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MORE HUNTING WASPS
by J. HENRI FABRE
TRANSLATED BY ALEXANDER TEIXEIRA DE MATTOS, F. Z. S.
The fourteen chapters contained in this volume complete the list of essays in the “Souvenirs entomologiques” devoted to Wasps. The remainder will be found in the two earlier volumes of this collected edition entitled “The Hunting Wasps” and the “Mason-wasps” respectively.
Chapter 2 has appeared before in my version of “The Life and Love of the Insect,” an illustrated volume of extracts translated by myself and published by Messrs. Adam and Charles Black (in America by the Macmillan Co.), and Chapter 10 in a similar miscellany translated by Mr. Bernard Miall published by Messrs. T. Fisher Unwin Ltd. (in America by the Century Co.) under the title of “Social Life in the Insect World.” These two chapters are included in the present book by arrangement with the original firms.
I wish to place on record my thanks to Mr. Miall for the valuable assistance which he has given me in preparing this translation.
ALEXANDER TEIXEIRA DE MATTOS.
Ventnor, I. W., 6 December, 1920.
CHAPTER 1. THE POMPILI.
CHAPTER 2. THE SCOLIAE.
CHAPTER 3. A DANGEROUS DIET.
CHAPTER 4. THE CETONIA-LARVA.
CHAPTER 5. THE PROBLEM OF THE SCOLIAE.
CHAPTER 6. THE TACHYTES.
CHAPTER 7. CHANGE OF DIET.
CHAPTER 8. A DIG AT THE EVOLUTIONISTS.
CHAPTER 9. RATIONING ACCORDING TO SEX.
CHAPTER 10. THE BEE-EATING PHILANTHUS.
CHAPTER 11. THE METHOD OF THE AMMOPHILAE.
CHAPTER 12. THE METHOD OF THE SCOLIAE.
CHAPTER 13. THE METHOD OF THE CALICURGI.
CHAPTER 14. OBJECTIONS AND REJOINDERS.
CHAPTER 1. THE POMPILI. (This essay should be read in conjunction with that on the Black-bellied Tarantula. Cf. “The Life of the Spider,” by J. Henri Fabre, translated by Alexander Teixeira de Mattos: chapter 1.–Translator’s Note.)
The Ammophila’s caterpillar (Cf. “The Hunting Wasps,” by J. Henri Fabre, translated by Alexander Teixeira de Mattos: chapters 13 and 18 to 20; and Chapter 11 of the present volume.–Translator’s Note.), the Bembex (Cf. idem: chapter 14.–Translator’s Note.), Gad-fly, the Cerceris (Cf. idem: chapters 1 to 3.–Translator’s Note.), Buprestis (A Beetle usually remarkable for her brilliant colouring. Cf. idem: chapter 1.–Translator’s Note.) and Weevil, the Sphex (Cf. idem: chapter 4 to 10.–Translator’s Note.), Locust, Cricket and Ephippiger (Cf. “The Life of the Grasshopper,” by J. Henri Fabre, translated by Alexander Teixeira de Mattos: chapters 13 and 14.–Translator’s Note.): all these inoffensive peaceable victims are like the silly Sheep of our slaughter-houses; they allow themselves to be operated upon by the paralyser, submitting stupidly, without offering much resistance. The mandibles gape, the legs kick and protest, the body wriggles and twists; and that is all. They have no weapons capable of contending with the assassin’s dagger. I should like to see the huntress grappling with an imposing adversary, one as crafty as herself, an expert layer of ambushes and, like her, bearing a poisoned dirk. I should like to see the bandit armed with her stiletto confronted by another bandit equally familiar with the use of that weapon. Is such a duel possible? Yes, it is quite possible and even quite common. On the one hand we have the Pompili, the protagonists who are always victorious; on the other hand we have the Spiders, the protagonists who are always overthrown.
Who that has diverted himself, however little, with the study of insects does not know the Pompili? Against old walls, at the foot of the banks beside unfrequented footpaths, in the stubble after the harvest, in the tangles of dry grass, wherever the Spider spreads her nets, who has not seen them busily at work, now running hither and thither, at random, their wings raised and quivering above their backs, now moving from place to place in flights long or short? They are hunting for a quarry which might easily turn the tables and itself prey upon the trapper lying in wait for it.
The Pompili feed their larvae solely on Spiders; and the Spiders feed on any insect, commensurate with their size, that is caught in their nets. While the first possess a sting, the second have two poisoned fangs. Often their strength is equally matched; indeed the advantage is not seldom on the Spider’s side. The Wasp has her ruses of war, her cunningly premeditated strokes: the Spider has her wiles and her set traps; the first has the advantage of great rapidity of movement, while the second is able to rely upon her perfidious web; the one has a sting which contrives to penetrate the exact point to cause paralysis, the other has fangs which bite the back of the neck and deal sudden death. We find the paralyser on the one hand and the slaughterer on the other. Which of the two will become the other’s prey?
If we consider only the relative strength of the adversaries, the power of their weapons, the virulence of their poisons and their different modes of action, the scale would very often be weighted in favour of the Spider. Since the Pompilus always emerges victorious from this contest, which appears to be full of peril for her, she must have a special method, of which I would fain learn the secret.
In our part of the country, the most powerful and courageous Spider- huntress is the Ringed Pompilus (Calicurgus annulatus, FAB.), clad in black and yellow. She stands high on her legs; and her wings have black tips, the rest being yellow, as though exposed to smoke, like a bloater. Her size is about that of the Hornet (Vespa crabro). She is rare. I see three or four of her in the course of the year; and I never fail to halt in the presence of the proud insect, rapidly striding through the dust of the fields when the dog-days arrive. Its audacious air, its uncouth gait, its war-like bearing long made me suspect that to obtain its prey it had to make some impossible, terrible, unspeakable capture. And my guess was correct. By dint of waiting and watching I beheld that victim; I saw it in the huntress’ mandibles. It is the Black-bellied Tarantula, the terrible Spider who slays a Carpenter-bee or a Bumble-bee outright with one stroke of her weapon; the Spider who kills a Sparrow or a Mole; the formidable creature whose bite would perhaps not be without danger to ourselves. Yes, this is the bill of fare which the proud Pompilus provides for her larva.
This spectacle, one of the most striking with which the Hunting Wasps have ever provided me, has as yet been offered to my eyes but once; and that was close beside my rural home, in the famous laboratory of the harmas. (The enclosed piece of waste land on which the author studied his insects in their native state. Cf. “The Life of the Fly,” by J. Henri Fabre, translated by Alexander Teixeira de Mattos: chapter 1.–Translator’s Note.) I can still see the intrepid poacher dragging by the leg, at the foot of a wall, the monstrous prize which she had just secured, doubtless at no great distance. At the base of the wall was a hole, an accidental chink between some of the stones. The Wasp inspected the cavern, not for the first time: she had already reconnoitred it and the premises had satisfied her. The prey, deprived of the power of movement, was waiting somewhere, I know not where; and the huntress had gone back to fetch it and store it away. It was at this moment that I met her. The Pompilus gave a last glance at the cave, removed a few small fragments of loose mortar; and with that her preparations were completed. The Lycosa (The Spider in question is known indifferently as the Black-bellied Tarantula and the Narbonne Lycosa.– Translator’s Note.) was introduced, dragged along, belly upwards, by one leg. I did not interfere. Presently the Wasp reappeared on the surface and carelessly pushed in front of the hole the bits of mortar which she had just extracted from it. Then she flew away. It was all over. The egg was laid; the insect had finished for better or for worse; and I was able to proceed with my examination of the burrow and its contents.
The Pompilus has done no digging. It is really an accidental hole with spacious winding passages, the result of the mason’s negligence and not of the Wasp’s industry. The closing of the cavity is quite as rough and summary. A few crumbs of mortar, heaped up before the doorway, form a barricade rather than a door. A mighty hunter makes a poor architect. The Tarantula’s murderess does not know how to dig a cell for her larva; she does not know how to fill up the entrance by sweeping dust into it. The first hole encountered at the foot of a wall contents her, provided that it be roomy enough; a little heap of rubbish will do for a door. Nothing could be more expeditious.
I withdraw the game from the hole. The egg is stuck to the Spider, near the beginning of the belly. A clumsy movement on my part makes it fall off at the moment of extraction. It is all over: the thing will not hatch; I shall not be able to observe the development of the larva. The Tarantula lies motionless, flexible as in life, with not a trace of a wound. In short, we have here life without movement. From time to time the tips of the tarsi quiver a little; and that is all. Accustomed of old to these deceptive corpses, I can see in my mind’s eye what has happened: the Spider has been stung in the region of the thorax, no doubt once only, in view of the concentration of her nervous system. I place the victim in a box in which it retains all the pliancy and all the freshness of life from the 2nd of August to the 20th of September, that is to say, for seven weeks. These miracles are familiar to us (Cf. “The Hunting Wasps”: passim.–Translator’s Note.); there is no need to linger over them here.
The most important matter has escaped me. What I wanted, what I still want to see is the Pompilus engaged in mortal combat with the Lycosa. What a duel, in which the cunning of the one has to overcome the terrible weapons of the other! Does the Wasp enter the burrow to surprise the Tarantula at the bottom of her lair? Such temerity would be fatal to her. Where the big Bumble-bee dies an instant death, the audacious visitor would perish the moment she entered. Is not the other there, facing her, ready to snap at the back of her head, inflicting a wound which would result in sudden death? No, the Pompilus does not enter the Spider’s parlour, that is obvious. Does she surprise the Spider outside her fortress? But the Lycosa is a stay-at-home animal; I do not see her straying abroad during the summer. Later, in the autumn, when the Pompili have disappeared, She wanders about; turning gipsy, she takes the open air with her numerous family, which she carries on her back. Apart from these maternal strolls, she does not appear to me to leave her castle; and the Pompilus, I should think, has no great chance of meeting her outside. The problem, we perceive, is becoming complicated: the huntress cannot make her way into the burrow, where she would risk sudden death; and the Spider’s sedentary habits make an encounter outside the burrow improbable. Here is a riddle which would be interesting to decipher. Let us endeavour to do so by observing other Spider-hunters; analogy will enable us to draw a conclusion.
I have often watched Pompili of every species on their hunting-expeditions, but I have never surprised them entering the Spider’s lodging when the latter was at home. Whether this lodging be a funnel plunging its neck into a hole in some wall, an awning stretched amid the stubble, a tent modelled upon the Arab’s, a sheath formed of a few leaves bound together, or a net with a guard-room attached, whenever the owner is indoors the suspicious Pompilus holds aloof. When the dwelling is vacant, it is another matter: the Wasp moves with arrogant ease over those webs, springes and cables in which so many other insects would remain ensnared. The silken threads do not seem to have any hold upon her. What is she doing, exploring those empty webs? She is watching to see what is happening on the adjacent webs where the Spider is ambushed. The Pompilus therefore feels an insuperable reluctance to make straight for the Spider when the latter is at home in the midst of her snares. And she is right, a hundred times over. If the Tarantula understands the practice of the dagger-thrust in the neck, which is immediately fatal, the other cannot be unacquainted with it. Woe then to the imprudent Wasp who presents herself upon the threshold of a Spider of approximately equal strength!
Of the various instances which I have collected of this cautious reserve on the Spider-huntress’ part I will confine myself to the following, which will be sufficient to prove my point. By joining, with silken strands, the three folioles which form the leaf of Virgil’s cytisus, a Spider has built herself a green arbour, a horizontal sheath, open at either end. A questing Pompilus comes upon the scene, finds the game to her liking and pops in her head at the entrance of the cell. The Spider immediately retreats to the other end. The huntress goes round the Spider’s dwelling and reappears at the other door. Again the Spider retreats, returning to the first entrance. The Wasp also returns to it, but always by the outside. Scarcely has she done so, when the Spider rushes for the opposite opening; and so on for fully a quarter of an hour, both of them coming and going from one end of the cylinder to the other, the Spider inside and the Pompilus outside.
The quarry was a valuable one, it seems, since the Wasp persisted for a long time in her attempts, which were invariably defeated; however, the huntress had to abandon them, baffled by this perpetual running to and fro. The Pompilus made off; and the Spider, once more on the watch, patiently awaited the heedless Midges. What should the Wasp have done to capture this much-coveted game? She should have entered the verdant cylinder, the Spider’s dwelling, and pursued the Spider direct, in her own house, instead of remaining outside, going from one door to the other. With such swiftness and dexterity as hers, it seemed to me impossible that the stroke should fail: the quarry moved clumsily, a little sideways, like a Crab. I judged it to be an easy matter; the Pompilus thought it highly dangerous. To-day I am of her opinion: if she had entered the leafy tube, the mistress of the house would have operated on her neck and the huntress would have become the quarry.
