THE YOUNG CRAB-SPIDERS
It is in July that some little Crab-spiders that I have in my laboratory come out of their eggs. Knowing their acrobatic habits, I have placed a bundle of slender twigs at the top of the cage in which they were born. All of them pass through the wire gauze and form a group on the summit of the brushwood, where they swiftly weave a roomy lounge of criss-cross threads. Here they stay, pretty quietly, for a day or two; then foot-bridges begin to be flung from one object to the next. This is the fortunate moment.
I put the bunch laden with beasties on a small table, in the shade, before the open window. Soon they begin to spin threads to carry them away, but slowly and unsteadily. They hesitate, go back, fall short at the end of a thread, climb up again. In short, much trouble for a poor result.
As matters continue to drag, it occurs to me, at eleven o’clock, to take the bundle of brushwood swarming with the little Spiders, all eager to be off, and place it on the window-sill, in the glare of the sun. After a few minutes of heat and light, things move much faster. The little Spiders run to the top of the twigs, bustle about actively. I cannot see them manufacturing the ropes or sending them floating at the mercy of the air; but I guess their presence.
Three or four Spiders start at a time, each going her own way. All are moving upwards, all are climbing some support, as can be told by the nimble motion of their legs. Moreover, you can see the thread behind them, where it is of double thickness. Then, at a certain height, individual movement ceases. The tiny animal soars in space and shines, lit up by the sun. Softly it sways, then suddenly takes flight.
What has happened? There is a slight breeze outside. The floating cable has snapped and the creature has gone off, borne on its parachute. I see it drifting away, showing, like a spot of light, against the dark foliage of the near cypresses, some forty feet distant. It rises higher, it crosses over the cypress-screen, it disappears. Others follow, some higher, some lower, hither and thither.
“Like the finish of a fireworks display.”
But the throng has finished its preparations; the hour has come to disperse in swarms. We now see, from the crest of the brushwood, a continuous spray of starters, who shoot up like tiny rockets and mount in a spreading cluster. In the end, it is like the bouquet at the finish of a fireworks display, the sheaf of rockets fired all at once. The comparison is correct down to the dazzling light itself. Flaming in the sun like so many gleaming points, the little Spiders are the sparks of that living fireworks. What a glorious send-off! What an entrance into the world!
Sooner or later, nearer or farther, the fall comes. To live, we have to descend, often very low, alas! The Spiderling, therefore, touches land. The parachute tempers her fall. She is not hurt.
The rest of her story escapes me. What infinitely tiny Midges does she capture before possessing the strength to stab her Bee? What are the methods, what the wiles of atom contending with atom? I know not. We shall find her again in spring, grown quite large and crouching among the flowers whence the Bee takes toll.
CHAPTER XXIII
THE LABYRINTH SPIDER
While the Garden Spiders are incomparable weavers, many other Spiders have even more ingenious devices for catching game. Some of them are real celebrities, who are mentioned in all the books.
Certain Bird Spiders, or American Tarantulas, live in a burrow like the Tarantula I have been telling you about, but their burrow is more perfect than hers. My Tarantula surrounds the mouth of her hole with a simple curb, a mere collection of tiny pebbles, sticks, and silk; the American ones fix a movable floor to theirs, a round shutter with a hinge, a groove, and a set of bolts. When one of these Tarantulas comes home, the lid drops into the groove and fits so exactly one cannot tell where it joins. If any one from outside tries to raise the trap-door, the Spider pushes the bolt,—that is to say, plants her claws into certain holes on the opposite side to the hinge,—props herself against the wall, and holds the door firmly.
Another, the Water Spider, builds herself an elegant silken diving-bell, in which she stores air. She waits in it for the coming of game and keeps cool meanwhile. On scorching hot days, hers must be a real palace of luxury, such as men have sometimes ventured to build under water, with mighty blocks of stone and marble. Tiberius, the wicked Roman Emperor, had such a submarine palace; but his is only a hateful memory, whereas the Water Spider’s dainty tower still flourishes.
If I had had the chance to observe these Spiders, I should gladly add a few unpublished facts to their life-history; but I must give up the idea. The Water Spider is not found in my district. The American Tarantula, the expert in hinged doors, I saw once only, by the side of a path. I was occupied with something else, and did not give it more than a passing glance. I have never seen it again.
