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The Life of the Caterpillar,
by J. Henri Fabre, 1916


YES, I shall find him; indeed I have him I already. A little chap of seven, with a wideawake face that doesn't get washed every day, bare feet and a pair of tattered breeches held up by a bit of string, a boy who comes regularly to supply the house with turnips and tomatoes, arrives one morning carrying his basket of vegetables. After the few sous due to his mother for the greens have been counted one by one into his hand, he produces from his pocket something which he found the day before, beside a hedge, while picking grass for the Rabbits:

"And what about this?" he asks, holding the thing out to me. "What about this? Will you have it?"

"Yes, certainly I'll have it. Try and find me some more, as many as you can, and I'll promise you plenty of rides on the roundabout on Sunday. Meanwhile, my lad, here's a penny for you. Don't make a mistake when you give in your accounts; put it somewhere where you won't mix it up with the turnip-money."

Dazzled with delight at the sight of so much wealth, my little ragamuffin promises to search with a will, already seeing visions of a fortune to be his.

When he has gone, I examine the thing. It is worth while. It is a handsome cocoon, blunt-shaped, not at all unlike the product of our Silk-worm nurseries, of a firm consistency and a tawny colour. The cursory information which I have picked up from books of reference makes me almost certain that it is the Bombyx of the Oak, the Oak Eggar. If this is so, what luck! I shall be able to continue my observations and perhaps complete what the Great Peacock began to show me.

The Oak Eggar is, in fact, a classic; there is not an entomological treatise but speaks of his exploits in the wedding-season. They tell us how a mother hatches in captivity, inside a room and even hidden in a box. She is far away from the country, amid the tumult of a big town. The event is nevertheless divulged to those whom it concerns in the woods and the meadows. Guided by some inconceivable compass, the males arrive, hastening from the distant fields; they go to the box, tap at it, fly round and round it.

I had read of these marvels; but seeing, seeing with one's own eyes, and at the same time experimenting a little is quite another matter. What does my penny purchase hold in store for me? Will the famous Bombyx emerge from it?

Let us call her by her other name: the Banded Monk. This unusual name of Monk is suggested by the male's dress: a monk's frock of a modest rusty brown. But in this case the stuff is a delicious velvet, with a pale transversal band and a little white, eye-shaped dot on the front wings.

The Banded Monk is not, in my region, a common Moth whom we are likely to catch if the fancy takes us to go out with a net at the proper season. I have never seen it about the village, especially not in my lonely enclosure, during all the twenty years that I have spent here. I am not a fervent hunter, I admit; the collector's dead insect interests me very little; I want it alive, in the full exercise of its faculties. But I make up for the absence of the collector's zeal by an attentive eye for all that enlivens the fields. A Moth so remarkable in size and costume would certainly not have escaped me had I met him.

The little seeker whom I had caught so nicely with a promise of the roundabout never made a second find. For three years I requisitioned friends and neighbours, especially the youngsters, those sharp-eyed scrapers of the brushwood; I myself scraped a great deal under masses of dead leaves, inspected stone-heaps, examined hollow tree-trunks. My trouble was in vain: the precious cocoon was nowhere to be found. Suffice it to say that the Banded Monk is very scarce in my neighbourhood. The importance of this detail will be seen when the time comes.

As I suspected, my solitary cocoon did belong to the famous Moth. On the 20th of August there emerges a female, corpulent and big-bellied, attired like the male, but in a lighter frock, more in the nankeen style. I establish her in a wire-gauze bell-jar in the middle of my study, on the big laboratory-table, littered with books, pots, trays, boxes, test-tubes and other engines of science. I have described the setting before: it is the same as in the case of the Great Peacock. The room is lighted by two windows looking out on the garden. One is closed, the other is kept open day and night. The Moth is placed between the two, in the shadow, some four or five yards away.

The rest of the day and the following day pass without anything worth mentioning. Hanging by her claws to the front of the trellis-work, on the side nearest the light, the prisoner is motionless, inert. There is no waving of the wings, no quivering of the antennæ. Even so did the female Great Peacock behave.

The mother Bombyx matures; her tender flesh hardens. By some process of which our science has not the remotest idea, she elaborates an irresistible bait which will bring callers flocking to her from the four corners of the heavens. What takes place in that fat body, what transformations are performed that shall presently revolutionize everything around? Were they known to us, the Moth's nostrums would add a cubit to our stature.

On the third day the bride is ready. The festivities burst into full swing. I was in the garden, already despairing of success, so long were things delayed, when, at about three o'clock in the afternoon, in very hot weather and brilliant sunshine, I saw a host of Moths gyrating in the embrasure of the open window.

