Volume 7 — Translated From Etudes Religieuses, Etc., Par Des Peres De La Compagnie De Jesus. The Flight Of Spiders. A Paper Read Before The French Academy Of Science, March, 1867.

About fifteen years ago, I was sitting in an arbor of my garden, reading, when a little spider fell on my book, whence I could not tell, and commenced to run over the very line I was reading. I blew hard to chase him away, but he would not go. He lifted himself strangely up, and I cannot explain how, but he lodged on a sprig of verdure just above my head. "Well," said I, "for a little animal like that, this is a wonderful feat! How has he accomplished it?" To satisfy myself, I took him up again, balanced him on my book, and, after assuring myself that he had no invisible thread to aid him, I blew again, and again the little fellow did the very same thing. With redoubled curiosity, I tried him once more, and, to see better, I sat down in the bright sunlight. Again I balanced him on the book, looked at him as closely as possible, and, when I felt assured no precaution could have escaped me, I blew once more. ... Resuming the same inclined position, the spider as quick as lightning darted the finest possible thread out of him, raised himself in the air, and disappeared.

I confess I was stupefied. Never had I imagined these little animals could fly without wings; so I consulted several works on zoology, but I was astonished to find there was no mention made of the flight of spiders, nor of the ejaculatory movement of which I had witnessed so curious an example. [Footnote 96]

So there was a new question presented to me, and my vocation to study the habits of these little animals—which hitherto had given me no concern—decided for me. I immediately lost all repugnance, all distaste, and threw away all the unjust precautions of which the spider is too often the object, and of which I was as culpable as any one else. And from that time I welcomed its appearance; was most happy to meet with it, looked for it, indeed, and studied its habits almost with furor. And I can say that, thanks to this hearty preoccupation, which never left me, I found every opportunity to follow my inclination, and knew where to find spiders in all sorts of unheard-of places.

Such are the singular effects of curiosity once excited, and still another proof that, in order to study nature well, we need only a mysterious glimpse of the unknown to redouble all our energies to explain it thoroughly.

And as in this study, trifling as it may appear, I seem to have met with facts not known hitherto, but which deserve to be understood, I here resume the principal ones: those that treat of the flying of spiders; of the habitation of some species in the air; and of the gossamer or air threads—a singular phenomenon, for a long time discussed in vain, but which I believe I have definitively solved. I only ask the naturalists to judge one fairly, not by theory, but by facts. And I am persuaded, if they will take the pains to verify what I advance, they will find me exact; and, if they begin doubtingly, I hope, after they have read my observations, they will conclude as others to whom I have communicated them. Mocking and incredulous at first, they have ended by believing their own eyes, and testifying to the evidence presented to them. May my labor prove useful, and, above all, contribute to the glory of the great God, whose just title is, Magnus in magnis, maximus in minimis.

I. Threads Thrown Out By Spiders.

The first thing that I perceived, and that put me on the track of the rest, was, as I have just said, that the greater part of aranéides, especially certain varieties of thomises lycoses, etc., besides the thread that they always draw with them, have the power of darting one or more of extraordinary length, and of which they make use to accomplish distances, to fasten their webs from one point to another, and even, as we shall see further on, to raise themselves in the air and there to seek their prey. The spider always points his abdomen to the side where he wishes to go. The thread shoots like an arrow, fastens itself by the end to the place destined, and the spider passes as under a suspended bridge. If this thread is cut, it is immediately replaced by another; and the ejaculation is so prompt, so rapid, the thread so straight, so tenuous, so brilliant, that it might be taken, if I may so express myself, for the jet of an imperceptible ray of light. To perceive this clearly, the spider must be held on a level with the eyes, which should be shaded, and examined with one's back to the sun.

The best time for such an observation is in the morning or evening, when the sun is low in the horizon and the temperature is mild; for without this latter condition the torpid spider is more inclined to creep along the earth than to throw out new threads.

Sometimes, to excite them, they may be held by their ordinary thread and gently shaken or blown upon—just a few puffs of breath—which they detest.