But it is not only the uncommon insects that are worth attention. The common ones, if carefully observed, can tell us things just as important. I am interested in the Labyrinth Spider, which I find oftener than any other in the fields. Several times a week, in July, I go to study my Spiders on the spot, early in the morning, before the sun beats fiercely on one’s neck. The children come with me, each provided with an orange in case they get thirsty.
We soon discover high silk buildings, the threads beaded with dew and glittering in the sun. The children are wonderstruck at those glorious chandeliers, so that they even forget their oranges for a moment. I am not indifferent to them, either. Our Spider’s labyrinth is a splendid spectacle. That and the concert of the Thrushes are worth getting up for.
Half an hour’s heat, and the magic jewels disappear with the dew. Now is the time to look at the webs. Here is one spreading its sheet over a large cluster of rock-roses; it is the size of a handkerchief. Many guy-ropes moor it to the brushwood. It covers the bush like a piece of white muslin.
The web is flat at the edges and gradually hollows into a crater, not unlike the bell of a hunting-horn. At the center is a funnel whose neck, narrowing by degrees, is eight or nine inches deep and leads back into the leafy thicket.
At the entrance to the tube sits the Spider, who looks at us and shows no great excitement at our presence. She is gray, modestly adorned on the thorax with two black ribbons and on the abdomen with two stripes in which white specks alternate with brown. She has a sort of double tail at the end of her body, a rather curious feature in a Spider.
I expected to find, at the bottom of the Spider’s funnel, a wadded cell where she might rest in her hours of leisure. On the contrary, there is only a sort of door, which stands always ajar so that the Spider may escape at any time through the grass and gain the open.
Above, in the Spider’s web, there is a forest of ropes. It might be the rigging of a ship disabled by a storm. They run from every twig of the supporting boughs, they are fastened to the tip of every branch. There are long ropes and short ropes, upright and slanting, straight and bent, taut and slack, all criss-cross and a-tangle, to the height of three feet or so. The whole makes a chaos of netting, a real labyrinth which none but the very strongest insects can break through.
There is nothing like the sticky snare of the Garden Spiders here. The threads are not sticky, but they are very bewildering. See this small Locust who has lighted on the rigging. He is unable to get a steady foothold on that shaky support; he flounders about; and the more he struggles, the more he is entangled. The Spider, looking at him from her funnel, lets him have his way. She does not run up the ropes; she waits until the desperate prisoner in his struggles falls on the main part of the web.
Then she comes, flings herself upon her prey, and slowly drains his blood. The Locust is lifeless at the first bite; the Spider’s poison has settled him.
When laying-time is at hand, the Spider changes her residence; she leaves her web, which is still in excellent condition; she does not come back to it. The time has come to make the nest. But where? The Spider knows well; I am in the dark. I spend whole mornings ransacking the bushes, until at last I learn the secret. The nest is some distance away from the web, in a low, thick cluster of bushes; it is a clumsy bundle of dead leaves, roughly drawn together with silk threads. Under this rude covering is a pouch of fine texture containing the egg-casket.
I am disappointed in the appearance of this Spider’s nest, until I remember that she probably cannot do better in the places where she builds. In the midst of a dense thicket, among a tangle of dead leaves and twigs, there is no room for an elegant piece of work. By way of experiment, I carry half a dozen Labyrinth Spiders into my laboratory near the laying-time, place them in large wire-gauze cages, standing in earthen pans filled with sand, with a sprig of thyme planted in the center to give a support for each nest. Now they will show what they can do.
The experiment works perfectly. By the end of August I have six nests, magnificent in shape and of a dazzling whiteness. The Spiders have had elbow-room, and they have done their best. The nests are ovals of exquisite white muslin, nearly as large as a Hen’s egg. They are open at either end. The front-entrance broadens into a gallery; the back-entrance tapers into a funnel-neck. It is somewhat the same construction as that of the Labyrinth web. Even the labyrinth is repeated, for in front of the bell-shaped mouth is a tangle of threads. The Spider has her pattern by heart, and uses it on all occasions.