It is the lovers coming to call upon their sweetheart. Some are just leaving the room, others going in, others again are perched upon the wall, resting as though jaded after a long journey. I see some approaching in the distance, over the walls, over the curtain of cypress-trees. They are hurrying up from all directions, but becoming more and more are. I missed the beginning of the reception; and the guests are nearly all here.

Let us go upstairs. This time, in broad daylight, without losing a single detail, I once more witness the bewildering spectacle into which the great night Moth initiated me. My study is filled with a swarm of males, whom I estimate at a glance to number about sixty, as far as it is possible to make a count in this seething mass. After circling a few times round the cage, several go to the open window, but return again forthwith and resume their evolutions. The most eager perch on the cage, hustle and trample on one another, fighting for the good places. Inside the barrier, the captive waits impassively, with her great paunch hanging against the wires. She gives not a sign of emotion in the presence of the turbulent throng.

Going in or going out, fussing round the cage or flitting through the room, for more than three hours they keep up their frenzied saraband. But the sun is sinking, the temperature becomes a little cooler. Chilled likewise is the ardour of the Moths. Many go out and do not come in again. Others take up their positions in readiness for the morrow; they settle on the transoms of the closed window, as the Great Peacocks did. The celebration is over for to-day. It will certainly be renewed to-morrow, for it is still without result, because of the wires.

But alas, to my great dismay, it is not renewed; and this through my own fault! Late in the day, some one brings me a Praying Mantis, worthy of attention because of her exceptionally small size. Preoccupied with the events of the afternoon, without thinking what I am doing, I hastily place the carnivorous insect in the cage that holds my Bombyx. Not for a moment do I dream that this cohabitation can turn out ill. The Mantis is such a little, slender thing; the other is so obese! And thus I entertained no apprehensions.

Ah, little did I know the bloodthirsty fury of which the grapnelled insect is capable! Next morning, to my bitter astonishment, I find the tiny Mantis devouring the huge Moth. The head and the front part of the breast have already disappeared. Horrible creature! What a disappointment I owe to you! Farewell to my researches, which I had cherished in my imagination all night long; not for three years shall I be able to resume them, for lack of a subject.

Bad luck must not, however, make us forget the little that we have learnt. At one sitting, some sixty males came. Considering the rarity of the Monk and remembering the years of fruitless searches conducted by my assistants and myself, we stand astounded at this number. With a female for a bait, the undiscoverable has suddenly become a multitude.

Now where did they come from? From every quarter and from very far, beyond a doubt. During my years of exploration of my neighbourhood, I have got to know every bush in it and every heap of stones; and I an in a position to declare that there are no Oak Eggars there. To make the swarm that filled my study, the whole of the surrounding district must have contributed, from this side and from that, within a radius which I dare not determine.

Three years pass; and fortune persistently entreated at last grants me two Monk-cocoons. Towards the middle of August, both of them, within a few days of each other, give me a female. This is a piece of luck which will allow me to vary and renew my tests.

I quickly repeat the experiments which have already procured me a most positive reply from the Great Peacock. The pilgrim of the day is no less clever than the pilgrim of the night. He baffles all my tricks. He hastens infallibly to the prisoner, in her wire-gauze cage, in whatever part of the house the apparatus be installed; he is able to discover her hidden in a cupboard; he guesses her secret presence in a box of any kind, provided that it be not tightly closed. He ceases to come, for lack of information, when the casket is hermetically sealed. Thus far we see merely a repetition of the feats of the Great Peacock.

A well-closed box, the air contained in which does not communicate with the outer atmosphere, leaves the Monk in complete ignorance of the prisoner's whereabouts. Not one arrives, even when the box is exposed for every eye to see in the window. This brings back, more urgently than ever, the idea of odoriferous effluvia, intransmissible through a wall of metal, cardboard, wood or glass, no matter which.

When put to the test, the great night Moth was not baffled by the naphthaline, whose powerful smell ought, to my thinking, to mask ultrasubtle emanations, imperceptible to any human nostrils. I repeat the experiment with the Monk. This time I lavish all the resources in the way of scents and stenches that my store of drugs permits.

I place the saucers, partly inside the wire-gauze cage, the female's prison, and partly all round it, in a continuous circle. Some contain naphthaline, others oil of lavender, others paraffin, others, lastly, alkaline sulphurs smelling of rotten eggs. Short of asphyxiating the prisoner, I can do no more.

These arrangements are made in the morning, so that the room may be thoroughly saturated when the trysting-hour arrives.

In the afternoon, the study has become an odious laboratory in which the penetrating aroma of lavender-oil and the foul stench of sulphuretted hydrogen predominate. Remember that I smoke in this room and plentifully at that. Will the concentrated odours of a gas-works, a smoker's divan, a scent-shop, an oil-well and a chemical factory succeed in putting oft the Monk?

