Insect Adventures

by Jean-Henri Fabre; Louise Hasbrouck Zimm

THE ATTACK

I leave the Wasp her fifth Worm, which she unearths with my help. I will tell in numbered paragraphs the various acts of the gorgeous drama that passes before my eyes. I am lying on the ground, close to the slaughterer, and not one detail escapes me.

1. The Sand-Wasp seizes the Caterpillar by the back of the neck with the curved pincers of her jaws. The Gray Worm struggles violently, rolling and unrolling its body. The Wasp is quite unconcerned: she stands aside and thus avoids the shocks. Her sting strikes the Caterpillar at the joint between the first ring and the head, in the middle of the under side, at a spot where the skin is more delicate. This is the most important blow, the one which will master the Gray Worm and make it more easy to handle.

“The gorgeous drama.”

2. The Sand-Wasp now leaves her prey. She flattens herself on the ground, with wild movements, rolling on her side, twitching and dangling her limbs, fluttering her wings, as though in danger of death. I am afraid that the huntress has received a nasty wound in the contest. I am overcome with emotion at seeing the plucky Wasp finish so piteously. But suddenly the Wasp recovers, smooths her wings, curls her antennæ, and returns briskly to the attack. What I had taken for the convulsions of approaching death was the wild enthusiasm of victory. The Wasp was congratulating herself on the way she had floored the enemy.

3. The Wasp grips the Caterpillar by the skin of the back, a little lower than before, and pricks the second ring, still on the under side. I then see her gradually going back along the Gray Worm, each time seizing the back a little lower down, clasping it with the jaws, those wide pincers, and each time driving the sting into the next ring. In this way are wounded the first three rings, with the true legs; the next two rings, which are legless; and the four rings, with the pro-legs, which are not real legs, but simply little protuberances. In all, nine stings. After the first prick of the needle, the Gray Worm offers but a feeble resistance.

4. Lastly, the Sand-Wasp, opening the forceps of her jaws to their full width, seizes the Caterpillar’s head and crunches it, squeezing it with a series of leisurely movements, without creating a wound. She pauses after each squeezing as if to learn the effect produced; she stops, waits, and begins again. This handling of the brain cannot be carried too far, or the insect would die; and strange to say, the Wasp does not wish to kill the Caterpillar.

The surgeon has finished. The poor patient, the Worm, lies on the ground on its side, half doubled up. It is motionless, lifeless, unable to resist when the Wasp drags it to the burrow, unable to harm the grub that is to feed upon it. This is the purpose of the Wasp’s proceedings. She is procuring food for her babies, which are as yet non-existent. She will drag the Caterpillar to her burrow and lay an egg upon it. When the grub comes out of the egg, it will have the Caterpillar to feed upon. But suppose this Caterpillar were active? One movement of his body would crush the egg against the wall of the cell. No, the Caterpillar must be motionless; but it must not be dead, for if it were, it would speedily decay and be unfit eating for the fastidious little grub. The Wasp, therefore, drives her poisoned sting into the nerve-centers of every segment whose movement could hurt the grub-baby. She does better than that. The victim’s head is still unhurt, the jaws are at work; they might easily, as the Caterpillar is dragged to the burrow, grip some bit of straw in the ground and stop progress. The Caterpillar, therefore, must be rendered torpid, and the Wasp does this by munching his head. She does not use her sting on the brain, because that would kill the Caterpillar; she merely squeezes it enough to make the Caterpillar unconscious.

Though we admire the wonderful skill of the Wasp, we cannot help feeling sorry for the victim, the poor Gray Worm. If we were farmers, however, we should not waste any pity on the Worm. These Caterpillars are a dreadful scourge to agricultural crops, as well as to garden produce. Curled in their burrows by day, they climb to the surface at night and gnaw the base or collar of plants. Everything suits them: ornamental plants and edible plants alike, flower-beds, market-gardens, and plants in fields. When a seedling withers without apparent cause, draw it to you gently; and the dying plant will come up, but maimed, cut from its root. The Gray Worm has passed that way in the night; its greedy jaws have cut the plant. It is as bad as the White Worm, the grub of the Cockchafer. When it swarms in a beet-country, the damage amounts to millions. This is the terrible enemy against which the Sand-Wasp comes to our aid. Let us not feel too sorry for it!