I have thus been able to scan closely, while watching their development, this instantaneous jet of thread, which could not be less than five or six yards long, that is, fifteen hundred or two thousand times the length of the spider. What a tremendous apparatus must be necessary to these little animals for so rapid an ejaculation, and one so disproportioned to their size! And especially if we consider that this thread, inasmuch as it adheres to the animal, has not the appearance of an independent organ, but seems solely to obey its will. Thus I have seen spiders, who seemed to miss the end desired with the first stroke, continue to hold the thread in the same direction, and actually palpitate, if I may so say, while striving to make it adhere.

But a truly interesting sight, and one obtained at a very trifling expense, is that which the thomises bufo offer, described by Walckenaer, in the first volume of his History of Insects, page 506. In truth, these araneides do not only throw out one thread, but an entire bundle of them, and are seemingly guided by the smaller threads, just as a peacock unfolds by degrees his splendid plumage.

And even in one's own room this sight may be enjoyed. It is only necessary to collect these thomises and keep them in separate boxes, and nourish them in winter with one fly or so a month. Then take the boxes out, put them on a table in a very warm room, and sit a little in the shade and watch them. Very soon from each box will appear a multitude of threads, of extreme freshness and fineness, which the spider throws into the air with inexhaustible profusion. At certain seasons of the year we can enjoy this spectacle again, and at even less expense.

II. Flight Of Spiders.

Another property not less remarkable that these araneides possess (thomises bufo, lycoces voraces, etc.) is that of flying; that is to say, of elevating themselves in the air, there sustaining themselves, and travelling about horizontally and vertically, with or without a thread; in a word, acting exactly as if in their own element. This fact I have witnessed a thousand times, and it has been certified to by a great number of people, who, at first incredulous, and alarmed for the laws of gravitation, were compelled to confess the reiterated testimony of their own eyes.

I had some pupils under my charge, and to them this study became a continued source of amusement. During their recreation, they found suitable spiders for me, and, when they brought them to me, I rested them on my fingers and made them mount upward in the air; and invariably, after having watched them for some moments, they were entirely lost to sight. But when I made the discovery—of which I will speak later—of the general migration which some species make yearly toward certain regions of the atmosphere, I had no longer any trouble to enjoy this performance to my heart's content.

The flight of spiders is sometimes very rapid, particularly when they start. They often escape from one's hands while they are carefully watched. This happened to me one day with a voracious lycose that I had for a long time importuned without success. Just as I was going to give him up as entirely stupefied, he suddenly escaped from me by a lateral movement, so rapid that for a moment I lost sight of him; but, when I found him a moment afterward, he was suspended quietly in the air. I also remarked that he set out without throwing any thread, and this was not the only time I made the same observation. I was experimenting one day with some amateurs in the interior court of the college where I live, and, having started a lycose, we saw him occupy himself at first with the neighboring galleries, running up and down for about twenty yards, about a tenth of a yard from the arch, against which he knocked himself from time to time, and groped about to look for a passage; not finding one, he threw himself back into the court, raised perpendicularly, and disappeared toward the clouds. His thread, if he had one, could not have been longer than a tenth of a yard. Ordinarily, however, before they ascend, they throw out a thread which they follow for a short time; then, arriving at a certain height, they break it, in order to navigate more easily. If any is left before them, they wind it rapidly with their feet, throw it aside, and form those pretty little crowns of white silk in form of cracknels, that we often see flying in the air in time of gossamers. Again, they balance themselves quietly with a thread which rises perpendicularly above them, and gives them the appearance of floating.

But a peculiarity still more remarkable in the flight of spiders is the attitude that they take in flying. They generally swim backward, that is to say, the back turned from the earth, the feet folded on the corselet, and perfectly immovable. How can such a flight be explained, for they are already heavier than the air? Plunged into alcohol, they sink quickly; but in the air they seem to possess an ease, a liberty, a facility of transport, so admirable that I have never been able to see in them the slightest motion, nor even an apparent increase of weight. Does not this fact present an interesting question for the skilful to contemplate?

