Social Life in the Insect World Part 6

Motionless in its weird position, the Mantis surveys the acridian, its gaze fixed upon it, its head turning gently as on a pivot as the other changes place. The object of this mimicry seems evident; the Mantis wishes to terrorise its powerful prey, to paralyse it with fright; for if not demoralised by fear the quarry might prove too dangerous.

Does it really terrify its prey? Under the s.h.i.+ning head of the Decticus, behind the long face of the cricket, who is to say what is pa.s.sing? No sign of emotion can reveal itself upon these immovable masks. Yet it seems certain that the threatened creature is aware of its danger. It sees, springing up before it, a terrible spectral form with talons outstretched, ready to fall upon it; it feels itself face to face with death, and fails to flee while yet there is time. The creature that excels in leaping, and might so easily escape from the threatening claws, the wonderful jumper with the prodigious thighs, remains crouching stupidly in its place, or even approaches the enemy with deliberate steps.[2]

It is said that young birds, paralysed with terror by the gaping mouth of a serpent, or fascinated by its gaze, will allow themselves to be s.n.a.t.c.hed from the nest, incapable of movement. The cricket will often behave in almost the same way. Once within reach of the enchantress, the grappling-hooks are thrown, the fangs strike, the double saws close together and hold the victim in a vice. Vainly the captive struggles; his mandibles chew the air, his desperate kicks meet with no resistance.

He has met with his fate. The Mantis refolds her wings, the standard of battle; she resumes her normal pose, and the meal commences.

In attacking the Truxalis and the Ephippigera, less dangerous game than the grey cricket and the Decticus, the spectral pose is less imposing and of shorter duration. It is often enough to throw forward the talons; this is so in the case of the Epeirus, which is seized by the middle of the body, without a thought of its venomous claws. With the smaller crickets, which are the customary diet in my cages as at liberty, the Mantis rarely employs her means of intimidation; she merely seizes the heedless pa.s.ser-by as she lies in wait.

When the insect to be captured may present some serious resistance, the Mantis is thus equipped with a pose which terrifies or perplexes, fascinates or absorbs the prey, while it enables her talons to strike with greater certainty. Her gins close on a demoralised victim, incapable of or unready for defence. She freezes the quarry with fear or amazement by suddenly a.s.suming the att.i.tude of a spectre.

The wings play an important part in this fantastic pose. They are very wide, green on the outer edge, but colourless and transparent elsewhere.

Numerous nervures, spreading out fan-wise, cross them in the direction of their length. Others, transversal but finer, cut the first at right angles, forming with them a mult.i.tude of meshes. In the spectral att.i.tude the wings are outspread and erected in two parallel planes which are almost in contact, like the wings of b.u.t.terflies in repose.

Between the two the end of the abdomen rapidly curls and uncurls. From the rubbing of the belly against the network of nervures proceeds the species of puffing sound which I have compared to the hissing of an adder in a posture of defence. To imitate this curious sound it is enough rapidly to stroke the upper face of an outstretched wing with the tip of the finger-nail.

In a moment of hunger, after a fast of some days, the large grey cricket, which is as large as the Mantis or larger, will be entirely consumed with the exception of the wings, which are too dry. Two hours are sufficient for the completion of this enormous meal. Such an orgy is rare. I have witnessed it two or three times, always asking myself where the gluttonous creature found room for so much food, and how it contrived to reverse in its own favour the axiom that the content is less than that which contains it. I can only admire the privileges of a stomach in which matter is digested immediately upon entrance, dissolved and made away with.

The usual diet of the Mantis under my wire cages consists of crickets of different species and varying greatly in size. It is interesting to watch the Mantis nibbling at its cricket, which it holds in the vice formed by its murderous fore-limbs. In spite of the fine-pointed muzzle, which hardly seems made for such ferocity, the entire insect disappears excepting the wings, of which only the base, which is slightly fleshy, is consumed. Legs, claws, h.o.r.n.y integuments, all else is eaten.

Sometimes the great hinder thigh is seized by the knuckle, carried to the mouth, tasted, and crunched with a little air of satisfaction. The swollen thigh of the cricket might well be a choice "cut" for the Mantis, as a leg of lamb is for us!

The attack on the victim begins at the back of the neck or base of the head. While one of the murderous talons holds the quarry gripped by the middle of the body, the other presses the head downwards, so that the articulation between the back and the neck is stretched and opens slightly. The snout of the Mantis gnaws and burrows into this undefended spot with a certain persistence, and a large wound is opened in the neck. At the lesion of the cephalic ganglions the struggles of the cricket grow less, and the victim becomes a motionless corpse. Thence, unrestricted in its movements, this beast of prey chooses its mouthfuls at leisure.