CHAPTER IX
THE WASP AND THE CRICKET

At the end of July the Yellow-winged Wasp tears the cocoon that has protected her till then and flies out of her underground cradle. During the whole of August she is often seen flitting about the fields in search of honey. But this careless life does not last long, for by the beginning of September the Wasp must begin to dig her burrows and search for game for her family. For her burrows she usually chooses some sandy soil on the high banks by the side of the road. One thing is necessary: the site must receive plenty of sunshine.

Ten or twelve Yellow-winged Wasps usually work together. They scrape the earth with their fore-feet like mischievous puppies. At the same time, each worker sings her glad song, which is a shrill noise, constantly broken off and rising higher or sinking lower in a regular rhythm. One would think they were a troop of merry companions singing to encourage each other in their work. Meanwhile, the sand flies, falling in a fine dust on their quivering wings; and the too-large gravel, removed bit by bit, rolls far away from the work yard. If a piece seems too heavy to be moved, the insect gets up steam with a shrill note which reminds one of the workman’s “Hoo!”

Soon the cave takes shape; the insect dives into it bodily. We still hear underground her untiring song, while every little while we catch a glimpse of her hind-legs, pushing a torrent of sand backwards to the mouth of the burrow. From time to time the Wasp comes outside the entrance to dust herself in the sun, and to rid herself of grains of sand. In spite of these interruptions, she manages to dig the gallery in two or three hours. Then she comes to her threshold to chant her triumph and give the finishing polish to her work by smoothing out some unevenness and carrying away a speck or two of earth.

There are two, three, or four cells in the Yellow-winged Wasp’s burrow, in each of which lies an egg. But the Wasp does not content herself with one burrow: she digs about ten, all in the month of September, and she has to get food for all of them. She has not a moment to lose, when, in so short a time, she has to dig her burrows, procure a dozen Crickets or more for food for her families, and stop the burrows up again. Besides, there are gray days and rainy days during the month, when she cannot work.

The Yellow-winged Wasp is not content with comparatively defenseless Beetles and Caterpillars; she hunts the powerful Cricket. Watch her chasing one. The terrified Cricket takes to flight, hopping as fast as he can; the Wasp pursues him hot-foot, reaches him, rushes upon him. There follows, in the dust, a confused struggle, wherein each fighter is in turn victor and vanquished, on top and underneath. The issue seems doubtful. But at last the Wasp triumphs. In spite of his vigorous kicks, in spite of the snaps of his pincer-like jaws, the Cricket is laid low and stretched upon his back.

The Wasp places herself upon him, belly to belly, but in the opposite direction. She grasps one of the threads at the tip of the Cricket’s abdomen with her mouth and masters with her fore-legs the convulsive efforts of his thick hinder-thighs. At the same time her middle-legs hug the heaving sides of the beaten insect, and her hind-legs force the joint of the neck to open wide. The Wasp then curves herself outward so as to offer the Cricket no chance to bite her, and drives her poisoned sting once into the victim’s neck, next into the joint of the front two rings of the thorax, or part next the neck, and lastly towards the abdomen. In less time than it takes to tell, the murder is done; and the Wasp, after making herself tidy again, gets ready to haul home the victim.

You must acknowledge she knows how to fight, better even than the Wasps who attack Beetles, or those who capture Caterpillars. Those insects cannot fly, they have no defensive weapons. What a difference between them and the Cricket! The Cricket is armed with dreadful jaws, capable of eating the vitals out of the Wasp if they succeed in seizing her; he has a pair of powerful legs, regular clubs bristling with a double row of sharp spikes, which can be used by the Cricket either to hop out of his enemy’s reach, or to send her sprawling with brutal kicks.

Notice, therefore, the precautions the Wasp takes before setting her sting in motion. She turns the Cricket upon his back so that he cannot use his hind-legs to escape. She controls his spurred legs with her fore-feet, so that he cannot kick her; and she keeps his jaws at a distance with her own hind-legs. She makes him motionless by grasping one of the threads at the end of the abdomen. An athlete, an expert wrestler, could not do better.

Consider, also, her science. She wishes to paralyze the prey without killing it, so that it will remain in a fit condition for food for her babies for many weeks. If she should leave the Cricket any power of motion, it would knock the eggs off; if she killed it entirely, it would decay. How does she produce this paralysis? She does just what a surgeon would advise her to do; she strikes the nerve-centers of the different parts of the Cricket’s body which are likely to do harm, the three nervous centers that set the legs in motion.

If we look at the Cricket a week, two weeks, or even longer after the murder, we shall see the abdomen moving slightly, a sign that he is still alive.