III. How Long They Can Remain In The Atmosphere?

At this portion of my history I have to relate facts the most curious and unexpected; and, unfortunately for me, more true than probable. I acknowledge I was loath to publish them, or assume concerning them any responsibility. But I was firmly convinced, and therefore hoped to be believed, especially by this generation of fearless naturalists, who are astonished at nothing in nature, and who, having often been surprised in the relation of almost incredible marvels, must certainly make allowances for a few more in another quarter.

Let us look at, for instance, the wonderful things related of the argyronete, or aquatic spider. [Footnote 97]

I could not tell anything more unlikely, so I will only exact for the atmosphere a companion to what the Père de Lignac discovered in the last century for the water. Yes, I pretend there are spiders that live in the air as well as those living in water, and that every year, from the earliest days of spring, there is, unknown to us, a general migration of spiders toward the atmosphere, where they pass their best season, form their nets, chase their prey, and only return to earth in the first fogs of autumn to find their quarters for the winter. I add, also, that this ascent and descent give rise to the curious phenomenon, still so badly explained, of the gossamer. And as it was to the study of this phenomenon that I owe my knowledge of the rest, may I be permitted here, by way of demonstration, to relate briefly the path I have followed and the proofs which have led to the conviction I express?

Attracted, as I was, by all that concerns spiders, I could not remain indifferent to a fact so important and interesting as the periodical apparition of those threads which in spring and autumn we see flying about in long white skeins, clinging to trees, to hedges, and to the vestments of the passers-by, carpeting the country in a few hours with more silk, and finer and whiter, than could be spun in a year by all the reels in the world. Admirable netting, glistening in the light of the setting sun, and reflecting the sweetest, softest tints of gold, vermilion, and emerald, and receiving the pretty and poetical name of "fils de la Vierge." Was there not between this phenomenon and my preceding observations a secret tie, some mysterious relation? I seemed to foresee it, and, setting to work immediately, rejected from the very beginning the usual explanation of this phenomenon.

How, indeed, can we admit these floating gossamers as merely the refuge webs of spiders, torn by the violence of the wind from the trees and forests and carried capriciously through the air? Will not the slightest observation convince us that they never appear but in the calmest moments, on days foggy in the morning, but afterward beautiful, and not preceding a storm; never in summer, often in the spring and autumn, and sometimes even in winter? If the winds carry them, why do they not appear in summer? Are violent winds and spider-webs both wanting? And who has ever seen one of these webs carried by a hurricane, especially in quantity sufficient to produce such a phenomenon? For the fall of gossamers sometimes lasts for almost entire days, and in certain countries during the middle of the day the fields are covered with them. Add, too, that violent winds are generally local, while this phenomenon is universal, and so periodical that in the same climates it appears at the same epochs, and, when one knows what produces it, it is easy to predict the time and day of the apparition.

Discontented, then, on this point with books and their explanations, I turn completely to the side of nature, and present all I observed.

From the first appearance of these threads in autumn, I was struck with the immense multitudes of new spiders met with everywhere, and which I had not seen during the summer. Little brown lycoses filled the air, so that it seemed as if it had rained them. If one walked in the fields, the meadows, the gardens, on the borders of the woods, among heaps of dried leaves, scattered all through the forest everywhere, could be seen myriads of these little brown spiders, jumping up and flying before me in every direction, and exactly such as I had already recognized as such excellent swimmers. After having passed the winter in the earth, in the holes of worms that they completed with a little silk, they reappeared after the cold in great numbers, to disappear again entirely in the first bright days of spring, and as if by enchantment. If one is seen again during the summer, we may be sure it is some female retarded by laying her eggs, and dragging laboriously her cocoon after her. Now, what has become of the others?

For several months I could not satisfy myself on this point, when, on the 21 St of October, 1856, in the enclosure of the little seminary of Iseure, near Moulins, I came to a positive decision, I was observing the fall of a large quantity of gossamers, which were falling on that day in large white flakes, when I perceived close to me in the air one of those little black spiders descending gradually, and as if she were jumping. She held by an invisible thread to a large flake, which came down slowly about seven or eight yards above her; but, keeping outside of it, she hung by the end of the long thread, like an aeronaut underneath his balloon. My attention once attracted, I noticed so great a number that I was astonished I had not taken care sooner; for there was scarcely a flake underneath which there were not one or two, and this sometimes even before the flake itself was visible. [Footnote 98]

Each one was separated by a slender thread, and followed the motion of its balloon. If they met a tree or a bush, they landed upon it; if not, coming close to the earth, they ran along and were lost in the verdure. If I approached them too quickly or made a noise, they remounted rapidly by their threads and went to disembark somewhere else.