CHAPTER VI

THE MANTIS.--COURTs.h.i.+P

The little we have seen of the customs of the Mantis does not square very well with the popular name for the insect. From the term _Prego-Dieu_ we should expect a peaceful placid creature, devoutly self-absorbed; and we find a cannibal, a ferocious spectre, biting open the heads of its captives after demoralising them with terror. But we have yet to learn the worst. The customs of the Mantis in connection with its own kin are more atrocious even than those of the spiders, who bear an ill repute in this respect.

To reduce the number of cages on my big laboratory table, to give myself a little more room, while still maintaining a respectable menagerie, I installed several females under one cover. There was sufficient s.p.a.ce in the common lodging and room for the captives to move about, though for that matter they are not fond of movement, being heavy in the abdomen.

Crouching motionless against the wire work of the cover, they will digest their food or await a pa.s.sing victim. They lived, in short, just as they lived on their native bushes.

Communal life has its dangers. When the hay is low in the manger donkeys grow quarrelsome, although usually so pacific. My guests might well, in a season of dearth, have lost their tempers and begun to fight one another; but I was careful to keep the cages well provided with crickets, which were renewed twice a day. If civil war broke out famine could not be urged in excuse.

At the outset matters did not go badly. The company lived in peace, each Mantis pouncing upon and eating whatever came her way, without interfering with her neighbours. But this period of concord was of brief duration. The bellies of the insects grew fuller: the eggs ripened in their ovaries: the time of courts.h.i.+p and the laying season was approaching. Then a kind of jealous rage seized the females, although no male was present to arouse such feminine rivalry. The swelling of the ovaries perverted my flock, and infected them with an insane desire to devour one another. There were threats, horrid encounters, and cannibal feasts. Once more the spectral pose was seen, the hissing of the wings, and the terrible gesture of the talons outstretched and raised above the head. The females could not have looked more terrible before a grey cricket or a Decticus. Without any motives that I could see, two neighbours suddenly arose in the att.i.tude of conflict. They turned their heads to the right and the left, provoking one another, insulting one another. The _pouf! pouf!_ of the wings rubbed by the abdomen sounded the charge. Although the duel was to terminate at the first scratch, without any more serious consequence, the murderous talons, at first folded, open like the leaves of a book, and are extended laterally to protect the long waist and abdomen. The pose is superb, but less terrific than that a.s.sumed when the fight is to be to the death.

Then one of the grappling-hooks with a sudden spring flies out and strikes the rival; with the same suddenness it flies back and a.s.sumes a position of guard. The adversary replies with a riposte. The fencing reminds one not a little of two cats boxing one another's ears. At the first sign of blood on the soft abdomen, or even at the slightest wound, one admits herself to be conquered and retires. The other refurls her battle standard and goes elsewhere to meditate the capture of a cricket, apparently calm, but in reality ready to recommence the quarrel.

Very often the matter turns out more tragically. In duels to the death the pose of attack is a.s.sumed in all its beauty. The murderous talons unfold and rise in the air. Woe to the vanquished! for the victor seizes her in her vice-like grip and at once commences to eat her; beginning, needless to say, at the back of the neck. The odious meal proceeds as calmly as if it were merely a matter of munching a gra.s.shopper; and the survivor enjoys her sister quite as much as lawful game. The spectators do not protest, being only too willing to do the like on the first occasion.

Ferocious creatures! It is said that even wolves do not eat one another.

The Mantis is not so scrupulous; she will eat her fellows when her favourite quarry, the cricket, is attainable and abundant.

These observations reach a yet more revolting extreme. Let us inquire into the habits of the insect at breeding time, and to avoid the confusion of a crowd let us isolate the couples under different covers.

Thus each pair will have their own dwelling, where nothing can trouble their honeymoon. We will not forget to provide them with abundant food; there shall not be the excuse of hunger for what is to follow.

We are near the end of August. The male Mantis, a slender and elegant lover, judges the time to be propitious. He makes eyes at his powerful companion; he turns his head towards her; he bows his neck and raises his thorax. His little pointed face almost seems to wear an expression.

For a long time he stands thus motionless, in contemplation of the desired one. The latter, as though indifferent, does not stir. Yet the lover has seized upon a sign of consent: a sign of which I do not know the secret. He approaches: suddenly he erects his wings, which are shaken with a convulsive tremor.

