THE WHITE-FACED DECTICUS: HIS HABITS
The White-faced Decticus (D. albifrons, Fabr.) stands at the head of
the Grasshopper clan in my district, both as a singer and as an insect
of imposing presence. He has a grey costume, a pair of powerful
mandibles and a broad ivory face. Without being plentiful, he does not
let himself be sought in vain. In the height of summer we find him
hopping in the long grass, especially at the foot of the sunny rocks
where the turpentine-tree takes root.
At the end of July I start a Decticus-menagerie. As a vivarium I adopt
a big wire-gauze cover standing on a bed of sifted earth. The
population numbers a dozen; and both sexes are equally represented.
The question of victuals perplexes me for some time. It seems as though
the regulation diet ought to be a vegetable one, to judge by the
Locust, who consumes any green thing. I therefore offer my captives the
tastiest and tenderest garden-stuff that my enclosure holds: leaves of
lettuce, chicory and corn-salad. The Dectici scarcely touch it with a
contemptuous tooth. It is not the food for them.
Perhaps something tough would suit their strong mandibles better. I try
various Graminaceæ, including the glaucous panic-grass, the miauco of
the Provençal peasant, the Setaria glauca of the botanists, a weed that
infests the fields after the harvest. The panic-grass is accepted by
the hungry ones, but it is not the leaves that they devour: they attack
only the ears, of which they crunch the still tender seeds with visible
satisfaction. The food is found, at least for the time being. We shall
see later.
In the morning, when the rays of the sun visit the cage placed in the
window of my study, I serve out the day’s ration, a sheaf of green
spikes of common grass picked outside my door. The Dectici come running
up to the handful, gather round it and, very peaceably, without
quarrelling among themselves, dig with their mandibles between the
bristles of the spikes to extract and nibble the unripe seeds. Their
costume makes one think of a flock of Guinea-fowl pecking the grain
scattered by the farmer’s wife. When the spikes are robbed of their
tender seeds, the rest is scorned, however urgent the claims of hunger
may be.
To break the monotony of the diet as much as is possible in these
dog-days, when everything is burnt up, I gather a thick-leaved, fleshy
plant which is not too sensitive to the summer heat. This is the common
purslane, another invader of our garden-beds. The new green stuff meets
with a good reception; and once again the Dectici dig their teeth not
into the leaves and the juicy stalks, but only into the swollen
capsules of half-formed grains.
This taste for tender seeds surprises me: δηκτικός, biting, fond of
biting, the lexicon tells us. A name that expresses nothing, a mere
identification-number, is able to satisfy the nomenclator; in my
opinion, if the name possesses a characteristic meaning and at the same
time sounds well, it is all the better for it. Such is the case here.
The Decticus is eminently an insect given to biting. Mind your finger
if the sturdy Grasshopper gets hold of it: he will rip it till the
blood comes.
And can this powerful jaw, of which I have to beware when I handle the
creature, possess no other function than to chew soft grains? Can a
mill like this have only to grind little unripe seeds? Something has
escaped me. So well-armed with mandibular pincers, so well-endowed with
masticatory muscles that swell out his cheeks, the Decticus must cut up
some leathery prey.
This time I find the real diet, the fundamental if not the exclusive
one. Some good-sized Locusts are let into the cage. I put in it the
species mentioned in a note below, [41] now one, now the other, as they
happen to get caught in my net. A few Grasshoppers [42] are also
accepted, but not so readily. There is every reason to think that, if I
had had the luck to capture them, the entire Locust and Grasshopper
family would have met the same fate, provided that they were not too
insignificant in size.
Any fresh meat tasting of Locust or Grasshopper suits my ogres. The
most frequent victim is the Blue-winged Locust. There is a deplorably
large consumption of this species in the cage. This is how things
happen: as soon as the game is introduced, an uproar ensues in the
mess-room, especially if the Dectici have been fasting for some time.
They stamp about and, hampered by their long shanks, dart forward
clumsily; the Locusts make desperate bounds, rush to the top of the
cage and there hang on, out of the reach of the Grasshopper, who is too
stout to climb so high. Some are seized at once, as soon as they enter.
The others, who have taken refuge up in the dome, are only postponing
for a little while the fate that awaits them. Their turn will come; and
that soon. Either because they are tired or because they are tempted by
the green stuff below, they will come down; and the Dectici will be
after them immediately.
Speared by the hunter’s fore-legs, the game is first wounded in the
neck. It is always there, behind the head, that the Locust’s shell
cracks first of all; it is always there that the Decticus probes
persistently before releasing his hold and taking his subsequent meals
off whatever joint he chooses.
