Social Life in the Insect World Part 11

The Sisyphus of the naturalists knows nothing of these tribulations.

Agile and lively, careless of slope or precipice, he trundles his load, which is sometimes food for himself, sometimes for his offspring. He is very rare hereabouts; I should never have succeeded in obtaining a sufficient number of specimens for my purpose but for an a.s.sistant whom I may opportunely present to the reader, for he will be mentioned again in these recitals.

This is my son, little Paul, aged seven. An a.s.siduous companion of the chase, he knows better than any one of his age the secrets of the Cigale, the Cricket, and especially of the dung-beetle, his great delight. At a distance of twenty yards his clear sight distinguishes the refuse-tip of a beetle's burrow from a chance lump of earth; his fine ear will catch the chirping of a gra.s.shopper inaudible to me. He lends me his sight and hearing, and I in return make him free of my thoughts, which he welcomes attentively, raising his wide blue eyes questioningly to mine.

What an adorable thing is the first blossoming of the intellect! Best of all ages is that when the candid curiosity awakens and commences to acquire knowledge of every kind. Little Paul has his own insectorium, in which the Scarabaeus makes his b.a.l.l.s; his garden, the size of a handkerchief, in which he grows haricot beans, which are often dug up to see if the little roots are growing longer; his plantation, containing four oak-trees an inch in height, to which the acorns still adhere.

These serve as diversions after the arid study of grammar, which goes forward none the worse on that account.

What beautiful and useful knowledge the teaching of natural history might put into childish heads, if only science would consider the very young; if our barracks of universities would only combine the lifeless study of books with the living study of the fields; if only the red tape of the curriculum, so dear to bureaucrats, would not strangle all willing initiative. Little Paul and I will study as much as possible in the open country, among the rosemary bushes and arbutus. There we shall gain vigour of body and of mind; we shall find the true and the beautiful better than in school-books.

To-day the blackboard has a rest; it is a holiday. We rise early, in view of the intended expedition; so early that we must set out fasting.

But no matter; when we are hungry we shall rest in the shade, and you will find in my knapsack the usual viatic.u.m--apples and a crust of bread. The month of May is near; the Sisyphus should have appeared. Now we must explore at the foot of the mountain, the scanty pastures through which the herds have pa.s.sed; we must break with our fingers, one by one, the cakes of sheep-dung dried by the sun, but still retaining a spot of moisture in the centre. There we shall find Sisyphus, cowering and waiting until the evening for fresher pasturage.

Possessed of this secret, which I learned from previous fortuitous discoveries, little Paul immediately becomes a master in the art of dislodging the beetle. He shows such zeal, has such an instinct for likely hiding-places, that after a brief search I am rich beyond my ambitions. Behold me the owner of six couples of Sisyphus beetles: an unheard-of number, which I had never hoped to obtain.

For their maintenance a wire-gauze cover suffices, with a bed of sand and diet to their taste. They are very small, scarcely larger than a cherry-stone. Their shape is extremely curious. The body is dumpy, tapering to an acorn-shaped posterior; the legs are very long, resembling those of the spider when outspread; the hinder legs are disproportionately long and curved, being thus excellently adapted to enlace and press the little pilule of dung.

Mating takes place towards the beginning of May, on the surface of the soil, among the remains of the sheep-dung on which the beetles have been feeding. Soon the moment for establishing the family arrives. With equal zeal the two partners take part in the kneading, transport, and baking of the food for their offspring. With the file-like forelegs a morsel of convenient size is shaped from the piece of dung placed in the cage.

Father and mother manipulate the piece together, striking it blows with their claws, compressing it, and shaping it into a ball about the size of a big pea.

As in the case of the _Scarabaeus sacer_, the exact spherical form is produced without the mechanical device of rolling the ball. Before it is moved, even before it is cut loose from its point of support, the fragment is modelled into the shape of a sphere. The beetle as geometer is aware of the form best adapted to the long preservation of preserved foods.

The ball is soon ready. It must now be forced to acquire, by means of a vigorous rolling, the crust which will protect the interior from a too rapid evaporation. The mother, recognisable by her slightly robuster body, takes the place of honour in front. Her long hinder legs on the soil, her forelegs on the ball, she drags it towards her as she walks backwards. The father pushes behind, moving tail first, his head held low. This is exactly the method of the Scarabaeus beetles, which also work in couples, though for another object. The Sisyphus beetles harness themselves to provide an inheritance for their larvae; the larger insects are concerned in obtaining the material for a banquet which the two chance-met partners will consume underground.

The couple set off, with no definite goal ahead, across the irregularities of the soil, which cannot be avoided by a leader who hauls backwards. But even if the Sisyphus saw the obstacles she would not try to evade them: witness her obstinate endeavour to drag her load up the wire gauze of her cage!