I also examined some of the flakes. They were all shining white mats, appearing as if they had been washed. Several contained wings and feet of flies, fragments of the case of little coleoptera, and other remnants of their aerial festivities.

This encounter was for me a revelation. I knew where the spiders, whom I had seen disappear so brusquely, took refuge, and, however rash my judgment may appear, I felt assured I had solved an interesting problem.

But to establish seriously and give to science an opinion so new and original as that the atmosphere may be peopled with spiders, I soon felt that more proof was necessary in order to sit down calmly under my personal conviction. So I concluded I should not be doing too much if I added to the verification of their descent that of their ascension, and could surprise them in this new migration. I waited, therefore, impatiently for the spring.

But that spring, and for five or six that followed it, great was my disappointment; for, though I perceived several isolated ascensions, yet nothing in the proportion I had imagined or that could justify my hypothesis. I began then to doubt seriously my success, when an incident occurred that relieved my embarrassment, and proved how trifling sometimes are the causes which lift the veil from nature. I was looking straight upward, but sitting close to the earth, and so as to be able as much as possible to exclude the sun from my eyes. And here, by the way, a fact is made palpable, by no means microscopic, but which has escaped so long not merely the observation of the crowd of vulgar observers, but of those even who are wide awake and study carefully; namely, that it is not necessary to carry one's nose always in the air, if I may so express myself, to examine closely, to investigate, or to render a faithful account of phenomena.

On looking upward—as an ascension only takes place on very beautiful days, succeeding generally to bad weather—spiders cannot be distinguished from the multitude of other insects which fill the air. But if, on a beautiful day, mild, calm, and brilliant in sunlight, succeeding as nearly as possible to a rain warm with the south wind, at about nine or ten o'clock in the morning, a post is chosen on an eminence of a meadow or an avenue, and there, as near the ground as may be, and crouching low, the observer will look horizontally, he will perceive a series of fire-works, formed of innumerable threads launched from every direction and inclined toward the sky. This is the prelude. Soon the spiders detach themselves and mount slowly by their threads. The most conspicuous are the thomises bufo, because they are the largest, and because they only ascend with an entire bundle of threads, which gives them the appearance of small comets.

Thus have I decided

1st. That there is not only one ascension every year, but several, at least partial ones; that they do not always take place in spring, but often in the autumn, and sometimes even in the winter; and in general, from the descent which has taken place in the beginning of autumn until the definitive ascension in the spring, there are but few favorable days of which the spiders do not profit to make an aerial journey, or at least to throw out a large number of threads. Thus, in the Beaujolais, where I have lived for several years, there were partial ascensions on the 1st, the 19th, and the 28th of November, 1864; the 21st, the 23d, and especially the 25th of October, the 9th of November, and the 6th of December, 1865. In 1866, the 18th and the 30th of January, the 3d of February, the 3d, 14th, and 31st of October, and the 17th of December. In 1867, the 10th of February, ... the last, however, less considerable than might have been predicted by the beauty of the day. The day previous was so mild, though cloudy, that many of the spiders may have embarked incognito. Many, also, may not have judged it a propos to fly away, for a great number still remained on the ground. I forgot to observe the temperature of all the days I have noted. The director of the Normal School of Villefranche having had the kindness to show me the meteorological register which he had kept with great care, I was able to prove that in calm weather only ten or twelve degrees of heat were necessary to induce them to mount upward. The least exposed begin; then immediately the others, so soon as the heat reaches them; but after three or four o'clock in the afternoon no more ascensions are perceived, unless they are provoked; and this does not always succeed,

2d. Before taking their flight, they generally cling to some elevated object that they meet with easily, such as shrubs, bushes, props of vines, or blades of grass escaped from the scythe. To these they affix their threads and warm themselves well in the sun before commencing their excursion. This is the happy moment for amateurs to make their observations, for there is scarcely a blade of grass that does not contain one or more; and, if the branches of young trees are suddenly struck with a slight blow, a great number are detached, suspended at the end of their threads; and very often rare specimens are thus found not discoverable elsewhere.

