THERE is an especial debt of gratitude] we owe to Jean Henri Fabre. Not on we to thank him for his great scienti which has extraordinarily enriched man's edge of the insect world, but we have to thai foe making this precious store accessible of us. Fabre is a phenomenon in the world of Science. He has been called "the insect's Homer." He is a great writer and his books are literary as well as scientific masterpieces. Rarely is this happy fusion attained. It is a pleasure therefore to add "The Life of the Caterpillar" — one of his most characteristic works — to the Modern Library. It tells the strange story of the most crucial and adventurous period in the life of our most beautiful flying insects — the caterpillar stage. Ex IJJiris . The -publishers will be 'pleased to send^ upon re- quest, an illustrated catalogue setting forth the -purpose and ideals of The Modern Library , and describing in detail each volume in the series. QEvery reader of books will find titles he has been looking for •, attractively printed, and ai an unusually low •price THE LIFE OF THE CATERPILLAR J. HENRI FABRE TRANSLATED BY ALEXANDER TEIXEIRA DE MATTOS FELLOW OF THE ZOOLOGICAL SOCIETY OF LONDON INTRODUCTION BY ROYAL DIXON JL "" THE MODERN LIBRARY PUBLISHERS :: :: NEW YORK Manufactured in the United States of America for The Modern Library, Inc., by H. Wolff ra CONTENTS TRA1 CHAPT ^SLATOR'S NOTF PAOK 5 s Ell I THE PINE PROCESSIONARY: LAY- ING THE EGGS .... 9 ^OT^~ II THE PINE PROCESSIONARY: THE* NEST; THE COMMUNITY , *7xA III THE PINE PROCESSIONARY: THE PROCESSION 56 V IV THE PINE PROCESSIONARY: ME- TEOROLOGY 90 \/ V VI THE PINE PROCESSIONARY: THE MOTH THE PINE PROCESSIONARY: THE STINGING POWER .... in y I28K VII VIII THE ARBUTUS CATERPILLAR AN INSECT VIRUS . . . . *5<> s* i6i\S IX THE PSYCHES: THE LAYING 1 86 X THE PSYCHES: THE CASES . 217 / XI THE GREAT PEACOCK 5 Contents XII THE BANDED MONK 279 XIII THE SENSE OF SMELL . . . 300 , XIV THE CABBAGE-CATERPILLAR . 33 H INDEX . 373 TRANSLATOR'S NOTE THIS, the sixth volume of the Collected Edition of Fabre's ' Entomological Works in English, is the first that I am pre- paring for publication since the author's death, on the nth of October, 1915, at an exceedingly advanced age. It contains all the essays, fourteen in number, which he wrote on Butterflies and Moths, or their caterpil- lars. Three of these, the chapters entitled The Great Peacock, The Banded Monk and The Sense of Smell, are included under the titles of The Great Peacock, The Oak Eggar and A Truffle-hunter: the Bolboceras Gallicus in a volume of miscellaneous extracts from the Souvenirs entomologiques translated by Mr. Bernard Miall and published by the Century Company. The volume in question is named Social Life in the Insect World; and I strongly recommend it to the reader, if only because of the excellent photographs from nature with which it is illustrated. Chapter III. of the present volume, The Pine Pro cessio nary: the Procession, has ap- Translator's Note peared in the Fortnightly Review; and Chap- ter XIV., The Cabbage Caterpillar , the last essay but one from the author's pen, written, 1 believe, within two or three years of his death, was first printed in the Century Maga- zine, some time before its publication in the original. It does not form part of the Sou- venirs entotnologiques. The remaining es- says are new in their English guise. Once more I wish to record my gratitude to Miss Frances Rodwell for the faithful as- sistance which she lias lent me in the prepara- tion of this volume, as in that of all the earlier volumes of the series. ALEXANDER TEIXEIRA DE MATTOS. CHELSEA, 1916, CHAPTER I THE PINE PROCESSIONARY : THE EGGS AND THE HATCHING THIS caterpillar has already had his story told by Reaumur,1 but it was a story marked by gaps. These were inevitable in the conditions under which the great man worked, for he had to receive all his mate- rials by barge from the distant Bordeaux Landes. The transplanted insect could not be expected to furnish its biographer with other than fragmentary evidence, very weak in those biological details which form the principal charm of entomology. To study the habits of insects one must observe them long and closely on their native heath, so to speak, in the place where their instincts have full and natural play. With caterpillars foreign to the Paris cli- mate and brought from the other end of France, Reaumur therefore ran the risk of 1Rene Antoine Ferchault de Reaumur (1683-1757), inventor of the Reaumur thermometer and author of Memoir es pour servir a I'histoire naturelle des insect es. —Translator's Note. 9 The Life of the Caterpillar missing many most interesting facts. This is what actually happened, just as it did on a later occasion in the case of another alien, the Cicada.1 Nevertheless, the information which he was able to extract from a few nests sent to him from the Landes is of the highest value. Better served than he by circumstances, I will take up afresh the story of the Proces- lonary Caterpillar of the Pine. If the subject does not come up to my hopes, it will certainly not be for lack of materials. In my harmas2 laboratory, now stocked with a few trees in addition to its bushes, stand some vigorous fir-trees, the Aleppo pine and the black Aus- trian pine, a substitute for that of the Landes. Every .year the caterpillar takes possession of them and spins his great purses in their branches. In the interest of the leaves, which are horribly ravaged, as though there had been a fire, I am obliged each winter to make *For the Cicada or Cigalc, an insect remotely akin to the Grasshopper and found more particularly in the south of France, cf. Social Life in the Insect World, by J. H. Fabre, translated by Bernard Miall : chaps, i to iv. —Translator's Note. 2The harmas was the enclosed piece of waste ground in which the author used to study his insects in their natural state.— Translator's Note. The Processionary: the Eggs a strict survey and to extirpate the nests with a long forked batten. You voracious little creatures, if I let you have your way, I should soon be robbed of the murmur of my once so leafy pines! To- day I will seek compensation for all the trouble I have taken. Let us make a com- pact. You have a story to tell. Tell it me; and for a year, for two years or longer, until I know more or less all about it, I shall leave you undisturbed, even at the cost of lament- able suffering to the pines. Having concluded the treaty and left the caterpillars in peace, I soon have abundant material for my observations. In return for my indulgence I get some thirty nests within a few steps of my door. If the collection were not large enough, the pine-trees in the neighbourhood would supply me with any necessary additions. But I have a preference and a decided preference for the population of my own enclosure, whose nocturnal habits are much easier to observe by lantern-light. With such treasures daily before my eyes, at any time that I wish and under natural con- ditions, I cannot fail to see the Processionary's story unfolded at full length. Let us try. The Life of the Caterpillar And first of all the egg, which Reaumur did not see. In the first fortnight of August, let us inspect the lower branches of the pines, on a level with our eyes. If we pay the least attention, we soon discover, here and there, on the foliage, certain little whitish cylinders spotting the dark green. These are the Bombyx' eggs: each cylinder is the cluster laid by one mother. The pine-needles are grouped in twos. Each pair is wrapped at its base in a cylindri- cal muff which measures about an inch long by a fifth or sixth of an inch wide. This muff, which has a silky appearance and is white slightly tinted with russet, is covered with scales that overlap after the manner of the tiles on a roof; and yet their arrange- ment, though fairly regular, is by no means geometrical. The general aspect is more or less that of an immature walnut-catkin. The scales are almost oval in form, semi- trar»sparent and white, with a touch of brown at the base and of russet at the tip. They are free at the lower end, which tapers slightly, but firmly fixed at the upper end, which is wider and blunter. You cannot de- tach them either by blowing on them or by 12 The Processionary: the rubbing them repeatedly with a hair-pencil. They stand up, like a fleece stroked the wrong way, if the sheath is rubbed gently upwards, and retain this bristling position indefinitely; they resume their original arrangement when the friction is in the opposite direction. At the same time, they are as soft as velvet to the touch. Carefully laid one upon the other, they form a roof that protects the eggs. It is impossible for a drop of rain or dew to penetrate under this shelter of soft tiles. The origin of this defensive covering is self-evident: the mother has stripped a part of her body to protect her eggs. Like the Eider-duck, she has made a warm overcoat for them out of her own down. Reaumur had already suspected as much from a very curious peculiarity of the Moth. Let me quote the passage : "The females," he says, "have a shiny patch on the upper part of their body, near the hind-quarters. The shape and gloss of this disk attracted my attention the first time that I saw it. I was holding a pin, with which I touched it, to examine its structure. The 13 The Life of the Caterpillar contact of the pin produced a little spectacle that surprised me : I saw a cloud of tiny spangles at once detach themselves. These spangles scattered in every direction : some seemed to be shot into the air, others to the sides; but the greater part of the cloud fell softly to the ground. "Each of those bodies which I am calling spangles is an extremely slender lamina, bear- ing some resemblance to the atoms of dust on the Moths' wings, but of course much big- ger. . . . The disk that is so noticeable on the hind-quarters of these Moths is there- fore a heap — and an enormous heap — of these scales. . . . The females seem to use them to wrap their eggs in; but the Moths of the Pine Caterpillar refused to lay while in my charge and consequently did not enlighten me as to whether they use the scales to cover their eggs or as to what they are doing with all those scales gathered round their hinder part, which were not given them and placed in that position to serve no purpose." You were right, my learned master: that dense and regular crop of spangles did not grow on the Moth's tail for nothing. Is 14 The Proeessionary: the Eggs there anything that has no object? You did not think so; I do not think so either. Every- thing has its reason for existing. Yes, you were well-inspired when you foresaw that the cloud of scales which flew out under the point of your pin must serve to protect the eggs. I remove the scaly fleece with my pincers and, as I expected, the eggs appear, looking like little white-enamel beads. Clustering closely together, they make nine longitudinal rows. In one of these rows I count thirty- five eggs. As the nine rows are very nearly alike, the contents of the cylinder amount in all to about three hundred eggs, a respectable family for one mother! The eggs of one row or file alternate exactly with those in the two adjoining files, so as to leave no empty spaces. They sug- gest a piece of bead-work produced with ex- quisite dexterity by patient fingers. It would be more correct still to compare them with a cob of Indian corn, with its neat rows of seeds, but a greatly reduced cob, the tininess of whose dimensions makes its mathematical precision all the more remarkable. The grains of the Moth's spike have a slight tend- ency to be hexagonal, because of their mu- 15 The Life of tne Caterpillar tual pressure; they are stuck close together, so much so that they cannot be separated. If force is used, the layer comes off the leaf in fragments, in small cakes always consisting of several eggs apiece. The beads laid are therefore fastened together by a glutinous varnish; and it is on this varnish that the broad base of the defensive scales is fixed. It would be interesting, if a favourable opportunity occurred, to see how the mother achieves that beautifully regular arrangement of the eggs and also how, as soon as she has laid one, all sticky with varnish, she makes a roof for it with a few scales removed one by one from her hind-quarters. For the moment, the very structure of the finished work tells us the course of the procedure. It is evident that the eggs are not laid in longi- tudinal files, but in circular rows, in rings, which lie one above the other, alternating their grains. The laying begins at the bot- tom, near the lower end of the double pine- leaf; it finishes at the top. The first eggs in order of date are those of the bottom ring; the last are those of the top ring. The ar- rangement of the scales, all in a longitudinal direction and attached by the end facing the 16 The Processionaryj the Eggs top of the leaf, makes any other method of progression inadmissible. Let us consider in the light of reflection the elegant edifice now before our eyes. Young or old, cultured or ignorant, we shall all, on seeing the Bombyx' pretty little spike, exclaim: "How handsome!" And what will strike us most will be not the beautiful enamel pearls, but the way in which they are put together with such geome- trical regularity. Whence we can draw a great moral, to wit, that an exquisite order governs the work of a 'creature without consciousness, one of the humblest of the humble. A paltry Moth follows the harmonious laws of order. If Micromegas1 took it into his head to leave Sirius once more and visit our planet, would he find anything to admire among us? Voltaire shows him to us using one of the diamonds of his necklace as a magnifying- glass in order to obtain some sort of view of the three-master which has run aground on his thumb-nail. He enters into conversation JThe eponymous hero of Voltaire's story of "the little great man," published in 1752 in imitation of Gulliver's Travels. — Translator's Note. 17 The Life of the Caterpillar with the crew. A nail-paring, curved like a horn, encompasses the ship and serves as a speaking-trumpet; a tooth-pick, which touches the vessel with its tapering end and the lips of the giant, some thousand fathoms above, with the other, serves as a telephone. The outcome of the famous dialogue is that, if we would form a sound judgment of things and see them under fresh aspects, there is nothing like changing one's planet. The probability then is that the Sirian would have had a rather poor notion of our artistic beauties. To him our masterpieces of statuary, even though sprung from the chisel of a Phidias, would be mere dolls of marble or bronze, hardly more worthy of in- terest than the children's rubber dolls are to us; our landscape-paintings would be re- garded as dishes of spinach smelling unpleas- antly of oil; our opera-scores would be de- scribed as very expensive noises. These things, belonging to the domain of the senses, possess a relative aesthetic value, subordinated to the organism that judges them. Certainly the Venus of Melos and the Apollo Belvedere are superb works; but even so it takes a special eye to appreciate them. 18 The Processionary: the Eggs Micromegas, if he saw them, would be full of pity for the leanness of human forms. To him the beautiful calls for something other than our sorry, frog-like anatomy. Show him, on the other hand, that sort of abortive windmill by means of which Pytha- goras, echoing the wise men of Egypt, teaches us the fundamental properties of the right- angled triangle. Should the good giant, con- trary to our expectation, happen not to know about it, explain to him what the windmill means. Once the light has entered his mind, he will find, just as we do, that there is beauty there, real beauty, not certainly in that hor- rible hieroglyphic, the figure, but in the un- changeable relation between the lengths of the three sides; he will admire as much as we do geometry the eternal balancer of space. There is, therefore, a severe beauty, be- longing to the domain of reason, the same in every world, the same under every sun, whether the suns be single or many, white or red, blue or yellow. This universal beauty is order. Everything is done by weight and measure, a great statement whose truth breaks upon us all the more vividly as we probe more deeply into the mystery of things. 19 The Life of the Caterpillar Is this order, upon which the equilibrium of the universe is based, the predestined result of a blind mechanism? Does it enter into the plans of an Eternal Geometer, as Plato had it? Is it the ideal of a supreme lover of beauty, which would explain everything? Why all this regularity in the curve of the petals of a flower, why all this elegance in the chasings on a Beetle's wing-cases? Is that infinite grace, even in the tiniest details, com- patible with the brutality of uncontrolled forces? One might as well attribute the artist's exquisite medallion to the steam- hammer which makes the slag sweat in the melting. These are very lofty thoughts concerning a miserable cylinder which will bear a crop of caterpillars. It cannot be helped. The mo- ment one tries to dig out the least detail of things, up starts a why which scientific inves- tigation is unable to answer. The riddle of the world has certainly its explanation other- where than in the little truths of our labora- tories. But let us leave Micromegas to phi- losophize and return to the commonplaces of observation. The Pine Bombyx has rivals in the art of The Processionary: the Eggs gracefully grouping her egg-beads. Among their number is the Neustrian Bombyx, whose caterpillar is known by the name of "Livery," because of his costume. Her eggs are as- sembled in bracelets around little branches varying greatly in nature, apple- and pear- branches chiefly. Any one seeing this elegant work for the first time would be ready to attribute it to the fingers of a skilled stringer of beads. My small son Paul opens eyes wide with surprise and utters an astonished "Oh!" each time that he comes upon the dear little bracelet. The beauty of order forces itself upon his dawning attention. Though not so long and marked above all by the absence of any wrapper, the ring of the Neustrian Bombyx reminds one of the other's cylinder, stripped of its scaly covering. It would be easy to multiply these instances of elegant grouping, contrived now in one way, now in another, but always with consum- mate art. It would take up too much time, however. Let us keep to the Pine Bombyx. The hatching takes place in September, a Jittle earIier"m~"mLe' tas& a 'little later1 in gjTgtfrer! SoTEat I may easily watch the new- born caterpillars in their first labours, I have The Life of the Caterpillar placed a few egg-laden branches in the wind- ow of my study. They are standing^ in a yglass of water which will keep them jgrpper- ^ly fresh for some tinie. . a The little caterpillars leave the egg in the Y^rnorning, at about eight o'clock. If I just \\ J^y/ lift the scales of the cylinder in process of hatching, I see black heads appear, which nibble and burst and push back the torn ceil- ings. The tiny creatures emerge slowly, some here and some there, all over the surface. After the hatching, the scaly cylinder is as regular and as fresh in appearance as if it were still inhabited. We do not perceive that it is deserted until we raise the spangles. The eggs, still arranged in regular rows, are now so many yawning goblets of a slightly translucent white; they lack the cap-shaped lid, which has been rent and destroyed by the new-born grubs. The puny creatures measure a millimetre1 at most in length. Devoid as yet of the bright red that will soon be their adornment, they - are pale-yellow, bristling with hairs, some rJy / shortish and black, others rather longer and / white. The head, of a glossy black, is big 1.O3Q inch. — Translator's Note. The Processionary : the Hatching in proportion. Its diameter is twice that of the body. This exaggerated size of the head implies a corresponding strength of jaw, capable of attacking tough food from the start. A huge head, stoutly clad in horn, is the predominant feature of the budding cater- pillar. These macrocephalous ones are, as we see, well-armed against the hardness of the pine- needles, so well-armed in fact that the meal begins almost immediately. After roaming for a few moments at random among the scales of the common cradle, most of the young caterpillars make for the double leaf that served as an axis for the native cylinder and spread themselves over it at length. Others go to the adjacent leaves. Here as well as there they fall to; and the gnawed leaf is hollowed into faint and very narrow grooves, bounded by the veins, which are left intact. From time to time, three or four who have eaten their fill fall into line and walk in step, but soon separate, each going his own way. This is practice for the coming processions. If I disturb them ever so little, they sway the front half of their bodies and wag their 2} The Life of the Caterpillar heads with a jerky movement similar to the action of an intermittent spring. But the sun reaches the corner of the wind- ow where the careful rearing is in progress. Then, sufficiently refreshed, the little family retreats to its native soil, the base of the double leaf, gathers into an irregular group and begins to spin. Its work is a gauze globule of extreme delicacy, supported on some of the neighbouring leaves. Under this tent, a very wide-meshed net, a siesta is taken during the hottest and brightest part of the day. In the afternoon, when the sun has gone from the window, the flock leaves its shelter, disperses around, sometimes forming a little procession within a radius of an inch, and starts browsing again. Thus the very moment of hatching pro- claims talents which age will develop without adding to their number. In less than an hour from the bursting of the egg, the caterpillar is both a processionary and a spinner. He also flees the light when taking refreshment. We shall soon find him visiting his grazing- grounds only at night. The spinner is very feeble, but so active that in twenty-four hours the silken globe at- The Processionary : the Hatching tains the bulk of a hazel-nut and in a couple of weeks that of an apple. Nevertheless, it is not the nucleus of the great establishment in which the winter is to be spent. It is a provisional shelter, very light and inexpensive in materials. The mildness of the season makes anything else unnecessary. The young caterpillars freely gnaw the logs, the poles be- tween which the threads are stretched, that is to say, the leaves contained within the silken tent. Their house supplies them at the same time with board and lodging. This excellent ar- rangement saves them from having to go out, a dangerous proceeding at their age. For these puny ones, the hammock is also the larder. Nibbled down to their veins, the supporting leaves wither and easily come unfastened from the branches; and the silken globe becomes a hovel that crumbles with the first gust of wind. The family then moves on and goes elsewhere to erect a new tent, lasting no longer than the first. Even so does the Arab move on, as the pastures around his camel-hide dwelling become exhausted. These temporary establishments are renewed several times over, always at greater heights than the last, so much so that the tribe, which was hatched on 25 The Life of the Caterpillar the lower branches trailing on the ground, gradually reaches the higher boughs and sometimes the very summit of the pine-tree. In a few weeks' time, a first moult replaces the humble fleece of the start, which is pale- coloured, shaggy and ugly, by another which lacks neither richness nor elegance. On the dorsal surface, the various segments, ex- cepting the first three, are adorned with a mosaic of six little bare patches, of a bright red, which stand out a little above the dark background of the skin. Two, the largest, are in front, two behind and one, almost dot- shaped, on either side of the quadrilateral. The whole is surrounded by a palisade of scarlet bristles, divergent and lying almost flat. The other hairs, those of the belly and sides, are longer and whitish. In the centre of this crimson marquetry stand two clusters of very short * bristles, gathered into flattened tufts which gleam in the sun like specks of gold. The length of the caterpillar is now about two centimetres1 and his width three or four millimetres." Such is the costume of middle age, which, like the earlier one, was unknown to Reaumur. xAbout three-quarters of an inch.— Translator's Note. 2.U7 to .156 inch.