room. I
hide, I do not move a muscle, for fear of breaking the silence. Will
the insect pick itself up? No, my precautions are superfluous. Alone,
left to itself, perfectly quiet, it remains motionless for as long a
time as when I was standing close beside it.
Perhaps the clear-sighted Scarites has seen me in my corner, at the
other end of the room; perhaps a subtle scent has revealed my presence
to him. We will do more, then. I cover him with a bell-glass which
will save him from being worried by the Flies and I leave the room; I
go downstairs into the garden. There is no longer anything likely to
disturb him. Doors and windows are closed. Not a sound from without;
no cause for alarm indoors. What will happen in the midst of that
profound silence?
Nothing more and nothing less than usual. After twenty, forty minutes'
waiting out of doors, I come upstairs again and return to my insect. I
find him as I left him, lying motionless on his back.
This experiment, many times repeated with different subjects, throws a
vivid light upon the question. It expressly assures us that the
attitude of death is not the ruse of an insect in danger. Here there
is nothing to alarm the creature. Around him all is silence, solitude,
repose. When he persists in his immobility it cannot now be to deceive
an enemy. I have no doubt about it: there is something else involved.
Besides, why should he need special defensive artifices? I could
understand that a weak, pacific, ill-protected insect might resort to
ruses when in danger; but in him, the warlike bandit, so well
armoured, it is more than I can understand. No insect on his native
sea-shore has the strength to resist him. The most powerful of them,
the Sacred Beetle and the Pimelia, are easy-going creatures which, so
far from molesting him, are fine booty for his burrow.
Can he be threatened by the birds? It is very doubtful. As a Carabus,
he is saturated with acrid humours which must make his body a far from
pleasing mouthful. For the rest, he lives hidden from the light of day
in a burrow where no one sees him; he emerges only at night, when the
birds are no longer inspecting the beach. There are no beaks about for
him to fear.
And this butcher of the Pimeliae and even occasionally of the Sacred
Beetles, this bully whom no danger threatens, is supposed to be such a
coward as to sham death on the slightest alarm! I take the liberty of
doubting this more and more.
I am confirmed in my doubts by the Smooth-skinned Scarites (_S.
lavigatus_, FAB.), a denizen of the same shores. The first insect is a
giant; the second, by comparison, is a dwarf. Otherwise he displays
the same shape, the same jet-black costume, the same armour, the same
habits of brigandage. Well, the Smooth-skinned Scarites, in spite of
his weakness and his smallness, is almost ignorant of the trick of
pretending to be dead. When molested for a moment and then turned on
his back, he at once picks himself up and flees. I can hardly obtain a
few seconds' immobility; once only, daunted by my obstinacy, the dwarf
remains motionless for a quarter of an hour.
How different from the giant, motionless the moment that he is thrown
upon his back, sometimes picking himself up only after an hour of
inaction! It is the reverse of what ought to happen, if the apparent
death were really a defensive ruse. The giant, confident in his
strength, should disdain this cowardly posture; the timid dwarf should
be quick to have recourse to it. And it is just the other way about.
What is there behind all this?
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 assailant. 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-glass or keep an assiduous 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 passing, 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 shore 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
titillations 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 shining 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 attitude, 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 attitude of death is
of very variable duration, governed as it is by a host of unsuspected
circumstances. 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 passionate 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 attitude 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
sunshine, is affected by the cold bath in a different degree from the
Scarites, who prowls about by night and spends his day in the
basement. 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 glass 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 attitude is exactly that which they would have assumed 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
fashion.
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 massive 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 multitude 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 attitude 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 Cockroaches.--_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 fashion. In short, there is
no guide to tell us in advance:
"This one will readily assume 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.