Years passed and the paralyser of the Spiders still refused to reveal her secret; I was badly served by circumstances, could find no leisure, was absorbed in unrelenting preoccupations. At length, during my last year at Orange, the light dawned upon me. My garden was enclosed by an old wall, blackened and ruined by time, where, in the chinks between the stones, lived a population of Spiders, represented more particularly by Segestria perfidia. This is the common Black Spider, or Cellar Spider. She is deep black all over, excepting the mandibles, which are a splendid metallic green. Her two poisoned daggers look like a product of the metal-worker’s art, like the finest bronze. In any mass of abandoned masonry there is not a quiet corner, not a hole the size of one’s finger, in which the Segestria does not set up house. Her web is a widely flaring funnel, whose open end, at most a span across, lies spread upon the surface of the wall, where it is held in place by radiating threads. This conical surface is continued by a tube which runs into a hole in the wall. At the end is the dining-room to which the Spider retires to devour at her ease her captured prey.
With her two hind-legs stuck into the tube to obtain a purchase and the six others spread around the orifice, the better to perceive on every side the quiver which gives the signal of a capture, the Segestria waits motionless, at the entrance of her funnel, for an insect to become entangled in the snare. Large Flies, Drone-flies, dizzily grazing some thread of the snare with their wings, are her usual victims. At the first flutter of the netted Fly, the Spider runs or even leaps forward, but she is now secured by a cord which escapes from the spinnerets and which has its end fastened to the silken tube. This prevents her from falling as she darts along a vertical surface. Bitten at the back of the head, the Drone-fly is dead in a moment; and the Segestria carries him into her lair.
Thanks to this method and these hunting-appliances–an ambush at the bottom of a silken whirlpool, radiating snares, a life-line which holds her from behind and allows her to take a sudden rush without risking a fall–the Segestria is able to catch game less inoffensive than the Drone-fly. A Common Wasp, they tell me, does not daunt her. Though I have not tested this, I readily believe it, for I well know the Spider’s boldness.
This boldness is reinforced by the activity of the venom. It is enough to have seen the Segestria capture some large Fly to be convinced of the overwhelming effect of her fangs upon the insects bitten in the neck. The death of the Drone-fly, entangled in the silken funnel, is reproduced by the sudden death of the Bumble-bee on entering the Tarantula’s burrow. We know the effect of the poison on man, thanks to Antoine Duges’ investigations. (Antoine Louis Duges (1797-1838), a French physician and physiologist, author of a “Traite de physiologie comparee de l’homme et des animaux” and other scientific works.–Translator’s Note.) Let us listen to the brave experimenter:
“The treacherous Segestria, or Great Cellar Spider, reputed poisonous in our part of the country, was chosen for the principal subject of our experiments. She was three-quarters of an inch long, measured from the mandibles to the spinnerets. Taking her in my fingers from behind, by the legs, which were folded and gathered together (this is the way to catch hold of live Spiders, if you would avoid their bite and master them without mutilating them), I placed her on various objects and on my clothes, without her manifesting the least desire to do any harm; but hardly was she laid on the bare skin of my fore-arm when she seized a fold of the epidermis in her powerful mandibles, which are of a metallic green, and drove her fangs deep into it. For a few moments she remained hanging, although left free; then she released herself, fell and fled, leaving two tiny wounds, a sixth of an inch apart, red, but hardly bleeding, with a slight extravasation round the edge and resembling the wounds produced by a large pin.
“At the moment of the bite, the sensation was sharp enough to deserve the name of pain; and this continued for five or six minutes more, but not so forcibly. I might compare it with the sensation produced by the stinging- nettle. A whitish tumefaction almost immediately surrounded the two pricks; and the circumference, within a radius of about an inch, was coloured an erysipelas red, accompanied by a very slight swelling. In an hour and a half, it had all disappeared, except the mark of the pricks, which persisted for several days, as any other small wound would have done. This was in September, in rather cool weather. Perhaps the symptoms would have displayed somewhat greater severity at a warmer season.”
Without being serious, the effect of the Segestria’s poison is plainly marked. A sting causing sharp pain and swelling, with the redness of erysipelas, is no trifling matter. While Duges’ experiment reassures us in so far as we ourselves are concerned, it is none the less the fact that the Cellar Spider’s poison is a terrible thing for insects, whether because of the small size of the victim, or because it acts with special efficacy upon an organization which differs widely from our own. One Pompilus, though greatly inferior to the Segestria in size and strength, nevertheless makes war upon the Black Spider and succeeds in overpowering this formidable quarry. This is Pompilus apicalis, VAN DER LIND, who is hardly larger than the Hive-bee, but very much slenderer. She is of a uniform black; her wings are a cloudy brown, with transparent tips. Let us follow her in her expeditions to the old wall inhabited by the Segestria: we will track her for whole afternoons during the July heats; and we will arm ourselves with patience, for the perilous capture of the game must take the Wasp a long time.
The Spider-huntress explores the wall minutely; she runs, leaps and flies; she comes and goes, flitting to and fro. The antennae quiver; the wings, raised above the back, continually beat one against the other. Ah, here she is, close to a Segestria’s funnel! The Spider, who has hitherto remained invisible, instantly appears at the entrance to the tube; she spreads her six fore-legs outside, ready to receive the huntress. Far from fleeing before the terrible apparition, she watches the watcher, fully prepared to prey upon her enemy. Before this intrepid demeanour the Pompilus draws back. She examines the coveted game, walks round it for a moment, then goes away without attempting anything. When she has gone, the Segestria retires indoors, backwards. For the second time the Wasp passes near an inhabited funnel. The Spider on the lookout at once shows herself on the threshold of her dwelling, half out of her tube, ready for defence and perhaps also for attack. The Pompilus moves away and the Segestria reenters her tube. A fresh alarm: the Pompilus returns; another threatening demonstration on the part of the Spider. Her neighbour, a little later, does better than this: while the huntress is prowling about in the neighbourhood of the funnel, she suddenly leaps out of the tube, with the lifeline which will save her from falling, should she miss her footing, attached to her spinnerets; she rushes forward and hurls herself in front of the Pompilus, at a distance of some eight inches from her burrow. The Wasp, as though terrified, immediately decamps; and the Segestria no less suddenly retreats indoors.
Here, we must admit, is a strange quarry: it does not hide, but is eager to show itself; it does not run away, but flings itself in front of the hunter. If our observations were to cease here, could we say which of the two is the hunter and which the hunted? Should we not feel sorry for the imprudent Pompilus? Let a thread of the trap entangle her leg; and it is all up with her. The other will be there, stabbing her in the throat. What then is the method which she employs against the Segestria, always on the alert, ready for defence, audacious to the point of aggression? Shall I surprise the reader if I tell him that this problem filled me with the most eager interest, that it held me for weeks in contemplation before that cheerless wall? Nevertheless, my tale will be a short one.
On several occasions I see the Pompilus suddenly fling herself on one of the Spider’s legs, seize it with her mandibles and endeavour to draw the animal from its tube. It is a sudden rush, a surprise attack, too quick to permit the Spider to parry it. Fortunately, the latter’s two hind-legs are firmly hooked to the dwelling; and the Segestria escapes with a jerk, for the other, having delivered her shock attack, hastens to release her hold; if she persisted, the affair might end badly for her. Having failed in this assault, the Wasp repeats the procedure at other funnels; she will even return to the first when the alarm is somewhat assuaged. Still hopping and fluttering, she prowls around the mouth, whence the Segestria watches her, with her legs outspread. She waits for the propitious moment; she leaps forward, seizes a leg, tugs at it and springs out of reach. More often than not, the Spider holds fast; sometimes she is dragged out of the tube, to a distance of a few inches, but immediately returns, no doubt with the aid of her unbroken lifeline.
The Pompilus’ intention is plain: she wants to eject the Spider from her fortress and fling her some distance away. So much perseverance leads to success. This time all goes well: with a vigorous and well-timed tug the Wasp has pulled the Segestria out and at once lets her drop to the ground. Bewildered by her fall and even more demoralized by being wrested from her ambush, the Spider is no longer the bold adversary that she was. She draws her legs together and cowers into a depression in the soil. The huntress is there on the instant to operate on the evicted animal. I have barely time to draw near to watch the tragedy when the victim is paralysed by a thrust of the sting in the thorax.
Here at last, in all its Machiavellian cunning, is the shrewd method of the Pompilus. She would be risking her life if she attacked the Segestria in her home; the Wasp is so convinced of it that she takes good care not to commit this imprudence; but she knows also that, once dislodged from her dwelling, the Spider is as timid, as cowardly as she was bold at the centre of her funnel. The whole point of her tactics, therefore, lies in dislodging the creature. This done, the rest is nothing.
The Tarantula-huntress must behave in the same manner. Enlightened by her kinswoman, Pompilus apicalis, my mind pictures her wandering stealthily around the Lycosa’s rampart. The Lycosa hurries up from the bottom of her burrow, believing that a victim is approaching; she ascends her vertical tube, spreading her fore-legs outside, ready to leap. But it is the Ringed Pompilus who leaps, seizes a leg, tugs and hurls the Lycosa from her burrow. The Spider is henceforth a craven victim, who will let herself be stabbed without dreaming of employing her venomous fangs. Here craft triumphs over strength; and this craft is not inferior to mine, when, wishing to capture the Tarantula, I make her bite a spike of grass which I dip into the burrow, lead her gently to the surface and then with a sudden jerk throw her outside. For the entomologist as for the Pompilus, the essential thing is to make the Spider leave her stronghold. After this there is no difficulty in catching her, thanks to the utter bewilderment of the evicted animal.
Two contrasting points impress me in the facts which I have just set forth: the shrewdness of the Pompilus and the folly of the Spider. I will admit that the Wasp may gradually have acquired, as being highly beneficial to her posterity, the instinct by which she first of all so judiciously drags the victim from its refuge, in order there to paralyse it without incurring danger, provided that you will explain why the Segestria, possessing an intellect no less gifted than that of the Pompilus, does not yet know how to counteract the trick of which she has so long been the victim. What would the Black Spider need to do to escape her exterminator? Practically nothing: it would be enough for her to withdraw into her tube, instead of coming up to post herself at the entrance, like a sentry, whenever the enemy is in the neighbourhood. It is very brave of her, I agree, but also very risky. The Pompilus will pounce upon one of the legs spread outside the burrow for defence and attack; and the besieged Spider will perish, betrayed by her own boldness. This posture is excellent when waiting for prey. But the Wasp is not a quarry; she is an enemy and one of the most dreaded of enemies. The Spider knows this. At the sight of the Wasp, instead of placing herself fearlessly but foolishly on her threshold, why does she not retreat into her fortress, where the other would not attack her? The accumulated experience of generations should have taught her this elementary tactical device, which is of the greatest value to the prosperity of her race. If the Pompilus has perfected her method of attack, why has not the Segestria perfected her method of defence? Is it possible that centuries upon centuries should have modified the one to its advantage without succeeding in modifying the other? Here I am utterly at a loss. And I say to myself, in all simplicity: since the Pompili must have Spiders, the former have possessed their patient cunning and the other their foolish audacity from all time. This may be puerile, if you like to think it so, and not in keeping with the transcendental aims of our fashionable theorists; the argument contains neither the subjective nor the objective point of view, neither adaptation nor differentiation, neither atavism nor evolutionism. Very well, but at least I understand it.
Let us return to the habits of Pompilus apicalis. Without expecting results of any particular interest, for in captivity the respective talents of the huntress and the quarry seem to slumber, I place together, in a wide jar, a Wasp and a Segestria. The Spider and her enemy mutually avoid each other, both being equally timid. A judicious shake or two brings them into contact. The Segestria, from time to time, catches hold of the Pompilus, who gathers herself up as best she can, without attempting to use her sting; the Spider rolls the insect between her legs and even between her mandibles, but appears to dislike doing it. Once I see her lie on her back and hold the Pompilus above her, as far away as possible, while turning her over in her fore-legs and munching at her with her mandibles. The Wasp, whether by her own adroitness or owing to the Spider’s dread of her, promptly escapes from the terrible fangs, moves to a short distance and does not seem to trouble unduly about the buffeting which she has received. She quietly polishes her wings and curls her antennae by pulling them while standing on them with her fore-tarsi. The attack of the Segestria, stimulated by my shakes, is repeated ten times over; and the Pompilus always escapes from the venomous fangs unscathed, as though she were invulnerable.
Is she really invulnerable? By no means, as we shall soon have proved to us; if she retires safe and sound, it is because the Spider does not use her fangs. What we see is a sort of truce, a tacit convention forbidding deadly strokes, or rather the demoralization due to captivity; and the two adversaries are no longer in a sufficiently warlike mood to make play with their daggers. The tranquillity of the Pompilus, who keeps on jauntily curling her antennae in face of the Segestria, reassures me as to my prisoner’s fate; for greater security, however, I throw her a scrap of paper, in the folds of which she will find a refuge during the night. She instals herself there, out of the Spider’s reach. Next morning I find her dead. During the night the Segestria, whose habits are nocturnal, has recovered her daring and stabbed her enemy. I had my suspicions that the parts played might be reversed! The butcher of yesterday is the victim of to-day.