— Translator's Note. 26 CHAPTER II THE PINE PROCESSIONARY: THE NEST; THE COMMUNITY NOVEMBER arrives, however, bringing cold weather; the time has come to build the stout winter tabernacle. High up in the pine the tip of a bough is chosen, with suitably close-packed and convergent leaves. The spinners surround it with a spreading network, which bends the adjacent leaves a little nearer and ends by incorporating them into the fabric. In this way they obtain an enclosure half silk, half leaves, capable of withstanding the inclemencies of the weather. Early in December the work has increased to the size of a man's two fists or more. In its ultimate perfection, it attains a volume of nearly half a gallon by the end of winter. It is roughly egg-shaped, tapering to a cert- ain length below and extended into a sheath which envelops the supporting branch. The origin of this silky extension is as follows: every evening between seven and nine o'clock, 27 The Life of the Caterpillar weather permitting, the caterpillars leave the nest and go down the bare part of the bough which forms the pole of the tent. The road is broad, for this axis is sometimes as wide as the neck of a claret-bottle. The descent is accomplished without any attempt at order and always slowly, so much so that the first caterpillars to come out have not yet dispersed before they are caught up by the others. The branch is thus covered by a con- tinuous bark of caterpillars, made up of the whole community, which gradually divides into squads and disperses to this side and that on the nearest branches to crop their leaves. Now not one of the caterpillars moves a step without working his spinneret. Therefore the broad downward path, which on the way back will be the ascending path, is covered, as the result of constant traffic, with a multi- tude of threads forming an unbroken sheath. It is obvious that this sheath, in which each caterpillar, passing backwards and forwards on his nocturnal rambles, leaves a double thread, is not an indicator laid down with the sole object of simplifying the journey back to the nest : a mere ribbon would be enough for that. Its use might well be to strengthen the The Processionary : the Nest edifice, to give it deeper foundations and to join it by a multitude of cables to the steady branch. The whole thing thus consists, above, of the home distended into an ovoid and, below, of the stalk, the sheath surrounding the sup- port and adding its resistance to that of the numerous other fastenings. Each nest that has not yet had its shape altered by the prolonged residence of the caterpillars shows in the centre a bulky, milk- white shell, with around it a wrapper of dia- phanous gauze. The central mass, formed of thickly-woven threads, has for a wall a thick quilt into which are absorbed, as sup- ports, numbers of leaves, green and intact. The thickness of this wall may be anything up to three-quarters of an inch. At the top of the dome are round openings, varying greatly in number and distribution, as wide across as an ordinary lead-pencil. These are the doors of the house, through which the caterpillars go in and out. All around the shell are projecting leaves, which the insects' teeth have respected. From the tip of each leaf there radiate, in graceful, undulating curves, threads which, loosely interlaced, form 29 The Life of the Caterpillar a light tent, a spacious verandah of careful workmanship, especially in the upper part. Here we find a broad terrace, on which, in the daytime, the caterpillars come and doze in the sun, heaped one upon the other, with rounded backs. The network stretching overhead does duty as an awning : it mode- rates the heat of the sun's rays; it also saves the sleepers from a fall when the bough rocks in the wind. Let us take our scissors and rip open the nest from end to end longitudinally. A wide window opens and allows us to see the ar- rangement of the inside. The first thing to strike us is that the leaves contained in the enclosure are intact and quite sound. The young caterpillars in their temporary esta- blishments gnaw the leaves within the silken wrapper to death; they thus have their larder stocked for a few days without having to quit their shelter in bad weather, a condition made necessary by their weakness. When they grow stronger and start working on their win- ter home, they are very careful not to touch the leaves. Why these new scruples? The reason is evident. If bruised, those leaves, the framework of the house, would 30 The Processionary : the Nest very soon wither and then be blown off with the first breath of wind. The silken purse, torn from its base, would collapse. On the other hand, if the leaves are respected, they remain vigorous and furnish a stout support against the assaults of winter. A solid fast- ening is superfluous for the summer tent, which lasts but a day; it is indispensable to the permanent shelter which will have to bear the burden of heavy snows and the buffeting of icy winds. Fully alive to these perils, the spinner of the pine-tree considers himself bound, however importunate his hunger, not to saw through the rafters of his house. Inside the nest, therefore, opened by my scissors I see a thick arcade of green leaves, more or less closely wrapped in a silky sheath whence dangle shreds of cast skin and strings of dried droppings. In short, -this interior is an extremely unpleasant place, a rag-shop and a sewage-farm in one, and corresponds in no way with the imposing exterior. All around is a solid wall of quilting and of closely-woven leaves. There are no cham- bers, no compartments marked off by parti- tion-walls. It is a single room, turned into a 31 The Life of the Caterpillar labyrinth by the colonnade of green leaves placed in rows one above the other through- out the oval hall. Here the caterpillars stay when resting, gathered on the columns, heaped in confused masses. When we remove the hopeless tangle at the top, we see the light filtering in at certain points of the roof. These luminous points cor- respond with the openings that communicate with the outer air. The network that forms a wrapper to the nest has no special exits. To pass through it in either direction, the caterpillars have only to push the sparse threads aside slightly. The inner wall, a com- pact rampart, has its doors; the flimsy outer veil has none. It is in the morning, at about ten o'clock, that the caterpillars leave their night-apart- ment and come to take the sun on their ter- race, under the awning which the points of the leaves hold up at a distance. They spend the whole day there dozing. Motionless, heaped together, they steep themselves de- liciously in warmth and from time to time be- tray their bliss by nodding and wagging their heads. At six or seven o'clock, when it grows dark, the sleepers awake, bestir themselves, 32 The Processionary : the Nest separate and go their several ways over the surface of the nest. We now behold an indeed delightful spec- tacle. Bright-red stripes meander in every direction over the white sheet of silk. One goes up, another comes down, a third moves aslant; others form a short procession. And, as they solemnly walk about in a splendid dis- order, each glues to the ground which it covers the thread that constantly hangs from its lip. Thus is the thickness of the shelter in- creased by a fine layer added- immediately above the previous structure; thus is the dwelling strengthened by fresh supports. The adjoining green leaves are taken into the net- work and absorbed in the building. If the tiniest bit of them remains free, curves radiate from that point, increasing the size of the veil and fastening it at a greater distance. Every evening, therefore, for an hour or two, great animation reigns on the surface of the nest, if the weather permits; and the work of consolidating and thickening the structure is carried on with indefatigable zeal. Do they foresee the future, these wary ones who take such precautions against the rigours of winter? Obviously not. Their few 33 The Life of the Caterpillar months' experience — if indeed experience can be mentioned in connection with a caterpillar — tells them of savoury bellyfuls of green stuff, of gentle slumbers in the sun on the ter- race of the nest; but nothing hitherto has made them acquainted with cold, steady rain, with frost, snow and furious blasts of wind. And these creatures, knowing naught of win- ter's woes, take the same precautions as if they were thoroughly aware of all that the incle- ment season holds in store for them. They work away at their house with an ardour that seems to say : "Oh, how nice and warm we shall be in our beds here, nestling one against the other, when the pine-tree swings aloft its frosted candelabra ! Let us work with a will ! Labore- mus!" Yes, caterpillars, my friends, let us work with a will, great and small, men and grubs alike, so that we may fall asleep peacefully; you with the torpor that makes way for your transformation into Moths, we with that last sleep which breaks off life only to renew it. Laboremus! Anxious to watch my caterpillars' habits in -detail, without having to sally forth by lan- 34 The Processionary : the Nest tern-light, often in bad weather, to see what happens in the pine-trees at the end of the en- closure, I have installed half-a-dozen nests in a greenhouse, a modest, glazed shelter which, though hardly any warmer than the air outside, at least affords protection from the wind and rain. Fixed in the sand, at a height of about eighteen inches, by the base of the bough that serves as both an axis and a frame- work, each nest receives for rations a bundle of little pine-branches, which are renewed as soon as they are consumed. I take my lan- tern every evening and pay my boarders a visit. This is the way in which most of my facts are obtained. After the day's work comes the evening meal. The caterpillars descend from the nest, adding a few more threads to the silvery sheath of the support, and reach the posy of fresh green stuff which is lying quite near. It is a magnificent sight to see the red-coated band lined up in twos and threes on each needle and in ranks so closely formed that the green sprigs of the bunch bend under the load. The diners, all motionless, all poking their heads forward, nibble in silence, placidly. Their broad black foreheads gleam in the 35 The Life of the Caterpillar rays of the lantern. A shower of granules drops on the sand below. These are the residues of easy-going stomachs, only too ready to digest their food. By to-morrow morning the soil will have disappeared under a greenish layer of this intestinal hail. Yes, indeed, it is a sight to see, one far more stimu- lating than that of the Silk-worms' mess-room. Young and old, we are all so much interested in it that our evenings almost invariably end in a visit to the greenhouse caterpillars. The meal is prolonged far into the night. Satisfied at last, some sooner, some later, they go back to the nest, where for a little longer, feeling their silk-glands filled, they continue spinning on the surface. These hard workers would scruple to cross the white carpet with- out contributing a few threads. It is getting on for one or even two o'clock in the morn- ing when the last of the band goes indoors. My duty as a foster-father is daily to re- new the bunch of sprigs, which are shorn to the last leaf; on the other hand, my duty as an historian is to enquire to what extent the diet can be varied. The district supplies me with Processionaries on the Scotch pine, the maritime pine and the Aleppo pine indif- The Processionary : the Nest ferently, but never on the other Coni ferae. Yet one would think that any resin-scented leaf ought to suit. So says chemical analysis. We must mistrust the chemist's retort when it pokes its nose into the kitchen. It may suc- ceed in making butter out of tallow-candles and brandy out of potatoes; but, when it tells us that the products are identical, we shall do well to refuse these abominations. Science, astonishingly rich as it is in poison, will never provide us with anything fit to eat, because, though the raw substance falls to a large ex- tent within its domain, that same substance escapes its methods the moment that it is wanted organized, divided and subdivided in- definitely by the process of life, as needed by the stomach, whose requirements are not to be met by measured doses of our reagents. The raw material of cell and fibre may per- haps be artificially obtained, some day; cell and fibre themselves, never. There's the rub with your chemical feeding. The caterpillars loudly proclaim the insur- mountable difficulty of the problem. Relying on my chemical data, I offer them the dif- ferent substitutes for the pine growing in my enclosure: the spruce, the yew, the thuja, the 37 The Life of the Caterpillar juniper, the cypress. What! Am I asking them, Pine Caterpillars, to bite into that? They will take good care not to, despite the tempting resinous smell ! They would die of hunger rather than touch it! One conifer and one only is excepted : the cedar. My charges browse upon its leaves with no appre- ciable repugnance. Why the cedar and not the others? I do not know. The caterpil- lar's stomach, fastidious as our own, has its secrets. Let us pass to other tests. I have just slit open longitudinally a nest whose internal structure I want to explore. Owing to the natural shrinkage of the split swan's-down, the deft reaches two fingers' breadth in the centre and tapers at the top and bottom. What will the spinners do in the presence of such a disaster? The operation is performed by day, while the caterpillars are slumbering in heaps upon the dome. As the living-room is de- serted at this time, I can cut boldly with the scissors without risk of damaging any part of the population. My ravages do not wake the sleepers : all day long not one appears upon the breach. This indifference looks as though it were due 38 The Processionary : the Nest to the fact that the danger is not yet known. Things will be different to-night, when the busy work begins again. However dull they may be, the caterpillars will certainly notice that hugh window which freely admits the deadly draughts of winter; and, possessing; any amount of padding, they will crowd round the dangerous gap and stop it up in a trice. Thus do we argue, forgetting the ani- mal's intellectual darkness. What really happens is that, when night falls, the indifference of the caterpillars re- mains as great as ever. The breach in fhe tent provokes not a sign of excitement. They move to and fro on the surface of the nest; they work, they spin as usual. There is no change, absolutely none, in their behaviour. When the road covered chances to bring some of them to the brink of the ravine, we see no alacrity on their part, no sign of anxiety, no attempt to close up the two edges of the slit. They simply strive to accomplish the difficult crossing and to continue their stroll as though they were walking on a perfect web. And they manage it somehow or other, by fixing the thread as far as the length of *heir body permits. 39 The Life of the Caterpillar Having once crossed the gulf, they pursue their way imperturbably, without stopping any more at the breach. Others come upon the scene and, using the threads already laid as foot-bridges, pass over the rent and walk on, leaving their own thread as they go. Thus the first night's work results in the laying over the cleft of a filmy gauze, hardly perceptible, tut just sufficient for the traffic of the colony. The same thing is repeated on the nights that follow; and the crevice ends by being closed with a scanty sort of Spider's web. And that is all. There is no improvement by the end of the winter. The window made by my scissors is still wide open, though thinly veiled; its black spindle shape shows from the top of the nest to the bottom. There is no darn in the split texture, no piece of swan's-down let in between the two edges to restore the roof to its original state. If the accident had happened in the open a:r and not under glass, the foolish spinners would probably have died of cold in their cracked house. Twice renewed with the same results, this test proves that the Pine Caterpillars are not alive to the danger of their split dwelling. The Processionary : the Nest Expert spinners though they be, they seem as unconscious of the ruin of their work as the spools in a factory are of a broken thread. They could easily make good the damage by stopping up the breach with the silk that is lavished elsewhere without urgent need; they could weave upon it a material as thick and solid as the rest of the walls. But no, they placidly continue their habitual task; they spin as they spun yesterday and as they will spin to-morrow, strengthening the parts that are already strong, thickening what is already- thick enough; and not one thinks of stopping the disastrous gap. To let a piece into that hole would mean weaving the tent all over again from the beginning; and no insect, how- ever industrious, goes back to what it has already done. I have often called attention to this feature in animal psychology; notably I have de- scribed the ineptitude of the caterpillar of the Great Peacock Moth.1 When the experi- menter lops the top off the complicated eel- trap which forms the pointed end -of the co- coon, this caterpillar spends the silk remaining lln the course of an essay on aberration of instinct in a certain Mason-wasp which is not yet translated into English. — Translator's Note. 41 The Life of the Caterpillar to him in work of secondary importance, in- stead of making good the series of cones, each fitting into the other, which are so essential to the hermit's protection. He continues his normal task imperturbably, as though nothing out of the way had taken place. Even so does the spinner in the pine-tree act with his burst tent. Your foster-parent must perpetrate yet another piece of mischief, O my Proces- •sionary; but this time it shall be to your advantage ! It does not take me long to per- ceive that the nests intended to last through the winter often contain a population much greater than that of the temporary shelters woven by the very young caterpillars. I also notice that, when they have attained their ulti- mate dimensions, these nests differ very con- siderably in size. The largest of them are equal to five or six of the smallest. What is the cause of these variations? Certainly, if all the eggs turned out well, the scaly cylinder containing the laying of a single mother would be enough to fill a splen- did purse : there are three hundred enamelled beads here for hatching. But in families which swarm unduly an enormous waste al- The Processionary: the Community ways takes places and restores the balance of things; if the called are legion, the chosen are a well thinned-out troop, as is proved by the Cicada, the Praying Mantis1 and the Cricket. The Pine Processionary, another crucible of organic matter of which various devourers take advantage, is also reduced in numbers immediately after the hatching. The delicate mouthful has shrunk to a few dozens of sur- vivors around the light globular network in which the family passes the sunny autumn days. Soon they will have to be thinking of the stoutly-built winter tent. At such a time, it would be a boon if they could be many, for from union springs strength. I suspect an easy method of fusion among a few families. To serve them as a guide in their peregrinations about the tree, the caterpillars have their silk ribbon, which they follow on their return, after describing a bend. They may also miss it and strike another, one differing in no respect from their own. This new ribbon marks the way to some nest situated in the neighbourhood. The strayed 1A predatory insect, akin to the Locusts and Crickets^ which, when at rest, adopts an attitude resembling that of prayer. Cf. Social Life in the Insect World: chaps, v to vii.— Translator's \'otc. The Lite oi the Caterpillar caterpillars, failing to distinguish it from their own ribbon, follow it conscientiously and in this manner end by reaching a strange dwell- ing. Suppose them to be peacefully received : what will happen? Once fused, the several groups assembled by the accident of the path will form a power- ful city, fitted to produce great works; the concerted weaklings will give rise to a strong, united body. This would explain the thickly- populated, bulky nests situated so near to others that have remained puny. The former would be the work of a syndicate incorporat- ing the interests of spinners collected from different parts; the latter would belong to families left in isolation by the luck of the road. It remains to be seen whether the chance- comers, guided by a strange ribbon, meet with a good reception in the new abode. The ex- periment is easily made upon the nests in the greenhouse. In the evening, at the hours devoted to grazing, I remove with a pruning- shears the different little branches covered with the population of one nest and lay them on the provisions of the neighbouring nest, which provisions are also overrun with cater- 44 The Processionary: the Community pillars. Or I can make shorter work of it by taking the whole bunch, well covered with the troop, of the first pouch and planting it right beside the bunch of the second, so that the leaves of the two mingle a little at the edges. There is not the least quarrelling between the real proprietors and the new arrivals. Both go on peacefully browsing, as though nothing had happened. And all without hesi- tation, when bed-time comes, make for the nest, like brothers who have always lived to- gether; all do some spinning before retiring to rest, thicken the blanket a little and are then swallowed up in the dormitory. By repeating the same operation next day and, if necessary, the day after, in order to collect the laggards, I succeed without the slightest difficulty in wholly depopulating the first nest and transferring all its caterpillars to the second. I venture to do something better still. The same method of transportation allows me to- quadruple the output of a spinning-mill by adding to it the workers of three similar es- tablishments. And, if I limit myself to this increase, the reason is not that any confusion 45 The Life of the Caterpillar manifests itself in this shifting of quarters, but that I see no bounds to my experiment, so cheerfully do the caterpillars accept any addition to their number. The more spin- ners, the more spinning : a very judicious rule of conduct. Let us add that the caterpillars which have been transported cherish no regrets for their old house. They are quite at home with the others and make no attempt to regain the nest whence they were banished by my arti- fices. It is not the distance that discourages them, for the empty dwelling is only half a yard away at most. If, for the purpose of my studies, I wish to restock the deserted nest, I am obliged once more to resort to transportation, which invariably proves suc- cessful. Later, in February, when an occasional fine day allows of long processions on the walls and the sand-covered shelf of the green- house, I am able to watch the fusing of two groups without personally intervening. All that I have to do is patiently to follow the evolutions of a file on the march. I see it sometimes, after leaving one nest, enter a different one, guided by some fortuitous 46 The Processionary: the Community change of route. Thenceforward the stran- gers form part of the community on the same footing as the others. In a like fashion, when the caterpillars walk abroad upon the tree at night, the scanty groups of the outset must increase and gather the number of spinners which an extensive building requires. Everything for everybody. So says the Pine Processionary, nibbling his leaves with- out quarrelling in the least over his neigh- bours' mouthfuls, or else entering — and being always peacefully received — another's home precisely as he would his own. Whether a member of the tribe or a stranger, he finds room in the refectory and room in the dormi- tory. The others' nest is his nest. The others' grazing-ground is his grazing-ground, in which he is entitled to his fair share, one neither greater nor smaller than the share of his habitual or casual companions. Each for all and all for each. So says the Processionary, who every evening spends his little capital of silk on enlarging a shelter that is often new to him. What would he do with his puny skein, if alone? Hardly any- thing. But there are hundreds and hundreds of them in the spinning-mill; and the result The Life of the Caterpillar of their infinitesimal contributions, woven into a common stuff, is a thick blanket capable of resisting the winter. In working for himself, each works for the others; and these on their side work as zealously for each. O lucky animals that know nothing of property, the mother of strife! O en- viable cenobites, who practise the strictest communism ! These habits of the caterpillars invite a few reflections. Generous minds, richer in illusions than in logic, set communism before us as the sovran cure for human ills. Is it practicable among mankind? At all times there have been, there still are and there always will be, fortunately, associations in which it is possible to forget in common some small part of the hardships of life; but is it possible to generalize? The caterpillars of the pine can give us much valuable information in this respect. Let us have no false shame : our material needs are shared by the animals; they strug- gle as we do to take part in the general ban- quet of the living; and the manner in which they solve the problem of existence is not to be despised. Let us then ask ourselves what The Processionary: the Community are the reasons that cause cenobitism to flour- ish among the Processionaries. One answer suggests itself inevitably, to be- gin with: the food problem, that terrible dis- turber of the world's tranquillity, is here non- existent. Peace reigns as soon as the stomach is certain of being filled without a struggle. A pine-needle or even less suffices for the caterpillar's meal; and that needle is always there, waiting to be eaten, is there in inex- haustible numbers, almost on the threshold of the home. When dinner-time arrives, we caterpillars go out, we take the air, we walk a little in procession; then, without laborious seeking, without jealous rivalries, we seat our- selves at the banquet. The table is plenti- fully spread and will never be bare, so large and generous is the pine; all that we need do is, from one evening to the next, to move our dining-room a little farther on. Conse- quently, there are no present and no future cares on the subject of provisions: the cater- pillar finds food to eat almost as easily as he finds air to breathe. The atmosphere feeds all creatures on air with a bounty which it is not necessary to crave. All unknown to itself, without the The Life of the Caterpillar agency of any effort or labour, the animal re- ceives its share of the most vital of elements. The niggardly earth, on the contrary, sur- renders its gifts only when laboriously forced. Not fruitful enough to satisfy every need, it leaves the division of the food to the fierce eagerness of competition. The mouthful to be procured engenders war between consumers. Look at two Ground-beetles coming at the same time upon a bit of Earth-worm. Which of the two shall have the morsel? The matter shall be decided by battle, desperate, ferocious battle. With these famished ones, who eat at long intervals and do not always eat their fill, communal life is out of the question. The Pine Caterpillar is free from these woes. He finds the earth as generous as the atmosphere; he finds eating as easy as breath- ing. Other instances of perfect communism might be named. All occur among species living on a vegetable diet, provided however that victuals are plentiful and obtainable with- out a hard search. An animal diet, on the contrary, a prey, always more or less difficult to secure, banishes cenobitism. Where the 50 The Processionary : the Community portion is too small for one, what excuse would there be for guests ? The Pine Processionary knows nothing of privation. He knows as little of family ties, another source of unrelenting competition. To make ourselves a place in the sun is but a half of the struggle imposed upon us by life: we must also, as far as possible, pre- pare a place for our successors; and, as the preservation of the species is of greater im- portance than that of the individual, the struggle for the future is even fiercer than the struggle for the present. Every mother re- gards the welfare of her offspring as her pri- mary law. Perish all else, provided that the brood flourish ! Every one for himself is her maxim, imposed by the rigours of the general conflict; every one for himself is her rule, the safeguard of the future. With maternity and its imperious duties, communism ceases to be practicable. At first sight, certain Hymenoptera1 seem to declare the contrary. We find, for instance, the Mason-bees of the Sheds2 nesting in myriads 1The order of insects embracing the Bees, Wasps, Ants, Saw-flies, Ichneumon-flies, etc.