A hopeless undertaking! Fixing her hinder claws in the meshes of the wire gauze the mother drags her burden towards her; then, enlacing it with her legs, she holds it suspended. The father, finding no purchase for his legs, clutches the ball, grows on to it, so to speak, thus adding his weight to that of the burden, and awaits events. The effort is too great to last. Ball and beetle fall together. The mother, from above, gazes a moment in surprise, and suddenly lets herself fall, only to re-embrace the ball and recommence her impracticable efforts to scale the wall. After many tumbles the attempt is at last abandoned.

Even on level ground the task is not without its difficulties. At every moment the load swerves on the summit of a pebble, a fragment of gravel; the team are overturned, and lie on their backs, kicking their legs in the air. This is a mere nothing. They pick themselves up and resume their positions, always quick and lively. The accidents which so often throw them on their backs seem to cause them no concern; one would even think they were invited. The pilule has to be matured, given a proper consistency. In these conditions falls, shocks, blows, and jolts might well enter into the programme. This mad trundling lasts for hours and hours.

Finally, the mother, considering that the matter has been brought to a satisfactory conclusion, departs in search of a favourable place for storage. The father, crouched upon the treasure, waits. If the absence of his companion is prolonged he amuses himself by rapidly whirling the pill between his hind legs, which are raised in the air. He juggles with the precious burden; he tests its perfections between his curved legs, calliper-wise. Seeing him frisking in this joyful occupation, who can doubt that he experiences all the satisfactions of a father a.s.sured of the future of his family? It is I, he seems to say, it is I who have made this loaf, so beautifully round; it is I who have made the hard crust to preserve the soft dough; it is I who have baked it for my sons!

And he raises on high, in the sight of all, this magnificent testimonial of his labours.

But now the mother has chosen the site. A shallow pit is made, the mere commencement of the projected burrow. The ball is pushed and pulled until it is close at hand. The father, a vigilant watchman, still retains his hold, while the mother digs with claws and head. Soon the pit is deep enough to receive the ball; she cannot dispense with the close contact of the sacred object; she must feel it bobbing behind her, against her back, safe from all parasites and robbers, before she can decide to burrow further. She fears what might happen to the precious loaf if it were abandoned at the threshold of the burrow until the completion of the dwelling. There is no lack of midges and tiny dung-beetles--Aphodiinae--which might take possession of it. It is only prudent to be distrustful.

So the ball is introduced into the pit, half in and half out of the mouth of the burrow. The mother, below, clasps and pulls; the father, above, moderates the jolts and prevents it from rolling. All goes well.

Digging is resumed, and the descent continues, always with the same prudence; one beetle dragging the load, the other regulating its descent and clearing away all rubbish that might hinder the operation. A few more efforts, and the ball disappears underground with the two miners.

What follows will be, for a time at least, only a repet.i.tion of what we have seen. Let us wait half a day or so.

If our vigilance is not relaxed we shall see the father regain the surface alone, and crouch in the sand near the mouth of the burrow.

Retained by duties in the performance of which her companion can be of no a.s.sistance, the mother habitually delays her reappearance until the following day. When she finally emerges the father wakes up, leaves his hiding place, and rejoins her. The reunited couple return to their pasturage, refresh themselves, and then cut out another ball of dung.

As before, both share the work; the hewing and shaping, the transport, and the burial in ensilage.

This conjugal fidelity is delightful; but is it really the rule? I should not dare to affirm that it is. There must be flighty individuals who, in the confusion under a large cake of droppings, forget the fair confectioners for whom they have worked as journeymen, and devote themselves to the services of others, encountered by chance; there must be temporary unions, and divorces after the burial of a single pellet.

No matter: the little I myself have seen gives me a high opinion of the domestic morals of the Sisyphus.

Let us consider these domestic habits a little further before coming to the contents of the burrow. The father works fully as hard as the mother at the extraction and modelling of the pellet which is destined to be the inheritance of a larva; he shares in the work of transport, even if he plays a secondary part; he watches over the pellet when the mother is absent, seeking for a suitable site for the excavation of the cellar; he helps in the work of digging; he carries away the rubbish from the burrow; finally, to crown all these qualities, he is in a great measure faithful to his spouse.

The Scarabaeus exhibits some of these characteristics. He also a.s.sists his spouse in the preparation of pellets of dung; he also a.s.sists her to transport the pellets, the pair facing each other and the female going backwards. But as I have stated already, the motive of this mutual service is selfish; the two partners labour only for their own good. The feast is for themselves alone. In the labours that concern the family the female Scarabaeus receives no a.s.sistance. Alone she moulds her sphere, extracts it from the lump and rolls it backwards, with her back to her task, in the position adopted by the male Sisyphus; alone she excavates her burrow, and alone she buries the fruit of her labour.