I replace the Pompilus by a Hive-bee. The interview is not protracted. Two hours later, the Bee is dead, bitten by the Spider. A Drone-fly suffers the same fate. The Segestria, however, does not touch either of the two corpses, any more than she touched the corpse of the Pompilus. In these murders the captive seems to have no other object than to rid herself of a turbulent neighbour. When appetite awakes, perhaps the victims will be turned to account. They were not; and the fault was mine. I placed in the jar a Bumble-bee of average size. A day later the Spider was dead; the rude sharer of her captivity had done the deed.
Let us say no more of these unequal duels in the glass prison and complete the story of the Pompilus whom we left at the foot of the wall with the paralysed Segestria. She abandons her prey on the ground and returns to the wall. She visits the Spider’s funnels one by one, walking on them as freely as on the stones; she inspects the silken tubes, dipping her antennae into them, sounding and exploring them; she enters without the least hesitation. Whence does she now derive the temerity thus to enter the Segestria’s haunts? But a little while ago, she was displaying extreme caution; at this moment, she seems heedless of danger. The fact is that there is no danger really. The Wasp is inspecting uninhabited houses. When she dives down a silken tunnel, she very well knows that there is no one in, for, had the Segestria been there, she would by this time have appeared on the threshold. The fact that the householder does not show herself at the first vibration of the neighbouring threads is a certain proof that the tube is vacant; and the Pompilus enters in full security. I would recommend future observers not to take the present investigations for hunting-tactics. I have already remarked and I repeat: the Pompilus never enters the silken ambush while the Spider is there.
Among the funnels inspected one appears to suit her better than the others; she returns to it frequently in the course of her investigations, which last for nearly an hour. From time to time she hastens back to the Spider lying on the ground; she examines her, tugs at her, drags her a little closer to the wall, then leaves her the better to reconnoitre the tunnel which is the object of her preference. Lastly she returns to the Segestria and takes her by the tip of the abdomen. The quarry is so heavy that she has great difficulty in moving it along the level ground. Two inches divide it from the wall. She gets to the wall, not without effort; nevertheless, once the wall is reached, the job is quickly done. We learn that Antaeus, the son of Mother Earth, in his struggle with Hercules, received new strength as often as his feet touched the ground; the Pompilus, the daughter of the wall, seems to increase her powers tenfold once she has set foot on the masonry.
For here is the Wasp hoisting her prey backwards, her enormous prey, which dangles beneath her. She climbs now a vertical plane, now a slope, according to the uneven surface of the stones. She crosses gaps where she has to go belly uppermost, while the quarry swings to and fro in the air. Nothing stops her; she keeps on climbing, to a height of six feet or more, without selecting her path, without seeing her goal, since she goes backwards. A lodge appears no doubt reconnoitred beforehand and reached, despite the difficulties of an ascent which did not allow her to see it. The Pompilus lays her prey on it. The silken tube which she inspected so lovingly is only some eight inches distant. She goes to it, examines it rapidly and returns to the Spider, whom she at length lowers down the tube.
Shortly afterwards I see her come out again. She searches here and there on the wall for a few scraps of mortar, two or three fairly large pieces, which she carries to the tube, to close it up. The task is done. She flies away.
Next day I inspect this strange burrow. The Spider is at the bottom of the silken tube, isolated on every side, as though in a hammock. The Wasp’s egg is glued not to the ventral surface of the victim but to the back, about the middle, near the beginning of the abdomen. It is white, cylindrical and about a twelfth of an inch long. The few bits of mortar which I saw carried have but very roughly blocked the silken chamber at the end. Thus Pompilus apicalis lays her quarry and her eggs not in a burrow of her own making, but in the Spider’s actual house. Perhaps the silken tube belongs to this very victim, which in that event provides both board and lodging. What a shelter for the larva of this Pompilus: the warm retreat and downy hammock of the Segestria!
Here then, already, we have two Spider-huntresses, the Ringed Pompilus and P. apicalis, who, unversed in the miner’s craft, establish their offspring inexpensively in accidental chinks in the walls, or even in the lair of the Spider on whom the larva feeds. In these cells, acquired without exertion, they build only an attempt at a wall with a few fragments of mortar. But we must beware of generalizing about this expeditious method of establishment. Other Pompili are true diggers, valiantly sinking a burrow in the soil, to a depth of a couple of inches. These include the Eight-spotted Pompilus (P. octopunctatus, PANZ.), with her black-and-yellow livery and her amber wings, a little darker at the tips. For her game she chooses the Epeirae (E. fasciata, E. sericea) (For the Garden-spiders known as the Banded Epeira and the Silky Epeira cf. “The Life of the Spider”: chapters 11, 13, 14 et passim.–Translator’s Note.), those fat Spiders, magnificently adorned, who lie in wait at the centre of their large, vertical webs. I am not sufficiently acquainted with her habits to describe them; above all, I know nothing of her hunting-tactics. But her dwelling is familiar to me: it is a burrow, which I have seen her begin, complete and close according to the customary method of the Digger-wasps.
CHAPTER 2. THE SCOLIAE.
Were strength to take precedence over the other zoological attributes, the Scoliae would hold a predominant place in the front rank of the Wasps. Some of them may be compared in size with the little bird from the north, the Golden-crested Wren, who comes to us at the time of the first autumn mists and visits the rotten buds. The largest and most imposing of our sting- bearers, the Carpenter-bee, the Bumble-bee, the Hornet, cut a poor figure beside certain of the Scoliae. Of this group of giants my district possesses the Garden Scolia (S. hortorum, VAN DER LIND), who is over an inch and a half in length and measures four inches from tip to tip of her outspread wings, and the Hemorrhoidal Scolia (S. haemorrhoidalis, VAN DER LIND), who rivals the Garden Scolia in point of size and is distinguished more particularly by the bundle of red hairs bristling at the tip of the abdomen.
A black livery, with broad yellow patches; leathery wings, amber-coloured, like the skin of an onion, and watered with purple reflections; thick, knotted legs, covered with sharp hairs; a massive frame; a powerful head, encased in a hard cranium; a stiff, clumsy gait; a low, short, silent flight: this gives you a concise description of the female, who is strongly equipped for her arduous task. The male, being a mere philanderer, sports a more elegant pair of horns, is more daintily clad and has a more graceful figure, without altogether losing the quality of robustness which is his consort’s leading characteristic.
It is not without a certain alarm that the insect-collector finds himself for the first time confronted by the Garden Scolia. How is he to capture the imposing creature, how to avoid its sting? If its effect is in proportion to the Wasp’s size, the sting of the Scolia must be something terrible. The Hornet, though she unsheath her weapon but once, causes the most exquisite pain. What would it be like if one were stabbed by this colossus? The prospect of a swelling as big as a man’s fist and as painful as the touch of a red-hot iron passes through our mind at the moment when we are bringing down the net. And we refrain, we beat a retreat, we are greatly relieved not to have aroused the dangerous creature’s attention.
Yes, I confess to having run away from my first Scoliae, anxious though I was to enrich my budding collection with this magnificent insect. There were painful recollections of the Common Wasp and the Hornet connected with this excess of prudence. I say excess, for to-day, instructed by long experience, I have quite recovered from my former fears; and, when I see a Scolia resting on a thistle-head, I do not scruple to take her in my fingers, without any precaution whatever, however large she may be and however menacing her aspect. My courage is not all that it seems to be; I am quite ready to tell the Wasp-hunting novice this. The Scoliae are notably peaceable. Their sting is an implement of labour far more than a weapon of war; they use it to paralyse the prey destined for their offspring; and only in the last extremity do they employ it in self- defence. Moreover, the lack of agility in their movements nearly always enables us to avoid their sting; and, even if we be stung, the pain is almost insignificant. This absence of any acute smarting as a result of the poison is almost constant in the Hunting Wasps, whose weapon is a surgical lancet and devised for the most delicate physiological operations.
Among the other Scoliae of my district I will mention the Two-banded Scolia (S. bifasciata, VAN DER LIND), whom I see every year, in September, working at the heaps of leaf-mould which are placed for her benefit in a corner of my paddock; and the Interrupted Scolia (S. interrupta, LATR.), the inhabitant of the sandy soil at the foot of the neighbouring hills. Much smaller than the two preceding insects, but also much commoner, a necessary condition of continuous observation, they will provide me with the principal data for this study of the Scoliae.
I open my old note book; and I see myself once more, on the 6th of August, 1857, in the Bois des Issards, that famous copse near Avignon which I have celebrated in my essay on the Bembex-wasps. (Cf. “The Hunting Wasps”: chapter 14.–Translator’s Note.) Once again, my head crammed with entomological projects, I am at the beginning of my holidays which, for two months, will allow me to indulge in the insect’s company.
A fig for Mariotte’s flask and Toricelli’s tube! (Edme Mariotte (1620- 1684), a French chemist who discovered, independently of Robert Boyle the Irishman (1627-1691), the law generally known as Boyle’s law, which states that the product of the volume and the temperature of a gas is constant at constant temperature. His flask is an apparatus contrived to illustrate atmospheric pressure and ensure a constant flow of liquid.–Translator’s Note.) (Evangelista Toricelli (1608-1647), a disciple of Galileo and professor of philosophy and mathematics at Florence. His “tube” is our mercury barometer. He was the first to obtain a vacuum by means of mercury; and he also improved the microscope and the telescope.–Translator’s Note.) This is the thrice-blest period when I cease to be a schoolmaster and become a schoolboy, the schoolboy in love with animals. Like a madder- cutter off for his day’s work, I set out carrying over my shoulder a solid digging-implement, the local luchet, and on my back my game-bag with boxes, bottles, trowel, glass tubes, tweezers, lenses and other impedimenta. A large umbrella saves me from sunstroke. It is the most scorching hour of the hottest day in the year. Exhausted by the heat, the Cicadae are silent. The bronze-eyed Gad-flies seek a refuge from the pitiless sun under the roof of my silken shelter; other large Flies, the sobre-hued Pangoniae, dash themselves recklessly against my face.
The spot at which I have installed myself is a sandy clearing which I had recognized the year before as a site beloved of the Scoliae. Here and there are scattered thickets of holm-oak, whose dense undergrowth shelters a bed of dead leaves and a thin layer of mould. My memory has served me well. Here, sure enough, as the heat grows a little less, appear, coming I know not from whence, some Two-banded Scoliae. The number increases; and it is not long before I see very nearly a dozen of them about me, close enough for observation. By their smaller size and more buoyant flight, they are easily known for males. Almost grazing the ground, they fly softly, going to and fro, passing and repassing in every direction. From time to time one of them alights on the ground, feels the sand with his antennae and seems to be enquiring into what is happening in the depths of the soil; then he resumes his flight, alternately coming and going.
What are they waiting for? What are they seeking in these evolutions of theirs, which are repeated a hundred times over? Food? No, for close beside them stand several eryngo-stems, whose sturdy clusters are the Wasps’ usual resource at this season of parched vegetation; and not one of them settles upon the flowers, not one of them seems to care about their sugary exudations. Their attention is engrossed elsewhere. It is the ground, it is the stretch of sand which they are so assiduously exploring; what they are waiting for is the arrival of some female, who bursting the cocoon, may appear from one moment to the next, issuing all dusty from the ground. She will not be given time to brush herself or to wash her eyes: three or four more of them will be there at once, eager to dispute her possession. I am too familiar with the amorous contests of the Hymenopteron clan to allow myself to be mistaken. It is the rule for the males, who are the earlier of the two, to keep a close guard around the natal spot and watch for the emergence of the females, whom they pester with their pursuit the moment they reach the light of day. This is the motive of the interminable ballet of my Scoliae. Let us have patience: perhaps we shall witness the nuptials.
The hours go by; the Pangoniae and the Gad-flies desert my umbrella; the Scoliae grow weary and gradually disappear. It is finished. I shall see nothing more to-day. I repeat my laborious expedition to the Bois des Issards over and over again; and each time I see the males as assiduous as ever in skimming over the ground. My perseverance deserved to succeed. It did, though the success was very incomplete. Let me describe it, such as it was; the future will fill up the gaps.
A female issues from the soil before my eyes. She flies away, followed by several males. With the luchet I dig at the point of emergence; and, as the excavation progresses, I sift between my fingers the rubbish of sand mixed with mould. In the sweat of my brow, as I may justly say, I must have removed nearly a cubic yard of material, when at last I make a find. This is a recently ruptured cocoon, to the side of which adheres an empty skin, the last remnant of the game on which the larva fed that wrought the said cocoon. Considering the good condition of its silken fabric, this cocoon may have belonged to the Scolia who has just quitted her underground dwelling before my eyes. As for the skin accompanying it, this has been so much spoilt by the moisture of the soil and by the grassy roots that I cannot determine its origin exactly. The cranium, however, which is better- preserved, the mandibles and certain details of the general configuration lead me to suspect the larva of a Lamellicorn.