After the Wasp has paralyzed her Cricket, she grips him with her feet, holding also one of his antennæ in her mouth, and in this manner flies off with him. She has to stop sometimes to take a minute’s rest. Then she once more takes up her burden and, with a great effort, carries him in one flight almost to her home. The Wasp I am watching alights in the middle of a Wasp village. She makes the rest of her way on foot. She bestrides her victim and advances, bearing her head proudly aloft and hauling the Cricket, who trails between her legs, by the antennæ held between her jaws. If the ground is bare, she has an easy time; but sometimes she meets with some spreading grass shoots, and then it is curious to see her marches and countermarches, her repeated attempts to get past, which she finally does by some means or other, either by flight or by taking another path.

At last she reaches home and places the Cricket so that his antennæ exactly touch the mouth of the burrow. The Wasp then leaves him and goes down hastily to the bottom of the cave, perhaps to see that everything is as it should be and no other Wasp has made her nest there. A few seconds later she reappears, showing her head out of doors and giving a little cry of delight. The Cricket’s antennæ are within her reach; she seizes them, and the game is brought quickly down to the lair.

When the Yellow-winged Wasp has stacked up three or four Crickets for each cell, she lays an egg on one of them and closes the burrow. She does this by sweeping the heaped-up sand outside the door down the burrow. She mixes fair-sized bits of gravel with the sand to make it stronger. If she cannot find gravel of the right size within reach, she goes and searches in the neighborhood, and seems to choose the pieces as carefully as a mason would choose the chief stones for his building. In a few moments she has closed up the underground dwelling so carefully that nothing remains to show where it has been. Then she goes on, digs another burrow, catches game for it, and walls it up. And so on. When she is through laying all her eggs, she goes back to the flowers, leading a careless, wandering life until the first cold snap puts an end to her existence, which has been so full of duties and excitements.

CHAPTER X
THE FLY-HUNTING WASP

You have read about the Wasps who store up paralyzed Caterpillars and Crickets for their babies’ food, then close up the cells and fly away; now you shall hear about a Wasp who feeds her children with fresh food from day to day. This is the Bembex, or the Fly-hunting Wasp, as I shall call her.

This Wasp digs her burrows in very soft, light sand, under a blazing sun and a blue sky. I go out and watch her sometimes on an unshaded plain where it is so hot that the only way to avoid sunstroke is to lie down at full length behind some sandy knoll, put one’s head down a rabbit-burrow, or provide one’s self with a large umbrella. The latter is what I did. If the reader will sit with me under the umbrella at the end of July, he will see the following sight.

A Fly-hunting Wasp arrives suddenly and alights, without any hesitation, at a spot which to my eyes looks exactly like the rest of the sandy surface. With her front feet, which are armed with rows of stiff hairs and remind one at the same time of a broom, a brush, and a rake, she works at clearing her underground dwelling. The insect stands on her four hind-legs, while the front ones first scratch and then sweep the shifting sand. She shoots the sand backwards so fast that it gushes in a curve like a stream of water, falling to the ground seven or eight inches away. This spray of dust is kept up evenly for five or ten minutes at a time by the swift, graceful Wasp.

Mingled with this dust are tiny bits of wood, decayed leaf stalks, particles of grit and other rubbish. The Wasp picks them up in her mouth and carries them away. This is really the purpose of her digging. She is sifting out the sand at the entrance to her home, which is all ready underground, having been dug some time before. The Wasp wishes to make the sand at the entrance to her burrow fine, light, and free from any obstacle, so that when she alights suddenly with a Fly for her children, she can dig an entrance to her home quickly. She does this work in her spare time, when her larva has enough food to last it for a while, so that she does not need to go hunting. She seems happy as she works so fast and eagerly, and who knows that she is not expressing in this way her mother’s satisfaction in watching over the roof of her house where her baby lives?

If we should take a knife and dig down into the sand where the Wasp-mother is scratching, we should find, first, an entrance corridor, as wide as one’s finger, and perhaps eight to twelve inches long, and then a room, hollowed out down below where the sand is damper and firmer. It is large enough to contain two or three walnuts; but all it does hold at present is a Fly, a golden-green Greenbottle, with a tiny white egg laid on the side. This is the Wasp’s egg. It will hatch out in about twenty-four hours, into a little worm, which will feed on the dead Fly. For the Fly is dead, and not paralyzed, as the food of other Wasp-babies often is.