This is his declaration. He throws himself timidly on the back of his corpulent companion; he clings to her desperately, and steadies himself.

The prelude to the embrace is generally lengthy, and the embrace will sometimes last for five or six hours.

Nothing worthy of notice occurs during this time. Finally the two separate, but they are soon to be made one flesh in a much more intimate fas.h.i.+on. If the poor lover is loved by his mistress as the giver of fertility, she also loves him as the choicest of game. During the day, or at latest on the morrow, he is seized by his companion, who first gnaws through the back of his neck, according to use and wont, and then methodically devours him, mouthful by mouthful, leaving only the wings.

Here we have no case of jealousy, but simply a depraved taste.

I had the curiosity to wonder how a second male would be received by a newly fecundated female. The result of my inquiry was scandalous. The Mantis in only too many cases is never sated with embraces and conjugal feasts. After a rest, of variable duration, whether the eggs have been laid or not, a second male is welcomed and devoured like the first. A third succeeds him, does his duty, and affords yet another meal. A fourth suffers a like fate. In the course of two weeks I have seen the same Mantis treat seven husbands in this fas.h.i.+on. She admitted all to her embraces, and all paid for the nuptial ecstasy with their lives.

There are exceptions, but such orgies are frequent. On very hot days, when the atmospheric tension is high, they are almost the general rule.

At such times the Mantis is all nerves. Under covers which contain large households the females devour one another more frequently than ever; under the covers which contain isolated couples the males are devoured more eagerly than usual when their office has been fulfilled.

I might urge, in mitigation of these conjugal atrocities, that the Mantis does not commit them when at liberty. The male, his function once fulfilled, surely has time to wander off, to escape far away, to flee the terrible spouse, for in my cages he is given a respite, often of a whole day. What really happens by the roadside and in the thickets I do not know; chance, a poor schoolmistress, has never instructed me concerning the love-affairs of the Mantis when at liberty. I am obliged to watch events in my laboratory, where the captives, enjoying plenty of suns.h.i.+ne, well nourished, and comfortably lodged, do not seem in any way to suffer from nostalgia. They should behave there as they behave under normal conditions.

Alas! the facts force me to reject the statement that the males have time to escape; for I once surprised a male, apparently in the performance of his vital functions, holding the female tightly embraced--but he had no head, no neck, scarcely any thorax! The female, her head turned over her shoulder, was peacefully browsing on the remains of her lover! And the masculine remnant, firmly anch.o.r.ed, continued its duty!

Love, it is said, is stronger than death! Taken literally, never has an aphorism received a more striking confirmation. Here was a creature decapitated, amputated as far as the middle of the thorax; a corpse which still struggled to give life. It would not relax its hold until the abdomen itself, the seat of the organs of procreation, was attacked.

The custom of eating the lover after the consummation of the nuptials, of making a meal of the exhausted pigmy, who is henceforth good for nothing, is not so difficult to understand, since insects can hardly be accused of sentimentality; but to devour him during the act surpa.s.ses anything that the most morbid mind could imagine. I have seen the thing with my own eyes, and I have not yet recovered from my surprise.

Could this unfortunate creature have fled and saved himself, being thus attacked in the performance of his functions? No. We must conclude that the loves of the Mantis are fully as tragic, perhaps even more so, than those of the spider. I do not deny that the limited area of the cage may favour the ma.s.sacre of the males; but the cause of such butchering must be sought elsewhere. It is perhaps a reminiscence of the carboniferous period when the insect world gradually took shape through prodigious procreation. The Orthoptera, of which the Mantes form a branch, are the first-born of the insect world.

Uncouth, incomplete in their transformation, they wandered amidst the arborescent foliage, already flouris.h.i.+ng when none of the insects sprung of more complex forms of metamorphosis were as yet in existence: neither b.u.t.terflies, beetles, flies, nor bees. Manners were not gentle in those epochs, which were full of the l.u.s.t to destroy in order to produce; and the Mantis, a feeble memory of those ancient ghosts, might well preserve the customs of an earlier age. The utilisation of the males as food is a custom in the case of other members of the Mantis family. It is, I must admit, a general habit. The little grey Mantis, so small and looking so harmless in her cage, which never seeks to harm her neighbours in spite of her crowded quarters, falls upon her male and devours him as ferociously as the Praying Mantis. I have worn myself out in trying to procure the indispensable complements to my female specimens. No sooner is my capture, strongly winged, vigorous and alert, introduced into the cage than he is seized, more often than not, by one of the females who no longer have need of his a.s.sistance and devoured. Once the ovaries are satisfied the two species of Mantis conceive an antipathy for the male; or rather they regard him merely as a particularly tasty species of game.