It is getting late. This is enough for to-day. I am worn out, but amply repaid for my exertions by a broken cocoon and the puzzling skin of a wretched grub. Young people who make a hobby of natural history, would you like to discover whether the sacred fire flows in your veins? Imagine yourselves returning from such an expedition. You are carrying on your shoulder the peasant’s heavy spade; your loins are stiff with the laborious digging which you have just finished in a crouching position; the heat of an August afternoon has set your brain simmering; your eyelids are tired by the itch of an inflammation resulting from the overpowering light in which you have been working; you have a devouring thirst; and before you lies the dusty prospect of the miles that divide you from your well-earned rest. Yet something stings within you; forgetful of your present woes you are absolutely glad of your excursion. Why? Because you have in your possession a shred of rotten skin. If this is so, my young friends, you may go ahead, for you will do something, though I warn you that this does not mean, by a long way, that you will get on in the world.
I examined this shred of skin with all the care that it deserved. My first suspicions were confirmed: a Lamellicorn, a Scarabaeid in the larval state, is the first food of the Wasp whose cocoon I have just unearthed. But which of the Scarabaeidae? And does this cocoon, my precious booty, really belong to the Scoliae? The problem is beginning to take shape. To attempt its solution we must go back to the Bois des Issards.
I did go back and so often that my patience ended by being exhausted before the problem of the Scoliae had received a satisfactory solution. The difficulties are great indeed, under the conditions. Where am I to dig in the indefinite stretch of sandy soil to light upon a spot frequented by the Scoliae? The luchet is driven into the ground at random; and almost invariably I find none of what I am seeking. To be sure, the males, flying level with the ground, give me a hint, at the outset, with their certainty of instinct, as to the spots where the females ought to be; but their hints are very vague, because they go so far in every direction. If I wished to examine the soil which a single male explores in his flight, with its constantly changing course, I should have to turn over, to the depth of perhaps a yard, at least four poles of earth. This is too much for my strength and the time at my disposal. Then, as the season advances, the males disappear, whereupon I am suddenly deprived of their hints. To know more or less where I should thrust my luchet, I have only one resource left, which is to watch for the females emerging from the ground or else entering it. With a great expenditure of time and patience I have at last had this windfall, very rarely, I admit.
The Scoliae do not dig a burrow which can be compared with that of the other Hunting Wasps; they have no fixed residence, with an unimpeded gallery opening on the outer world and giving access to the cells, the abodes of the larvae. They have no entrance- and exit-doors, no corridor built in advance. If they have to make their way underground, any point not hitherto turned over serves their purpose, provided that it be not too hard for their digging-tools, which, for that matter, are very powerful; if they have to come out, the point of exit is no less indifferent. The Scolia does not bore the soil through which she passes: she excavates and ploughs it with her legs and forehead; and the stuff shifted remains where it lies, behind her, forthwith blocking the passage which she has followed. When she is about to emerge into the outer world, her advent is heralded by the fresh soil which heaps itself into a mound as though heaved up by the snout of some tiny Mole. The insect sallies forth; and the mound collapses, completely filling up the exit-hole. If the Wasp is entering the ground, the digging-operations, undertaken at an arbitrary point, quickly yield a cavity in which the Scolia disappears, separated from the surface by the whole track of shifted material.
I can easily trace her passage through the thickness of the soil by certain long, winding cylinders, formed of loose materials in the midst of compact and stable earth. These cylinders are numerous; they sometimes run to a depth of twenty inches; they extend in all directions, fairly often crossing one another. Not one of them ever exhibits so much as a suspicion of an open gallery. They are obviously not permanent ways of communication with the outer world, but hunting-trails which the insect has followed once, without going back to them. What was the Wasp seeking when she riddled the soil with these tunnels which are now full of running sands? No doubt the food for her family, the larva of which I possess the empty skin, now an unrecognizable shred.
I begin to see a little light: the Scoliae are underground workers. I already expected as much, having before now captured Scoliae soiled with little earthy encrustations on the joints of the legs. The Wasp, who is so careful to keep clean, taking advantage of the least leisure to brush and polish herself, could never display such blemishes unless she were a devoted earth-worker. I used to suspect their trade, now I know it. They live underground, where they burrow in search of Lamellicorn-grubs, just as the Mole burrows in search of the White Worm. (The larva of the Cockchafer. This grub takes three years or more to arrive at maturity underground.– Translator’s Note.) It is even possible that, after receiving the embraces of the males, they but very rarely return to the surface, absorbed as they are by their maternal duties; and this, no doubt, is why my patience becomes exhausted in watching for their entrance and their emergence.
It is in the subsoil that they establish themselves and travel to and fro; with the help of their powerful mandibles, their hard cranium, their strong, prickly legs, they easily make themselves paths in the loose earth. They are living ploughshares. By the end of August, therefore, the female population is for the most part underground, busily occupied in egg-laying and provisioning. Everything seems to tell me that I should watch in vain for the appearance of a few females in the broad daylight; I must resign myself to excavating at random.
The result was hardly commensurate with the labour which I expended on digging. I found a few cocoons, nearly all broken, like the one which I already possessed, and, like it, bearing on their side the tattered skin of a larva of the same Scarabaeid. Two of these cocoons which are still intact contained a dead adult Wasp. This was actually the Two-banded Scolia, a precious discovery which changed my suspicions into a certainty.
I also unearthed some cocoons, slightly different in appearance, containing an adult inmate, likewise dead, in whom I recognized the Interrupted Scolia. The remnants of the provisions again consisted of the empty skin of a larva, also a Lamellicorn, but not the same as the one hunted by the first Scolia. And this was all. Now here, now there, I shifted a few cubic yards of soil, without managing to find fresh provisions with the egg or the young larva. And yet it was the right season, the egg-laying season, for the males, numerous at the outset, had grown rarer day by day until they disappeared entirely. My lack of success was due to the uncertainty of my excavations, in which I had nothing to guide me over the indefinite area covered.
If I could at least identify the Scarabaeidae whose larvae form the prey of the two Scoliae, the problem would be half solved. Let us try. I collect all that the luchet has turned up: larvae, nymphs and adult Beetles. My booty comprises two species of Lamellicorns: Anoxia villosa and Euchlora Julii, both of whom I find in the perfect state, usually dead, but sometimes alive. I obtain a few of their nymphs, a great piece of luck, for the larval skin which accompanies them will serve me as a standard of comparison. I come upon plenty of larvae, of all ages. When I compare them with the cast garment abandoned by the nymphs, I recognize some as belonging to the Anoxia and the rest to the Euchlora.
With these data, I perceive with absolute certainty that the empty skin adhering to the cocoon of the Interrupted Scolia belongs to the Anoxia. As for the Euchlora, she is not involved in the problem: the larva hunted by the Two-banded Scolia does not belong to her any more than it belongs to the Anoxia. Then with which Scarabaeid does the empty skin which is still unknown to me correspond? The Lamellicorn whom I am seeking must exist in the ground which I have been exploring, because the Two-banded Scolia has established herself there. Later–oh, very long afterwards!–I recognized where my search was at fault. In order not to find a network of roots beneath my luchet and to render the work of excavation lighter, I was digging the bare places, at some distance from the thickets of holm-oak; and it was just in those thickets, which are rich in vegetable mould, that I should have sought. There, near the old stumps, in the soil consisting of dead leaves and rotting wood, I should certainly have come upon the larva so greatly desired, as will be proved by what I have still to say.
Here ends what my earlier investigations taught me. There is reason to believe that the Bois des Issards would never have furnished me with the precise data, in the form in which I wanted them. The remoteness of the spot, the fatigue of the expeditions, which the heat rendered intensely exhausting, the impossibility of knowing which points to attack would undoubtedly have discouraged me before the problem had advanced a step farther. Studies such as these call for home leisure and application, for residence in a country village. You are then familiar with every spot in your own grounds and the surrounding country and you can go to work with certainty.
Twenty-three years have passed; and here I am at Serignan, where I have become a peasant, working by turns on my writing-pad and my cabbage-patch. On the 14th of August, 1880, Favier (An ex-soldier who acted as the author’s gardener and factotum.–Translator’s Note.) clears away a heap of mould consisting of vegetable refuse and of leaves stacked in a corner against the wall of the paddock. This clearance is considered necessary because Bull, when the lovers’ moon arrives, uses this hillock to climb to the top of the wall and thence to repair to the canine wedding the news of which is brought to him by the effluvia borne upon the air. His pilgrimage fulfilled, he returns, with a discomfited look and a slit ear, but always ready, once he has had his feed, to repeat the escapade. To put an end to this licentious behaviour, which has cost him so many gaping wounds, we decided to remove the heap of soil which serves him as a ladder of escape.
Favier calls me while in the midst of his labours with the spade and barrow:
“Here’s a find, sir, a great find! Come and look.”
I hasten to the spot. The find is a magnificent one indeed and of a nature to fill me with delight, awakening all my old recollections of the Bois des Issards. Any number of females of the Two-banded Scolia, disturbed at their work, are emerging here and there from the depth of the soil. The cocoons also are plentiful, each lying next to the skin of the victim on which the larva has fed. They are all open but still fresh: they date from the present generation; the Scoliae whom I unearth have quitted them not long since. I learnt later, in fact, that the hatching took place in the course of July.
In the same heap of mould is a swarming colony of Scarabaeidae in the form of larvae, nymphs and adult insects. It includes the largest of our Beetles, the common Rhinoceros Beetle, or Oryctes nasicornis. I find some who have been recently liberated, whose wing-cases, of a glossy brown, now see the sunlight for the first time; I find others enclosed in their earthen shell, almost as big as a Turkey’s egg. More frequent is her powerful larva, with its heavy paunch, bent into a hook. I note the presence of a second bearer of the nasal horn, Oryctes Silenus, who is much smaller than her kinswoman, and of Pentodon punctatus, a Scarabaeid who ravages my lettuces.
But the predominant population consists of Cetoniae, or Rosechafers, most of them enclosed in their egg-shaped shells, with earthen walls encrusted with dung. There are three different species: C. aurata, C. morio and C. floricola. Most of them belong to the first species. Their larvae, which are easily recognized by their singular talent for walking on their backs with their legs in the air, are numbered by the hundred. Every age is represented, from the new born grub to the podgy larva on the point of building its shell.
This time the problem of the victuals is solved. When I compare the larval slough sticking to the Scolia’s cocoons with the Cetonia-larvae or, better, with the skin cast by these larvae, under cover of the cocoon, at the moment of the nymphal transformation, I establish an absolute identity. The Two-banded Scolia rations each of her eggs with a Cetonia-grub. Behold the riddle which my irksome searches in the Bois des Issards had not enabled me to solve. To-day, at my threshold, the difficult problem becomes child’s play. I can investigate the question easily to the fullest possible extent; I need not put myself out at all; at any hour of the day, at any period that seems favourable, I have the requisite elements before my eyes. Ah, dear village, so poor, so countrified, how happily inspired was I when I came to ask of you a hermit’s retreat, where I could live in the company of my beloved insects and, in so doing, set down not too unworthily a few chapters of their wonderful history!
According to the Italian observer Passerini, the Garden Scolia feeds her family on the larvae of Oryctes nasicornis, in the heaps of old tan-waste removed from the hot-houses. I do not despair of seeing this colossal Wasp coming to establish herself one day in my heaps of leaf-mould, in which the same Scarabaeid is swarming. Her rarity in my part of the country is probably the only cause that has hitherto prevented the realization of my wishes.
I have just shown that the Two-banded Scolia feeds in infancy on Cetonia- larvae and particularly on those of C. aurata, C. morio and C. floricola. These three species dwell together in the rubbish-heap just explored; their larvae differ so little that I should have to examine them minutely to distinguish the one from the other; and even then I should not be certain of succeeding. It seems probable that the Scolia does not choose between them, that she uses all three indiscriminately. Perhaps she even assails other larvae, inhabitants, like the foregoing, of heaps of rotting vegetable-matter. I therefore set down the Cetonia genus generally as forming the prey of the Two-banded Scolia.
Lastly, round about Avignon, the Interrupted Scolia used to prey upon the larva of the Shaggy Anoxia (A. villosa). At Serignan, which is surrounded by the same kind of sandy soil, without other vegetation than a few sparse seed-bearing grasses, I find her rationing her young with the Morning Anoxia (A. matutinalis). Oryctes, Cetoniae and Anoxiae in the larval state: here then is the prey of the three Scoliae whose habits we know. The three Beetles are Lamellicorns, Scarabaeidae. We shall have occasion later to consider the reason of this very striking coincidence.