At the end of two or three days the Wasp-grub will have eaten up the little Fly. Meanwhile the mother Wasp remains in the neighborhood and you see her sometimes feeding herself by sipping the honey of the field flowers, sometimes settling happily on the burning sand, no doubt watching the outside of the house. Every now and then she sifts the sand at the entrance; then she flies away for a while. But, however long she may stay away, she never forgets the young larva who has food enough to last only a short time; her mother’s instinct tells her the hour when the grub has finished its food and wants more. She therefore returns to the nest, which, you must remember, does not show in the least from the surface of the ground, as the shifting sand has filled in the entrance; she knows, however, exactly where to look for it; she goes down into the earth, this time carrying a larger piece of game. After leaving this in the underground room she again leaves the house and waits outside until the time comes to serve a third course. This is not long, for the little worm is getting a larger appetite all the time. Again the mother appears with another Fly.

For nearly two weeks, while the larva is growing up, the meals thus follow in succession, one by one, as needed, and coming closer together as the infant grows larger. Towards the end of the two weeks, the mother is kept as busy as she can be satisfying her hungry child, now a large, fat grub. You see her at every moment coming back with a fresh capture, at every moment setting out again upon the chase. She does not cease her efforts until the grub is stuffed full and refuses its food. I have counted and found that sometimes the grub will eat as many as eighty-two Flies.

I have wondered sometimes why this Wasp does not lay up a store of food, as the other Wasps do, close the door of her burrow and fly away, instead of waiting about, as she does so patiently. I realize that she does not do so because her Flies would not keep; they would spoil and be unfit for eating. But why does she kill the Fly instead of paralyzing it? Possibly because the Fly would not make a satisfactory preserved food; it is so slight and frail, it would shrivel up and there would be nothing of it; it must be eaten fresh to be worth anything. Another reason almost certainly is that the Fly has to be captured very quickly, on the wing. There is not time for the Wasp to aim her sting, as the Wasps do who are killing clumsy Worms or fat Crickets on the ground. She must attack with claws, mouth or sting wherever she can, and this method of attack kills at once.

It is not easy to surprise a Wasp hunting, as she flies far away from where her burrow lies; but one day I had a quite unexpected experience as I was sitting in the hot sun under my umbrella. I was not the only one to enjoy the shade of the umbrella. Gad-flies of various kinds would take refuge under the silken dome and sit peacefully on every part of the tightly stretched cover. To while away the hours when I had nothing to do, it amused me to watch their great gold eyes, which shone like carbuncles under my umbrella; I loved to follow their solemn progress when some part of the ceiling became too hot and obliged them to move a little way on.

One day, bang! The tight cover resounded like the skin of a drum. Perhaps an oak had dropped an acorn on the umbrella. Presently, one after the other, bang, bang, bang! Can some practical joker be flinging acorns or little pebbles at my umbrella? I leave my tent and look around: nothing! I hear the same sharp sounds again. I look up at the ceiling and the mystery is explained. The Fly-hunting Wasps of the neighborhood, who all eat Gad-flies, had discovered the rich game that was keeping me company and were impudently coming into my shelter to seize the Flies on the ceiling. Things were going to perfection: I had only to sit still and look.

Every moment a Wasp would enter, swift as lightning, and dart up to the silken ceiling, which resounded with a sharp thud. Some rumpus was going on aloft, where so lively was the fray that one could not tell which was attacker, which attacked. The struggle did not last long: the Wasp would soon retire with a victim between her legs. The dull herd of Gad-flies would not leave the dangerous shelter. It was so hot outside! Why get excited?

“One day, bang!”

Let us watch the Wasp as she returns to the burrow with her capture held under her body between her legs. As she draws near her home, she makes a shrill humming, which has something plaintive about it and which lasts until the insect sets foot to earth. The Wasp hovers above the sand and then dips down, very slowly and cautiously, all the time humming. If her keen eyes see anything unusual, she slows up in her descent, hovers for a second or two, goes up again, comes down again and flies away, swift as an arrow. We shall see in a few moments what it is that makes her hesitate. Soon she is back again, looks at things once more from a height, then comes down slowly and alights at a spot which looks exactly like the rest of the sandy surface.

I think she has landed more or less on chance, and will now look about for the entrance to her home. But no; she is exactly over her burrow. Without once letting go her prey, she scratches a little in front of her, gives a push with her head, and at once enters, carrying the Fly. The sand falls in, the door closes, and the Wasp is at home. It makes no difference that I have seen this Wasp return to her nest hundreds of times; I am always astonished to behold the keen-sighted insect find without hesitation a door which does not show at all.