This palace of silk is a guard-house. Behind the soft, milky, partly transparent wall glimmers the egg-casket, its shape vaguely suggesting the star of some order of knighthood. It is a large pocket, of a splendid dead-white, with pillars on every side which keep it motionless in the center of the nest. There are about ten of these pillars; they are slender in the middle and wider at both ends. They form corridors around the central room. The mother walks gravely to and fro under the arches of these corridors, which are like the cloisters of a nunnery; she stops first here, then there; she listens to all that happens inside the satin wrapper of her egg-wallet. I would not disturb her for anything; but I find, from nests I have picked up in the fields, that the purse contains about a hundred eggs, very pale amber-yellow beads.
When I remove the outer white-satin wall, I come upon a kernel of earthy matter, grains of sand mixed with the silk. However did they get there? Did they soak through the rain-water? No, the wrapper is spotless white outside. They have been put there by the mother herself. She has built around her eggs, to protect them from parasites, a wall composed of a great deal of sand and a little silk.
Inside this is still another silken wrapper, and then come the little Spiders, already hatched out and moving about in their nursery.
But, to go back—why does the mother leave her fine web when laying-time comes, and make her nest so far away? She has her reason, you may depend upon it. Her large net, like a sheet, with the labyrinth stretched above, is very conspicuous; parasites will not fail to come running at this signal, showing up against the green; if her nest is near, they will certainly find it; and a strange grub, feasting on a hundred new-laid eggs, will ruin her home. So the wise Labyrinth Spider shifts her quarters, and goes off at night to explore the neighborhood for a less dangerous retreat for her coming family. The low brambles dragging along the ground, keeping their leaves through the winter, and catching the dead leaves from the oaks hard by, or rosemary tufts, low and bushy, suit her perfectly. In such spots I usually find her nest.
Many Spiders leave their nests after they have laid the eggs, but the Labyrinth, like the Crab-spider, remains to watch over hers. She does not become thin and wither away, like the Crab-spider. She keeps her appetite, she is on the lookout for Locusts; and so she builds a hunting-box, a tangle of threads, on the outside of her nest.
When she is not hunting, as we have seen, she walks the corridors around her eggs, she listens to find out if all is well. If I shake the nest at any point with a straw, she quickly runs up to inquire what is happening. Probably she keeps off parasites in this way.
The Spider’s appetite for Locusts shows that she must have more to do. Insects, unlike some human beings, eat only that they may work. When I watch her, I find out what this work is. For nearly another month, I see her adding layer upon layer to the walls of her nest. These were at first semi-transparent; they become thick and opaque. This is why the Spider eats, so that she may fill her silk-glands and make a thick wrapper for her nest.
About the middle of September the little Spiders come out of their eggs, but they do not leave their house, where they are to spend the winter packed in soft wadding. The mother continues to watch and spin, but she grows less active from day to day. She eats fewer Locusts; she sometimes scorns those whom I myself entangle in her trap. But for four or five months longer she keeps on making her inspection-rounds of her egg-casket, happy at hearing the new-born Spiders swarming inside. At last, when October ends, she clutches her children’s nursery and dies. She has done all that a mother’s devotion can do; the special Providence that watches over tiny animals will do the rest. When spring comes, the youngsters will come out of their snug homes and scatter all over the neighborhood on their floating threads, like the little Crab-spiders you have read about.
CHAPTER XXIV
THE BUILDING OF A SPIDER’S WEB
The smallest garden contains the Garden Spiders, all clever weavers.
Let us go every evening, step by step, from one border of tall rosemaries to the next. Should things move too slowly, we will sit down at the foot of the shrubs, where the light falls favorably, and watch with unwearying attention. Let us give ourselves a title, “Inspector of Spiders’ Webs!” There are not many people in that profession, and we shan’t make any money by it; but never mind, we shall learn some very interesting things.
The Spiders I watch are young ones, much slenderer than they will be in the late autumn. They work by day, work even in the sun, whereas the old ones weave only at night. Work starts in July, a couple of hours before sunset.
The spinstresses of my inclosures then leave their daytime hiding-places, choose their posts and begin to spin, one here, another there. There are many of them; we can choose where we please. Let us stop in front of this one, whom we surprise in the act of laying the foundations of her web. She runs about the rosemary hedge, from the tip of one branch to another, within the limits of some eighteen inches. Gradually, she puts a thread in position, drawing it from her body with the combs attached to her hind-legs. She comes and goes impetuously, as though at random; she goes up, comes down, goes up again, dives down again and each time strengthens the points of contact with threads distributed here and there. The result is a sort of frame. The shapeless structure is what she wishes; it marks out a flat, free, and perpendicular space. This is all that is necessary.