It is a very judicious bite. The Locust is hard to kill. Even when
beheaded, he goes on hopping. I have seen some who, though half-eaten,
kick out desperately and succeed, with a supreme effort, in releasing
themselves and jumping away. In the brushwood, that would be so much
game lost.
The Decticus seems to know all about it. To overcome his prey, so
prompt to escape by means of its two powerful levers, and to render it
helpless as quickly as possible, he first munches and extirpates the
cervical ganglia, the main seat of innervation. Is this an accident, in
which the assassin’s choice plays no part? No, for I see the murder
performed invariably in the same way when the prey is in possession of
its full strength; and again no, because, when the Locust is offered in
the form of a fresh corpse, or when he is weak, dying, incapable of
defence, the attack is made anywhere, at the first spot that presents
itself to the assailant’s jaws. In such cases the Decticus begins
either with a haunch, the favourite morsel, or with the belly, back or
chest. The preliminary bite in the neck is reserved for difficult
occasions.
This Grasshopper, therefore, despite his dull intellect, possesses the
art of killing scientifically of which we have seen so many instances
elsewhere; [43] but with him it is a rude art, falling within the
knacker’s rather than the anatomist’s domain.
Two or three Blue-winged Locusts are none too many for a Decticus’
daily ration. It all goes down, save the wings and wing-cases, which
are disdained as too tough. In addition, there is a snack of tender
millet-grains stolen every now and again to make a change from the
banquet of game. They are big eaters, are my boarders; they surprise me
with their gormandizing and even more with their easy change from an
animal to a vegetable diet.
With their accommodating and anything but particular stomachs, they
could render some slight service to agriculture, if there were more of
them. They destroy the Locusts, many of whom, even in our fields, are
of ill fame; and they nibble, amid the unripe corn, the seeds of a
number of plants which are obnoxious to the husbandman.
But the Decticus’ claim to the honours of the vivarium rests upon
something much better than his feeble assistance in preserving the
fruits of the earth: in his song, his nuptials and his habits we have a
memorial of the remotest times.
How did the insect’s ancestors live, in the palæozoic age? They had
their crude and uncouth side, banished from the better-proportioned
fauna of to-day; we catch a vague glimpse of habits now almost out of
use. It is unfortunate for our curiosity that the fossil remains are
silent on this magnificent subject.
Luckily we have one resource left, that of consulting the successors of
the prehistoric insects. There is reason to believe that the Locustids
[44] of our own period have retained an echo of the ancient customs and
can tell us something of the manners of olden time. Let us begin by
questioning the Decticus.
In the vivarium the sated herd are lying on their bellies in the sun
and blissfully digesting their food, giving no other sign of life than
a gentle swaying of the antennæ. It is the hour of the after-dinner
nap, the hour of enervating heat. From time to time a male gets up,
strolls solemnly about, raises his wing-cases slightly and utters an
occasional tick-tick. Then he becomes more animated, hurries the pace
of his tune and ends by grinding out the finest piece in his
repertoire.
Is he celebrating his wedding? Is his song an epithalamium? I will make
no such statement, for his success is poor if he is really making an
appeal to his fair neighbours. Not one of his group of hearers gives a
sign of attention. Not a female stirs, not one moves from her
comfortable place in the sun. Sometimes the solo becomes a concerted
piece sung by two or three in chorus. The multiple invitation succeeds
no better. True, their impassive ivory faces give no indication of
their real feelings. If the suitors’ ditty indeed exercises any sort of
seduction, no outward sign betrays the fact.
According to all appearances, the clicking is addressed to heedless
ears. It rises in a passionate crescendo until it becomes a continuous
rattle. It ceases when the sun vanishes behind a cloud and starts
afresh when the sun shows itself again; but it leaves the ladies
indifferent.
She who was lying with her shanks outstretched on the blazing sand does
not change her position; her antennary threads give not a quiver more
and not a quiver less; she who was gnawing the remains of a Locust does
not let go the morsel, does not lose a mouthful. To look at those
heartless ones, you would really say that the singer was making a noise
for the mere pleasure of feeling himself alive.
It is a very different matter when, towards the end of August, I
witness the start of the wedding. The couple finds itself standing face
to face quite casually, without any lyrical prelude whatever.
Motionless, as though turned to stone, with their foreheads almost
touching, the two exchange caresses with their long antennæ, fine as
hairs. The male seems somewhat preoccupied. He washes his tarsi; with
the tips of his mandibles he tickles the soles of his feet. From time
to time he gives a stroke of the bow: tick; no more.