— Translator's Note. 2Cf. The Mason-bees, by J. Henri Fabre, translated by Alexander Teixeira de Mattos, passim. — Translator's Note. 51 The Life of the Caterpillar on the same tiles and building a monumental edifice at which all the mothers work. Is this really a community? Not at all. It is a city in which the inhabitants have neighbours, not collaborators. Each mother kneads her pots of honey; each amasses a dowry for her off- spring and nothing but a dowry for her off- spring; each wears herself out for her family and only for her family. Oh, it would be a serious business if some one merely came and alighted on the brim of a cell that did not belong to her; the mistress of the house would give her to understand, by means of a sound drubbing, that manners such as those are not to be endured ! She would have to skedaddle very quickly, unless she wanted a fight. The rights of property are sacred here. Even the much more social Hive-bee is no exception to the rule of maternal egoism. To each hive one mother. If there be two, civil war breaks out and one of them perishes by the other's dagger or else quits the country, followed by a part of the swarm. Although virtually fit to lay eggs, the other Bees, to the number of some twenty thousand, re- nounce maternity and vow themselves to celi- bacy in order to bring up the prodigious 52 The Processionary : the Community family of the one and only mother. Here, communism reigns, under certain aspects ; but, for the immense majority, motherhood is forthwith abolished. Even so with the Wasps, the Ants, the Termites1 and the various social insects. Life in common costs them dear. Thousands and thousands remain incomplete and become the humble auxiliaries of a few who are sexually endowed. But, whenever maternity is the general portion, individualism reappears, as among the Mason-bees, notwithstanding their show of communism. TheJPine Caterpillars are exempt from the duty rJ prf»cpr\m]^ fli^fqrA" They have lip rather are obscureiy^^fmeparmg one, as id^rudi'men?al:\r''a?'an ttrar1s"not yet but must one day be. With the blossom- ing of maternity, that flower of adult age, individual property will not fail to appear, attended by its rivalries. The insect now so peaceable will, like the others, have its dis- plays of selfish intolerance. The mothers will isolate themselves, jealous of the double pine-needle in which the cylinder of eggs is to be fixed; the males, fluttering their wings, 1White Ants. — Translator's Note. 53 The Life of the Caterpillar will challenge one another for the possession of the coveted bride, it is not a serious strug- gle among these easy-going ones, but still it presents a faint picture of those mortal affrays which the mating so often produces. Love rules the world by battle; it too is a hotbed of competition. The_caterpillar, being almost sexless, is in- jifferent to amorous instincts. This is the first condition for living pacifically in com- mon. But it is not enough. The perfect concord of the community demands among all its members an equal division of strength and talent, of taste and capacity for work. This condition, which perhaps is the most import- ant of all, is fulfilled preeminently. If there were hundreds, if there w^?eA thousands of them in the same nest, there Wfculd be no dif- ference between any of thefffi They are all the same size and equally ^stron{y;~a.ll wear the sarrie^ "(Tress ; all possess the same gift for spinning; and all with equal 7.63.1 expend the contents, of their silk-glands ^or the general welfare. No one~~!cfles, no one lounges^llong when there is work to be done. With no other stimulus than the sat- isfaction of doing their duty, every evening, 54 The Processionary: the Community when the weather is favourable, they all spin with equal industry and drain to the last drop their reservoirs of silk, which have become distended during the day. In their tribe there is no question of skilled or unskilled, of strong or weak, of abstemious or gluttonous; there are neither hard-workers nor idlers, neither savers nor spendthrifts. What one does the others do, with a like zeal, no more and no less well. It is a splendid world of equality truly, but, alas, a world of caterpillars ! If it suited us to go to school to the Pine Pror^ssionary, we should soon see the inanity of our levelling and communistic theories. Equality is a magnificent political catchword, but little more. Where is it, this equality of ours? In our social groups, could we find as many as two persons exactly equal in strength, health,, intelligence, capacity for work, foresight and all the other gifts which are the great factors of prosperity? Where should we find anything analogous to the exact parity prevailing among caterpillars? No- where. Inequality is our law. And a good thing, toch A sound which is invariably the same, how- ever often multiplied, does not constitute a 55 The Life of the Caterpillar harmony. We need dissimilarities, sounds loud and soft, deep and shrill; we need even discords which, by their harshness, throw into relief the sweetness of the chords. In the same way, human societies are harmonious only with the aid of contraries. If the dreams of our levellers could be realized, we should sink to the monotony of the caterpillar so- cieties; art, science, progress and the lofty flights of the imagination would slumber in- definitely in the dead calm of mediocrity. Besides, if this general levelling were ef- fected, we should still be very far from com- munism. To achieve that, we should have to do away with the family, as the caterpil- lars and Plato teach us; we should need abundance of food obtained without any ef- fort. So long as a mouthful of bread is diffi- cult to acquire, demanding, an industry and labour of which we are not all equally capable, so long as the family remains the sacred rea- son for our foresight, so long will the generous theory of all for each and each for all be absolutely impracticable. And then should we gain by abolishing the struggle for the daily bread of ourselves and those dependent on us ? It is very doubtfu). 56 The Processionary : the Community We should be getting rid of this world's two great joys, work and the family, the only joys that give any value to life; we should be stifling exactly that which makes our great- ness. And the result of this bestial sacrilege would be a community of human caterpillars. Thus does the Pine Processionary teach us by his example. CHAPTER III THE PINE PROCESSIONARY : THE PROCESSION DROVER Dingdong's Sheep followed the Ram which Panurge had maliciously thrown overboard and leapt nimbly into the sea, one after the other, "for you know," says Rabelais, "it is the nature of the sheep al- ways to follow the first, wheresoever it goes ; which makes Aristotle mark them for the most silly and foolish animals in the world."1 The Pine Caterpillar is even more sheep- like, not from foolishness, but from necessity : where the first goes all the others go, in a regular string, with not an empty space be- tween them. They proceed in single file, in a continuous row, each touching with its head the rear of the one in front of it. The complex twists and turns described in his vagaries by the caterpillar leading the van are scrupulously described by all the others. No Greek theoria winding its way to the Eleusinian festivals was 1Book IV., chap. viii. — Translator's Note. S8 The Processionary: the Procession ever more orderly. Hence the name of Processionary given to the gnawer of the pine. His character is complete when we add that he is a rope-dancer all his life long: he walks only on the tight-rope, a silken rail placed in position as he advances. The caterpillar who chances to be at the head of the proces- sion dribbles his thread without ceasing and fixes it on the path which his fickle preferences cause him to take. The thread is so tiny that the eye, though armed with a magnifying- glass, suspects it rather than sees it. But a second caterpillar steps on the slender footboard and doubles it with his thread; a third trebles it; and all the others, however many there be, add the sticky spray from their spinnerets, so much so that, when the proces- sion has marched by, there remains, as a record of its passing, a narrow white ribbon whose dazzling whiteness shimmers in the sun. Very much more sumptuous than ours, their system of road-making consists in uphol- stering with silk instead of macadamizing. We sprinkle our roads with broken stones and level them by the pressure of a heavy steam- roller; they lay over their paths a soft satin 59 The Life of the Caterpillar rail, a work of general interest to which each contributes his thread. What is the use of all this luxury? Could they not, like other caterpillars, walk about without these costly preparations? I see two reasons for their mode of progression. It is night when the Processionaries sally forth to browse upon the pine-leaves. They leave their nest, situated at the top of a bough, in profound darkness; they go down the denuded pole till they come to the nearest branch that has not yet been gnawed, a branch which be- comes lower and lower by degrees as the con- sumers finish stripping the upper storeys; they climb up this untouched branch and spread over the green needles. When they have had their suppers and be- gin to feel the keen night air, the next thing is to return to the shelter of the house. Measured in a straight line, the distance is not great, hardly an arm's length; but it can- not be covered in this way on foot. The caterpillars have to climb down from one crossing to the next, from the needle to the twig, from the twig to the branch, from the branch to the bough and from the bough, by a no les* angular path, to go back home. It 60 The Processionary: the Procession is useless to rely upon sight as a guide on this long and erratic journey. The Processional^ it \f true, f^jsjjye ocular specks of Jij^JieadT'Eut' they are so difficult to make out through the magnifying- glass, that we" cannot attribute to them any great power of vision. Besides, what good would those short-'slghted lenses be in the absence of light, in black darkness? It is equally useless to think of the sense of smell. Has the Processional any olfactory powers or has he not ? I do not know. With- out giving a positive answer to the question, I can at least declare that his sense of smell is exceedingly dull and in no way suited to help him find his way. This is proved, in my experimenWJTy a number of hungry cater- pillars that, after a long fast, pass close be- side a pine-branch without betraying any eagerness or showing a sign of stopping. It is the sense of touch that tells them where they are. So long as their lips do not chance to light upon the pasture-land, not one of them settles there, though he be ravenous. They do not hasten to food which they have scented from afar; they stop at a branch which they encounter on their way. 61 The Life of the Caterpillar Apart from sight and smell, what remains to guide them in returning to the nest? The ribbon spun on the road. In the Cretan laby- rinth, Theseus would have been lost but for the clue of thread with which Ariadne sup- plied him. The spreading maze of the pine- needles is, especially at night, as inextricable a labyrinth as that constructed for Minos. The Processionary finds his way through it, without the possibility of a mistake, by the aid of his bit of silk. At the time for going home, each easily recovers either his own thread or one or other of the neighbouring threads, spread fanwise by the diverging herd ; one by one the scattered tribe line up on the common ribbon, which started from the nest; and the sated caravan finds its way back to the manor with absolute certainty. Longer expeditions are made in the day- time, even in winter, if the weather be fine. Our caterpillars then come down from the tree, venture on the ground, march in proces- sion for a distance of thirty yards or so. The object of these sallies is not to look for food, for the native pine-tree is far from being ex- hausted : the shorn branches hardly count amid the vast leafage. Moreover, the caterpillars 62 The Processionary: the Procession observe complete abstinence till nightfall. The trippers have no other object than a con- stitutional, a pilgrimage to the outskirts to see what these are like, possibly an inspection of the locality where, later on, they mean to bury themselves in the sand for their meta- morphosis. It goes without saying that, in these greater evolutions, the guiding cord is not neglected. It is now more necessary than ever. All con- tribute to it from the produce of their spin- nerets, as is the invariable rule whenever there is a progression. Not one takes a step for- ward without fixing to the path the thread hanging from his lip. If the series forming the procession be at all long, the ribbon is dilated sufficiently to make it easy to find; nevertheless, on the homeward journey, it is not picked up with- out some hesitation. For observe that the caterpillars when on the march never turn completely; to wheel round on their tight-rope is a method utterly unknown to them. In order therefore to regain the road already covered, they have to describe a zig-zag whose windings and extent are determined by the leader's fancy. Hence come gropings and 63 The Life of the Caterpillar roamings which are sometimes prolonged to the point of causing the herd to spend the night out of doors. It is not a serious mat- ter. They collect into a motionless cluster. To-morrow the search will start afresh and will sooner or later be successful. Oftener still the winding curve meets the guide-thread at the first attempt. As soon as the first caterpillar has the rail between his legs, all hesitation ceases; and the band makes for the nest with hurried steps. The use of this silk-tapestried roadway is evident from a second point of view. To pro- tect himself against the severity of the win- ter which he has to face when working, the Pine Caterpillar weaves himself a shelter in which he spends his bad hours, his days of enforced idleness. Alone, with none but the meagre resources of his silk-glands, he would find difficulty in protecting himself on the top of a branch buffeted by the winds. A sub- stantial dwelling, proof against snow, gales and icy fogs, requires the cooperation of a large number. Out of the individual's piled- up atoms, the community obtains a spacious and durable establishment. The enterprise takes a long time to com- 64 The Processionary: the Procession plete. Every evening, when the weather per- mits, the building has to be strengthened and enlarged. It is indispensable, therefore, that the corporation of workers should not be dis- solved while the stormy season continues and the insects are still in the caterpillar stage. But, without special arrangements, each noc- turnal expedition at grazing-time would be a cause of separation. At that moment of ap- petite for food there is a return to indi- vidualism. The caterpillars become more or less scattered, settling singly on the branches around; each browses his pine-needle sepa- rately. How are they to find one another afterwards and become a community again? The several threads left on the road make this easy. With that guide, every caterpillar, however far he may be, comes back to his companions without ever missing the way. They come hurrying from a host of twigs, from here, from there, from above, from be- low; and soon the scattered legion reforms into a group. The silk thread is something more than a road-making expedient: it is the social bond, the system that keeps the mem- bers of the community indissolubly united. At the head of every procession, long or 65 The Life of the Caterpillar short, goes a first caterpillar whom I will call the leader of the march or file, though the word leader, which I use for want of a bet- ter, is a little out of place here. Nothing, in fact, distinguishes this caterpillar from the others : it just depends upon the order in which they happen to line up ; and mere chance brings him to the front. Among the Proces- sionaries, every captain is an officer of for- tune. The actual leader leads; presently he will be a subaltern, if the file should break up in consequence of some accident and be formed anew in a different order. His temporary functions give him an atti- tude of his own. While the others follow passively in a close file, he, the captain, tosses himself about and with an abrupt movement flings the front of his body hither and thither. As he marches ahead he seems to be seeking his way. Does he in point of fact explore the country ? Does he choose the most practicable places? Or are his hesitations merely the re- sult of the absence of a guiding thread on ground that has not yet been covered? His subordinates follow very placidly, reassured by the cord which they hold between their legs; he, deprived of that support, is uneasy. 66 The Processionary: the Procession Why cannot I read what passes under his black, shiny skull, so like a drop of tar? To judge by actions, there is here a small dose of discernment which is able, after experi- menting, to recognize excessive roughnesses, over-slippery surfaces, dusty places that offer no resistance and, above all, the threads left by other excursionists. This is all or nearly all that my long acquaintance with the Pro- cessionaries has taught me as to their men- tality. Poor brains, indeed; poor creatures, whose commonwealth has its safety hanging upon a thread ! The processions vary greatly in length. The finest that I have seen manoeuvring on the ground measured twelve or thirteen yards and numbered about three hundred caterpil- lars, drawn up with absolute precision in a wavy line. But, if there were only two in a row, the order would still be perfect: the second touches and follows the first. By February I have processions of all lengths in the greenhouse What tricks can I play upon them ? I see only two : to do away with the leader; and to cut the thread. The suppression of the leader of the file produces nothing striking. If the thing is 67 The Life of the Caterpillar done without creating a disturbance, the pro- cession does not alter its ways at all. The second caterpillar, promoted to captain, knows the duties of his rank off-hand: he se- lects and leads, or rather he hesitates and gropes. The breaking of the silk ribbon is not very important either. I remove a caterpillar from the middle of the file. With my scis- sors, so as not to cause a commotion in the ranks, I cut the piece of ribbon on which he stood and clear away every thread of it. As a result of this breach, the procession ac- quires two marching leaders, each independent of the other. It may be that the one in the rear joins the file ahead of him, from which he is separated by but a slender interval; in that case, things return to their original con- dition. More frequently, the two parts do not become reunited. In that case, we have two distinct processions, each of which wanders where it pleases and diverges from the other. Nevertheless, both will be able to return to the nest by discovering sooner or later, in the course of their peregrinations, the ribbon on the other side of the break. These two experiments are only moderately 68 The Processionary : the Procession interesting. I have thought out another, one more fertile in possibilities. I propose to make the caterpillars describe a close circuit, after the ribbons running from it and liable to bring about a change of direction have been destroyed. The locomotive engine pursues its invariable course so long as it is not shunted on to a branch-line. If the Processionaries find the silken rail always clear in front of them, with no switches anywhere, will they continue on the same track, will they persist in following a road that never comes to an end? What we have to do is to produce this circuit, which is unknown under ordinary con- ditions, by artificial means. The first idea that suggests itself is to seize with the forceps the silk ribbon at the back of the train, to bend it without shaking it and to bring the end of it ahead of the file. If the caterpillar marching in the van steps upon it, the thing is done : the others will follow him faithfully. The operation is very simple in theory but very difficult in practice and produces no useful results. The ribbon, which is extremely slight, breaks under the weight of the grains of sand that stick to it and are lifted with it. If it does not break, the cater- 69 The Life of the Caterpillar pill rs at the back, however delicately we may go to work, feel a disturbance which makes them curl up or even let go. There is a yet greater difficulty: the leader refuses the ribbon laid before him; the cut end makes him distrustful. Failing to see the regular, uninterrupted road, he slants off to the right or left, he escapes at a tangent. If I try to interfere and to bring him back to the path of my choosing, he persists in his re- fusal, shrivels up, does not budge; and soon the whole procession is in confusion. We will not insist: the method is a poor one, very wasteful of effort for at best a problematical success. We ought to interfere as little as possible and obtain a natural closed circuit. Can it be done? Yes. It lies in our power, without the least meddling, to see a procession march along a perfect circular track. I owe this re- sult, which is eminently deserving of our at- tention, to pure chance. On the shelf with the layer of sand in which the nests are planted stand some big palm- vases measuring nearly a yard and a half in circumference at the top. The caterpillars often scale the sides and climb up to the 70 The Processionary : the Procession moulding which forms a cornice around the opening. This place suits them for their pro cessions, perhaps because of the absolute firm- ness of the surface, where there is no fear of landslides, as on the loose, sandy soil be- low; and also, perhaps, because of the hori- zontal position, which is favorable to repose after the fatigue of the ascent. It provides me with a circular track all ready-made. I have nothing to do but wait for an occasion propitious to my plans. This occasion is not long in coming. On the 3Oth of January, 1896, a little be- fore twelve o'clock in the day, I discover a numerous troop making their way up and gradually reaching the popular cornice. Slow- ly, in single file, the caterpillars climb the great vase, mount the ledge and advance in regular procession, while others are constantly arriving and continuing the series. I wait for the string to close up, that is to say, for the leader, who keeps following the circular moulding, to return to the point from which he started. My object is achieved in a quarter of an hour. The closed circuit is realized magnificently, in something very nearJy ap- proaching a circle. The Life of the Caterpillar The next thing is to get rid of the rest of the