For the moment, the business in hand is to move the heap of leaf-mould to some other place, with the wheelbarrow. This is Favier’s work, while I myself collect the disturbed population in glass jars, in order to put them back into the new rubbish-heap with all the consideration which my plans owe to them. The laying-time has not yet set in, for I find no eggs, no young Scolia-larvae. September apparently will be the propitious month. But there are bound to be many injured in the course of this upheaval; some of the Scoliae have flown away who will perhaps have a certain difficulty in finding the new site; I have disarranged everything in the overturned heap. To allow tranquility to be restored and habit to resume its rounds, to give the population time to increase and replace the fugitives and the injured, it would be best, I think, to leave the heap alone this year and not to resume my investigations until the next. After the thorough confusion due to the removal, I should jeopardize success by being too precipitate. Let us wait one year more. I decide accordingly, curb my impatience and resign myself. We will simply confine ourselves to enlarging the heap, when the leaves begin to fall, by accumulating the refuse that strews the paddock, so that we may have a richer field of operations.
In the following August, my visits to the mound of leaf-mould become a daily habit. By two o’clock in the afternoon, when the sun has cleared the adjacent pine-trees and is shining on the heap, numbers of male Scoliae arrive from the neighbouring fields, where they have been slaking their thirst on the eryngo-heads. Incessantly coming and going with an indolent flight, they circle round the heap. If some female rise from the soil, those who have seen her dart forward. A not very turbulent affray decides which of the suitors shall be the possessor; and the couple fly away over the wall. This is a repetition of what I used to see in the Bois des Issards. By the time that August is over. The males have ceased to show themselves. The mothers do not appear either: they are busy underground, establishing their families.
On the 2nd of September, I decide upon a search with my son Emile, who handles the fork and the shovel, while I examine the clods dug up. Victory! A magnificent result, finer than any that my fondest ambition would have dared to contemplate! Here is a vast array of Cetonia-larvae, all flaccid, motionless, lying on their backs, with a Scolia’s egg sticking to the centre of their abdomen; here are young Scolia-larvae dipping their heads into the entrails of their victims; here are others farther advanced, munching their last mouthfuls of a prey which is drained dry and reduced to a skin; here are some laying the foundation of their cocoons with a reddish silk, which looks as if it had been dyed in Bullock’s blood; here are some whose cocoons are finished. There is plenty of everything, from the egg to the larva whose period of activity is over. I mark the 2nd of September as a red-letter day; it has given me the final key to a riddle which has kept me in suspense for nearly half a century.
I place my spoils religiously in shallow, wide-mouthed glass jars containing a layer of finely sifted mould. In this soft bed, which is identical in character with the natal surroundings, I make some faint impressions with my fingers, so many cavities, each of which receives one of my subjects, one only. A pane of glass covers the mouth of the receptacle. In this way I prevent a too rapid evaporation and keep my nurselings under my eyes without fear of disturbing them. Now that all this is in order, let us proceed to record events.
The Cetonia-larvae which I find with a Scolia’s egg upon their ventral surface are distributed in the mould at random, without special cavities, without any sign of some sort of structure. They are smothered in the mould, just as are the larvae which have not been injured by the Wasp. As my excavations in the Bois des Issards told me, the Scolia does not prepare a lodging for her family; she knows nothing of the art of cell-building. Her offspring occupies a fortuitous abode, on which the mother expends no architectural pains. Whereas the other Hunting Wasps prepare a dwelling to which the provisions are carried, sometimes from a distance, the Scolia confines herself to digging her bed of leaf-mould until she comes upon a Cetonia-larva. When she finds a quarry, she stabs it on the spot, in order to immobilize it; and, again on the spot, she lays an egg on the ventral surface of the paralysed creature. That is all. The mother goes in quest of another prey without troubling further about the egg which has just been laid. There is no effort of carting or building. At the very spot where the Cetonia-grub is caught and paralysed, the Scolia-larva hatches, grows and weaves its cocoon. The establishment of the family is thus reduced to the simplest possible expression.
CHAPTER 3. A DANGEROUS DIET.
The Scolia’s egg is in no way exceptional in shape. It is white, cylindrical, straight and about four millimetres long by one millimetre thick. (About .156 x .039 inch.–Translator’s Note.) It is fixed, by its fore-end, upon the median line of the victim’s abdomen, well to the rear of the legs, near the beginning of the brown patch formed by the mass of food under the skin.
I watch the hatching. The grub, still wearing upon its hinder parts the delicate pellicle which it has just shed, is fixed to the spot to which the egg itself adhered by its cephalic extremity. A striking spectacle, that of the feeble creature, only this moment hatched, boring, for its first mouthful, into the paunch of its enormous prey, which lies stretched upon its back. The nascent tooth takes a day over the difficult task. Next morning the skin has yielded; and I find the new-born larva with its head plunged into a small, round, bleeding wound.
In size the grub is the same as the egg, whose dimensions I have just given. Now the Cetonia-larva, to meet the Scolia’s requirements, averages thirty millimetres in length by nine in thickness (1.17 x .35 inch.– Translator’s Note.), whence follows that its bulk is six or seven hundred times as great as that of the newly-hatched grub of the Scolia. Here certainly is a quarry which, were it active and capable of wriggling and biting, would expose the nurseling to terrible attacks. The danger has been averted by the mother’s stiletto; and the fragile grub attacks the monster’s paunch with as little hesitation as though it were sucking the breast.
Day by day the young Scolia’s head penetrates farther into the Cetonia’s belly. To pass through the narrow orifice made in the skin, the fore-part of the body contracts and lengthens out, as though drawn through a die- plate. The larva thus assumes a rather strange form. Its hinder half, which is constantly outside the victim’s belly, has the shape and fulness usual in the larvae of the Digger-wasps, whereas the front half, which, once it has dived under the skin of the exploited victim, does not come out again until the time arrives for spinning the cocoon, tapers off suddenly into a snake-like neck. This front part is moulded, so to speak, by the narrow entrance-hole made in the skin and henceforth retains its slender formation. As a matter of fact, a similar configuration recurs, in varying degrees, in the larvae of the Digger-wasps whose ration consists of a bulky quarry which takes a long time to consume. These include the Languedocian Sphex, with her Ephippiger, and the Hairy Ammophila, with her Grey Worm. There is none of this sudden constriction, dividing the creature into two disparate halves, when the victuals consist of numerous and comparatively small items. The larva then retains its usual shape, being obliged to pass, at brief intervals, from one joint in its larder to the next.
>From the first bite of the mandibles, until the whole head of game is consumed, the Scolia-larva is never seen to withdraw its head and its long neck from inside the creature which it is devouring. I suspect the reason of this persistence in attacking a single point; I even seem to perceive the need for a special art in the manner of eating. The Cetonia-larva is a square meal in itself, one large dish, which has to retain a suitable freshness until the end. The young Scolia, therefore, must attack with discretion, at the unvarying point chosen by the mother on the ventral surface, for the entrance-hole is at the exact point where the egg was fixed. As the nurseling’s neck lengthens and dives deeper, the victim’s entrails are nibbled gradually and methodically: first, the least essential; next, those whose removal leaves yet a remnant of life; lastly, those whose loss inevitably entails death, followed very soon by putrefaction.
At the first bites we see the victim’s blood oozing through the wound. It is a highly-elaborated fluid, easy of digestion, and forms a sort of milk- diet for the new-born grub. The little ogre’s teat is the bleeding paunch of the Cetonia-larva. The latter will not die of the wound, at least not for some time. The next thing to be tackled is the fatty substance which wraps the internal organs in its delicate folds. This again is a loss which the Cetonia can suffer without dying then and there. Now comes the turn of the muscular layer which lines the skin; now, that of the essential organs; now, that of the nerve-centres and the trachean network, whereupon the last gleam of light is extinguished and the Cetonia reduced to a mere bag, empty but intact, save for the entrance-hole made in the middle of the belly. >From now onwards, these remains may rot if they will: the Scolia, by its methodical fashion of consuming its victuals, has succeeded in keeping them fresh to the very last; and now you may see it, replete, shining with health, withdraw its long neck from the bag of skin and prepare to weave the cocoon in which its development will be completed.
It is possible that I may not be quite accurate as to the precise order in which the organs are consumed, for it is not easy to perceive what happens inside the exploited larva’s body. The ruling feature in this scientific method of eating, which proceeds from the parts less to the parts more necessary to preserve a remnant of life, is none the less obvious. If direct observation did not already to some degree confirm it, a mere examination of the half-eaten larva would do so in the most positive fashion.
The Cetonia-larva is at first a plump grub. Drained by the Scolia’s tooth, it gradually becomes limp and wrinkled. In a few days’ time it resembles a shrivelled bit of bacon-fat and then a bag whose two sides have fallen in. Yet this bit of bacon and this bag have the same characteristic look of fresh meat as had the grub before it was bitten into. Despite the persistent nibbling of the Scolia, life continues, holding at bay the inroads of putrefaction until the mandibles have given their last bites. Does not this remnant of tenacious vitality in itself show that the organs of primary importance are the last to be attacked? Does it not prove that there is a progressive dismemberment passing from the less essential to the indispensable?
Would you like to see what becomes of a Cetonia-larva when the organism is wounded in its vital centres at the very beginning? The experiment is an easy one; and I made a point of trying it. A sewing-needle, first softened and flattened into a blade, then retempered and sharpened, gives me a most delicate scalpel. With this instrument I make a fine incision, through which I remove the mass of nerves whose remarkable structure we shall soon have occasion to study. The thing is done: the wound, which does not look serious, has left the creature a corpse, a real corpse. I lay my victim on a bed of moist earth, in a jar with a glass lid; in fact, I establish it in the same conditions as those of the larvae on which the Scoliae feed. By the next day, without changing shape, it has turned a repulsive brown; presently it dissolves into noisome putrescence. On the same bed of earth, under the same glass cover, in the same moist, warm atmosphere, the larvae three-quarters eaten by the Scoliae retain, on the contrary, the appearance of healthy flesh.
If a single stroke of my dagger, fashioned from the point of a needle, results in immediate death and early putrefaction; if the repeated bites of the Scolia gut the creature’s body and reduce it almost to a skin without completely killing it, the striking contrast between these two results must be due to the relative importance of the organs injured. I destroy the nerve-centres and inevitably kill my larva, which is putrid by the following day; the Scolia attacks the reserves of fat, the blood, the muscles and does not kill its victim, which will provide it with wholesome food until the end. But it is clear that, if the Scolia were to set to work as I did, there would be nothing left, after the first few bites, but an actual corpse, discharging fluids which would be fatal to it within twenty- four hours. The mother, it is true, in order to assure the immobility of her prey, has injected the poison of her sting into the nerve-centres. Her operation cannot be compared with mine in any respect. She practises the method of the skilful physiologist who induces anaesthesia; I go to work like the butcher who chops, cuts and disembowels. The sting leaves the nerve-centres intact. Deprived of sensibility by the poison, they have lost the power of provoking muscular contractions; but who can say that, numbed as they are, they no longer serve to maintain a faint vitality? The flame is extinguished, but there is still a glowing speck upon the wick. I, a rough blunderer, do more than blow out the lamp: I throw away the wick and all is over. The grub would do the same if it bit straight into the mass of nerves.
Everything confirms the fact: the Scolia and the other Hunting Wasps whose provisions consist of bulky heads of game are gifted with a special art of eating, an exquisitely delicate art which saves a remnant of life in the prey devoured, until it is all consumed. When the prey is a small one, this precaution is superfluous. Consider, for instance, the Bembex-grubs in the midst of their heap of Flies. The prey seized upon is broached on the back, the belly, the head, the thorax, indifferently. The larva munches a given spot, which it leaves to munch a second, passing to a third and a fourth, at the bidding of its changing whims. It seems to taste and select, by repeated trials, the mouthfuls most to its liking. Thus bitton at several points, covered with wounds, the Fly is soon a shapeless mass which would putrefy very quickly if the meagre dish were not devoured at a single meal. Allow the Scolia-grub the same unlicensed gluttony: it would perish beside its corpulent victim, which should have kept fresh for a fortnight, but which almost from the beginning would be no more than a filthy putrescence.
This art of careful eating does not seem easy to practise: at least, the larva, if ever so little diverted from its usual courses, is no longer able to apply its talent as a capable trencherman. This will be proved by experiment. I must begin by observing that, when I spoke of my larva which turned putrid within twenty-four hours, I adopted an extreme case for the sake of greater clearness. The Scolia, taking its first bite, does not and cannot go to such lengths. Nevertheless it behooves us to enquire whether, in the consumption of the victuals, the initial point of attack is a matter of indifference and whether the rummaging through the entrails of the victim entails a determined order, without which success is uncertain or even impossible. To these delicate questions no one, I think, can reply. Where science is silent, perhaps the grub will speak. We will try.