IV. To What Height Do They Raise Themselves in the Atmosphere?

On this point I have not been able to make any direct observation. Perhaps I have dreamed of offering objections to the concourse of intrepid human navigators who undertake such perilous excursions in the air, and for my interest in the study I have found two excellent reasons. The first, that it would be well for them to know that, if they have not had rivals, they have had precursors, who, for 6000 years, have executed silently and noiselessly what they have claimed for themselves by every effort of puffs and publicity. The second, and a still more serious objection and that I believe will truly interest the future in this young industry, is that if the argyronete and its bell has given to science the instrument with which the divers explore the depths of the sea, why may not the study of aerial spiders furnish for aeronauts—these divers in air—the complete apparatus which they require to raise themselves to any height, direct their movements, and maintain themselves at will? Have not these little animals resolved this problem for centuries? Yet the present state of aerostation does not afford ground sufficient for comparison.

We are, therefore, reduced to conjecture; and, if I may be permitted to express mine, this is what I think:

I believe that spiders rise to the same height where on the fine days of summer one can see the swallows and martins hover, almost lost to sight, in pursuit of gnats that people these regions of the atmosphere. I found this belief on the webs of spiders seen falling in autumn, that seem to come at least from nearly such heights. They begin to be seen at a hundred or a hundred and fifty yards, and there is no great temerity in affirming that they have already traversed a good part of their course. An observation made in 1864, if conclusive, would tend to make remoter still the habitation of spiders; for the fog that determined the fall that year was a high fog, that is to say, one of those uniform mists that hide the sky for several days together, and seem to extend to a great height. But, I repeat, this is all conjecture. One good observation would have been worth far more.'

V. Conjectures On The Mode Of Building Of Spiders In The Air.

Perhaps here I should stop, and, having stated facts, leave to others their explanation. How do spiders sustain themselves in the air? How can they so long brave the winds, the rains, the storms; arrange their webs in emptiness and without apparent means of support? Prudence counsels me to avoid these questions, but my rôle of simple observer permits them. However, in waiting for better things, I decide still to hazard some conjectures, were it only to prove that a fact once admitted, it would not be absolutely impossible for the wisest to explain it.

The first idea that came to me was that these spider-webs raise themselves in the air as the kites of children, and, made fast to the tops of trees and edifices by long threads, they are sustained by their own lightness. This idea was suggested to me by a sight I was witness to one day at the Seminary of Vals, near Le Puy. From a corner where I was in shadow, I perceived distinctly on each high ridge of the roof, lightened by the rays of the sun, long threads which rose perpendicularly in the air, like large cords, balancing themselves slowly right and left, without ever going out of a certain field of oscillation. But I soon gave up this idea. How admit, in truth, that on two or three threads, and without any other means of support, spiders could weave their true webs? Would not some of these aerial constructions tumble down every day, ruined by their own weight? while it is acknowledged they only fall in autumn, and always together.

I therefore rather incline to believe that the spiders are sustained in the air by the distention of an interior vesicle, analogous to that of fish, and that they ejaculate by their threads, which are numerous, and pierced with an infinity of little tubes, large bundles of threads, by which are taken the insects that serve for their prey; that they resist the winds as fish do the tossing of the sea, and their threads, being glutinous, are not dampened by the rain; and also being excellent conductors of caloric, as is proved by the abundant drops of dew which they pearl near the earth, on the hedges, etc.; and if after a calm night they are touched by an autumn fog, these heavy and moistened threads weaken and fall one over the other, and form the silky flakes that are seen from ten to eleven o'clock in the morning, flying about in cloudy days with the spiders who inhabited them during the summer. This, hoping for better, is the explanation I hazard, and I submit it with the rest to the appreciation of competent men. If only these pages attract attention to a merited subject, and provoke numerous observations, which alone can ever fully elucidate it, the author will be more than repaid for the few researches he has presented in this article.