Not at all. A little before three, the Moths arrive, as numerous as ever. They go to the cage, which I have taken pains to cover with a thick kitchen-cloth, so as to increase the difficulty. Though they see nothing after they have entered, though they are steeped in a foreign atmosphere in which any subtle fragrance should have been annihilated, they fly towards the prisoner and try to get at her by slipping under the folds of the cloth. My artifices are fruitless.

After this reverse, so definite in its results, which repeats what my naphthaline experiment with the Great Peacock taught me, I ought, logically speaking, to give up the theory that odorous effluvia serve as a guide to the Moths invited to the nuptial feast. That I did not do so was due to a casual observation. The unexpected, the fortuitous, often provides us with one of those surprises which show us the road to the truth, hitherto sought in vain.

One afternoon, trying to discover whether sight plays any part in the search, once that the Moths have entered the room, I place the female in a glass bell-jar and give her a little oak-branch, with withered leaves, as a perch. The apparatus is put on a table, opposite the open window. On entering, the Moths cannot fail to see the prisoner, standing as she does where they are bound to pass. The pan with its layer of sand, in which the female spent the previous night and the morning under a wire-gauze cover, is in my way. I put it, without premeditation, on the floor at the other end of the room, in a corner which is only dimly lighted. It is seven yards from the window.

The result of these preparations upsets all my ideas. Of the Moths arriving, none stops at the glass bell, where the female is plainly visible, in the full light. They pass by with utter indifference. Not a glance in her direction, not an enquiry. They all fly right to the far end of the room, to the dusky corner where I placed the tray and the cage. They alight on the trellised top and explore it at length, flapping their wings and hustling one another a little. All the afternoon, until sunset, they dance around the deserted dome the same saraband to which the actual presence of the female would give rise. At last they fly away, but not all of them. There are persistent ones who refuse to go, rooted to the spot by some magic attraction.

A strange result indeed: my Moths hasten to where there is nothing, take their stand there and will not he dissuaded by the repeated warnings of their eyes; they pass without stopping for a moment at the bell-glass in which the female cannot fail to be perceived by one or other of those coming and going. Befooled by a lure, they pay no attention to the real thing.

What is it that deceives them? The whole of the night before and all this morning, the female has sojourned under the wire-gauze cover, either hanging to the trelliswork, or resting on the sand in the pan. Whatever she touched, above all with her fat belly apparently, has become impregnated, as the result of long contact, with certain emanations. There you have her bait, her love-philtre; there you have what revolutionizes the world of Monks. The sand retains it for a time and spreads its effluvia around.

It is smell therefore that guides the Moths, that gives them information at a distance. Dominated by the sense of smell, they take no notice of what their eyes tell them; they pass by the glass prison in which their lady-love is now interned; they go to the wires, to the sand, on which the magic cruets have shed their contents; they race to the wilderness where naught remains of the witch but the scented evidence of her sojourn.

The irresistible philtre takes a certain time to elaborate. I picture it as an exhalation which is gradually given off and saturates everything that touches the fat, motionless creature. When the glass bell stands directly on the table or, better still, on a square of glass, the communication between the interior and the outer air is insufficient; and the males, perceiving nothing by the sense of smell, keep away, however long the experiment be continued. At the actual moment, I cannot substantiate this non-transmission through a screen, for, even if I establish ample communication, if I separate the bell from its support by means of three wedges, the Moths do not come at first, however many there may be in the room. But wait for half an hour, more or less: the alembic of feminine flavours begins its distilling and the rush of visitors takes place as usual.

Now that I possess these data, this unexpected light on the subject, I am at liberty to vary my experiments, all of which lead to the same conclusion. In the morning, I establish the female under a wire-gauze cover. Her perch is a little oak-twig similar to the last. Here, motionless, as though dead, she remains for long hours, buried in the tuft of leaves that is to be impregnated with her emanations. When visiting-time approaches, I withdraw the twig, perfectly saturated, and lay it on a chair, near the open window. On the other hand, I leave the female under her cover, well in view on the table, in the middle of the room.

The Moths arrive, first one, then two and three, soon five and six. They come in, go out, come in again, fly up and down, go to and fro, keeping all the time to the neighbourhood of the chair with its oak-branch. Not one makes for the big table, a few paces farther into the room, where the female is waiting for them under the trellised dome. They are hesitating, that is clear; they are seeking.

At last they find. And what do they find? The very twig which in the morning had served the pot-bellied matron as a bed. With wings swiftly fluttering, they alight upon the branch; they explore it above and below, probe it, lift it and move it, until at last the little bit of foliage drops on the floor. The probing between the leaves continues none the less. Under the buffeting of the wings and the clawing of the feet, the stick is now running along the ground, like a scrap of paper pawed by a kitten.