I move from its position a Scolia-grub which has attained a quarter or a third of its full growth. The long neck plunged into the victim’s belly is rather difficult to extract, because of the need of molesting the creature as little as possible. I succeed, by means of a little patience and repeated strokes with the tip of a paint-brush. I now turn the Cetonia- larva over, back uppermost, at the bottom of the little hollow made by pressing my finger in the layer of mould. Lastly, I place the Scolia on its victim’s back. Here is my grub under the same conditions as just now, with this difference, that the back and not the belly of its victim is presented to its mandibles.
I watch it for a whole afternoon. It writhes about; it moves its little head now in this direction, now in that, frequently laying it on the Cetonia, but without fixing it anywhere. The day draws to a close; and still it has accomplished nothing. There are restless movements, nothing more. Hunger, I tell myself, will eventually induce it to bite. I am wrong. Next morning I find it more anxious than the day before and still groping about, without resolving to fix its mandibles anywhere. I leave it alone for half a day longer without obtaining any result. Yet twenty-four hours of abstinence must have awakened a good appetite, above all in a creature which, if left undisturbed, would not have ceased eating.
Excessive hunger cannot induce it to nibble at an unlawful spot. Is this due to feebleness of the teeth? By no means: the Cetonia’s skin is no tougher on the back than on the belly; moreover, the grub is capable of perforating the skin when it leaves the egg; a fortiori, it must be more capable of doing so now that it has attained a sturdy growth. Thus we see no lack of ability, but an obstinate refusal to nibble at a point which ought to be respected. Who knows? On this side perhaps the grub’s dorsal vessel would be wounded, its heart, an organ indispensable to life. The fact remains that my attempts to make the grub tackle its victim from the back have failed. Does this mean that it entertains the least suspicion of the danger which it might incur were it to produce putrefaction by awkwardly carving its victuals from the back? It would be absurd to give such an idea a moment’s consideration. Its refusal is dictated by a preordained decree which it is bound to obey.
My Scolia-grubs would die of starvation if I left them on their victim’s back. I therefore restore matters as they were, with the Cetonia-larva belly uppermost and the young Scolia on top. I might utilise the subjects of my previous experiments; but, as I have to take precautions against the disturbance which may have been caused by the test already undergone, I prefer to operate on new patients, a luxury in which the richness of my menagerie allows me to indulge. I move the Scolia from its position, extract its head from the entrails of the Cetonia-larva and leave it to its own resources on its victim’s belly. Betraying every symptom of uneasiness, the grub gropes, hesitates, casts about and does not insert its mandibles anywhere, though it is now the ventral surface which it is exploring. It would not display greater hesitation if placed on the back of the larva. I repeat, who knows? On this side it might perhaps injure the nervous plexus, which is even more essential than the dorsal vessel. The inexperienced grub must not drive in its mandibles at random; its future is jeopardized if it gives a single ill-judged bite. If it gnaws at the spot where I myself operated with my needle wrought into a scalpel, its victuals will very soon turn putrid. Once more, then, we witness an absolute refusal to perforate the skin of the victim elsewhere than at the very point where the egg was fixed.
The mother selects this point, which is undoubtedly that most favourable to the future prosperity of the larva, though I am not able clearly to discern the reasons for her choice; she fixes the egg to it; and the place where the opening is to be made is henceforth determined. It is here that the grub must bite: only here, never elsewhere. Its invincible refusal to tackle the Cetonia in any other part, even though it should die of starvation, shews us how rigorous is the rule of conduct with which its instinct is inspired.
As it gropes about, the grub laid on the victim’s ventral surface sooner or later rediscovers the gaping wound from which I have removed it. If this takes too long for my patience, I can myself guide its head to the place with the point of a paint-brush. The grub then recognizes the hole of its own making, slips its neck into it and little by little dives into the Cetonia’s belly, so that the original state of affairs appears to be exactly restored. And yet its successful rearing is henceforth highly problematical. It is possible that the larva will prosper, complete its development and spin its cocoon; it is also possible–and the case is not unusual–that the Cetonia-larva will soon turn brown and putrid. We then see the Scolia itself turn brown, distended as it is with putrescent foodstuffs, and then cease all movement, without attempting to withdraw from the sanies. It dies on the spot, poisoned by its excessively high game.
What can be the meaning of this sudden corruption of the victuals, followed by the death of the Scolia, when everything appeared to have returned to its normal condition? I see only one explanation. Disturbed in its activities and diverted from its usual courses by my interference, the grub, when replaced on the wound from which I extracted it, was unable to rediscover the lode at which it was working a few minutes earlier; it thrust its way at random into the victim’s entrails; and a few untimely bites extinguished the last sparks of vitality. Its confusion rendered it clumsy; and the mistake cost it its life. It dies poisoned by the rich food which, if consumed according to the rules, should have made it grow plump and lusty.
I was anxious to observe the deadly effects of a disturbed meal in another fashion. This time the victim itself shall disorder the grub’s activities. The Cetonia-larva, as served up to the young Scolia by its mother, is profoundly paralysed. Its inertia is complete and so striking that it constitutes one of the leading features of this narrative. But we will not anticipate. For the moment, the thing is to substitute for this inert larva a similar larva, but one not paralysed, one very much alive. To ensure that it shall not double up and crush the grub, I confine myself to reducing it to helplessness, leaving it otherwise just as I extracted it from its burrow. I must also be careful of its legs and mandibles, the least touch of which would rip open the nurseling. With a few turns of the finest wire I fix it to a little slab of cork, with its belly in the air. Next, to provide the grub with a ready-made hole, knowing that it will refuse to make one for itself, I contrive a slight incision in the skin, at the point where the Scolia lays her egg. I now place the grub upon the larva, with its head touching the bleeding wound, and lay the whole on a bed of mould in a transparent beaker protected by a pane of glass.
Unable to move, to wriggle, to scratch with its legs or snap with its mandibles, the Cetonia-larva, a new Prometheus bound, offers its defenceless flanks to the little Vulture destined to devour its entrails. Without too much hesitation, the young Scolia settles down to the wound made by my scalpel, which to the grub represents the wound whence I have just removed it. It thrusts its neck into the belly of its prey; and for a couple of days all seems to go well. Then, lo and behold, the Cetonia turns putrid and the Scolia dies, poisoned by the ptomaines of the decomposing game! As before, I see it turn brown and die on the spot, still half inside the toxic corpse.
The fatal issue of my experiment is easily explained. The Cetonia-larva is alive in every sense. True, I have, by means of bonds, suppressed its outward movements, in order to provide the nurseling with a quiet meal, devoid of danger; but it was not in my power to subdue its internal movements, the quivering of the viscera and muscles irritated by its forced immobility and by the Scolia’s bites. The victim is in possession of its full power of sensation; and it expresses the pain experienced as best it may, by contractions. Embarrassed by these tremors, these twitches of suffering flesh, incommoded at every mouthful, the grub chews away at random and kills the larva almost as soon as it has started on it. In a victim paralysed by the regulation sting, the conditions would be very different. There are no external movements, nor any internal movements either, when the mandibles bite, because the victim is insensible. The grub, undisturbed in any way, is then able, with an unfaltering tooth, to pursue its scientific method of eating.
These marvellous results interested me too much not to inspire me with fresh devices when I pursued my investigations. Earlier enquiries had taught me that the larvae of the Digger-wasps are fairly indifferent to the nature of the game, though the mother always supplies them with the same diet. I had succeeded in rearing them on a great variety of prey, without paying regard to their normal fare. I shall return to this subject later, when I hope to demonstrate its great philosophical significance. Let us profit by these data and try to discover what happens when we give the Scolia food which is not properly its own.
I select from my heap of garden-mould, that inexhaustible mine, two larvae of the Rhinoceros Beetle, Oryctes nasicornis, about one-third full-grown, so that their size may not be out of proportion to the Scolia’s. It is in fact almost identical with the size of the Cetonia. I paralyse one of them by giving an injection of ammonia in the nerve-centres. I make a fine incision in its belly and I place the Scolia on the opening. The dish pleases my charge; and it would be strange indeed if this were not so, considering that another Scolia-grub, the larva of the Garden Scolia, feeds on the Oryctes. The dish suits it, for before long it has burrowed half-way into the succulent paunch. This time all goes well. Will the rearing be successful? Not a bit of it! On the third day, the Oryctes decomposes and the Scolia dies. Which shall we hold responsible for the failure, myself or the grub? Myself who, perhaps too unskilfully, administered the injection of ammonia, or the grub which, a novice at dissecting a prey differing from its own, did not know how to practise its craft upon a changed victim and began to bite before the proper time?
In my uncertainty, I try again. This time I shall not interfere, so that my clumsiness cannot be to blame. As I described when speaking of the Cetonia- larva, the Oryctes-larva now lies bound, quite alive, on a strip of cork. As usual, I make a small opening in the belly, to entice the grub by means of a bleeding wound and facilitate its access. I obtain the same negative result. In a little while, the Oryctes is a noisome mass on which the nurseling lies poisoned. The failure was foreseen: to the difficulties presented by a prey unknown to my charge was added the commotion caused by the wriggling of an unparalysed animal.
We will try once more, this time with a victim paralysed not by me, an unskilled operator, but by an adept whose ability ranks so high that it is beyond discussion. Chance favours me to perfection: yesterday, in a warm sheltered corner, at the foot of a sandy bank, I discovered three cells of the Languedocian Sphex, each with its Ephippiger and the recently laid egg. This is the game I want, a corpulent prey, of a size suited to the Scolia and, what is more, in splendid condition, artistically paralysed according to rule by a master among masters.
As usual, I install my three Ephippigers in a glass jar, on a bed of mould; I remove the egg of the Sphex and on each victim, after slightly incising the skin of the belly, I place a young Scolia-grub. For three or four days my charges feed upon this game, so novel to them, without any sign of repugnance or hesitation. By the fluctuations of the digestive canal I perceive that the work of nutrition is proceeding as it should; things are happening just as if the dish were a Cetonia-larva. The change of diet, complete though it is, has in no way affected the appetite of the Scolia- grubs. But this prosperous condition does not last long. About the fourth day, a little sooner in one case, a little later in another, the three Ephippigers become putrid and the Scoliae die at the same time.
This result is eloquent. Had I left the egg of the Sphex to hatch, the larva coming out of it would have fed upon the Ephippiger; and for the hundredth time I should have witnessed an incomprehensible spectacle, that of an animal which, devoured piecemeal for nearly a fortnight, grows thin and empty, shrivels up and yet retains to the very end the freshness peculiar to living flesh. Substitute for this Sphex-larva a Scolia-larva of almost the same size; let the dish be the same though the guest is different; and healthy live flesh is promptly replaced by pestilent rotten flesh. That which under the mandibles of the Sphex would for a long while have remained wholesome food promptly becomes a poisonous liquescence under the mandibles of the Scolia.
It is impossible to explain the preservation of the victuals until finally consumed by supposing that the venom injected by the Wasp when she delivers her paralysing stings possesses antiseptic properties. The three Ephippigers were operated on by the Sphex. Able to keep fresh under the mandibles of the Sphex-larvae, why did they promptly go bad under the mandibles of the Scolia-larvae? Any idea of an antiseptic must needs be rejected: a liquid preservative which would act in the first case could not fail to act in the second, as its virtues would not depend on the teeth of the consumer.
Those of you who are versed in the knowledge attaching to this problem, investigate, I beg you, search, sift, see if you can discover the reason why the victuals keep fresh when consumed by a Sphex, whereas they promptly become putrid when consumed by a Scolia. For me, I see only one reason; and I very much doubt whether any one can suggest another.
Both larvae practise a special art of eating, which is determined by the nature of the game. The Sphex, when sitting down to an Ephippiger, the food that has fallen to its lot, knows thoroughly how to consume it and how to preserve, to the very end, the glimmer of life which keeps it fresh; but, if it has to browse upon a Cetonia-grub, whose different structure would confuse its talents as a dissector, it would soon have nothing before it but a heap of putrescence. The Scolia, in its turn, is familiar with the method of eating the Cetonia-grub, its invariable portion; but it does not understand the art of eating the Ephippiger, though the dish is to its taste. Unable to dissect this unknown species of game, its mandibles slash away at random, killing the creature outright as soon as they take their first bites of the deeper tissues of the victim. That is the whole secret.
One more word, on which I shall enlarge in another chapter. I observe that the Scoliae to which I give Ephippigers paralysed by the Sphex keep in excellent condition, despite the change of diet, so long as the provisions retain their freshness. They languish when the game goes high; and they die when putridity supervenes. Their death, therefore, is due not to an unaccustomed diet, but to poisoning by one or other of those terrible toxins which are engendered by animal corruption and which chemistry calls by the name of ptomaines. Therefore, notwithstanding the fatal outcome of my three attempts, I remain persuaded that the unfamiliar method of rearing would have been perfectly successful had the Ephippigers not gone bad, that is, if the Scoliae had known how to eat them according to the rules.