Yet one would think that this was the very moment at which to make the
most of his strong points. Why not declare his flame in a fond couplet,
instead of standing there, scratching his feet? Not a bit of it. He
remains silent in front of the coveted bride, herself impassive.
The interview, a mere exchange of greetings between friends of
different sexes, does not last long. What do they say to each other,
forehead to forehead? Not much, apparently, for soon they separate with
nothing further; and each goes his way where he pleases.
Next day, the same two meet again. This time, the song, though still
very brief, is in a louder key than on the day before, while being
still very far from the burst of sound to which the Decticus will give
utterance long before the pairing. For the rest, it is a repetition of
what I saw yesterday: mutual caresses with the antennæ, which limply
pat the well-rounded sides.
The male does not seem greatly enraptured. He again nibbles his foot
and seems to be reflecting. Alluring though the enterprise may be, it
is perhaps not unattended with danger. Can there be a nuptial tragedy
here, similar to that which the Praying Mantis has shown us? Can the
business be exceptionally grave? Have patience and you shall see. For
the moment, nothing more happens.
A few days later, a little light is thrown upon the subject. The male
is underneath, lying flat on the sand and towered over by his powerful
spouse, who, with her sabre exposed, standing high on her hind-legs,
overwhelms him with her embrace. No, indeed: in this posture the poor
Decticus has nothing of the victor about him! The other, brutally,
without respecting the musical-box, is forcing open his wing-cases and
nibbling his flesh just where the belly begins.
Which of the two takes the initiative here? Have not the parts been
reversed? She who is usually provoked is now the provoker, employing
rude caresses capable of carrying off the morsel touched. She has not
yielded to him; she has thrust herself upon him, disturbingly,
imperiously. He, lying flat on the ground, quivers and starts, seems
trying to resist. What outrageous thing is about to happen? I shall not
know to-day. The floored male releases himself and runs away.
But this time, at last, we have it. Master Decticus is on the ground,
tumbled over on his back. Hoisted to the full height of her shanks, the
other, holding her sabre almost perpendicular, covers her prostrate
mate from a distance. The two ventral extremities curve into a hook,
seek each other, meet; and soon from the male’s convulsive loins there
is seen to issue, in painful labour, something monstrous and
unheard-of, as though the creature were expelling its entrails in a
lump.
It is an opalescent bag, similar in size and colour to a
mistletoe-berry, a bag with four pockets marked off by faint grooves,
two larger ones above and two smaller ones below. In certain cases the
number of cells increases and the whole assumes the appearance of a
packet of eggs such as Helix aspersa, the Common Snail, lays in the
ground.
The strange concern remains hanging from the lower end of the sabre of
the future mother, who solemnly retires with the extraordinary wallet,
the spermatophore, as the physiologists call it, the source of life for
the ovules, in other words the cruet which will now in due course
transmit to the proper place the necessary complement for the evolution
of the germs.
A capsule of this kind is a rare, an infinitely rare thing in the world
of to-day. So far as I know, the Cephalopods [45] and the Scolopendras
[46] are, in our time, the only other animals that make use of the
queer apparatus. Now Octopuses and Millepedes date back to the earliest
ages. The Decticus, another representative of the old world, seems to
tell us that what is a curious exception now might well have been a
more or less general rule originally, all the more so as we shall come
upon similar incidents in the case of the other Grasshoppers.
When the male has recovered from his shock, he shakes the dust off
himself and once more begins his merry click-clack. For the present let
us leave him to his joys and follow the mother that is to be, pacing
along solemnly with her burden, which is fastened with a plug of jelly
as transparent as glass.
At intervals she draws herself up on her shanks, curls into a ring and
seizes her opalescent load in her mandibles, nibbling it calmly and
squeezing it, but without tearing the wrapper or shedding any of the
contents. Each time, she removes from the surface a particle which she
chews and then chews again slowly, ending by swallowing it.
This process is continued for twenty minutes or so. Then the capsule,
now drained, is torn off in a single piece, all but the jelly plug at
the end. The huge, sticky mass is not let go for a moment, but is
munched, ground and kneaded by the insect’s mandibles and at last
gulped down whole.
At first I looked upon the horrible banquet as no more than an
individual aberration, an accident: the Decticus’ behaviour was so
extraordinary; no other instance of it was known to me. But I have had
to yield to the evidence of the facts. Four times in succession I
surprised my captives dragging their wallet and four times I saw them
soon tear it, work at it solemnly with their mandibles for hours on end
and finally gulp it down. It is therefore the rule: when its contents
have reached their destination, the fertilizing capsule, possibly a
powerful stimulant, an unparalleled dainty, is chewed, enjoyed and
swallowed.