While the twig is moving away with its band of explorers, two new arrivals come upon the scene. On their way, they have to pass the chair, which for a brief spell bore the leafy stick. They stop at it and eagerly investigate the very spot which but now was covered by the branch. And yet, in their case as in that of the others, the real object of their desires is close by them, under a wire gauze which I have omitted to veil. No one notices it. On the floor, the Monks continue to hustle the mattress on which the female lay in the morning on the chair, they still fumble at the spot where this bedding was first placed. The sun goes down; the time comes to depart. Besides, the effluvia of passion are growing fainter, are dispersing. The visitors go away without more ado. Good-bye till to-morrow.

The following tests tell me that any material, no matter what, can take the place of the leafy branch, that chance inspiration of mine. Some time in advance, I place the female on a couch of cloth or flannel, of wadding or paper. I even subject her to the hardship of a camp-bed of wood, glass, marble or metal. All these objects, after a contact of sufficient length, have the same powerful attraction for the males as the mother Monk herself. They retain this property to a varying extent, according to their nature. The best are wadding, flannel, dust, sand, in short, porous objects. Metals, marble and glass, on the contrary, soon lose their efficacy. Lastly, anything on which the female has rested communicates its virtue to other places by simple contact, as witness the Moths crowding to the seat of the cane-bottomed chair after the oak-branch had fallen from it.

Let us use one of the best beds, flannel, for instance, and we shall see a curious thing. I place at the bottom of a long test-tube or of a narrow-necked bottle, just wide enough to allow of the Moth's passage, a piece of flannel on which the mother has been lying all the morning. The callers go into the vessels, flounder about, do not know how to get out again. I have invented a mouse-trap for them by means of which I could do terrific execution. Let us release the poor things, remove the piece of stuff and put it away in an hermetically closed box. The infatuated Moths go back to the test-tube, headlong reenter the trap. They are attracted by the effluvia which the saturated flannel has imparted to the glass.

I am fully convinced. To summon the Moths of the district to the wedding, to apprise them at a distance of her presence and to guide them, the bride emits an extremely subtle scent, imperceptible to our own organs of smell. With the mother Monk held to their nostrils, those around me perceive not the least odour, not even the youngest, whose senses are not yet vitiated.

This quintessence easily impregnates every object on which the female rests for any length of time; and thenceforth the actual object becomes as potent a centre of attraction as the mother herself, until the emanations are dispelled.

Nothing visible betrays the bait. On a piece of paper, a recent resting-place around which the visitors crowd, there is not an appreciable trace, no moisture of any kind; the surface is just as clean as before the impregnation.

The product is slowly elaborated and has to accumulate a little while before manifesting its full strength. When taken from her couch and placed elsewhere, the female loses her attractions for the time and becomes an object of indifference; it is the resting-place, saturated by long contact, that draws the newcomers. But the batteries are recharged and the deserted one recovers her power.

The appearance of the warning effluvium is delayed for a longer or shorter period according to the species. The newly-hatched Moth has to mature for a time and to put her distillery in order. A female Great Peacock, born in the morning, sometimes has visitors that same evening, but oftener on the second day, after preparations lasting some forty hours. The female Banded Monk adjourns her summons longer than that: her banns of marriage are not published until after two or three days' waiting.

Let us return for a moment to the problematical functions of the antennæ. The male Monk sports a sumptuous pair, similar to those of the Great Peacock, who vies with him in his matrimonial expeditions. Are we to look upon these hairy feelers as a guiding compass? I repeat, without laying much stress on the matter, my former amputations. None of the patients comes back. We must be chary of drawing inferences, however. The Great Peacock has shown us that the failure to return is due to more serious reasons than amputation of the horns.

Moreover, a second Monk, the Clover Bombyx, nearly akin to the first and, like him, superbly plumed, sets us an exceedingly perplexing problem. He is fairly plentiful around my place; even in the enclosure I find his cocoon, which might easily be confused with that of the Oak Bombyx. I am deceived at first by the resemblance. Out of six cocoons, from which I expected to obtain Banded Monks, six females of the other species hatch at the end of August. Well, around those six females, born in my house, never a male appears, though there is no doubt that the tufted ones are present in the neighbourhood.

If spreading feathered antennæ are really organs for receiving information at a distance, why are not my richly-horned neighbours informed of what is happening in my study? Why do their fine plumes leave them indifferent to events that would bring the Banded Monk hastening up in crowds? Once more, the organ does not determine the aptitude. This one is gifted and that one is not, despite organic similarity.

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