What a delicate and dangerous thing is the art of eating in these carnivorous larvae supplied with a single victim, which they have to spend a fortnight in consuming, on the express condition of not killing it until the very end! Could our physiological science, of which, with good reason, we are so proud, describe, without blundering, the method to be followed in the successive mouthfuls? How has a miserable grub learnt what our knowledge cannot tell us? By habit, the Darwinians will reply, who see in instinct an acquired habit.
Before deciding this serious matter, I will ask you to reflect that the first Wasp, of whatever kind, that thought of feeding her progeny on a Cetonia-grub or on any other large piece of game demanding long preservation could necessarily have left no descendants unless the art of consuming food without causing putrescence had been practised, with all its scrupulous caution, from the first generation onwards. Having as yet learnt nothing by habit or by atavistic transmission, since it was making a first beginning, the nurseling would bite into its provender at random. It would be starving, it would have no respect for its prey. It would carve its joint at random; and we have just seen the fatal consequence of an ill- directed bite. It would perish–I have just proved this in the most positive manner–it would perish, poisoned by its victim, already dead and putrid.
To prosper, it would have, although a novice, to know what was permitted and what forbidden in ransacking the creature’s entrails; nor would it be enough for the larva to be approximately in possession of this difficult secret: it would be indispensable that it should possess the secret completely, for a single bite, if delivered before the right moment, would inevitably involve its own demise. The Scoliae of my experiments are not novices, far from it: they are the descendants of carvers that have practised their art since Scoliae first came into the world; nevertheless they all perish from the decomposition of the rations supplied, when I try to feed them on Ephippigers paralysed by the Sphex. Very expert in the method of attacking the Cetonia, they do not know how to set about the business of discreetly consuming a species of game new to them. All that escapes them is a few details, for the trade of an ogre fed on live flesh is familiar to them in its general features; and these unheeded details are enough to turn their food into poison. What, then, happened in the beginning, when the larva bit for the first time into a luscious victim? The inexperienced creature perished; of that there is not a shadow of doubt, unless we admit an absurdity and imagine the larva of antiquity feeding upon those terrible ptomaines which so swiftly kill its descendants to-day.
Nothing will ever make me admit and no unprejudiced mind can admit that what was once food has become a horrible poison. What the larva of antiquity ate was live flesh and not putrescence. Nor can it be admitted that the chances of fortune can have led at the first trial to success in a system of nourishment so full of pit-falls: fortuitous results are preposterous amid so many complications. Either the feeding is strictly methodical at the beginning, in conformity with the organic exigencies of the prey devoured, and the Wasp established her race; or else it was hesitating, without determined rules, and the Wasp left no successor. In the first case we behold innate instinct; in the second acquired habit.
A strange acquisition, truly! An acquisition presumed to be made by an impossible creature; an acquisition supposed to develop in no less impossible successors! Though the snow-ball, slowly rolling, at last becomes an enormous sphere, it is still necessary that the starting-point shall not have been NIL. The big ball implies the little ball, as small as you please. Now, in harking back to the origin of these acquired habits, if I interrogate the possibilities I obtain zero as the only answer. If the animal does not know its trade thoroughly, if it has to acquire something, all the more if it has to acquire everything, it perishes: that is inevitable; without the little snow-ball the big snow-ball cannot be rolled. If it has nothing to acquire, if it knows all that it needs to know, it flourishes and leaves descendants behind it. But then it possesses innate instinct, the instinct which learns nothing and forgets nothing, the instinct which is steadfast throughout time.
The building up of theories has never appealed to me: I suspect them one and all. To argue nebulously upon dubious premises likes me no better. I observe, I experiment and I let the facts speak for themselves. We have just heard these facts. Let each now decide for himself whether instinct is an innate faculty or an acquired habit.
CHAPTER 4. THE CETONIA-LARVA.
The Scolia’s feeding-period lasts, on the average, for a dozen days or so. By then the victuals are no more than a crumpled bag, a skin emptied of the last scrap of nutriment. A little earlier, the russet-yellow tint announces the extinction of the last spark of life in the creature that is being devoured. The empty skin is pushed back to make space; the dining-room, a shapeless cavity with crumbling walls, is tidied up a little; and the Scolia-grub sets to work on its cocoon without further delay.
The first courses form a general scaffolding, which finds a support here and there on the earthen walls, and consist of a rough, blood-red fabric. When the larva is merely laid, as required by my investigations, in a hollow made with the finger-tip in the bed of mould, it is not able to spin its cocoon, for want of a ceiling to which to fasten the upper threads of its network. To weave its cocoon, every spinning larva is compelled to isolate itself in a hammock slung in an open-work enclosure, which enables it to distribute its thread uniformly in all directions. If there be no ceiling, the upper part of the cocoon cannot be fashioned, because the worker lacks the necessary points of support. Under these conditions my Scolia-grubs contrive at most to upholster their little pit with a thick down of reddish silk. Discouraged by futile endeavours, some of them die. It is as if they had been killed by the silk which they omit to disgorge because they are unable to make the right use of it. This, if we were not watchful, would be a very frequent cause of failure in our attempts at artificial rearing. But, once the danger has been perceived, the remedy is simple. I make a ceiling over the cavity by laying a short strip of paper above it. If I want to see how matters are progressing, I bend the strip into a semicircle, into a half-cylinder with open ends. Those who wish to play the breeder for themselves will be able to profit by these little practical details.
In twenty-four hours the cocoon is finished; at least, it no longer allows us to see the grub, which is doubtless making the walls of its dwelling still thicker. At first the cocoon is a vivid red; later it changes to a light chestnut-brown. Its form is that of an ellipsoid, with a major axis 26 millimetres in length, while the minor axis measures 11 millimetres. (1.014 x .429 inch.–Translator’s Note.) These dimensions, which incidentally are inclined to vary slightly, are those of the female cocoons. In the other sex they are smaller and may measure as little as 17 millimetres in length by 7 millimetres in width. (.663 x .273 inch.– Translator’s Note.)
The two ends of the ellipsoid have the same form, so much so that it is only thanks to an individual peculiarity, independent of the shape, that we can tell the cephalic from the anal extremity. The cephalic pole is flexible and yields to the pressure of my tweezers; the anal pole is hard and unyielding. The wrapper is double, as in the cocoons of the Sphex. (Cf. “The Hunting Wasps”: chapters 4 to 10 et passim.–Translator’s Note.) The outer envelope, consisting of pure silk, is thin, flexible and offers little resistance. It is closely superimposed upon the inner envelope and is easily separated from it everywhere, except at the anal end, where it adheres to the second envelope. The adhesion of the two wrappers at one end and the non-adhesion at the other are the cause of the differences which the tweezers reveal when pinching the two ends of the cocoon.
The inner envelope is firm, elastic, rigid and, to a certain point, brittle. I do not hesitate to look upon it as consisting of a silken tissue which the larva, towards the end of its task, has steeped thoroughly in a sort of varnish prepared not by the silk-glands but by the stomach. The cocoons of the Sphex have already shown us a similar varnish. This product of the chylific ventricle is chestnut-brown. It is this which, saturating the thickness of the tissue, effaces the bright red of the beginning and replaces it by a brown tint. It is this again which, disgorged more profusely at the lower end of the cocoon, glues the two wrappers together at that point.
The perfect insect is hatched at the beginning of July. The emergence takes place without any violent effraction, without any ragged rents. A clean, circular fissure appears at some distance from the top; and the cephalic end is detached all of a piece, as a loose lid might be. It is as though the recluse had only to raise a cover by butting it with her head, so exact is the line of division, at least as regards the inner envelope, the stronger and more important of the two. As for the outer wrapper, its lack of resistance enables it to yield without difficulty when the other gives way.
I cannot quite make out by what knack the Wasp contrives to detach the cap of the inner shell with such accuracy. Is it the art practised by the tailor when cutting his stuff, with mandibles taking the place of scissors? I hardly venture to admit as much: the tissue is so tough and the circle of division so precise. The mandibles are not sharp enough to cut without leaving a ragged edge; and then what geometrical certainty they would need for an operation so perfect that it might well have been performed with the compasses!
I suspect therefore that the Scolia first fashions the outer sac in accordance with the usual method, that is, by distributing the silk uniformly, without any special preparation of one part of the wall more than of another, and that it afterwards changes its method of weaving in order to attend to the main work, the inner shell. In this it apparently imitates the Bembex (Cf. “The Hunting Wasps”: chapters 14 to 16.– Translator’s Note.), which weaves a sort of eel-trap, whose ample mesh allows it to gather grains of sand outside and encrust them one by one in the silky network, and completes the performance with a cap fitting the entrance to the trap. This provides a circular line of least resistance, along which the casket breaks open afterwards. If the Scolia really works in the same manner, everything is explained: the eel-trap, while still open, enables it to soak with varnish both the inside and the outside of the inner shell, which has to acquire the consistency of parchment; lastly, the cap which completes and closes the structure leaves for the future a circular line capable of splitting easily and neatly.
This is enough on the subject of the Scolia-grub. Let us go back to its provender, of whose remarkable structure we as yet know nothing. In order that it may be consumed with the delicate anatomical discretion imposed by the necessity of having fresh food to the last, the Cetonia-grub must be plunged into a state of absolute immobility: any twitchings on its part–as the experiments which I have undertaken go to prove–would discourage our nibbling larva and impede the work of carving, which has to be effected with so much circumspection. It is not enough for the victim to be unable to move from place to place beneath the soil: in addition to this, the contractible power in its sturdy muscular organism must be suppressed.
In its normal state, this larva, at the very least disturbance, curls itself up, almost as the Hedgehog does; and the two halves of the ventral surface are laid one against the other. You are quite surprised at the strength which the creature displays in keeping itself thus contracted. If you try to unroll it, your fingers encounter a resistance far greater than the size of the animal would have caused you to suspect. To overcome the resistance of this sort of spring coiled upon itself, you have to force it, so much so that you are afraid, if you persist, of seeing the indomitable spiral suddenly burst and shoot forth its entrails.
A similar muscular energy is found in the larvae of the Oryctes (Also known as the Rhinoceros Beetle.–Translator’s Note.), the Anoxia (A Beetle akin to the Cockchafer.–Translator’s Note.), the Cockchafer. Weighed down by a heavy belly and living underground, where they feed either on leaf-mould or on roots, these larvae all possess the vigorous constitution needed to drag their corpulence through a resisting medium. All of them also roll themselves into a hook which is not straightened without an effort.
Now what would become of the egg and the new-born grub of the Scoliae, fixed under the belly, at the centre of the Cetonia’s spiral, or inside the hook of the Oryctes or the Anoxia? They would be crushed between the jaws of the living vice. It is essential that the arc should slacken and the hook unbend, without the least possibility of their returning to a state of tension. Indeed, the well-being of the Scoliae demands something more: those powerful bodies must not retain even the power to quiver, lest they derange a method of feeding which has to be conducted with the greatest caution.
The Cetonia-grub to which the Two-banded Scolia’s egg is fastened fulfils the required conditions admirably. It is lying on its back, in the midst of the mould, with its belly fully extended. Long accustomed though I be to this spectacle of victims paralysed by the sting of the Hunting Wasp, I cannot suppress my astonishment at the profound immobility of the prey before my eyes. In the other victims with flexible skins, Caterpillars, Crickets, Mantes, Ephippigers, I perceived at least some pulsations of the abdomen, a few feeble contortions under the stimulus of a needle. There is nothing of the sort here, nothing but absolute inertia, except in the head, where I see, from time to time, the mouth-parts open and close, the palpi give a tremor, the short antennae sway to and fro. A prick with the point of a needle causes no contraction, no matter what the spot pricked. Though I stab it through and through, the creature does not stir, be it ever so little. A corpse is not more inert. Never, since my remotest investigations, have I witnessed so profound a paralysis. I have seen many wonders due to the surgical talent of the Wasp; but to-day’s marvel surpasses them all.
I am doubly surprised when I consider the unfavourable conditions under which the Scolia operates. The other paralysers work in the open air, in the full light of day. There is nothing to hinder them. They enjoy full liberty of action in seizing the prey, holding it in position and sacrificing it; they are able to see the victim and to parry its means of defence, to avoid its spears, its pincers. The spot or spots to be attained are within their reach; they drive the dagger in without let or hindrance.
What difficulties, on the other hand, await the Scolia! She hunts underground, in the blackest darkness. Her movements are laboured and uncertain, owing to the mould, which is continually giving way all round her; she cannot keep her eyes on the terrible mandibles, which are capable of cutting her body in two with a single bite. Moreover, the Cetonia-grub, perceiving that the enemy is approaching, assumes its defensive posture, rolls itself up and makes a shield for its only vulnerable part, the ventral surface, with its convex back. No, it cannot be an easy operation to subdue the powerful larva in its underground retreat and to stab with the precision which immediate paralysis requires.