CHAPTER VII

THE MANTIS.--THE NEST

Let us take a more pleasant aspect of the insect whose loves are so tragic. Its nest is a marvel. In scientific language it is known as the _ootek_, or the "egg-box." I shall not make use of this barbarous expression. As one does not speak of the "egg-box" of the t.i.tmouse, meaning "the nest of the t.i.tmouse," why should I invoke the box in speaking of the Mantis? It may look more scientific; but that does not interest me.

The nest of the Praying Mantis may be found almost everywhere in places exposed to the sun: on stones, wood, vine stocks, the twigs of bushes, stems of dried gra.s.s, and even on products of human industry, such as fragments of brick, rags of heavy cloth, and pieces of old boots. Any support will suffice, so long as it offers inequalities to which the base of the nest may adhere, and so provide a solid foundation. The usual dimensions of the nest are one and a half inches long by three-quarters of an inch wide, or a trifle larger. The colour is a pale tan, like that of a grain of wheat. Brought in contact with a flame the nest burns readily, and emits an odour like that of burning silk. The material of the nest is in fact a substance similar to silk, but instead of being drawn into a thread it is allowed to harden while a ma.s.s of spongy foam. If the nest is fixed on a branch the base creeps round it, envelops the neighbouring twigs, and a.s.sumes a variable shape according to the accidents of support; if it is fixed on a flat surface the under side, which is always moulded by the support, is itself flat. The nest then takes the form of a demi-ellipsoid, or, in other words, half an egg cut longitudinally; more or less obtuse at one end, but pointed at the other, and sometimes ending in a short curved tail.

In all cases the upper face is convex and regular. In it we can distinguish three well-marked and longitudinal zones. The middle zone, which is narrower than the others, is composed of thin plates arranged in couples, and overlapping like the tiles of a roof. The edges of these plates are free, leaving two parallel series of fissures by which the young can issue when the eggs are hatched. In a nest recently abandoned this zone is covered with fine cast-off skins which s.h.i.+ver at the least breath, and soon disappear when exposed to the open air. I will call this zone the zone of issue, as it is only along this bell that the young can escape, being set free by those that have preceded them.

In all other directions the cradle of this numerous family presents an unbroken wall. The two lateral zones, which occupy the greater part of the demi-ellipsoid, have a perfect continuity of surface. The little Mantes, which are very feeble when first hatched, could not possibly make their way through the tenacious substance of the walls. On the interior of these walls are a number of fine transverse furrows, signs of the various layers in which the ma.s.s of eggs is disposed.

Let us cut the nest in half transversely. We shall then see that the ma.s.s of eggs const.i.tutes an elongated core, of very firm consistency, surrounded as to the bottom and sides by a thick porous rind, like solidified foam. Above the eggs are the curved plates, which are set very closely and have little freedom; their edges const.i.tuting the zone of issue, where they form a double series of small overlapping scales.

The eggs are set in a yellowish medium of h.o.r.n.y appearance. They are arranged in layers, in lines forming arcs of a circle, with the cephalic extremities converging towards the zone of issue. This orientation tells us of the method of delivery. The newly-born larvae will slip into the interval between two adjacent flaps or leaves, which form a prolongation of the core; they will then find a narrow pa.s.sage, none too easy to effect, but sufficient, having regard to the curious provision which we shall deal with directly; they will then reach the zone of issue. There, under the overlapping scales, two pa.s.sages of exit open for each layer of eggs. Half the larvae will issue by the right-hand pa.s.sage, half by that on the left hand. This process is repeated for each layer, from end to end of the nest.

Let us sum up those structural details, which are not easily grasped unless one has the nest before one. Lying along the axis of the nest, and in shape like a date-stone, is the ma.s.s of eggs, grouped in layers.

A protective rind, a kind of solidified foam, envelops this core, except at the top, along the central line, where the porous rind is replaced by thin overlapping leaves. The free edges of these leaves form the exterior of the zone of issue; they overlap one another, forming two series of scales, leaving two exits, in the shape of narrow crevices, for each layer of eggs.

[Ill.u.s.tration: 1. NEST OF THE PRAYING MANTIS.