Oblivious of the gravid mother and the future brood, the male gives her no a.s.sistance in her exhausting task. How different to the little pellet-maker, the Sisyphus!

It is now time to visit the burrow. At no very great depth we find a narrow chamber, just large enough for the mother to move around at her work. Its very exiguity proves that the male cannot remain underground; so soon as the chamber is ready he must retire in order to leave the female room to move. We have, in fact, seen that he returns to the surface long before the female.

The contents of the cellar consist of a single pellet, a masterpiece of plastic art. It is a miniature reproduction of the pear-shaped ball of the Scarabaeus, a reproduction whose very smallness gives an added value to the polish of the surface and the beauty of its curves. Its larger diameter varies from half to three-quarters of an inch. It is the most elegant product of the dung-beetle's art.

But this perfection is of brief duration. Very soon the little "pear"

becomes covered with gnarled excrescences, black and twisted, which disfigure it like so many warts. Part of the surface, which is otherwise intact, disappears under a shapeless ma.s.s. The origin of these knotted excrescences completely deceived me at first. I suspected some cryptogamic vegetation, some _Spheriaecaea_, for example, recognisable by its black, knotted, incrusted growth. It was the larva that showed me my mistake.

The larva is a maggot curved like a hook, carrying on its back an ample pouch or hunch, forming part of its alimentary ca.n.a.l. The reserve of excreta in this hunch enables it to seal accidental perforations of the sh.e.l.l of its lodging with an instantaneous jet of mortar. These sudden emissions, like little worm-casts, are also practised by the Scarabaeus, but the latter rarely makes use of them.

The larvae of the various dung-beetles utilise their alimentary residues in rough-casting their houses, which by their dimensions lend themselves to this method of disposal, while evading the necessity of opening temporary windows by which the ordure can be expelled. Whether for lack of sufficient room, or for other reasons which escape me, the larva of the Sisyphus, having employed a certain amount in the smoothing of the interior, ejects the rest of its digestive products from its dwelling.

Let us examine one of these "pears" when the inmate is already partly grown. Sooner or later we shall see a spot of moisture appear at some point on the surface; the wall softens, becomes thinner, and then, through the softened sh.e.l.l, a jet of dark green excreta rises and falls back upon itself in corkscrew convolutions. One excrescence the more has been formed; as it dries it becomes black.

What has occurred? The larva has opened a temporary breach in the wall of its sh.e.l.l; and through this orifice, in which a slight thickness of the outer glaze still remains, it has expelled the excess of mortar which it could not employ within. This practice of forming oubliettes in the sh.e.l.l of its prison does not endanger the grub, as they are immediately closed, and hermetically sealed by the base of the jet, which is compressed as by a stroke of a trowel. The stopper is so quickly put in place that the contents remain moist in spite of the frequent breaches made in the sh.e.l.l of the "pear." There is no danger of an influx of the dry outer air.

The Sisyphus seems to be aware of the peril which later on, in the dog-days, will threaten its "pear," small as it is, and so near the surface of the ground. It is extremely precocious. It labours in April and May when the air is mild. In the first fortnight of July, before the terrible dog-days have arrived, the members of its family break their sh.e.l.ls and set forth in search of the heap of droppings which will furnish them with food and lodging during the fierce days of summer.

Then come the short but pleasant days of autumn, the retreat underground and the winter torpor, the awakening of spring, and finally the cycle is closed by the festival of pellet-making.

One word more as to the fertility of the Sisyphus. My six couples under the wire-gauze cover furnished me with fifty-seven inhabited pellets.

This gives an average of more than nine to each couple; a figure which the _Scarabaeus sacer_ is far from attaining. To what should we attribute this superior fertility? I can only see one cause: the fact that the male works as valiantly as the female. Family cares too great for the strength of one are not too heavy when there are two to support them.

CHAPTER XIII

A BEE-HUNTER: THE _PHILANTHUS AVIPORUS_

To encounter among the Hymenoptera, those ardent lovers of flowers, a species which goes a-hunting on its own account is, to say the least of it, astonishing. That the larder of the larvae should be provisioned with captured prey is natural enough; but that the provider, whose diet is honey, should itself devour its captives is a fact both unexpected and difficult to comprehend. We are surprised that a drinker of nectar should become a drinker of blood. But our surprise abates if we consider the matter closely. The double diet is more apparent than real; the stomach which fills itself with the nectar of flowers does not gorge itself with flesh. When she perforates the rump of her victim the Odynerus does not touch the flesh, which is a diet absolutely contrary to her tastes; she confines herself to drinking the defensive liquid which the grub distils at the end of its intestine. For her this liquid is doubtless a beverage of delicious flavour, with which she relieves from time to time her staple diet of the honey distilled by flowers, some highly spiced condiment, appetiser or aperient, or perhaps--who knows?--a subst.i.tute for honey. Although the qualities of the liquid escape me, I see at least that Odynerus cares nothing for the rest.