We wish that we might witness the struggle between the two adversaries and see at first hand what happens, but we cannot hope to succeed. It all takes place in the mysterious darkness of the soil; in broad daylight, the attack would not be delivered, for the victim must remain where it is and then and there receive the egg, which is unable to thrive and develop except under the warm cover of vegetable mould. If direct observation is impracticable, we can at least foresee the main outlines of the drama by allowing ourselves to be guided by the warlike manoeuvres of other burrowers.
I picture things thus: digging and rummaging through the heap of mould, guided perhaps by that singular sensibility of the antennae which enables the Hairy Ammophila to discover the Grey Worm (The caterpillar of the Turnip Moth. Cf. “The Hunting Wasps”: chapters 18 to 20.–Translator’s Note.) underground, the Scolia ends by finding a Cetonia-larva, a good plump one, in the pink of condition, having reached its full growth, just what the grub which is to feed on it requires. Forthwith, the assaulted victim, contracting desperately, rolls itself into a ball. The other seizes it by the skin of the neck. To unroll it is impossible to the insect, for I myself have some trouble in doing so. One single point is accessible to the sting: the under part of the head, or rather of the first segments, which are placed outside the coil, so that the grub’s hard cranium makes a rampart for the hinder extremity, which is less well defended. Here the Wasp’s sting enters and here only can it enter, within a narrowly circumscribed area. One stab only of the lancet is given at this point, one only because there is no room for more; and this is enough: the larva is absolutely paralysed.
The nervous functions are abolished instantly; the muscular contractions cease; and the animal uncoils like a broken spring. Henceforth motionless, it lies on its back, its ventral surface fully exposed from end to end. On the median line of this surface, towards the rear, near the brown patch due to the alimentary broth contained in the intestine, the Scolia lays her egg and without more ado, leaves everything lying on the actual spot where the murder was committed, in order to go in search of another victim.
This is how the deed must be done: the results prove it emphatically. But then the Cetonia-grub must possess a very exceptional structure in its nervous organization. The larva’s violent contraction leaves but a single point of attack open to the sting, the under part of the neck, which is doubtless uncovered when the victim tries to defend itself with its mandibles; and yet a stab in this one point produces the most thorough paralysis that I have ever seen. It is the general rule that larvae possess a centre of innervation for each segment. This is so in particular with the Grey Worm, the sacrificial victim of the Hairy Ammophila. The Wasp is acquainted with this anatomical secret: she stabs the caterpillar again and again, from end to end, segment by segment, ganglion by ganglion. With such an organization the Cetonia-grub, unconquerably coiled upon itself would defy the paralyser’s surgical skill.
If the first ganglion were wounded, the others would remain uninjured; and the powerful body, actuated by these last, would lose none of its powers of contraction. Woe then to the egg, to the young grub held fast in its embrace! And how insurmountable would be the difficulties if the Scolia, working in the profound darkness amid the crumbling soil and confronted by a terrible pair of mandibles, had to stab each segment in turn with her sting, with the certainty of method displayed by the Ammophila! The delicate operation is possible in the open air, where nothing stands in the way, in broad daylight, where the sight guides the scalpel, and with a patient which can always be released if it becomes dangerous. But in the dark, underground, amidst the ruins of a ceiling which crumbles in consequence of the conflict and at close quarters with an opponent greatly her superior in strength, how is the Scolia to guide her sting with the accuracy that is essential if the stabs are to be repeated?
So profound a paralysis; the difficulty of vivisection underground; the desperate coiling of the victim: all these things tell me that the Cetonia- grub, as regards its nervous system, must possess a structure peculiar to itself. The whole of the ganglia must be concentrated in a limited area in the first segments, almost under the neck. I see this as clearly as though it had been revealed to me by a post-mortem dissection.
Never was anatomical forecast more fully confirmed by direct examination. After forty-eight hours in benzine, which dissolves the fat and renders the nervous system more plainly visible, the Cetonia-grub is subjected to dissection. Those of my readers who are familiar with these investigations will understand my delight. What a clever school is the Scolia’s! It is just as I thought! Admirable! The thoracic and abdominal ganglia are gathered into a single nervous mass, situated within the quadrilateral bounded by the four hinder legs, which legs are very near the head. It is a tiny, dull-white cylinder, about three millimetres long by half a millimetre wide. (.117 x .019 inch.–Translator’s Note.) This is the organ which the Scolia’s sting must attack in order to secure the paralysis of the whole body, excepting the head, which is provided with special ganglia. >From it run numbers of filaments which actuate the feet and the powerful muscular layer which is the creature’s essential motor organ. When examined merely through the pocket-lens, this cylinder appears to be slightly furrowed transversely, a proof of its complex structure. Under the microscope, it is seen to be formed by the close juxtaposition, the welding, end to end, of the ganglia, which can be distinguished one from the other by a slight intermediate groove. The bulkiest are the first, the fourth and the tenth, or last; these are all very nearly of equal size. The rest are barely half or even a third as large as those mentioned.
The Interrupted Scolia experiences the same hunting and surgical difficulties when she attacks, in the crumbling, sandy soil, the larvae of the Shaggy Anoxia or of the Morning Anoxia, according to the district; and these difficulties, if they are to be overcome, demand in the victim a concentrated nervous system, like the Cetonia’s. Such is my logical conviction before making my examination; such also is the result of direct observation. When subjected to the scalpel, the larva of the Morning Anoxia shows me its centres of innervation for the thorax and the abdomen, gathered into a short cylinder, which, placed very far forward, almost immediately after the head, does not run back beyond the level of the second pair of legs. The vulnerable point is thus easily accessible to the sting, despite the creature’s posture of defence, in which it contracts and coils up. In this cylinder I recognize eleven ganglia, one more than in the Cetonia. The first three, or thoracic, ganglia are plainly distinguishable from one another, although they are set very close together; the rest are all in contact. The largest are the three thoracic ganglia and the eleventh.
After ascertaining these facts, I remembered Swammerdam’s investigations into the grub of the Monoceros, our Oryctes nasicornis. (Jan Swammerdam (1637-1680), the Dutch naturalist and anatomist.–Translator’s Note.) I chanced to possess an abridgement of the “Biblia naturae,” the masterly work of the father of insect anatomy. I consulted the venerable volume. It informed me that the learned Dutchman had been struck, long before I was, by an anatomical peculiarity similar to that which the larvae of the Cetoniae and Anoxiae had shown me in their nerve-centres. Having observed in the Silk-worm a nervous system formed of ganglia distinct one from the other, he was quite surprised to find that, in the grub of the Oryctes, the same system was concentrated into a short chain of ganglia in juxtaposition. His was the surprise of the anatomist who, studying the organ qua organ, sees for the first time an unusual conformation. Mine was of a different nature: I was amazed to see the precision with which the paralysis of the victim sacrificed by the Scolia, a paralysis so profound in spite of the difficulties of an underground operation, had guided my forecast as to structure when, anticipating the dissection, I declared in favour of an exceptional concentration of the nervous system. Physiology perceived what anatomy had not yet revealed, at all events to my eyes, for since then, on dipping into my books, I have learnt that these anatomical peculiarities, which were then so new to me, are now within the domain of current science. We know that, in the Scarabaeidae, both the larva and the perfect insect are endowed with a concentrated nervous system.
The Garden Scolia attacks Oryctes nasicornis; the Two-banded Scolia the Cetonia; the Interrupted Scolia the Anoxia. All three operate below ground, under the most unfavourable conditions; and all three have for their victim a larva of one of the Scarabaeidae, which, thanks to the exceptional arrangement of its nerve-centres, lends itself, alone of all larvae, to the Wasp’s successful enterprises. In the presence of this underground game, so greatly varied in size and shape and yet so judiciously selected to facilitate paralysis, I do not hesitate to generalize and I accept, as the ration of the other Scoliae, larvae of Lamellicorns whose species will be determined by future observation. Perhaps one of them will be found to give chase to the terrible enemy of my crops, the voracious White Worm, the grub of the Cockchafer; perhaps the Hemorrhoidal Scolia, rivalling in size the Garden Scolia and like her, no doubt, requiring a copious diet, will be entered in the insects’ “Who’s Who” as the destroyer of the Pine-chafer, that magnificent Beetle, flecked with white upon a black or brown ground, who of an evening, during the summer solstice, browses on the foliage of the fir-trees. Though unable to speak with certainty or precision, I am inclined to look upon these devourers of Scarabaeus-grubs as valiant agricultural auxiliaries.
The Cetonia-larva has figured hitherto only in its quality of a paralysed victim. We will now consider it in its normal state. With its convex back and its almost flat ventral surface, the creature is like a semi-cylinder in shape, fuller in the hinder portion. On the back, each of the segments, except the last, or anal, segment, puckers into three thick pads, bristling with stiff, tawny hairs. The anal segment, much wider than the rest, is rounded at the end and coloured a deep brown by the contents of the intestine, which show through the translucent skin; it bristles with hairs like the other segments, but is level, without pads. On the ventral surface, the segments have no creases; and the hairs, though abundant, are rather less so than on the back. The legs, which are quite well-formed, are short and feeble in comparison with the animal’s size. The head has a strong, horny cap for a cranium. The mandibles are powerful, with bevelled tips and three or four teeth on the edge of the bevel.
Its mode of locomotion marks it as an idiosyncratic, exceptional, fantastic creature, having no fellow, that I know of, in the insect world. Though endowed with legs–a trifle short, it is true, but after all as good as those of a host of other larvae–it never uses them for walking. It progresses on its back, always on its back, never otherwise. By means of wriggling movements and the purchase afforded by the dorsal bristles, it makes its way belly upwards, with its legs kicking the empty air. The spectator to whom these topsy-turvy gymnastics are a novelty thinks at first that the creature must have had a fright of some sort and that it is struggling as best it can in the face of danger. He puts it back on its belly; he lays it on its side. Nothing is of any use; it obstinately turns over and resumes its dorsal progress. That is its manner of travelling over a flat surface; it has no other.
This reversal of the usual mode of walking is so peculiar to the Cetonia- larva that it is enough in itself to reveal the grub’s identity to the least expert eyes. Dig into the vegetable mould formed by the decayed wood in the hollow trunks of old willow-trees, search at the foot of rotten stumps or in heaps of compost; and, if you come upon a plumpish grub moving along on its back, there is no room for doubt: your discovery is a Cetonia- larva.
This topsy-turvy progress is fairly swift and is not less in speed to that of an equally fat grub travelling on its legs. It would even be greater on a polished surface, where walking on foot is hampered by incessant slips, whereas the numerous hairs of the dorsal pads find the necessary support by multiplying the points of contact. On polished wood, on a sheet of paper and even on a strip of glass, I see my grubs moving from point to point with the same ease as on a surface of garden mould. In the space of one minute, on the wood of my table, they cover a distance of eight inches. The pace is no swifter on a horizontal bed of sifted mould. A strip of glass reduces the distance covered by one half. The slippery surface only half paralyses this strange method of locomotion.
We will now place side by side with the Cetonia-grub the larva of the Morning Anoxia, the prey of the Interrupted Scolia. It is very like the larva of the Common Cockchafer. It is a fat, pot-bellied grub, with a thick, red cap on its head and armed with strong, black mandibles, which are powerful implements for digging and cutting through roots. The legs are sturdy and end in a hooked nail. The creature has a long, heavy, brown paunch. When placed on the table, it lies on its side; it struggles without being able to advance or even to remain on its belly or back. In its usual posture it is curled up into a narrow hook. I have never seen it straighten itself completely; the bulky abdomen prevents it. When placed on a surface of moist sand, the ventripotent creature is no better able to shift its position: curved into a fish-hook, it lies on its side.
To dig into the earth and bury itself, it uses the fore-edge of its head, a sort of weeding-hoe with the two mandibles for points. The legs take part in this work, but far less effectually. In this way it contrives to dig itself a shallow pit. Then, bracing itself against the wall of the pit, with the aid of wriggling movements which are favoured by the short, stiff hairs bristling all over its body, the grub changes its position and plunges into the sand, but still with difficulty.
Apart from a few details, which are of no importance here, we may repeat this sketch of the Anoxia-grub and we shall have, if the size be at least quadrupled, a picture of the larva of Oryctes nasicornis, the monstrous prey of the Garden Scolia. Its general appearance is the same: there is the same exaggeration of the belly; the same hook-like curve; the same incapacity for standing on its legs. And as much may be said of the larva of Scarabaeus pentodon, a fellow-boarder of the Oryctes and the Cetonia.
CHAPTER 5. THE PROBLEM OF THE SCOLIAE.
Now that all the facts have been set forth, it is time to collate them. We already know that the Beetle-hunters, the Cerceres (Cf. “The Hunting