ascending column, which would disturb the fine order of the procession by an excess of newcomers; it is also important that we should do away with all the silken paths, both new and old, that can put the cornice into communication with the ground. With a thick hair-pencil I sweep away the surplus climbers; with a big brush, one that leaves no smell behind it — for this might after- wards prove confusing — I carefully rub down the vase and get rid of every thread which the caterpillars have laid on the march. When these prepara- tions are finished, a curious sight awaits us. In the uninterrupted circular procession there is no longer a leader. Each caterpillar is preceded by another on whose heels he fol- lows, guided by the silk track, the work of the whole party; he again has a companion close behind him, following him in the same orderly way. And this is repeated without variation throughout the length of the chain. None commands, or rather none modifies the trail according to his fancy; all obey, trusting in the guide who ought normally to lead the 72 The Processionary : the Procession march and who in reality has been abolished by my trickery. From the first circuit of the edge of the tub the rail of silk has been laid in position and is soon turned into a narrow ribbon by the procession, which never ceases dribbling its thread as it goes. The rail is simply doubled and has no branches anywhere, for my brush has destroyed them all. What will the caterpillars do on this deceptive, closed path? Will they walk endlessly round and round until their strength gives out entirely? The old schoolmen were fond of quoting Buridan's1 Ass, that famous Donkey who, when placed between two bundles of hay, starved to death because he was unable to decide in favour of either by breaking the equilibrium between two equal but opposite attractions. They slandered the worthy ani- mal. The Ass, who is no more foolish than any one else, would reply to the logical snare by feasting off both bundles. Will my cater- 1Jean Buridan (circa i^oo-circa 1360), a famous scholastic doctor, who was several times rector of the university of Paris and subsequently founded the uni- versity of Vienna. He forms the subject of many legends, including that of the argument known by his name, of which no trace is to be found in any of his works. — Translator's Note. The Life of the Caterpillar pillars show a little of his mother wit? Will they, after many attempts, be able to break the equilibrium of their closed circuit, which keeps them on a road without a turning? Will they make up their minds to swerve to this side or that, which is the only method of reaching their bundle of hay, the green branch yonder, quite near, not two feet oft ? I thought that they would and I was wrong. I said to myself: "The procession will go on turning for some time, for an hour, two hours perhaps; then the caterpillars will perceive their mis- take. They will abandon the deceptive road and make their descent somewhere or other." That they should remain up there, hard pressed by hunger and the lack of cover, when nothing prevented them from going away, seemed to me inconceivable imbecility. Facts, however, forced me to accept the in- credible. Let us describe them in detail. The circular procession begins, as I have said, on the 3Oth of January, about midday, in splendid weather. The caterpillars march at an even pace, each touching the stern of the one in front of him. The unbroken chain eliminates the leader with his changes of direc- 74 The Processionary: the Procession tion; and all follow mechanically, as faithful to their circle as are the hands of a watch. The headless file has no liberty left, no will; it has become mere clock-work. And this continues for hours and hours. My success goes far beyond my wildest suspicions. I stand amazed at it, or rather I am stupefied. Meanwhile, the multiplied circuits change the original rail into a superb ribbon a twelfth of an inch broad. I can easily see it glittering on the red ground of the pot. The day is drawing to a close and no alteration has yet taken place in the position of the trail. A striking proof confirms this. The trajectory is not a plane curve, but one which, at a certain point, deviates and goes down a little way to the lower surface of the cornice, returning to the top some eight inches farther. I marked these two points of devia- tion in pencil on the vase at the outset. Well, all that afternoon and, more conclusive still, on the following days, right to the end of this mad dance, I see the string of caterpillars dip under the ledge at the first point and come to the top again at the second. Once the first thread is laid, the road to be pursued is perma- nently established. 75 The Life of the Caterpillar If the road does not vary, the speed does. I measure nine centimetres1 a minute as the average distance covered. But there are more or less lengthy halts; the pace slackens at times, especially when the temperature falls. At ten o'clock in the evening the walk is little more than a lazy swaying of the body. I foresee an early halt, in consequence of the cold, of fatigue and doubtless also of hunger. Grazing-time has arrived. The caterpil- lars have come crowding from all the nests in the greenhouse to browse upon the pine- branches planted by myself beside the silken purses. Those in the garden do the same, for the temperature is mild. The others, lined up along the earthenware cornice, would gladly take part in the feast; they are bound to have an appetite after a ten hours' walk. The branch stands green and tempting not a hand's breadth away. To reach it they need but go down; and the poor wretches, foolish slaves of their ribbon that they are, cannot make up their minds to do so. I leave the famished ones at half-past ten, persuaded that they will take counsel with their pillow and *$l/2 inches. — Translator's Note. The Processionary : the Procession that on the morrow things will have resumed their ordinary course. I was wrong. I was expecting too much of them when I accorded them that faint gleam of intelligence which the tribulations of a distressful stomach ought, one would think, to have aroused. I visit them at dawn. They are lined up as on the day before, but motion- less. When the air grows a little warmer, they shake off their torpor, revive and start walking again. The circular procession be- gins anew, like that which I have already seen. There is nothing more and nothing less to be noted in their machine-like obstinacy. This time it is a bitter night. A cold snap has supervened, was indeed foretold in the evening by the garden caterpillars, who re- fused to come out despite appearances which to my duller senses seemed to promise a con- tinuation of the fine weather. At daybreak the rosemary-walks are all asparkle with rime and for the second time this year there is a sharp frost. The large pond in the garden is frozen over. What can the caterpillars in the conservatory be doing? Let us go and see. All are ensconced in their nests, except the 77 The Life of the Caterpillar stubborn processionists on the edge of the vase, who, deprived of shelter as they are, seem to have spent a very bad night. I find them clustered in two heaps, without any at- tempt at order. They have suffered less from the cold, thus huddled together. 'Tis an ill wind, that blows nobody any good. The severity of the night has caused the ring to break into two segments which will, perhaps, afford a chance of safety. Each group, as it revives and resumes its walk, will presently be headed by a leader who, not being obliged to follow a caterpillar in front of him, will possess some liberty of movement and perhaps be able to make the procession swerve to one side. Remember that, in the ordinary processions, the caterpillar walking ahead acts as a scout. While the others, if nothing oc- curs to create excitement, keep to their ranks, he attends to his duties as a leader and is con- tinually turning his head to this side and that, investigating, seeking, groping, making his choice. And things happen as he decides : the band follows him faithfully. Remember also that, even on a road which has already been travelled and beribboned, the guiding cater- pillar continues to explore. 78 The Processionary : the Procession There is reason to believe that the Proces- sionaries who have lost their way on the ledge will find a chance of safety here. Let us watch them. On recovering from their tor- por, the two groups line up by degrees into two distinct files. There are therefore two leaders, free to go where they please, inde- pendent of each other. Will they succeed in leaving the enchanted circle? At the sight of their large black heads swaying anxiously from side to side, I am inclined to think so for a moment. But I am soon undeceived. As the ranks fill out, the two sections of the chain meet and the circle is recon- stituted. The momentary leaders once more become simple subordinates; and again the caterpillars march round and round all day. For the second time in succession, the night, which is very calm and magnificently starry, brings a hard frost. In the morning the Pro- cessionaries on the tub, the only ones who have camped out unsheltered, are gathered into a heap which largely overflows both sides of the fatal ribbon. I am present at the awakening of the numbed ones. The first to take the road is, as luck will have it, outside 79 The Life of the Caterpillar the track. Hesitatingly he ventures into un- known ground. He reaches the top of the rim and descends upon the other side on the earth in the vase. He is followed by six others, no more. Perhaps the rest of the troop, who have not fully recovered from their nocturnal torpor, are to lazy to bestir themselves. The result of this brief delay is a return to the old track. The caterpillars embark on the silken trail and the circular march is re- sumed, this time in the form of a ring with a gap in it. There is no attempt, however, to strike a new course on the part of the guide whom this gap has placed at the head. A chance of stepping outside the magic circle has presented itself at last; and he does not kno\\ how to avail himself of it. As for the caterpillars who have made their way to the inside of the vase, their lot is hard- ly improved. They climb to the top of the palm, starving and seeking for food. Finding nothing to eat that suits them, they retrace their steps by following the thread which they have left on the way, climb the ledge of the pot, strike the procession again and, without further anxiety, slip back into the r;ir - 80 The Procession ary: the Procession Once more the ring is complete, once more the circle turns and turns. Then when will the deliverance come? There is a legend tliat tells of poor souls dragged along in an endless round until the hellish charm is broken by a drop of holy water. What drop will good fortune sprinkle on my Processionaries to dissolve their circle and bring them back to the nest? I see only two means of conjuring the spell and ob- taining a release from the circuit. These two means are two painful ordeals. A strange linking of cause and effect : from sorrow and wretchedness good is to come. And, first, shrivelling as the result of cold. The caterpillars gather together without any order, heap themselves some on the path, some, more numerous these, outside it. Among the latter there may be, sooner or later, some revolutionary who, scorning the beaten track, will trace out a new road and lead the troop back home. We have just seen an instance of it. Seven penetrated to the interior of the vase and climbed the palm. True, it was an attempt with no result, but still an attempt. For complete success, all that need be done would have been to take the Si The Life of the Caterpillar opposite slope. An even chance is a great thing. Another time we shall be more suc- cessful. In the second place, the exhaustion due to fatigue and hunger. A lame' one stops, unable to go farther. In front of the de- faulter the procession still continues to wend its way for a short time. The ranks close up and an empty space appears. On coming to himself and resuming the march, the cater- pillar who has caused the breach becomes a leader, having nothing before him. The least desire for emancipation is all that he wants to make him launch the band into a new path which perhaps will be the saving path. In short, when the Processionaries' train is in difficulties, what it needs, unlike ours, is to run off the rails. The side-tracking is left to the caprice of a leader who alone is capable of turning to the right or left; and this .leader is absolutely non-existent so long as the ring remains unbroken. Lastly, the breaking of the circle, the one stroke of luck, is the result of a chaotic halt, caused principally by excess of fatigue or cold. The liberating accident, especially that of fatigue, occurs fairly often. In the course of 82 The Process! on ary: the Procession the same day, the moving circumference is cut up several times into two or three sec- tions; but continuity soon returns and no change takes place. Things go on just the same. The bold innovator who is to save the situation has not yet had his inspiration. There is nothing new on the fourth day, after an icy night like the previous one; no- thing to tell except the following detail. Yes- terday I did not remove the trace left by the few caterpillars who made their way to the inside of the vase. This trace, together with a junction connecting it with the circular road. is discovered in the course of the morning. Half the troop takes advantage of it to visit the earth in the pot and climb the palm; the other half remains on the ledge and continues to walk along the old rail. In the afternoon the band of emigrants rejoins the others, the circuit is completed and things return to their original condition. We come to the fifth day. The night frost becomes more intense, without however as yet reaching the greenhouse. It is fol- lowed by bright sunshine in a calm and limpid sky. As soon as the sun's rays have warmed the panes a little, the caterpillars, lying in 83 The Life of the Caterpillar heaps, wake up and resume their evolutions on the ledge of the vase. This time the fine order of the beginning is disturbed and a cert- ain disorder becomes manifest, apparently an omen of deliverance near at hand. The scouting-path inside the vase, which was up- holstered in silk yesterday and the day before, is to-day followed to its origin on the rim by a part of the band and is then abandoned after a short loop. The other caterpillars follow the usual ribbon. The result of this bifurcation is two almost equal files, walking along the ledge in the same direction, at a short distance from each other, sometimes meeting, separating farther on, in even7 case with some lack of order. Weariness increases the confusion. The crippled, who refuse to go on, are many. Breaches increase; files are split up into sec- tions each of which has its leader, who pokes the front of his body this way and that to explore the ground. Everything seems to point to the disintegration which will bring safety. My hopes are once more disap- pointed. Before the night the single file is reconstituted and the invincible gyration re- sumed. 84 The Processionary: the Procession Heat comes, just as suddenly as the cold did. To-day, the 4th of February, is a beauti- ful, mild day. The greenhouse is full of life. Numerous festoons of caterpillars, is- suing from the nests, meander along the sand on the shelf. Above them, at every moment, the ring on the ledge of the vase breaks up and comes together again. For the first time I see daring leaders who, drunk with heat, standing only on their hinder prolegs at the extreme edge of the earthenware rim, fling themselves forward into space, twisting about, sounding the depths. The endeavour is fre- quently repeated, while the whole troop stops. The caterpillars' heads give sudden jerks; their bodies wriggle. One of the pioneers decides to take the plunge. He slips under the ledge. Four fol- low him. The others, still confiding in the perfidious silken path, dare not copy him and continue to go along the old road. The short string detached from the general chain gropes about a great deal, hesitates long on the side of the vase; it goes half-way down, then climbs up again slantwise, rejoins and takes its place in the procession. This time the attempt has failed, though at the foot of 85 The Life of the Caterpillar the vase, not nine inches away, there lay a bunch of pine-needles which I had placed there with the object of enticing the hungry ones. Smell and sight told them nothing. Near as they were to the goal, they went up again. No matter, the endeavour has its uses. Threads were laid on the way and will serve as a lure to further enterprise. The road of deliverance has its first landmarks. And two days later, on the eighth day of the experi- ment, the caterpillars — now singly, anon in small groups, then again in strings of some length — come down from the ledge by following the staked-out path. At sun- set the last of the laggards is back in the nest. Now for a little arithmetic. For seven times twenty-four hours the caterpillars have remained on the ledge of the vase. To make an ample allowance for stops due to the weari- ness of this one or that and above all for the rest taken during the colder hours of the night, we will deduct one-half of the time. This leaves eighty-four hours' walking. The average pace is nine centimetres1 a minute. 13^2 inches. — Translator's Note. 86 The Processionary : the Procession The aggregate distance covered, therefore, is 453 metres, a good deal more than a quarter of a mile, which is a great walk for these little crawlers. The circumference of the vase, the perimeter of the track, is exactly I m. 35. l Therefore the circle covered, always in the same direction and always without result, was described three hundred and thirty-five times. These figures surprise me, though I am already familiar with the abysmal stupidity of insects as a class whenever the least acci- dent occurs. I feel inclined to ask myself whether the Processionaries were not kept up there so long by the difficulties and dangers of the descent rather than by the lack of any gleam of intelligence in their benighted minds. The facts, however, reply that the descent is as easy as the ascent. The caterpillar has a very supple back, well adapted for twisting round projections or slip- ^ ease vertically or horizontally, with his back down or up. Besides, he never mov^S fui- ward until tie has ftxed his thread to the ground. With this support to his feet, he 14 feet 5 inches. — Translator's Note. The Life of the Caterpillar has no falls to fear, no matter what his position. I had a proof of this before my eyes du- ring a whole week. As I have already said, the track, instead of keeping on one level, bends twice, dips at a certain point under the ledge of the vase and reappears at the top a little farther on. At one part of the cir- cuit, therefore, the procession walks on the lower surface of the rim; and this inverted position implies so little discomfort or dan- ger that it is renewed at each turn for all the caterpillars from first to last. It is out of the question then to suggest the dread of a false step on the edge of the rim which is so nimbly turned at each point of inflexion. The caterpillars in distress, starved, shelterless, chilled with cold at night, cling obstinately to the silk ribbon covered hun- dreds of times, because they lack the rudi- mentary glimmers of reason which would advice them to abandon it. Experience and reflection are not in their province. The ordeal of a five hundred yards' march and three to four hundred turns teach them nothing; and it takes casual circum- stances to bring them back to the nest. They The Processionary : the Procession would perish on their insidious ribbon if the disorder of the nocturnal encampments and the halts due to fatigue did not cast a few threads outside the circular path. Some three or four move along these trails, laid -without an object, stray a little way and, thanks to their wanderings, prepare the descent, which is at last accomplished in short strings fa- voured by chance. The school most highly honoured to-day is very anxious to find the origin of reason in the dregs of the animal kingdom. Let me call its attention to the Pine Processionary CHAPTER IV THE PINE PROCESSIONARY : METEOROLOGY IN JANUARY a second moult occurs, leaving the caterpillar less fair to the eye, while at the same time endowing him with some very peculiar organs. When the mo- ment has come to shed their skins, the Pro- cessionaries cluster higgledy-piggledy on the dome of the nest and there, if the weather be mild, remain motionless day and night. It would seem as though the fact of their con- tact, of their mutual discomfort, while thus heaped together, furnishes a resistance, a ful- crum, which favours the process of excoriation. After this second moult, the hairs on the middle of the back are of a dull reddish colour, which is made paler still by the inter- position of numerous Long white hairs. But this faded costume is accompanied by the singular organs which attracted the attention of Reaumur, who was greatly perplexed as to their function. In the place originally oc- cupied by the scarlet mosaic, eight segments of the caterpillar are now cleft by a broad 00 The Processionary : Meteorology transversal gash, a sort of thick-lipped mouth, which opens and gapes wide at the caterpil- lar's will, or closes without leaving a visible trace. From each of these expanding mouths rises a tumour with a fine, colourless skin, as though the creature were exposing its tender inside and inflating it, for the appearance is almost that which would be presented by the viscera protruding through skin incised by the scalpel. Two large dark-brown dots occupy the front face of the protuberance. At the back are two short, flat tufts of russet bristles, which in the sunlight shine with a rich brilliancy. All around is a radiating border of long white hairs, spread almost flat. This protuberance is extremely sensitive. At the slightest irritation it goes in again and disappears under the dark integument. In its place opens an oval crater, a sort of huge stoma, which swiftly brings its lips together, closes and entirely disappears. The long white hairs that form a moustache and im- perial around this mouth follow the move- ments of the contracting lips. After first radiating from a centre and lying flat, these hairs rise like levelled wheat which the wind The Life of the Caterpillar has caught from beneath and meet to form a transversal crest, perpendicular to the crea- ture's back. This hairy erection produces a sudden modification in the caterpillar's aspect. The red shiny bristles have disappeared, buried under the dark skin; the white hairs, now standing on end, form a hirsute mane; an ashy tinge has crept into the general colour of the costume. When calm is restored, as soon happens, the slits open and yawn afresh ; the sensitive protuberances emerge, quick to disappear once more should any cause for alarm occur. These alternate expansions and contractions are rapidly repeated. I provoke them at will in various ways. A slight puff of tobacco- smoke immediately causes the stomata to yawn and the protuberances to emerge. One would think that the insect was putting itself on its guard and displaying some special ap- paratus of information. Before long the pro- tuberances go in again. A second puff of smoke brings them out once more. But, if the smoke is too abundant, too acrid, the caterpillar wriggles and writhes without open- ing his apparatus. The Processionary : Meteorology Or else I touch one or other of these un- covered protuberances, very delicately, with a bit of straw. The pimple affected imme- diately contracts, draws into itself, like the horns of the Snail, and is replaced by a ga- ping mouth, which in its turn closes. Usually, but not always, the segment excited by the contact of my straw is imitated by the others, both front and back, which close their ap- paratus one by one. When undisturbed and in repose, the cater- pillar generally has his dorsal slits expanded; in moving, he sometimes opens and sometimes closes them. In either case expansion and contraction are frequently repeated. Con- stantly coming together and retreating under the skin, the lips of the mouth-like opening therefore end by losing their brittle mous- taches of russet hairs, which break off. In this way a sort of dust collects at the bottom of the crater, a dust formed of broken hairs, which, thanks to their barbs, soon collect into little tufts. When the slit expands rather sud- denly, the central projection shoots out on the insect's sides its load of hairy remnants, which the least breath blows into a cloud of golden atoms highly disagreeable to the ob- 93 The Life of the Caterpillar server. I shall have something to say presently of the itch to which he is at such times exposed. Are these peculiar stomata designed merely to collect the adjoining bristles and to grind them to powder? Are these fine-skinned papillae, which inflate and ascend from the depths of their hiding-place, intended to get rid of the accumulation of broken hairs? Or is it the sole function of this peculiar ap- paratus to prepare, at the expense of the cater- pillar's fleece, an irritant dust which shall act as a means of defence? Nothing tells us so. Certainly the caterpillar is not armed against the enquirer who from time to time takes it into his head to come and examine him through a magnifying-glass. It is even very doubtful whether he troubles at all about those passionate caterpillar-lovers, Calosoma sycophanta1 among insects and the Cuckoo among birds. Those who consume such fare have a stomach expressly fashioned for the purpose, a stomach that laughs at blistering hairs and possibly finds an appetizing stimu- lant in their sting. No, I do not see the mo- tives that prompted the Processionary to 1A large carnivorous Beetle. — Translator's Note. 94 The Processionary : Meteorology cleave his back with so many slits, if he merely strips himself of his hair to throw an irri- tating dust in our eyes. There must certainly be something else in question. Reaumur mentions these openings, of which he made a brief study. He calls them stigmata and is inclined to take them for ex- ceptional breathing-holes. That they are not, O my master; no insect contrives air-holes on its back! Moreover, the magnifying-glass re- veals no channel of communication with the interior. Respiration plays no part here; the solution of the enigma must lie elsewhere. The protuberances that rise from those ex- panded cavities are formed of a soft, pale, hairless membrane, which gives the impression of a visceral hernia, as though the caterpillar were wounded and exposing its delicate en- trails to the air. The sensitiveness just here is great. The lightest touch with the point of a hair-pencil causes the immediate in- drawing of the protuberances and the closing of the containing lips. The touch of a solid object even is not essential. I pick up a tiny drop of water on the point of a pin and, without shaking it off, present this drop to the sensitive projection. 