Once the pouch is emptied the larva is abandoned as useless offal, a certain sign of non-carnivorous appet.i.tes. Under these conditions the persecutor of Chrysomela can no longer be regarded as guilty of an unnatural double dietary.

We may even wonder whether other species also are not apt to draw some direct profit from the hunting imposed upon them by the needs of the family. The procedure of Odynerus in opening the a.n.a.l pouch is so far removed from the usual that we should not antic.i.p.ate many imitators; it is a secondary detail, and impracticable with game of a different kind.

But there may well be a certain amount of variety in the means of direct utilisation. Why, for example, when the victim which has just been paralysed or rendered insensible by stinging contains in the stomach a delicious meal, semi-liquid or liquid in consistency, should the hunter scruple to rob the half-living body and force it to disgorge without injuring the quality of its flesh? There may well be robbers of the moribund, attracted not by their flesh but by the appetising contents of their stomachs.

As a matter of fact there are such, and they are numerous. In the first rank we may cite that hunter of the domestic bee, _Philanthus aviporus_ (Latreille). For a long time I suspected Philanthus of committing such acts of brigandage for her own benefit, having many times surprised her gluttonously licking the honey-smeared mouth of the bee; I suspected that her hunting of the bee was not undertaken entirely for the benefit of her larvae. The suspicion was worth experimental confirmation. At the time I was interested in another question also: I wanted to study, absolutely at leisure, the methods by which the various predatory species dealt with their victims. In the case of Philanthus I made use of the improvised cage already described; and Philanthus it was who furnished me with my first data on the subject. She responded to my hopes with such energy that I thought myself in possession of an unequalled method of observation, by means of which I could witness again and again, to satiety even, incidents of a kind so difficult to surprise in a state of nature. Alas! the early days of my acquaintance with Philanthus promised me more than the future had in store for me!

Not to antic.i.p.ate, however, let us place under the bell-gla.s.s the hunter and the game. I recommend the experiment to whomsoever would witness the perfection with which the predatory Hymenoptera use their stings. The result is not in doubt and the waiting is short; the moment the prey is perceived in an att.i.tude favourable to her designs, the bandit rushes at it, and all is over. In detail, the tragedy develops as follows:

I place under a bell-gla.s.s a Philanthus and two or three domestic bees.

The prisoners climb the gla.s.s walls, on the more strongly lighted side; they ascend, descend, and seek to escape; the polished, vertical surface is for them quite easy to walk upon. They presently quiet down, and the brigand begins to notice her surroundings. The antennae point forward, seeking information; the hinder legs are drawn up with a slight trembling, as of greed and rapacity, in the thighs; the head turns to the right and the left, and follows the evolutions of the bees against the gla.s.s. The posture of the scoundrelly insect is strikingly expressive; one reads in it the brutal desires of a creature in ambush, the cunning patience that postpones attack. The choice is made, and Philanthus throws herself upon her victim.

Turn by turn tumbled and tumbling, the two insects roll over and over.

But the struggle soon quiets down, and the a.s.sa.s.sin commences to plunder her prize. I have seen her adopt two methods. In the first, more usual than the other, the bee is lying on the ground, upon its back, and Philanthus, mouth to mouth and abdomen to abdomen, clasps it with her six legs, while she seizes its neck in her mandibles. The abdomen is then curved forward and gropes for a moment for the desired spot in the upper part of the thorax, which it finally reaches. The sting plunges into the victim, remains in the wound for a moment, and all is over.

Without loosing the victim, which is still tightly clasped, the murderer restores her abdomen to the normal position and holds it pressed against that of the bee.

By the second method Philanthus operates standing upright. Resting on the hinder feet and the extremity of the folded wings, she rises proudly to a vertical position, holding the bee facing her by her four anterior claws. In order to get the bee into the proper position for the final stroke, she swings the poor creature round and back again with the careless roughness of a child dandling a doll. Her pose is magnificent, solidly based upon her sustaining tripod, the two posterior thighs and the end of the wings, she flexes the abdomen forwards and upwards, and, as before, stings the bee in the upper part of the thorax. The originality of her pose at the moment of striking surpa.s.ses anything I have ever witnessed.

The love of knowledge in matters of natural history is not without its cruelties. To make absolutely certain of the point attained by the sting, and to inform myself completely concerning this horrible talent for murder, I have provoked I dare not confess how many a.s.sa.s.sinations in captivity. Without a single exception, the bee has always been stung in the throat. In the preparations for the final blow the extremity of the abdomen may of course touch here and there, at different points of the thorax or abdomen, but it never remains there, nor is the sting unsheathed, as may easily be seen. Once the struggle has commenced the Philanthus is so absorbed in her operations that I can remove the gla.s.s cover and follow every detail of the drama with my magnifying-gla.s.s.