A special thread, the foundation of the stronger net which will be built later, is stretched across the area of the other. It can be told from the others by its isolation, its position at a distance from any twig that might interfere with its swaying length. It never fails to have, in the middle, a thick white point, formed of a little silk cushion.
The time has come to weave the hunting-snare. The Spider starts from the center, which bears the white signpost, and, running along the cross-thread, hurriedly reaches the circumference, that is to say, the irregular frame inclosing the free space. Still with the same sudden movement, she rushes from the outside to the center; she starts again backwards and forwards, makes for the right, the left, the top, the bottom; she hoists herself up, dives down, climbs up again, runs down and always returns to the central landmark by roads that slant in the most unexpected manner. Each time a radius or spoke is laid, here, there, or elsewhere, in what looks like mad disorder.
Any one looking at the finished web, so neat and regular in appearance, would think that the Spider laid the spokes in an orderly fashion, one after the other. She does nothing of the sort, but she knows what she is about, all the same. After setting a few spokes in one direction, the Spider runs across to the other side to draw some in the opposite direction. These sudden changes have a reason; they show us how clever the Spider is in her business. If she began by laying all the spokes on one side, she would pull the web out of shape or even destroy it. She must put some on the other side to balance. She is a past mistress of the secrets of rope-building, without serving an apprenticeship.
One would think that this interrupted and apparently disordered labor must result in a confused piece of work. Wrong: the rays are equidistant and form a beautifully regular circle. Their number is a characteristic mark of the different species. The Angular Epeira places twenty-one in her web, the Banded Epeira thirty-two, the Silky Epeira forty-two. These numbers are not absolutely fixed; but the variation is very slight.
Now which of us would undertake, offhand, without much preliminary experiment and without measuring-instruments, to divide a circle into a given quantity of sectors or parts of equal width? The Garden Spider, though weighted with a wallet and tottering on threads shaken by the wind, performs the delicate division without stopping to think. She achieves it by a method which seems mad according to our notions of geometry. Out of disorder she brings order. We are amazed at the result obtained. How does this Spider come to succeed with her difficult problem, so strangely managed? I am still asking myself the question.
The laying of the radii or spokes is finished. The Spider takes her place in the center, on the little cushion. Stationed on this support, she slowly turns round and round. She is engaged on a delicate piece of work. With an extremely thin thread, she describes from spoke to spoke, starting from the center, a spiral line with very close coils. This is the center of the web. I will call it the “resting-floor.”
The thread now becomes thicker. The first could hardly be seen; the second is plainly visible. The Spider shifts her position with great slanting strides, turns a few times, moving farther and farther from the center, fixes her line each time to the spoke which she crosses, and at last comes to a stop at the lower edge of the frame. She has described a spiral with coils of rapidly-increasing width. The average distance between the coils, even in the webs of the young Spiders, is about one third of an inch.
This spiral is not a curved line. All curves are banished from the Spiders’ work; nothing is used but the straight line and its combinations. This line forms the cross-bars, or supporting rungs, connecting the spokes, or radii.
All this is but a support for the snaring-web. Clinging on the one hand to the radii, on the other to the cross-bars, the Spider covers the same ground as when laying the first spiral, but in the opposite direction: formerly, she moved away from the center; now she moves towards it and with closer and more numerous circles. She starts from the end of the first spiral, near the outside of the web.
What follows is hard to observe, for the movements are very quick and jerky, consisting of a series of sudden little rushes, sways, and bends that bewilder the eye. The two hind-legs, the weaving implements, keep going constantly. One draws out the thread from the spinneret, and passes it to the other, which lays it on the radius. As soon as the radius is touched, the thread sticks to it by its own glue.
The Spider, without a stop of any kind, turns and turns and turns, drawing nearer to the center and always fixing her thread at each spoke which she crosses. At last, at some distance from the center, on the edge of what I have called the resting-floor, the Spider suddenly ends her spiral. She next eats the little cushion in the center, which is a mat of ends of saved silk. She does this to economize silk, for after she has eaten it the cushion will be turned into silk for the next web she spins.
Two Spiders, the Banded and the Silky, sign their work by laying a broad white ribbon in a thick zigzag from the center to the lower edge of the web. Sometimes they put a second band of the same shape, but a little shorter, opposite the first, on the upper part of the web.