If this, as we are entitled to believe, is a relic of ancient manners,
we must admit that the insect of old had singular customs. Réaumur
tells us of the startling operations of the Dragon-flies when pairing.
This again is a nuptial eccentricity of primeval times.
When the Decticus has finished her strange feast, the end of the
apparatus still remains in its place, the end whose most visible part
consists of two crystalline nipples the size of pepper-corns. To rid
itself of this plug, the insect assumes a curious attitude. The
ovipositor is driven half-way into the earth, perpendicularly. That
will be the prop. The long hind-legs straighten out, raise the creature
as high as possible and form a tripod with the sabre.
Then the insect again curves itself into a complete circle and, with
its mandibles, crumbles to atoms the end of the apparatus, consisting
of a plug of clearest jelly. All these remnants are scrupulously
swallowed. Not a scrap must be lost. Lastly, the ovipositor is washed,
wiped, smoothed with the tips of the palpi. Everything is put in order
again; nothing remains of the cumbrous load. The normal pose is resumed
and the Decticus goes back to pilfering the ears of millet.
To return to the male. Limp and exhausted, as though shattered by his
exploit, he remains where he is, all shrivelled and shrunk. He is so
motionless that I believe him dead. Not a bit of it! The gallant fellow
recovers his spirits, picks himself up, polishes himself and goes off.
A quarter of an hour later, when he has taken a few mouthfuls, behold
him stridulating once more. The tune is certainly lacking in spirit. It
is far from being as brilliant or prolonged as it was before the
wedding; but, after all, the poor old crock is doing his best.
Can he have any further amorous pretensions? It is hardly likely.
Affairs of that kind, calling for ruinous expenditure, are not to be
repeated: it would be too much for the works of the organism.
Nevertheless, next day and every day after, when a diet of Locusts has
duly renewed his strength, the Decticus scrapes his bow as noisily as
ever. He might be a novice, instead of a glutted veteran. His
persistence surprises me.
If he be really singing to attract the attention of his fair
neighbours, what would he do with a second wife, he who has just
extracted from his paunch a monstrous wallet in which all life’s
savings were accumulated? He is thoroughly used up. No, once more, in
the big Grasshopper these things are too costly to be done all over
again. To-day’s song, despite its gladness, is certainly no
epithalamium.
And, if you watch him closely, you will see that the singer no longer
responds to the teasing of the passers’ antennæ. The ditties become
fainter from day to day and occur less frequently. In a fortnight the
insect is dumb. The dulcimer no longer sounds, for lack of vigour in
the player.
At last the decrepit Decticus, who now scarcely touches food, seeks a
peaceful retreat, sinks to the ground exhausted, stretches out his
shanks in a last throe and dies. As it happens, the widow passes that
way, sees the deceased and, breathing eternal remembrance, gnaws off
one of his thighs.
The Green Grasshopper behaves similarly. A couple isolated in a cage
are subjected to a special watch. I am present at the end of the
pairing, when the future mother is carrying, fixed to the point of her
sword, the pretty raspberry which will occupy our attention later. [47]
Debilitated by recent happenings, the male at this moment is mute. Next
day, his strength returns; and you hear him singing as ardently as
ever. He stridulates while the mother is scattering her eggs over the
ground; he goes on making a noise long after the laying is done and
when nothing more is wanted to perpetuate the race.
It is quite clear that this persistent singing has not an amorous
appeal for its object: by this time, all of that is over, quite over.
Lastly, one day or another, life fails and the instrument is dumb. The
eager singer is no more. The survivor gives him a funeral copied from
that of the Decticus: she devours the best bits of him. She loved him
so much that she had to eat him up.
These cannibal habits recur in most of the Grasshopper tribe, without
however equalling the atrocities of the Praying Mantis, who treats her
lovers as dead game while they are still full of life. The Decticus
mother, the Green Grasshopper and the rest at least wait until the poor
wretches are dead.
I will except the Ephippiger, who is so meek in appearance. In my cage,
when laying-time is at hand, she has no scruples about taking a bite at
her companions, without possessing the excuse of hunger. Most of the
males end in this lamentable fashion, half-devoured. The mutilated
victim protests; he would rather, he could indeed go on living. Having
no other means of defence, he produces with his bow a few grating
sounds which this time decidedly are not a nuptial song. Dying with a
great hole in his belly, he utters his plaint in a like manner as
though he were rejoicing in the sun. His instrument strikes the same
note whether it express sorrow or gladness.