95 The Life of the Caterpillar At the moment when contact occurs the ap- paratus contracts and closes up. The recoil of the Snail's horns, withdrawing the visual and olfactory organs into their sheaths, is no prompter. Everything seems to prove that these op- tional tumours, appearing and disappearing at the caterpillar's will, are instruments of sensorial perception. The caterpillar exposes them to obtain information; he shelters them under his skin to preserve their delicate func- tions. Now what is it that they perceive? This is a difficult question, in which the habits of the Processionary alone can afford us a little guidance. During the whole winter, the Pine Cater- pillars are active only at night. In the day- time, when the weather is fine, they readily repair to the dome of the nest and there re- main motionless, gathered into heaps. It is the hour of the open-air siesta, under the pale December and January sun. As yet none leaves the home. It is quite late in the even- ing, towards nine o'clock, when they set out, marching in an irregular procession, to browse on the leaves of the branches hard by. Their grazing is a protracted affair. The flock re- 96 The Processionary : Meteorology turns late, some time after midnight, when the temperature falls too low. Secondly, it is in the heart of winter, du- ring the roughest months, that the Proces- sionary displays his full activity. Indefatiga- bly at this time of year he spins, adding each night a new web to his silken tent; at this time, whenever the weather permits, he ven- tures abroad on the neighbouring boughs to feed, to grow and to renew his skein of silk. By a very remarkable exception, the harsh season marked by inactivity and lethargic re- pose in other insects is for him the season of bustle and labour, on condition, of course, that the inclemencies of the weather do not exceed certain limits. If the north wind blow too violently, so that it is like to sweep the flock away; if the cold be too piercing, so that there is a risk of freezing to death; if it snow, or rain, or if the mist thicken into an icy drizzle, the caterpillars prudently stay at home, sheltering under their weatherproof tent. It would be convenient to some extent to foresee these inclemencies. The caterpillar dreads them. A drop of rain sets him in a flutter; a snowflake exasperates him. To 97 The Life of the Caterpillar start for the grazing-grounds at dark of night, in uncertain weather, would be dangerous, for the procession goes some distance and travels slowly. The flock would fare ill before re- gaining shelter did any sudden atmospheric trouble supervene, an event of some frequency in the bad season of the year. So that he may be informed in this particular during his nocturnal winter rambles, can the Pine Cater- pillar be endowed with some sort of meteoro- logical aptitudes? Let us describe how the suspicion occurred to me. Divulged I know not how, my rearing of caterpillars under glass acquired a certain re- nown. It was talked about in the village. The forest-ranger, a sworn enemy to de- structive insects, wanted to see the grazing of the famous caterpillars, of whom he had re- tained a too poignant memory ever since the day when he gathered and destroyed their nests in a pine-wood under his charge. It was arranged that he should call the same evening. He arrives at the appointed hour, accom- panied by a friend. For a moment we sit and chat in front of the fire; then, when the .clock strikes nine, the lantern is lit and we 08 The Processionary : Meteorology all three enter the greenhouse. The visitors are eager for the spectacle of which they have heard such wonderful things, while I am cert- ain of satisfying their curiosity. But, but ... what is this? Not a cater- pillar on the nests, not one on the fresh ration of branches! Last night and on the previous nights they came out in countless numbers; to-night not one reveals himself. Can it be that they are merely late in going to dinner? Can their habitual punctuality be at fault be- cause appetite has not yet arrived? We must be patient. . . . Ten o'clock. Nothing. Eleven. Still nothing. Midnight was at hand when we abandoned our watch, convinced that it would be vain to prolong the sitting. You can imagine what an abject fool I looked at having thus to send my guests away. Next day I thought that I dimly perceived the explanation of this disappointment. It rained in the night and again in the morning. Snow, not the earliest of the year, but so far the most abundant, whitened the brow of the Ventoux.1 Had the caterpillars, more 1The highest mountain in the neighbourhood of Serignan. Cf. The Hunting Wasps, by J. Henri Fabre, translated by Alexander Teixeira de Mattos: chap, xl — Translator's .Vote. 99 The Life of the Caterpillar sensitive than any of us to atmospheric changes, refused to venture forth because they anticipated what was about to happen ? Had they foreseen the rain and the snow, which nothing seemed to announce, at all events to us? After all, why not? Let us continue to observe them and we shall see whether the coincidence is fortuitous or not. On this memorable day, therefore, the I3th of December, 1895, I institute the caterpil- lars' meteorological observatory. I have at my disposal absolutely none of the apparatus dear to science, not even a modest ther- mometer, for my unlucky star continues in the ascendant, proving as unkind to-day as when I learnt chemistry with pipe-bowls for cruci- bles and bottles that once contained sweets for retorts. I confine myself to visiting nightly the Processionaries in the greenhouse and those in the garden. It is a hard task, espe- cially as I have to go to the far end of the enclosure, often in weather when one would not turn a Dog out of doors. I set down the acts of the caterpillars, whether they come out or stay at home ; I note the state of the sky during the day and at the moment of my evening examination. The Processionary : Meteorolog) To this list I add the meteorological chart of Europe which the Temps publishes daily. If I want more precise data, I request the Normal School at Avignon to send me, on occasions of violent disturbances,- the barome- trical records of its observatory. These are the only documents at my disposal. Before we come to the results obtained, let me once more repeat that my caterpillars' meteorological institute has two stations : one in the greenhouse and one in the open air, on the pines in the enclosure. The first, pro- tected against the wind and rain, is that which I prefer: it provides more regular and more continuous information. In fact, the open- air caterpillars often enough refuse to come out, even though the general conditions be favourable. It is enough to keep them at home if there be too strong a wind shaking the boughs, or even a little moisture dripping on the web of the nests. Saved from these two perils, the greenhouse caterpillars have only to consider atmospheric incidents of a higher order. The small variations escape them; the great alone make an impression on them: a most useful point for the observer and going a long way towards solving the The Life of the Caterpillar problem for him. The colonies under glass, therefore, provide most of the material for my notes; the colonies in the open air add their testimony, which is not always quite clear. Now what did they tell me, those green- house caterpillars who, on the i3th of Decem- ber, refused to show themselves to my guest, the forest-ranger? The rain that was to fall that night could hardly have alarmed them: they were so well sheltered. The snow about to whiten Mont Ventoux was nothing to them: it was so far away. Moreover, it was neither snowing yet nor raining. Some ex- traordinary atmospheric event, profound and of vast extent, must have been occurring. The charts in the Temps and the bulletin of the Normal School told me as much. A cyclonic disturbance, coming from the British Isles, was passing over our district; an atmospheric depression the like of which the season had not as yet known, had spread in our direction, reaching us on the i3th and persisting, in a more or less accentuated form, until the 22nd. At Avignon the barometer suddenly fell half an inch, to 29.1 in., on the 1 3th and lower still, to 29 in., on the I9th. The Processionary : Meteorology During this period of ten days, the garden caterpillars made no sortie on the pine-trees. True, the weather was changeable. There were a few showers of fine rain and some violent gusts of the mistral; but more fre- quently there were days and nights when the sky was superb and the temperature moder- ate. The prudent anchorites would not al- low themselves to be caught. The low pres- sure peristed, menacing them; and so they stopped at home. In the greenhouse things happen rather dif- ferently. Sorties take place, but the staying-in days are still more numerous. It looks as though the caterpillars, alarmed at first by the unexpected things happening overhead, had reassured themselves and resumed work, feel- ing nothing, in their shelter, of what they would have suffered out of doors — rain, snow and furious mistral blasts — and had then sus- pended their work again when the threats of bad weather increased. There is, indeed, a fairly accurate agree- ment between the oscillations of the barome- ter and the decisions of the herd. When the column of mercury rises a little, they come out ; when it falls they remain at home. Thus 103 The Life of the Caterpillar on the 1 9th, the night of the lowest press- ure, 29 in., not a caterpillar ventures out- side. As the wind and rain can have no effect on my colonies under glass, one is led to sup- pose that atmospheric pressure, with its physiological results, so difficult to define, is here the principal factor. As for the tem- perature, within moderate limits there is no need to discuss it. The Processionaries have a robust constitution, as behoves spinners who work in the open air in midwinter. However piercing the cold, so long as it does not freeze, when the hour comes for working or feeding they spin on the surface of the nest or browse on the. neighbouring branches. Another example. According to the me- teorological chart in the Temps, a depression whose centre is near the lies Sanguinaires, at the entrance of the Gulf of Ajaccio, reaches my neighbourhood, with a minimum of 29.2 in., on the 9th of January. A tempestuous wind gets up. For the first time this year there is a respectable frost. The ice on the large pond in the garden is two or three inches thick. This wild weather lasts for five days. Of course, the garden caterpillars do not 104 The Processionary . Meteorology sally forth on the pine-trees while these are battered by such a gale. The remarkable part of the business is that the greenhouse caterpillars do not venture out of their nests either. And yet for them there are no boughs dangerously shaken, ro cold piercing beyond endurance, for it is not freezing under the glass. What keeps them in can be only the passage of that wave of depression. On the I5th the storm ceases; and the barometer remains between 29.6 and 30 in. for the rest of the month and a good part of February. During this long period there are magnificent sorties every evening, especially in the greenhouse. On the 23rd and 24th of February, sud- denly the Processionaries stop at home again, for no apparent reason. Of the six nests under cover, only two have a few rare cater- pillars out on the pine-branches, while previ- ously, in the case of all six, I used every night to see the leaves bending under the weight of an innumerable multitude. Warned by this forecast, I enter in my notes: "Some deep depression is about to reach us." And I have guessed right. Two days later, 105 The Life of the Caterpillar sure enough, the meteorological record of the Temps gives me the following information: a minimum of 29.2 in., coming from the Bay of Biscay on the 22nd, reaches Algeria on the 23rd and spreads over the Provence coast on the 24th. There is a heavy snow- fall at Marseilles on the 25th. "The ships," I read in my paper, "present a curious spectacle, with their yards and rig- ging white. That is how the people of Mar- seilles, little used to such sights, picture Spitz- bergen and the North Pole." Here certainly is the gale which my cater- pillars foresaw when they refused to go out last night and the night before; here is the centre of disturbance which revealed itself at Serignan by a violent and icy north wind on the 25th and the following days. Again I perceive that the greenhouse caterpillars are alarmed only at the approach of the wave of atmospheric disturbance. Once the first uneasiness caused by the depression had abated, they came out again, on the 25th and the following days, in the midst of the gale as though nothing extraordinary were hap- pening. 106 The Processionary: Meteorology From the sum ofmvQHfrvifi°"fi that t_he_Pine ^rocessronary_jsj;rn inently sensi- tive to atmospheric vicissitudes, an excel- lent quality, having regard to his way of life in the sharp winter nights. He fore- "sees the storm which would imperil his CUSlQn His caaci capacity for scenting bad weather very soon won the confidence of the household. When we had to go into Orange to renew our provisions, it became the rule to consult him the night before; and, according to his ver- dict, we went or stayed at home. His oracle never deceived us. In the same way, simple folk that we were, we used in the old days to interrogate the Dor-beetle,1 another doughty nocturnal worker. But, a little de- moralized by imprisonment in a cage and ap- parently devoid of any special sensitive ap- paratus, performing his evolutions, moreover, in the mild autumn evenings, the celebrated Dung-beetle could never rival the Pine Cater- pillar, who is active during the roughest sea- son of the year and endowed, as everything lGeotrupes stercorarius, a large Dung-beetle. Cf. The Life and Love of the Insect, by J. Henri Fabre, translated by Alexander Teixeira de Mattos : chap, ix — Translator's Note. 107 The Life of the Caterpillar would seem to affirm, with organs quick to perceive the great atmospheric fluctuations. Rural lore abounds in meteorological fore- casts derived from animals. The Cat, sit- ting in front of the fire and washing behind her ears with a saliva-smeared paw, fore- tells another cold snap; the Cock, crowing at unusual hours, announces the return of fine weather; the Guinea-fowl, with her screech- ing, as of a scythe on the grindstone, points to rain; the Hen, standing on one leg, her plu- mage ruffled, her head sunk on her neck, feels a hard frost coming; the pretty green Tree- frog inflates his throat like a bladder at the approach of a storm and, according to the Provencal peasant, says : "Ploiira, ploiira; it will rain, it will rain!'* This rustic meteorology, the heritage of the centuries, does not show up so badly beside our scientific meteorology. Are not we ourselves living barometers? Every veteran complains of his glorious scars when the weather is about to break. One man, though unwounded, suffers from insomnia or from bad dreams; another, though a brain-worker, cannot drag an idea out of his impotent head. Each of us, in 1 08 The Processionary : Meteorology his own way, is tried by the passage of those huge funnels which form in the atmosphere and hatch the storm. Could the insect, with its exceptionally delicate organization, escape this kind of im- pression? It is unbelievable. The insect, more than any other ceature, should be an animated meteorological instrument, as truth- ful in its forecasts, if we knew how to read them, as the lifeless instruments of our obser- vatories, with their mercury and their catgut. All, in different degrees, possess a general im- pressionability analogous to our own and exer- cised without the aid of specific organs. Some, better-gifted because of their mode of life, might well be furnished with special meteoro- logical apparatus. The Pine Processionary seems to belong to this number. In his second costume, when the segments bear on their dorsal faces an elegant red mosaic, he differs apparently from other caterpillars only by a more delicate gen- eral impressionability, unless this mosaic be endowed with aptitudes unknown elsewhere. If the nocturnal spinner is still none too generously equipped, it must be remembered that the season which he passes in this ccn- iog The Life of the Caterpillar dition is nearly always clement. The really formidable nights hardly set in before Janu- ary. But then, as a safeguard in his pere- grinations, the Pine Processionary cleaves his back with a series of mouths which yawn open to sample the air from time to time and to give a warning of the sudden storm. Until further evidence is forthcoming, therefore, the dorsal slits are, to my mind, meteorological instruments, barometers in- fluenced by the main fluctuations of the atmo- sphere. To go beyond suspicions, though these are well based, is for me impossible. I lack the equipment necessary to delve more deeply into the subject. But I have given a hint. It is for those, who are better favoured in the matter of resources to find the final solu- tion of this interesting problem. t;o CHAPTER V THE PINE PROCESSIONARY: THE MOTH WHEN March comes, the caterpillars reared in domesticity never cease pro- cessioning. Many leave the greenhouse, which remains open; they go in search of a suitable spot for the approaching metamor- phosis. . This is the final exodus, the definite abandonment of the nest and the pine-tree. The pilgrims are much faded, whitish, with a few russet hairs on their backs. On the 2Oth of March I spend a whole morning watching the evolutions of a file some three yards in length, containing about a hundred emigrants. The procession toils grimly along, undulating over the dusty ground, where it leaves a furrow. Then it breaks into a small number of groups, which crowd together and remain quiescent save for sudden oscillations of the hind-quarters. After a halt of varying duration, these groups resume their march, henceforward forming independent processions. They take no settled direction. This one in The Life of the Caterpillar goes forward, that one goes back; one turns to the left and another to the right. There is no rule about their marching, no positive goal. One procession, after describing a loop, retraces its steps. Yet there is a general tend- ency towards that wall of the greenhouse which faces the south and reflects the sun's rays with added fervour. The sole guide, il would seem, is the amount of sun which a place obtains; the directions whence the great- est heat comes are preferred. After a couple of hours of marching and countermarching, the fragmentary proces- sions, comprising each a score of caterpillars, reach the foot of the wall. Here the soil is powdery, very dry, easy to burrow in, al- though made somewhat firmer by tufts of grass. The caterpillar at the head of the row explores with his mandibles, digs a little, in- vestigates the nature of the ground. The others, trusting their leader, follow him with docility, making no attempts of their own. Whatever the foremost decides will be adopted by all. Here, in the choice of a mat- ter so important as the spot whereat the trans- formation shall take place, there is no in- dividual initiative. There is only one will, 112 The Processionary : the Moth the leader's. There is only one head, so to speak; the procession may be compared with the chain of segments of an enormous worm. Finally some spot is recognized as propi- tious. The leading caterpillar halts, pushes with his head, digs with his mandibles. The others, still in a continuous line, arrive one by one and likewise come to a halt. Then the file breaks up into a swarming heap, in which each of the caterpillars resumes his liberty. All their backs are joggling pell-mell ; all their heads are plunged into the dust; all their feet are raking, all their mandibles excavating the soil The worm has chopped itself into a gang of independent workers. An excavation is formed in which, little by little, the caterpillars bury themselves. For some time to come, the undermined soil cracks and rises and covers itself with little mole- hills; then all is still. The caterpillars have' descended to a depth of three inches. This is as far as the roughness of the soil permits them to go. In looser soil, the excavation would attain a much greater depth. The greenhouse shelf, supplied with fine sand, has provided me with cocoons placed at a depth of from eight to twelve inches. I would not 113 The Life of the Caterpillar assert that the interment might not be made still lower down. For the most part, the burial is effected in common, by more or less numerous clusters and at depths which vary greatly, according to the nature of the soil. A fortnight later, let us dig at the point where the descent underground was made. Here we shall find the cocoons assembled in bunches, cocoons of sorry appearance, soiled as they are with earthy particles held by silken threads. When stripped of their rough ex- terior, they are not without a certain elegance. They are narrow ellipsoids, pointed at both ends, measuring twenty-five millimetres in length and nine millimetres1 in thickness. The silk of which they are composed is very fine and of a dull white. The fragility of the walls is remarkable when we have seen the enormous quantity of silk expended on the construction of the nest. A prodigious spinner where his winter habi- tation is concerned, the caterpillar finds his glands exhausted and is reduced to the strictly necessary amount when the time conies for making the cocoon. Too poor in silk, he strengthens his flimsy cell with a facing of ^•975 by .351 inch. — Translator's Note. 114 The Processionary : the Moth earth. With him it is not the industry of the Bembex,1 who inserts grains of sand in her silky web and makes a solid casket of the whole; it is a summary sort of art, devoid of delicacy, which just casually sticks to- gether the surrounding earthy refuse. Moreover, if circumstances demand it, the Pine Caterpillar can do without earth. In the very midst of the nest I have sometimes — very rarely, it is true — discovered cocoons which were perfectly clean. Not a scrap of alien matter defiled their fine white silk. I have obtained similar specimens by placing caterpillars under a bell-glass in a pan pro- vided only with a few pine-twigs. Better still: an entire procession, a good-sized one too, gathered at the opportune moment and enclosed in a large box containing no sand nor any material whatever, spun its cocoons with no other support than the bare walls. These exceptions, provoked by circumstances in which the caterpillar is not free to act ac- cording to his wont, does not in any way in- validate the rule. To prepare for the trans- formation, the Processionary buries himself, iCf. The Hunting Wasps: chaps, xiv to xvii.-TYanj- lator's Note. US The Life of the Caterpillar to the depth of nine inches and more, if the soil permit. Here a curious problem forces itself upon the observer's mind. How does the Moth contrive to ascend from the catacombs into which the caterpillar has descended? Not in the finery of her perfect state — the big wings with their delicate scales, the sweep- ing antenna-plumes — dare she brave the as- perities of the soil, or she would issue thence all tattered, rumpled and unrecognizable. And this is not the case: far from it. More- over, what means can she employ, she so feeble, to break the crust of earth into which the original dust will have turned after the slightest of showers? The Moth appears at the end of July or in August. The burial took place in March. Rain must have fallen during this lapse of time, rain which beats down the soil, cements it and leaves it to harden once evaporation has set in. Never could a Moth, unless at- tired and equipped with tools for the pur- pose, break her way through such an obstacle. She would perforce require a boring-tool and a costume of extreme simplicity. Guided by these considerations, I institute a few experi- 116 The Processionary : the Moth ments which will give me the key to the riddle. In April I make a copious collection of cocoons. Of these I place ten or twelve at the bottom of test-tubes of different diameters and, last of all, I fill the apparatus with sandy soil, sifted and very slightly moistened. The contents are pressed down, but in moderation, for fear of injuring the cocoons below. When the month of August comes, the column of earth, damp at the outset, has set so firmly, thanks to evaporation, that, when I reverse the test-tube, nothing trickles out. On the other hand, some cocoons have been kept naked under a metallic cover. These will teach me what the buried cocoons would not be able to show. They furnish me, in fact, with records of the greatest interest. On issu- ing from the cocoon, the Pine Bombyx has her finery bundled up and presents the appear- ance of a cylinder with rounded ends. The wings, the principal obstacle to underground labour, are pressed against the breast like nar- row scarves; the antennas, another serious em- barrassment, have not yet unfolded their plumes and are turned back along the Moth's sides. The hair, which later forms a dense 157 The Life of the Caterpillar fleece, is laid flat, pointing backwards. The legs alone are free, fairly active and endowed with a certain vigour. Thanks to this arrange- ment, which does away with all awkward pro- jections, the ascent through the soil is made possible. True, every Moth, at the moment of quit- ting her shell, is this sort of swathed mummy; but the Pine Bombyx has in addition an ex- ceptional aptitude rendered necessary by the fact that she hatches under the ground. While the others, once out of the cocoon, hasten to spread their wings and are power- less to defer their development, she, by virtue of an indispensable privilege, remains in her compact and wrapped-up condition as long as circumstances demand it. Under my bell- glasses I see some who, though born upon the surface, for twenty-four hours drag them- selves over the sand or cling to the pine- branches, before untying their sashes and un- furling them as wings. This delay is evidently essential. To as- cend from beneath the earth and reach the open air, the Moth has to bore a long tun- nel, which requires time. She will take good care not to spread her hnery before emer- 118 The Processionary : the Moth ging, 'for it would hamper her and would it- self be rumpled and badly creased. There- fore the cylindrical mummy persists until the deliverance is effected; and, if liberty happen to be acquired before the appointed moment, the final evolution does not take place until after a lapse of time in conformity with usage. We are acquainted with the equipment for emergence, the tight-fitting jerkin in- dispensable in a narrow gallery. Now, where is the boring-tool ? The legs, though free, would here be insufficient: they would scrape the earth laterally, enlar- ging the diameter of the shaft, but could not prolong the exit vertically, above the insect's head. This tool must be in front. Pass the tip of your finger over the Moth's head. You will feel a few very rough wrinkles. The magnifying-glass shows us more. We find, between the eyes and higher up, four or five transversal scales, so set as to overlap one another; they are hard and black and are trimmed crescent-wise at the ends. The longest and strongest is the upper- most, which is in the middle of the forehead. 119 The Life of the Caterpillar There you have the centre-bit of your boring- tool. To make our tunnels in granitic rocks we tip our drills with diamond points. For a similar task the Bombyx, a living drill, wears implanted on her forehead a row of crescents, hard and durable as steel, a regular twist- bit. Without suspecting its use, Reaumur was perfectly aware of this marvellous im- plement, which he called scaly stairs : "What does it profit this Moth," he asks, "that she should thus have the front of her head formed like scaly stairs? That is just what I do not know." My test-tubes, learned master, will tell us. By good fortune, of the numerous Moths as- cending from the bottom of my apparatus through a column of sand solidified by the evaporation of the original moisture, some are making their way upwards against the side of the tube, enabling me to follow their ma- noeuvres. I- see them raising their cylindrical bodies, butting with their heads, jerking now in one direction, now in another The nature of their task is obvious. The centre-bits, with an alternating movement, are boring into the agglutinated sand. The powdery wreckage The Processionary : the Moth trickles down from overhead and is at once thrust backward by the legs. A little space forms at the top of the vault ; and the Moth moves so much nearer to the surface. By the following day, the whole column, ten inches in height, will be perforated with a straight, perpendicular shaft. Shall we now form an idea of the total work performed? Let us turn the test-tube upside down. The contents, as I have said, will not fall out, for they have set into a block; but from the tunnels bored by the Moth trickles all the sand crumbled by the crescents of the drill. The result is a cylin- drical gallery, of the width of a lead-pencil, very cleanly cut and reaching to the bottom of the solid mass. Are you satisfied, my master? Do you now perceive the great utility of the scaly stairs ? Would you not say that we have here a magnificent example of an instrument super- latively fitted for a definite task? I share this opinion, for I think, with you, that a sovereign Reason has in all things coordi- nated the means and the end. But let me tell you: we are called old- fashioned, you and I ; with our conception of 121 The Life of the Caterpillar a world ruled by an Intelligence, we are quite out of the swim. Order, balance, harmony: that is all silly nonsense. The universe is a fortuitous arrangement in the chaos of the possible. What is white might as easily be black, what is round might be angular, what is regular might be shapeless and harmony might just as well be discord. Chance has de- cided all things. Yes, we are a pair of prejudiced old fogeys when we linger with a certain fondness over the marvels of perfection. Who troubles about these futilities nowadays? So-called serious science, the science which spells honour, profit and renown, consists in slicing your animal with very costly instruments into tiny circular sections. My housekeeper does as much with a bunch of carrots, with no higher pretention than to concoct a modest dish, which is not an invariable success. In the problem of life are we more successful when we have split a fibre into four and cut a cell into shavings? It hardly seems so. Th'e riddle is as dark as ever. Ah, how much better is your method, my dear master; above all, how much loftier your philosophy, ho'.v much more wholesome and invigorating! 122 The Procesbionary : the Moth Here at last is the Moth at the surface. With the deliberate slowness demanded by so delicate an operation, she spreads her bunched wings, extends her antennas and puffs out her fleece. Her costume is a modest one: upper wings grey, striped with a few crinkly brown streaks; under-wings white; thorax covered with thick grey fur; abdomen clad in bright- russet velvet. The last segment has a pale- gold sheen. At first sight it appears bare. It is not, however; but, in place of hairs like those of the other segments, it has, on its dor- sal surface, scales so well assembled and so close together that the whole seems to form a continuous block, like a nugget. Let us touch this trinket with the point of a needle. However gently we rub, a multi- tude of scales come off and flutter at the least breath, shining like mica spangles. Their concave form, their shape, an elongated oval, their colouring, white in the lower half but reddish gold in the upper, give them, if we allow for the difference in size, a certain re- semblance to the scales surrounding the heads of some of the centaury tribe. Such is the golden fleece of which the mother will de- spoil herself in order to cover the cylinder of 123 The Life of the Caterpillar her eggs. The nugget of her hind-quarters, exfoliated spangle by spangle, will form a roof for the germs arranged like the grain in a corn-cob. I was anxious to watch the actual placing of these pretty tiles, which are fixed at the pale end with a speck of cement, leaving the coloured end free. Circumstances did not favour me. Inactive all day, motionless on some needle of the lower branches, the Moth, whose life is very short, moves only in the darkness of the night. Both her mating and egg-laying are nocturnal. On the morrow, all is finished: the Bombyx has lived. Under these conditions, it was impossible, by the doubtful beams of a lantern, to follow satisfactorily the labour of the mother on the pine-trees in the garden. I was no more fortunate with the captives in my bell-glasses. A few did lay their eggs, but always at a very advanced hour of the night, an hour which found my vigilance at fault. The light of a candle and eyes heavy with sleep were of little avail when it came to analysing the subtle operations of the mother as she puts her scales in place. We 124 The Procession ary : the Moth will say nothing of the little that was imper- fectly seen. Let us close with a few words of sylvi- cultural practice. The Pine Processionary is a voracious caterpillar who, while respecting the terminal bud, protected by its scales and its resinous varnish, completely denudes the bough and imperils the tree by leaving it bald. The green pine-needles, that mane in which the vegetable vigour of the tree resides, are shorn to the roots. How are we to remedy this? When consulted on the subject, the forest- ranger of my parish told me that the custom is to go from tree to tree with pruning-shears fitted on a long pole and to cut down the nests, afterwards burning them. The method is a troublesome one, for the silken purses are often at considerable heights. Moreover, it i< not without danger. Attacked by the hairy dust, the destroyers soon experience intolera- ble discomfort, a torture of irritation which makes them refuse to continue the work. To my thinking it would be better to operate before the appearance of the nests. The Pine Bombyx is a very bad flyer. In- capable of soaring, almost like the Silk-moth, 125 The Life of the Caterpillar she flutters about and blunders to earth again; and her best efforts barely succeed in bringing her to the lower branches, which almost drag along the ground. Here are deposited the cylinders of eggs, at a height of six feet at most. It is the young caterpillars who, from one provisional encampment to another, gradually ascend, attaining, stage by stage, the summits upon which they weave their final dwellings. Once we grasp this peculiarity, the rest is plain sailing. In August we inspect the lower foliage of the tree: an easy examination, for it is car- ried on no higher than our heads. Towards the far end of the twigs it is easy to espy the Bombyx' eggs, packed into cylinders that resemble scaly catkins. Their size and their whitish colour make them show up amid the sombre green. Gathered with the double pine-needle that bears them, these cylinders are crushed under foot, a summary fashion of stamping out an evil before it spreads. This I have done in the case of the few pine-trees in my enclosure. And the same might be done in the wider forest expanses and more especially in parks and gardens, where symmetrical foliation is one of the The Processionary : the Moth great beauties of the tree. I will add that it is wise to prune every bough that droops to earth and to keep the foot of the conifer bare to a height of six feet or so. In the ab- sence of these lower stairs, the only ones that the Bombyx with her clumsy flight can reach, she will not be able to populate the tree. CHAPTER VI THE PINE PROCESSIONARY : THE STINGING POWER THE Pine Processionary has three cos- tumes: that of infancy, a scanty, ragged fleece, a mixture of black and white; that of middle age, the richest of the three, when the segments deck themselves on their dorsal sur- face with golden tufts and a mosaic of bare patches, scarlet in colour; and that of ma- turity, when the rings are cleft by slits which one by one open and close their thick lips, champing and grinding their bristling russet beards and chewing them into little pellets, which are thrown out on the creature's sides when the bottom of the pocket swells up like a tumour. When wearing this last costume, the cater- pillar is very disagreeable to handle, or even to observe at close quarters. I happened, quite unexpectedly, to learn this, more tho- roughly than I wished. After unsuspectingly passing a whole mo'rn- 128 The Stinging Power ing with my insects, stooping over them, mag- nifying-glass in hand, to examine the work- ing of their slits. I found TIV forehead and eyelids suffering with redness for twenty-four hours and afflicted with an itching even more painful and persistent than that produced by the sting of a nettle. On seeing me come down to dinner in this sad plight, with my eyes reddened and swollen and my face unrecognizable, the family anxiously en- quired what had happened to me and were not reassured until I told them of my mis- hap. I unhesitatingly attribute my painful ex- perience to the red hairs ground to powder and collected into flakes, My breath sought them out in the open pockets and carried them to my face, which was very near. The un- thinking intervention of my hands, which now and again sought to ease the discomfort, merely aggravated the ill by spreading the irritating dust. No, the search for truth on the back of the Proc»ssionary is not all sunshine. It was only after a night's rest that I found myself pretty well recovered, the incident having no further ill effects. Let us continue, however. 129 The Life of the Caterpillar It is well to substitute premeditated experi- ments for chance facts. The little pockets of which the dorsal slits form the entrance are encumbered, as I have said, with hairy refuse, either scattered or gathered into flakes. With the point of ?. paint-brush I collect, when they gape open, a little of their contents and rub it on my wrist or on the inside of my fore-arm. I have not long to wait for the result. Soon the skin turns red and is covered with pale lenticular swellings, similar to those pro- duced by a nettle-sting. Without being very sharp, the pain was extremely unpleasant. By the following day, itching, redness and lenticu- lar swellings had all disappeared. This is the usual sequence of events; but let me not omit to say that the experiment does not always succeed. The efficacy of the fluffy dust appears subject to great varia- tions. There have been occasions when I have rubbed myself with the whole caterpillar, or with his cast skin, or with the brdken hairs gathered on a paint-brush, without producing any unpleasant results. The irritant dust seems to vary in quality according to certain 130 The Stinging Power circumstances which I have not been able to discover. From my various tests it is evident that the discomfort is caused by the delicate hairs which the lips of the dorsal mouths, gaping and closing again, never cease grinding, to the detriment of their beards and moustaches. The edges of these slits, as their bristles rub off, furnish the stinging dust. Having established this fact, let us proceed to more serious experiments. In the middle of March, when the Processionaries for the most part h?.ve migrated underground, I de- cide to open a few nests, as I wish to collect their last inhabitants for the purpose, of my investigations. Without taking any precau- tions, my fingers tug at the silken dwelling, which is made of solid stuff; they tear it into shreds, search it through and through, turn it inside out and back again. Once more and this time in a more serious fashion, I am the victim of my unthinking enthusiasm. Hardly is the operation com- pleted, when the tips of my fingers begin to hurt in good earnest, especially in the more delicate part protected by the edge of the nail. The feeling is like the sharp pain of a sore 131 The Life of the Caterpillar that is beginning to fester. All the rest of the day and all through the night, the pain persists, troublesome enough to rob me of my sleep. ' It does not quiet down until the following day, after twenty-four hours of petty torment. How did this new misadventure befall me? I had not handled the caterpillars: indeed, there were very few of them in the nest at the time. I had come upon no shed skins, for the moults do not take place inside the silken purse. When the moment has come to doff the second costume, that of the red mo- saic, the caterpillars cluster outside, on the dome of their dwelling, and there leave in a single heap their old clothes entangled with bits of silk. What is left to explain the un- pleasant consequences to which the handling of the nest exposes us? The broken red bristles are left, the fallen hairs forming a dust that is invisible with- out a very careful examination. For a long time the Processionaries crawl and swarm about the nest; they pass to and fro, penetrating the thickness of the wall when they go to the pastures and when they return to their dormitory. Whether motionless or 132 The Stinging Power on the move, they are constantly opening and closing their apparatus of information, the dorsal mouths. At the moment of closing, the lips of these slits, rolling on each other like the cylinders of a flattening-mill, catch hold of the fluff near them, tear it out and break it into fragments which the bottom of the pocket, presently reascending, shoots outside. Thus myriads of irritant particles are dis- seminated and subtly introduced into every part of the nest. The shirt of Nessus burnt the veins of whoso wore it; the silk of the Processionary, another poisoned fabric, sets on fire the fingers that handle it. The loathsome hairs long retain their viru- lence. I was once sorting out some handfuls of cocoons, many of which were diseased. As the hardness of the contents was usually an indication that something was wrong, I tore open the doubtful cocoons with my fingers, in order to save the non-contaminated chrysalids. My sorting was rewarded with the same kind of pain, especially under the edges of the nails, as I had already suffered when tearing the nests. The cause of the irritation on this occasion was sometimes the dry skin discarded by the The Life of the Caterpillar Processionary on becoming a chrysalis and sometimes the shrivelled caterpillar turned into a sort of chalky cylinder through the invasion of the malignant fungus. Six months later, these wretched cocoons were still capable of producing redness and irritation. Examined under the microscope, the russet hairs, the cause of the itching, are stiff rods, very sharp at either end and armed with barbs along the upper half. Their structure has absolutely nothing in common with nettle- hairs, those tapering phials whose hard point snaps off, pouring an irritant fluid into the tiny wound. The plant from whose Latin name, Urtica, we derive the word urtication borrowed the design of its weapon from the fangs of the venomous serpents; it obtains its effect, not by the wound, but by the poison introduced into the wound. The Processionary employs a different method. The hairs, which have naught resembling the ampullary reservoir of the nettle-hairs, must be poisoned on the sur- face, like the assegais of the Kafirs and Zulus. Do they really penetrate the epidermis? Are they like the savage's javelin, which can- 1.34 The Stinging Power not be extracted once it has gone in ? With their barbs, do they enter all the more deeply because of the quivering of the outraged flesh ? There is no ground for believing anything of the kind. In vain do I scrutinize the injured spot through the magnify ing-glass; I can see no sign of the implanted dart. Neither could Reaumur, when an encounter with the Oak Processionary set him scratching himself. He had his suspicions, but could state nothing definitely. No; despite their sharp points and their barbs, which make them, under the micro- scope, such formidable spears, the Proces- sionary's russet hairs are not darts designed to imbed themselves in the skin and to pro- voke irritation by pricking. Many caterpillars, all most inoffensive, have a coat of bristles which, under the micro- scope, resolve themselves into barbed javelins, quite harmless in spite of their threatening aspect. Let me mention a couple of these peaceable halberdiers. Early in spring, we see, crossing the paths, a briskly-moving caterpillar who inspires repu- nance by his ferocious hairiness, which ripples like ripe corn. The ancient naturalists, with 135 The Life of the Caterpillar their artless and picturesque nomenclature, called him the Hedgehog. The term isworthy of the creature, which, in the moment of danger, rolls itself up like a Hedgehog, pre- senting its spiny armour on all sides to the enemy. On its back is a dense mixture of black hairs and hairs of ashen-gray; while on the sides and fore-part of the body is a stiff mane of bright russet. Black, grey or russet, all this fierce-looking coat is heavily barbed. One hesitates to touch this horror with the finger-tips. Still, encouraged by my example, seven-year-old Paul,- with his tender child's skin, gathers handfuls of the repulsive insect with no more apprehension than if he were picking a bunch of violets. He fills his boxes with it; he rears it on elm-leaves and handles it daily, for he knows that from this frightful creature he will one day obtain a superb Moth (Chelonia caja, LINN.), clad in scarlet velvet, with the lower wings red and the upper white, sprinkled with brown spots. What resulted from the child's familiarity with the shaggy creature? Not even a trace of itching on his delicate skin. I do not speak of mine, which is tanned by the years. In the osier-beds of our local stream, the 136 The Stinging Power rushing Aygues, a thorny shrub abounds which, at the advent of autumn, is covered with an infinity of very sour red berries. Its crabbed boughs, which bear but little ver- dure, are hidden under their clusters of ver- milion balls. It is the sallow thorn or sea buckthorn (Hippophae rhamnoides). In April, a very hairy but rather pretty caterpillar lives at the expense of this shrub's budding leaves. He has on his back five dense tufts of hair, set side by side and arranged like the bristles of a brush, tufts deep-black in the centre and white at the edges. He waves two divergent plumes in front of him and sports a third on his crupper, like a feathery tail. These three are black hair- pencils of extreme delicacy. His greyish Moth, flattened motionless on the bark, stretches his long fore-legs, one against the other, in front of him. You would take them, at a first glance, for antennae of exaggerated proportions. This pose of the extended limbs has won the insect the scientific label of Orgyia, arm's length; and also the vulgar and more expressive denomination of Patte etendue, or outstretched paw. Little Paul has not failed, with my aid, to i37 The Life of the Caterpillar rear the pretty bearer of the tufts and brushes. How many times, with his sensitive finger, has he not .stroked the creature's furry cos- tume? He found it softer than velvet. And yet, enlarged under the microscope, the cater- pillar's hairs are horrible barbed spears, no less menacing than those of the Processionary. The resemblance goes no farther: handled without precautions, the tufted caterpillar does not provoke even a simple rash. No- thing could be more harmless than his coat. It is evident, then, that the cause of the irritation lies elsewhere than in the barbs. If the barbed bristles were enough to poison the fingers, most hairy caterpillars would be dan- gerous, for nearly all have spiny bristles. We find, on the contrary, that virulence is be- stowed upon a very small number, which are not distinguished from the rest by any special structure of the hair. That the barbs have a part to play, that of fixing the irritant atom upon the epidermis, of keeping it anchored in its place, is, after all, possible; but the shooting pains cannot by any means be caused by the mere prick of so delicate a harpoon. Much less slender, the hairs clustered 138 The Stinging Power into pads on the prickly pears are fero- ciously barbed. Woe to the fingers that handle this kind of velvet too confidently ! At the least touch they are pierced with har- poons whose extraction involves a severe tax upon our patience. Other inconvenience there is little or none, for the action of the barb is in this case purely mechanical. Supposing — a very doubtful thing — that the Processionary's hairs could penetrate our skin, they would act likewise, only with less effect, if they had merely their sharp points and their barbs. What then do they possess in addition? They must have, not inside them, like the hairs of the nettle, but outside, on the surface, an irritant agent ; they must be coated with a poisonous mixture, which makes them act by simple contact. Let us remove this virus, by means of a solvent; and the Processionary's darts, re- duced to their insignificant mechanical action, will be harmless. The solvent, on the other hand, rid of all hairs by filtration, will be charged with the irritant element, which we shall be able to test without the agency of the hairs. Isolated and concentrated, the sting- ing element, far from losing by this treat- i39 The Life of the Caterpillar ment, ought to gain in virulence. So reflec- tion tells us. The solvents tried are confined to three: water, spirits of wine and sulphuric ether. I employ the latter by preference, although the other two, spirits qf wine especially, have yielded satisfactory results. To simplify the experiment, instead of submitting to the action of the solvent the entire caterpillar, who would complicate the extract with his fats and his nutritive juices, I prefer to employ the cast skin alone. I therefore collect, on the one hand, the heap of dry skins which the moult of the second phase has left on the dome of the silken dwelling and, on the other hand, the skins which the caterpillars have rejected in their cocoons before becoming chrysalids; and I leave the two lots to infuse, separately, in sul- phuric ether for twenty-four hours. The in- fusion is colourless. The liquid, carefully filtered, is exposed to spontaneous evapora- tion; and the skins are rinsed with ether in the filter, several times over. There are now two tests to be made : one with the skins and one with the product of maceration. The first is as conclusive as can 140 The Stinging Power be. Hairy as in the normal state and per- fectly dried, the skins of both lots, drained by the ether, produce not the slightest effect, although I rub myself with them, without the least caution, at the juncture of the fingers, a spot very sensitive to stinging. The hairs are the same as before the action of the solvent : they have lost none of their barbs, of their javelin-points; and yet they are ineffectual. They produce no pain or incon- venience whatever. Deprived of their toxic smearing, these thousands of darts become so much harmless velvet. The Hedgehog Cater- pillar and the Brush Caterpillar are not more inoffensive. The second test is more positive and so conclusive in its painful effects that one hardly likes to try it a second time. When the ethereal infusion is reduced by spontaneous evaporation to a few drops, I soak in it a slip of blotting-paper folded in four, so as to form a square measuring something over an inch. Too unsuspecting of my product, I do things on a lavish scale, both as regards the super- ficial area of my poor epidermis and the quantity of the virus. To any one who might wish to renew the investigation I should re- 141 The Life of the Caterpillar commend a less generous dose. Lastly, the square of paper, that novel sort of mustard- plaster, is applied to the under surface of the fore-arm. A thin waterproof sheeting covers it, to prevent it from drying too rapidly ; and a bandage holds it in place. For the space of ten hours, I feel nothing; then I experience an increasing itch and a burning sensation acute enough to keep me awake for the greater part of the night. Next day, after twenty-four hours of contact, the poultice is removed. A red mark, slightly swollen and very clearly outlined, occu- pies the square which the poisoned paper covered. The skin feels sore, as though it had been cauterized, and looks as rough as shagreen. From each of its tiny pustules trickles a drop of serous fluid, which hardens into a substance similar in colour to gum-arabic. This oozing continues for a couple of days and more. Then the inflamation abates; the pain, hitherto very trying, quiets down; the skin dries and comes off in little flakes. All is over, except the red mark, which remains for a long time, so tenacious in its effects is this extract of Processionary. Three weeks after the ex- 142 The Stinging Power periment, the little square on the fore-arm subjected to the poison is still discoloured. For thus branding one's self, does one at least obtain some small reward? Yes. A little truth is the balm spread upon the wound; and indeed truth is a sovran balm. It will come presently to solace us for much greater sufferings. For the moment, this painful experiment shows us that the irritation has not as its primary cause the hairiness of the Procession- ary. Here is no hair, no barb, no dart. All of that has been retained by the filter. We have nothing now but a poisonous agent ex- tracted by the solvent, the ether. This ir- ritant element recalls, to a certain extent, that of cantharides, which acts by simple con- tact. My square of poisoned blotting-paper was a sort of plaster, which, instead of raising the epidermis in great blisters, makes it bristle with tiny pustules. The part played by the barbed hairs, those atoms which the least movement of the air disseminates in all directions, is confined to conveying to our face and hands the irritant substance in which they are impregnated. Their barbs hold them in place and thus per- 143 The Life of the Caterpillar mit the virus to act. It is even probable that, by means of slight scratches which would otherwise pass unnoticed, they assist the action of the stinging fluid. Shortly after handling the Processionaries, a delicate epidermis becomes tumefied, red and painful. Without being immediate, the action of the caterpillar is prompt. The extract made with ether, on the other hand, causes pain and rubefaction only after a longish in- terval. What does it need to produce more rapid ulceration? To all appearances, the action of the hairs. The direct stinging caused by the caterpillar is nothing like so serious as that produced by the ethereal extract concentrated in a few drops. Never before, in my most painful mis- adventures, whether with the silken purses or their inhabitants, have I seen my skin covered with serous pustules and peeling off in flakes. This time it is a veritable sore, anything but pleasing to the eye. The aggravation is easily explained. I soaked in the ether some fifty discarded skins. The few drops which remained after the evaporation and which were absorbed by the square of blotting-paper represented, there- 144 The Stinging Power fore, the virulence of a single insect fifty times increased. My little blistering-plaster was equivalent to the contact of fifty cater- pillars at the same spot. There is no doubt that, if we left them to steep in considerable numbers, we should obtain extracts of really formidable strength. It is quite possible that medical science will one day make good use of this powerful counter-irritant, which is ut- terly different from cantharides. Whether voluntary victims of our curiosity, which, while affording no other satisfaction than that of knowledge, exposes us to an into- lerable itch, or sufferers through an accident, what can we do to give a little relief to the irritation caused by the Processionary? It is good to know the origin of the evil, but it would be better to apply a remedy. One day, with both hands sore from the prolonged examination of a nest, I try without success lotions of alcohol, glycerine, oil and soapsuds. Nothing does any good. I then remember a palliative employed by Reaumur against the sting of the Oak Processionary. Without telling us how he came to know of the strange specific, the master rubbed himself with parsley and felt a good deal the better 145 The Life of the Caterpillar for it. He adds that any other leaf would probably assuage the irritation in the same way. This is a fitting occasion for reopening the subject. Here, in a corner of the garden, is parsley, green and abundant as one could wish. What other plant can we compare with it? I choose the purslain, the spontaneous guest of my vegetable-beds. Mucilaginous and fleshy as it is, it readily crushes, yielding an emollient liniment. I rub one hand with parsley and the other with purslain, pressing hard enough to reduce the leaves to a paste. The result deserves attention. With the parsley, the burning is a little less acute, it is true, but, though relieved, it per- sists for a long time yet and continues trouble- some. With the purslain, the petty torture ceases almost at once and so completely that I no longer notice it. My nostrum possesses incontestable virtues. I recommend it quietly, without blatant advertisement, to any one who may be persecuted by the Processionary. Foresters, in their war upon caterpillars' nests, should find great relief from it. I have also obtained good results with the leaves of the tomato and the lettuce; and. 146 The Stinging Power without pursuing this botanical survey further, I remain convinced, with Reaumur, that any tender juicy foliage would possess a certain efficacy. As for the mode of action of this specific, I admit that I do not understand it, any more than I can perceive the mode of action of the caterpillar's virus. Moliere's medical student explained the soporific properties of opium by saying: "Qiria est in eo virtus dormitava cujus est proprietas sensus assonpire." Let us say likewise : the crushed herb calms the burning itch because it possesses a calm- ing virtue whose property is to assuage itching. The quip is a good deal more philosophical than it looks. What do we know of our remedies or of anything? We perceive effects, but we cannot get back to their causes. In my village and for some distance around it, there is a popular belief that to relieve the pain of a Wasp's or Bee's sting all that we need do is to rub the part stung with three sorts of herbs. Take, they say, three kinds of herbs, the first that come to hand, make them 147 The Life of the Caterpillar into a bunch and rub hard. The prescription, by all accounts, is infallible. I thought at first that this was one of those therapeutic absurdities which have their birth in rustic imaginations. After making a trial, I admit that what sounds like a nonsensical remedy sometimes has something genuine about it. Friction with three kinds of herbs does actually deaden the sting of the Wasp or Bee. I hasten to add that the same success is achieved with a single herb; and so the result agrees with what the parsley and purslain have taught .us in respect of the irritation caused by the Processionary. Why three herbs when one is enough? Three is the preeminently lucky number; it smacks of witchcraft, which is far from de- tracting from the virtues of the unguent. All rustic medicine has a touch of magic about it; and there is merit in doing things by threes. Perhaps the specific of the three herbs may even date back to the materia mcdica of an- tiquity. Dioscorides recommends rpiqwXXov: it is, he states, good for the bite of venomous serpents. To determine this celebrated three- leaved plant exactly would not be easy. Is it 148 The Stinging Power a common clover? The psoralea, with its pitchy odour? The menyanthes, or uck-bean, that inmate of the chilly peat-bogs? The oxalis, the wood-sorrel of the country-side? We cannot tell for certain. The botany of those days was innocent of the descriptive conscientiousness of ours. The plant which acted as a poison-antidote grouped its leaves by threes. That is its essential characteristic. Again the cabalistic number, essential tcr medical virtues as conceived by the first heal- ers. The peasant, a tenacious conservative, has preserved the ancient remedy, but, by a happy inspiration, has changed the three original leaves into three different herbs; he has elaborated the r/oe'^r'AAor into the three- fold foliage which he crushes on the Bee's sting. I seem to perceive a certain relation between these artless wr.ys and the crushing of parsley as described by Reaumur, 149 CHAPTER VII THE ARBUTUS CATERPILLAR 1HAVE not found many species of urtica- ting caterpillars in the small corner of my investigations. I know of two only: the Pine Caterpillar and the Arbutus Caterpillar. The latter belongs to the genus Liparis. His Moth, who is a glorious snowy white, with the last rings of the abdomen bright russet, is very like Liparis auriftua, FAB., from whom she differs not only in size — she is smaller — but, above all, in the field of operations se- lected by her caterpillar. Is the species class- ified in our lists? I do not know; and really it is hardly worth while to enquire. What does a Latin name matter, when one cannot mistake the insect? I shall be sparing of de- tail concerning the Arbutus Caterpillar, for he is far less interesting in his habits than the Pine Processionary. Only his ravages and his poison deserve serious attention. On the Serignan hills, sunny heights upon which the Mediterranean vegetation comes to an end, the arbutus, or strawberry-tree, 150 The Arbutus Caterpillar abounds : a magnificent shrub, with lustrous evergreen foliage, vermilion fruit, round and fleshy as strawberries, and hanging clusters of little white bells resembling those of the lily of the valley. When the frosts come at the approach of December, nothing could be more charming than the arbutus, decking its gay verdure with both fruits and flowers, with coral balls and plump little bells. Alone of our flora, it combines the flowering of to-day with the ripening of yesterday. Then the bright-red raspberries — the dar- bouses, as we call them here — beloved by the Blackbird, grow soft and sweet to the palate. The housewives pluck them and make them into preserves that are not without merit. As for the shrub itself, when the season for cut- ting has come, it is not, despite its beauty, respected by the woodman. It serves, like any trivial brushwood, in the making of faggots for heating ovens. Frequently, too, the showy arbutus is ravaged by a caterpillar yet more to be dreaded than the woodcutter. After this glutton has been at it, it could not look more desolate had it been scorched and black- ened by fire. The Moth, a pretty little, snow-white Borru I5T The Life of the Caterpillar byx, with superb antennary plumes and a cot- ton-wool tippet on her thorax, lays her eggs on a leaf of the arbutus and, in so doing, starts the evil. You see a little cushion with pointed ends, rather less than an inch in length; a white eiderdown, tinged with russet, thick, very soft and formed of hairs fixed with a little gum by the end that points towards the upper ex- tremity of the leaf. The eggs are sunk in the thickness of this soft shelter. They pos- sess a metallic sheen and look like so many nickel granules. Hatching takes place in September. The first meals are made at the expense of the native leaf; the later ones at the expense of the leaves all around. One surface only is nibbled, usually the upper; the other remains intact, trellised by the network of veins, which are too horny for the new-born grubs. The consumption of leaves is effected with scrupulous economy. Instead of grazing at hazard and using up the pasturage at the dic- tates of individual caprice, the flock progresses gradually from the base to the tip of the leaf, with all heads ranged in a frontal attack, almost in a straight line. Not a bite is taken 152 The Arbutus Caterpillar beyond this line, until all that lies on this side of it is eaten up. As it advances, the flock throws a few threads across the denuded portion, where nothing remains but the veins and the epi- dermis of the opposite surface. Thus is woven a gossamer veil serving as a shelter from the fierce rays of the sun and as the parachute which is essential to these weak- lings, whom a puff of wind would carry away. As the result of a more rapid desiccation on the ravaged surface, the leaf soon begins to curl of its own accord, curving into a gondola which is covered by a continuous awning stretched from end to end. The herbage is then exhausted. The flock abandons it and begins again elsewhere in the near neighbour- hood. After various temporary pastures of this kind, in November, when the cold weather is at hand, the caterpillars settle permanently at the end of a bough. Nibbled one by one on their upper surfaces, the leaves of the terminal bunch draw close to their neighbours, which, excoriated in their turn, do the same, until the whole forms a bundle, which looks as if it had been scorched, lashed together with mag- J53 The Life of the Caterpillar nificent white silk. This is the winter habita- tion, whence the family, still very feeble, will not issue until the fine weather returns. The assembling of this leafy framework is not due to any special industry on the cater- pillars' part; they do not stretch their threads from leaf to leaf and then, by pulling at these ropes, bring the various pieces of the structure into contact. It is merely the result of des- iccation on the nibbled surfaces. Fixed cables, it is true, solidly bind together the leaves brought close to one another by the contrac- tion due to their aridity; but they do not in any way play the part of a motive mechanism in the work of the assemblage. No hauling-ropes are here, no capstans to move the timbers. The feeble creatures would be incapable of such effort. The thing hap- pens of itself. Sometimes a floating thread, the plaything of the air, enlaces some adjacent leaf. This chance footbridge tempts the ex- plorers, who hasten to strip the accidental prize; and, without other labour, yet one more leaf bends of its own accord and is added to the enclosure. For the most part, the house is built by eating; a lodging is procured by dint of banqueting. 154 The Arbutus Caterpillar A comfortable house, tightly closed and well-caulked, proof against rain and snow. We, to guard ourselves against draughts, put sand-bags against the cracks of our doors and windows; the extravagant little Arbutus Cat- erpillar applies pipings of silk-velvet to his shutters. Things should be cosy inside, how- ever damp the fog. In bad weather, the rain drips into my house. The leaf-dwelling knows nothing of such troubles, so true is it that animals often enjoy advantages which rele< gate human industry to the second rank. In this shelter of silk and foliage, the worst three or four months of the year are passed in a state of complete abstinence. No out- ings; not a bite of food. In March, this torpor ceases; and the recluses, those starving bellies, shift their quarters. The community now splits up into squads, which spread themselves anyhow over the ad- jacent verdure. This is the period of serious devastation. The caterpillars no longer con- fine themselves to nibbling one surface of the leaf; their keen appetites demand the whole of it, down to the stalk. And now, stage by stage, halt by halt, the arbutus is shorn bare. The vagabonds do not return to their win- 155 The Life of the Caterpillar ter dwelling, which has become too closely cramped. They reassemble in groups and weave, here, there and everywhere, shapeless tents, temporary huts, abandoned for others as the pasturage round about becomes ex- hausted. The denuded boughs, to all seem- ing ravaged by fire, take on the look of squalid drying-grounds hung with rags. In June, having acquired their full growth, the caterpillars leave the arbutus-tree, descend to earth and spin themselves, amid the dead leaves, a niggardly cocoon, in which the in- sect's hairs to some extent supplement its silk. A month later, the Bombyx appears. In his final dimensions, the caterpillar mea- sures nearly an inch and a quarter in length. His costume does not lack richness or origin- ality: a black skin with a double row of orange specks on the back; long grey hairs arranged in bunches; short, snow-white tufts on the sides; and a couple of brown-velvet protuberances on the first two rings of the ab- domen and also on the last ring but one. The most remarkable feature, however, consists of two tiny craters, always open wide : two cunningly fashioned goblets which might have been wrought from a drop of red seal- 156 The Arbutus Caterpillar ing-wax. The sixth and seventh segments of the abdomen are the only ones that bear these vermilion goblets, placed in the middle of the back. I do not know the function of these little cups. Perhaps they should be regarded as organs of information, similar to the Pine Processionary's dorsal mouths. The Arbutus Caterpillar is much dreaded in the village. Woodcutters, faggot-binders, brushwood-gatherers, all are unanimous in re- viling him. They have such a painfully vivid memory of the irritation that, when I listen to them, I can hardly repress a movement of the shoulders to relieve the imaginary itching in the middle of my back. I seem to feel the arbutus-faggot, laden with its glowing rags, rubbing my bare skin. It is, it appears, a disagreeable job to cut down the shrub alive with caterpillars during the hottest part of the day and to shake, under the blows of the axe, that sort of upas-tree, shedding poison in its shade. As for me, I have no complaint to make of my relations with the ravager of the arbutus. I have very often handled him; I have applied his fur to the tips of my fingers, my neck and even my face, for hours at a time; I have ripped up The Life of the Caterpillar '.he nests to extract their populations for the purpose of my researches; but I have never been inconvenienced. Save in exceptional cir- cumstances, the approach of the moult per- haps, this would need a skin less tough than mine. The thin skin of a child does not enjoy the same immunity, as witness little Paul, who, having helped me to empty some nests and to collect the inhabitants with my forceps, was for hours scratching his neck, which was dot- ted with red wheals. My ingenuous assistant was proud of his sufferings in the cause of science, which resulted from heedlessness and also perhaps from bravado. In twenty-four hours, the trouble disappeared, without leav- ing any serious consequences. All this hardly tallies with the painful ex- periences of which the woodcutters talk. Do they exaggerate? That is hardly credible; they are so unanimous. Then something must have been lacking in my experiments: the pro- pitious moment apparently, the proper degree of maturity in the caterpillar, the high tem- perature which aggravates the poison. To show itself in its full severity, the urtica- tion demands the cooperation of certain un- 158 The Arbutus Caterpillar defined circumstances; and this cooperation was wanting. Chance perhaps will one day teach me more than I want to know; I shall be attacked in the manner familiar to the woodcutters and shall pass a night in torment, tossing and turning as though on a bed of live coals. What the direct contact of the caterpillar did not teach me the artifices of chemistry will demonstrate with a violence which I was far from expecting. I treat the caterpillar with ether, just as I treated the slough of the Pine Processionary. The number of the creatures taken for the infusion — they are pretty small as yet, are scarcely half the size which they will attain when mature — is about a hundred. After a couple of days' maceration, I filter the liquid and leave it to evaporate freely. With the few drops that remain I soak a square of blotting-paper folded in four and apply it to the inner surface of my fore- arm, with a thin rubber sheet and a bandage. It is an exact repetition of what I did with the Pine Processionary. Applied in the morning, the blister hardly takes effect until the following night. Then by degrees the irritation becomes unendurable; 150 The Life of the Caterpillar and the burning sensation is so acute that I am tormented every moment with the desire to tear off the bandage. However, I hold out. but at the cost of a sleepless, feverish night. How well I now understand what the woodcutters tell me ! I had less than a square inch of skin subjected to the torture. What would it be if Ihad my back, shoulders, neck, face and arms tormented in this fashion? f pity you with all my heart, you labourers who are troubled by the hateful creature. On the morrow, the infernal paper is re- moved. The skin is red and swollen, co- vered with tiny pimples whence ooze drops of serous fluid. For five days the itching per- sists, with a sharp, burning pain, and the run- ning from the pimples continues. Then the dead skin dries and comes off in scabs. All is over, save the redness, which is still percep- tible a month later. The demonstration is accomplished; the Arbutus Caterpillar, capable as he^ is of pro- ducing, under certain conditions, the same ef- fects which I obtain by artificial means, fully deserves his odious reputation. 160 CHAPTER VIII AN INSECT VIRUS ONE step forward has been taken, but only a very little one as yet, in the problem of the stinging caterpillars. The drenching with ether teaches us that hairiness plays a very secondary part in the matter. With its dust of broken bristles, which the least breath wafts in all directions, it bothers us by depo- siting and fixing its irritant coating upon us; but this virus does not originate in the crea- ture's fleece; it comes from elsewhere. What is the source of it? I will enter into a few details. Perhaps, in so doing, I shall be of service to the novice. The subject, which is very simple and sharply defined, will show us how one question gives rise to another; how experimental tests con- firm or upset hypotheses, which are, as it were, a temporary scaffolding; and, lastly, how logic, that severe examiner, leads us by de- grees to generalities which are far more im- portant than anything that we were led to anticipate at the outset. 161 The Life of the Caterpillar And, first of all, does the Pine Procession- ary possess a special glandular structure which elaborates the virus, as do, for in- stance, the poison-glands of the Wasps and Bees? By no means. Anatomy shows that the internal structure of the stinging cater- pillar is similar to that of the harmless one. There is nothing more and nothing less. The poisonous product, of unlocalized ori- gin, results, therefore, from a general process in which the entire organism is brought into play. It should, in consequence, be found in the blood, after the manner of urea in higher animals. This is a suggestion of grave im- port, but after all quite valueless without the conclusive verdict of actual experiment. Five or six Processionaries, pricked with the point of a needle, furnish me with a few drops of blood. I allow these to soak into a small square of blotting-paper, which I then apply to my fore-arm with a waterproof bandage. It is not without a certain anxiety that I await the outcome of the experiment. The result will show whether the conclusions already forming in my mind will receive a solid basis or vanish into thin air. At a late hour of the night, the pain wakes 162 An Insect Virus me, a pain which this time is an intellectual joy. My anticipations were correct. The blood does indeed contain the venomous sub- stance. It causes itching, swelling, a burning sensation, an exudation of serum and, lastly, a shedding of the skin. I learn more than I had hoped to learn. The test is more valuable than that of mere contact with the caterpillar could have been. Instead of treating myself with the small quantity of poison with which the hairs are smeared, I have gone to the source of the irritant substance and I thereby gain an increase of discomfort. Very happy in my suffering, which sets me on a safe path, I continue my enquiry by argu- ing thus: the virus in the blood cannot be a living substance, one that takes part in the working of the organism; it is rather, like urea, a form of decay, an offthrow of the vital process, a waste product which is expelled as and when it forms. If this be the case, I ought to find it in the caterpillar's droppings, which are made up of both the digestive and the urinary residues. Let us describe the new experiment, which is no less positive than the last. I leave a few pinches of very dry droppings, such as are 163 The Life of the Caterpillar found in abundance in the old nests, to soak for two days in sulphuric ether. The liquid, coloured as it is with the chlorophyll of the caterpillar's food, turns a dirty green. Then I repeat precisely the process which I men- tioned when I wanted to prove the innocuous- ness of the hairs deprived of their poisonous varnish. I refer to it a second time in order thoroughly to explain the method pursued and to save repetition in the various experiments undertaken. The infusion is filtered, spontaneously eva- porated and reduced to a few drops, with which I soak my stinger. This consists of a small piece of blotting-paper, folded in four to increase the thickness of the pad and to give it a greater power of absorption. An area of a square inch or less suffices; in some cases it is even too much. A novice in this kind of research-work, I was too lavish with the liniment; and in return for my generosity I had such a bad time that I make a point of warning any reader desirous of repeating the experiment upon his own person. Fully soaked, the square of paper is applied to the fore-arm, on the inner surface, where the skin is more tender. A sheet of rubber 164 An Insect Virus covers it and, being waterproof, guards against the loss of the poison. Finally, a linen bandage keeps the whole in place. On the afternoon of the 4th of June 1897, a memorable date for me, I test, as I have just said, the etheric extract of the Procession- ary's droppings. All night long, I feel a vio- lent itching, a burning sensation and shooting pains. On the following day, after twenty hours of contact, I remove the dressing. The venomous liquid, too lavishly employed in my fear of failure, has considerably over- flowed the limits of the square of paper. The parts which it has touched and still more the portion covered by the pad are swollen and very red; moreover, in the latter case, the skin is ridged, wrinkled and mortified. It smarts a little and itches; and that is all. On the following day, the swelling becomes more pronounced and goes deep into the mus- cles, which, when touched with the finger, throb like an inflamed cheek. The colour is a bright carmine and extends all round the spot which the paper covered. This is due to the escape of some of the liquid. There is a plentiful discharge of serum, oozing from the sore in tiny drops. The smarting and itching The Life of the Caterpillar increase and become so intense, especially du- ring the night, that, to get a little sleep, I am driven to employ a palliative, vaseline with borax and a lint dressing. In five days' time, it has developed into a hideous ulcer, which looks more painful than it really is. The red, swollen flesh, quivering and denuded of its epidermis, provokes com- miseration. The person who night and morn- ing renews my dressing of lint and vaseline is almost sick at the sight. "One would think," she says, "that the dogs had been gnawing your arm. I do hope you won't try any more of those horrible de- coctions." I allow my sympathetic nurse to talk away and am already meditating further experi- ments, some of which will be equally painful. 0 sacred truth, what can rival thy power over us mortals ! Thou turnest my petty torment into contentment; thou makest me rejoice in my flayed arm! What shall I gain by it all? 1 shall know why a wretched caterpillar sets us scratching ourselves. Nothing more; and that is enough for me. Three weeks later, new skin is forming, but is covered all over with painful little pimples. 166 An Insect Virus The swelling diminishes; the redness persists and is still very marked. The effect of the infernal paper lasts a long time. At the end of a month, I still feel an itching, a burning irritation, which is intensified by the warmth of the bed-clothes. At last, a fortnight later, all has disappeared but the redness, of which I shall retain the marks for a long time yet, though it grows gradually fainter and fainter, It will take three months or more to vanish altogether. We now have some light on the problem : the Processionary's virus is certainly an off- throw of the organic factory, a waste product of the living edifice. The caterpillar discards it with his excrement. But the material of the droppings has a twofold origin : the greater part represents the digestive residuum; the rest, in a much smaller proportion, is com- posed of the urinary products. To which of the two does the virus belong? Before going farther, let us permit ourselves a digression which will assist us in our subsequent en- quiries. Let us ask what advantages the Pro- cessionary derives from his urticating product. I already hear the answer: "It is a means of protection, of defence. 167 i he Lite of the Caterpillar With his poisoned mane, he repels ih& enemy." I do not clearly perceive the bearing of this explanation. I think of the creature's recog- nized enemies: of the larva of Calosoma sycophanta, which lives in the nests of the Processionary of the Oak and gobbles up the inhabitants with never a thought of their burn- ing fleece; of the Cuckoo, another mighty con- sumer, so we are told, of the same caterpillars, who gorges on them to the point of implant- ing in his gizzard a bristling coat of their hairs. I am not aware if the Processionary of the Pine pays a like tribute. I do know of at least one of his exploiters. This is a Dermestes,1 who establishes himself in the silken city and feeds upon the remains of the defunct caterpillars. This ghoul assures us of the existence of other consumers, all fur- nished with stomachs expressly fashioned for such highly-seasoned fare. For every har- vest of living creatures there is always a har- vester. No, the theory of a special virus, expressly prepared to defend the Processionary and his JA Bacon-beetle. — Translator's Note. 168 An Insect Virus emulators in urtication, is not the last word on the subject. I should find it difficult to believe in such a prerogative. Why have these cater- pillars, more than others, need of protection? What reasons would make of them a caste apart, endowed with an exceptional defensive venom ? The part which they play in the en- tomological world does not differ from that of other caterpillars, hairy or smooth. It is the naked caterpillars who, in default of a mane capable of striking awe into the assailant, ought, one would think, to arm themselves against danger and impregnate themselves with corrosives, instead of remaining a meek and easy prey. Is it likely that the shaggy, bristling caterpillar should anoint his fleece with a formidable cosmetic and his smooth- coated kinsman be unfamiliar with the che- mical properties of the poison beneath his satin skin ! These contradictions do not in- spire confidence. Have we not here, rather, a property com- mon to all caterpillars, smooth-skinned or hairy? Among the latter, there might be some, just a few, who, under certain special conditions which will need to be defined, would be quick to reveal by urtication the 169 The Life of the Caterpillar venomous nature of their organic refuse; the others, the vast majority, living outside these conditions, even though endowed with the necessary product, would be inexpert at the stinging business and would not produce irritation by contact. In all, the same virus is to be found, resulting from an identical vital process. Sometimes it is brought into promin- ence by the itching which it produces; some- times, indeed most often, it remains latent, unrecognized, if our artifices do not intervene. What shall these artifices be? Something very simple. I address myself to the Silk- worm. If there be an inoffensive caterpillar in the world, it is certainly he. Women and children take him up by the handful in our .Silkworm-nurseries; and their delicate fingers are none the worse for it. The satin-skinned caterpillar is perfectly innocuous to a skin al- most as tender as his own. But this lack of caustic venom is only ap- parent. I treat with ether the excretions of the Silkworm; and the infusion, concentrated into a few drops, is tested according to the usual method. The result is wonderfully de- finite. A smarting sore on the arm, similar in its mode of appearance and in its effects to 170 An Insect Virus that produced by the droppings of the Proces- sionary, assures me that logic was right. Yes, the virus which makes one scratch so much, which blisters and eats away the skin, is not a defensive product vested in only a few caterpillars. I recognize it, with its invariable properties, even in a caterpillar which at first sight appears as though it could not possess anything of the kind. The Silkworm's virus, besides, is not un- known in my village. The casual observation of the peasant-woman has outstripped the precise observation of the man of science. The women and girls entrusted with the rearing of the Silkworm — the magnanarelles as they are called — complain of certain tribulations caused, they say, by lou verm di magnan, the Silkworms' poison. This trouble consists of a violent itching of the eyelids, which become red and swollen. In the case of the more susceptible, there is a rash and the skin peels off the fore-arm, which the turned-up sleeves fail to protect during work. I now know the cause of this little trouble, my plucky magnanarelles. It is not contact with the worm that afflicts you ; you need have no fear of handling him. It is only the litter The Life of the Caterpillar that you need distrust. There, jumbled up with the remains of the mulberry-leaves, is a copious mass of droppings, impregnated with the substance which has just so painfully eaten into my skin ; there and there only is lou verin, as you call it. It is a relief merely to know the cause of one's trouble; but I will provide you with an- other consolation. When you remove the lit- ter and renew the leaves, you should raise the irritant dust as little as possible; you should avoid lifting your hands to your face, above all to your eyes; and it is just as well to turn down your sleeves in order to protect your arms. If you take these precautions, you will suffer no unpleasantness. The successful result obtained with the Silk- worm caused me to foresee a similar success with any caterpillar that I might come across. The facts fully confirmed my expectations. I tested the stercoral pellets of various cater- pillars, not selected, but just as the hazard of collecting provided them : the Great Tortoise- shell, the Heath Fritillary, the Large Cab- bage Butterfly, the Spurge Hawk-moth, the Great Peacock Moth, the Death's-head Moth, the Puss-moth, the Tiger-moth and the Arbu- An Insect Virus tus Liparis. All my tests, with not a single exception, brought about stinging, of various degrees of violence, it is true. I attribute these differences in the result to the greater or lesser quantities of the virus employed, for it is impossible to measure the dose. So the indicating excretion is common to all the caterpillars. By a very unexpected rever- sion of the usual order of things, the popular repugnance is well-founded; prejudice be- rnmes frijifl}! all rflffri'llarq arp We must draw a distinction, however: with the same venomous properties, some are inof- fensive and others, far less numerous, are to- be feared. Whence comes this difference? I note that the caterpillars marked out as stinging live in communities and weave them- selves dwellings of silk, in which they stay for long periods. Moreover, they are furry. Of this number are the Pine Processionary, the Oak Processionary and the caterpillars of various Lipares. Let us consider the first-named in parti- cular. His nest, a voluminous bag spun at the tip of a branch, is magnificent in its silky whiteness, on the outside; inside, it is a dis- gusting cesspit. The colony remains in it all The Life of the Caterpillar day and for the greater part of the night. It sallies forth in procession only in the late hours of twilight, to browse upon the adjacent foliage. This long internment leads to a con- siderable accumulation of droppings in the heart of the dwelling. From all the threads of this labyrinth hang chaplets of these droppings; the walls are upholstered with them in all the corridors; the little narrow chambers are encumbered with them. From a nest the size of a man's head I have obtained, with a sieve, over three-quarters of a pint of stercoral pellets. Now it is in the midst of this ordure that the caterpillars live and have their being; in the midst of it they move, swarm and sleep. The results of this utter contempt for the rules of cleanliness are obvious. Certainly, the Processionary does not soil his coat by contact with those dry pellets; he leaves his home with his costume neat and glossy, sug- gesting not a suspicion of uncleanliness. No matter: by constantly rubbing against the droppings, his bristles are inevitably smeared with virus and their barbs poisoned. The caterpillar becomes irritant, because his man- 174 An Insect Virus ner of life subjects him to prolonged contact with his own ordure. . Now consider the Hedgehog Caterpillar. ~"_ imleifl, de"!JplLB Ills herce and hirsute aspect? Because he lives in isolation " and is always on the move. His mane, apt FtTough it be to collect and retain irritant part- ^icles. will never give us the itch, for the simple reason that the caterpillar does not lie JX^jMp^&crfQpn^ Distributeaallover trie fields andfaf from numerous, owing to the caterpillar's solitary habits, the droppings, though poisonous, cannot transfer their pro- perties to a fleece which does not come into contact with them. If the Hedgehog lived in a community, in a nest serving as a cess- pit, he would be the foremost of our stinging caterpillars. At first sight, the barrack-rooms of the Silkworm-nurseries seem to fulfil the condi- tions necessary to the surface venom of the worms. Each change of litter results in the removal of basketfuls of droppings from the trays. Over this heaped-up ordure the Silk- worms swarm. How is it that they do not acquire the poisonous properties of their own excrement ? 175 The Life of the Caterpillar I see two reasons. In the first place, they are hairless; and a brusjilike coat may well be indispensable to the collection of the virus. In the second place, far from lying in the tilth, they live above the soiled stratum, being largely separated from it by the bed of leaves, which is renewed several times a day. Despite crowding, the population of a tray has no- thing that can be compared with the ordinary habits of the Processionary ; and so it remains harmless, in spite of its stercoral toxin. These first enquiries lead us to conclusions which themselves are very remarkable. All caterpillars excrete an urticating matter, which is identical throughout the series. But, if the poison is to manifest itself and to cause us that characteristic itching, it is indispensa- ble that the caterpillar shall dwell in a com- munity, spending long periods in the nest, a silken bag laden with droppings. These fur- nish the virus; the caterpillar's hairs collect it and transfer it to us. The time has come to tackle the problem from another point of view. Is this for- midalle matter which always accompanies the excretions a digestive residuum? Is it not rather one of those waste substances which 176 An Insect Virus the organism engenders while at work, waste substances designated by the general appel- lation of urinary products? To isolate these products, to collect them separately, would scarcely be practicable, if we did not have recourse to what follows on the metamorphosis. Every Moth, on emer- ging from her chrysalis, rejects a copious mixture of uric acid and various humours of which very little is as yet known. It may be compared with the broken plaster of a building rebuilt on a new plan and represents the by-products of the mighty labours accom- plished in the transfigured insect. These re- mains are essentially urinary products, with no admixture of digested foodstuffs. To what insect shall I apply for this re- siduum ? Chance does many things. I col- lect, from the old elm-tree in the garden, about a hundred curious caterpillars. They have seven rows of prickles of an amber yel- low, a sort of bush with four or five branches. I shall learn from the Butterfly that they be- long to the Great Tortoiseshell (Vanessa polychloros, LIN.). Reared on elm-leaves under a wire-gauze cover, my caterpillars undergo their trans- The Life of the Caterpillar formation towards the end of May. Their chrysalids are specked with brown on a whitish ground and display on the under sur- face six radiant silvery spots, a sort of decora- tive -tinsel, like so many mirrors. Fixed by the tail with a silken pad, they hang from the top of the dome, swinging at the least move- ment and emitting vivid flashes of light from their reflectors. My children are amazed at this living chandelier. It is a treat for them when I allow them to come and admire it in my animal studio. Another surprise awaits them, this time a tragic one, however. A fortnight later, the Butterflies emerge. I have placed under the cover a large sheet of white paper, which will receive the desired products. I call the child- ren. What do they see on the paper? Large spots of blood. Under their very eyes, from up there, at the top of the dome, a butterfly lets fall a great red drop : plop ! No joy for the children to-day; anxiety rather, almost fear. I send them away, saying to them : "Be sure and remember, kiddies, what you have just seen; and, if ever any one talks to you about showers of blood, don't be silly and 178 An Insect Virus frightened. A pretty Butterfly is the cause of those blood-red stains, which have been known to terrify country-folk. The moment she is born, she casts out, in the form of a red liquid, the remains of her old caterpillar body, a body remodelled and reborn in a beautiful shape. That is the whole secret." When my artless visitors have departed, I resume my examination of the rain of blood falling under the rover. Still clinging to the shell of its chrysalis, each Tortoiseshell ejects and sheds upon the paper a great red drop, which, if left standing, deposits a powdery pink sediment, composed of urates. The liquid is now a deep crimson. When the whole thing is perfectly dry, I cut out of the spotted paper some of the richer stains and steep the bits in ether. The spots on the paper remain as red as at the outset; and the liquid assumes a light lemon tint. When reduced by evaporation to a few drops, this liquid provides me with what I require to soak my square of blotting-paper. What shall I say to avoid repeating my- self? The effects of the new caustic are pre- cisely the same as those which I experienced when I used the droppings of the Proces- 179 The Life of the Caterpillar sionary. The same itching, the same burning, the same swelling with the flesh throbbing and inflamed, the same serous exudation, the same peeling of the skin, the same persistent redness, which lingers for three or four months, long after the ulceration itself has disappeared. Without being very painful, the sore is so irksome and above all looks so ugly that 1 swear never to let myself in for it again. Henceforth, without waiting for the thing to eat into my flesh, I shall remove the cater- pillar plaster as soon as I feel a conclusive itching. In the course of these painful experiences, friends upbraid me with not having recourse to the assistance of some animal, such as the Guinea-pig, that stock victim of the physiolo- gists. I take no note of their reproaches. The animal is a stoic. It says nothing of its sufferings. If, the torture being a little too intense, it complains, I am in no position to interpret its cries exactly or to attribute them to a definite impression. The Guinea-pig will not say: "It smarts, it itches, it burns." He will simply say: 180 An Insect Virus "That hurts." As I want to know the details of the sensa- tions experienced, the best thing is to resort to my own skin, the only witness on whose evi- dence I can rely implicitly. At the risk of provoking a smile, I will venture on another confession. As I begin to see into the matter more clearly, I hesitate to torture or destroy a single creature in God's great community. The life of the least of these is a thing to be respected. We can take it away, but we cannot give it. Peace to those innocents, so little interested in our investigations! What does our restless curiosity matter to their calm and sacred ignorance? If we wish to know, let us pay the price ourselves as far as possible. The acquisition of an idea is well worth the sacrifice of a bit of skin. The Elm Tortoiseshell, with her rain of blood, may leave us to a certain extent in doubt. Might not this strange red substance, with its unusual appearance, contain a poison which is likewise exceptional? I address my- self therefore to the Mulberry Bombyx, to the Pine Bombyx and to the Great Peacock. The Life of the Caterpillar I collect the uric excretions ejected by the newly hatched Moths. This time, the liquid is whitish, sullied here and there with uncertain tints. There is no blood-red colouration ; but the result is the same. The virulent energy manifests itself in the most definite manner. Therefore the Pn> cessionary's virus exists equally in all cater- jTHTars, in all Butterflies and Moths emerging frornthe chrysalis; and this virus'Tr'aTy^ product of the organism, a urinary product. The curiosity ot our minds Is Insatiable. The moment a reply is obtained, a fresh quest- ion arises. Why should the Lepidoptera alone be endowed in this manner? The or- ganic labours accomplished within them can- not differ greatly, as to the nature of the materials, from those presiding over the maintenance of life in other insects. There- fore these others also elaborate a by-product which has stinging powers. This can be veri- fied— and that forthwith — with the elements at my disposal. The first reply is furnished by Cetonia floricola, of which Beetle I collect half a dozen chrysalids from a heap of leaves half- converted into mould. A box receives my An Insect Virus find, laid on a sheet of white paper, on which the urinary fluid of the perfect insect will fall as soon as the caskets are broken. The weather is favourable and I have not long to wait. The thing is done: the mat- ter rejected is white, the usual colour of these residua, in the great majority of insects, at the moment of the metamorphosis. Though by no means abundant, it nevertheless provokes on my fore-arm a violent itching, together with mortification of the skin, which comes off in flakes. The reason why it does not dis- play a more distinct sore is that I judged it prudent to end the experiment. The burning and itching tell me enough as to the results of a contact unduly prolonged. Now to the Hymenoptera. I have not in my possession, I regret to say, any of those with whom my rearing-chambers used for- merly to provide me, whether Honey-bee or Hunting Wasps. I have only a Green Saw- fly, whose larva lives in numerous families on the leaves of the alder. Reared under cover, this larva provides me with enough tiny black droppings to fill a thimble. That is sufficient : the urtication is quite definite. I take next the insects with incomplete The Life of the Caterpillar transformations. My recent rearings have given me quite a collection of excretions ema- nating from the Orthoptera. I consult those of the Vine Ephippiger1 and the Great Grey Locust. Both sting to a degree which once more makes me regret my lavish hand. We will be satisfied with this; indeed my arms demand as much, for, tattooed with red squares, they refuse to make room for fresh brandings. The examples are sufficiently varied to impose the following conclusion : the stT" virusisfound in a