The Wasp does not always hesitate in the air before alighting at her house, and when she does, it is because she sees her nest is threatened by a very grave danger. Her plaintive hum shows anxiety; she never gives it when there is no peril. But who is the enemy? It is a miserable little Fly, feeble and harmless in appearance, whom we have mentioned in another chapter. The Wasp, the scourge of the Fly-tribe, the fierce slayer of large Gad-flies, does not enter her home because she sees herself watched by another Fly, a tiny dwarf, who would make scarcely a mouthful for her larvæ.

I feel just as I should if I saw my Cat fleeing in terror from a Mouse. Why does the Wasp not pounce upon the little wretch of a Fly and get rid of her? I do not know. It must be because this wretched little Fly has her tiny part to play in the universe, as well as the Wasp. These things are ordered somehow, in a way we do not understand.

As I shall mention elsewhere, this is the Fly that lays her eggs on the game the Wasp puts in the nest for her own baby; and the Fly’s offspring eat the food of the Wasp-grub, and sometimes eat the grub itself, if provisions are scarce. The way the Fly manages her business is interesting. She never enters the Wasp’s burrow, but she waits with the greatest patience for the moment when the Wasp dives into her home, with her game clasped between her legs. Just as she has half her body well within the entrance and is about to disappear underground, the Fly dashes up and settles on the piece of game that projects a little way beyond the hinder end of the Wasp; and while the latter is delayed by the difficulty of entering, the former, with wonderful swiftness, lays an egg on the prey, or even two or three in quick succession. The hesitation of the Wasp, hampered by her load, lasts but the twinkling of an eye. No matter: the Gnat has accomplished what she wished to, and now she goes and squats in the sun, close to the burrow, and plans fresh deeds of darkness.

A number of these Flies, usually three or four, are apt to station themselves on the sand at one time near a burrow, of which they well know the entrance, carefully hidden though it be. Their dull-brown color, their great blood-red eyes, their astonishing patience, have often reminded me of a picture of brigands, clad in dark clothes, with red handkerchiefs around their heads, waiting in ambush for an opportunity to hold up some travelers.

It is when the poor Wasp sees these brigands that she hesitates. At last she comes nearer, however. The Midges then take flight and follow behind the Wasp. If she turns, they turn also, so as to keep exactly behind her; if she advances, they advance; if she retreats, they retreat. She cannot keep them off. At last she grows weary and alights; they also alight, still behind her. The Wasp darts off again, with an indignant whimpering; the Midges dart after her. The Wasp tries one more way to get rid of them. She flies far away at full speed, hoping that they will follow and lose their way. But they know too much for that. They settle down on the sand again near the burrow and wait for her to come back. Come she does; the pursuit begins all over again; the mother’s patience is worn out, and at last they have a chance to lay their eggs as she goes into the burrow.

We shall end our chapter with the story of the Wasp-grub to whom no accidents happen, into whose burrow no nasty Fly-eggs enter. For two weeks it eats and grows; then it begins to weave its cocoon. It has not very much silk in its body to use for this, so it uses grains of sand to strengthen it. First it pushes away the remains of its food and forces them into a corner of the cell. Then, having swept its floor, it fixes to the different walls of its room threads of a beautiful white silk, forming a web which makes a kind of scaffold for the next work.

It then weaves a hammock of silk in the center of the threads. This hammock is like a sack open wide at one end and closed at the other in a point. The grub, leaning half out of its hammock, picks up the sand almost grain by grain with its mouth. If any grain found is too large, it is thrown away. When the sand is sorted in this way, the grub brings some into the hammock in its mouth, and begins to spread it in an even layer on the lower side of the hammock-sack; it adds grains also to the upper side, fixing them in the silk as one would place stones in putty.

The cocoon is still open at one end. It is time to close it. The grub weaves a cap of silk which fits the mouth of the sack exactly, and lays grains of sand one by one upon this foundation. The cocoon is all finished now, except that the grub gives some finishing touches to the inside by glazing the walls with varnish to protect its delicate skin from the rough sand. It then goes peacefully to sleep, to wait for its transformation into a Wasp like its mother.

CHAPTER XI
PARASITES

In August or September, let us go into some gorge with bare and sun-scorched sides. When we find a slope well-baked by the summer heat, a quiet corner with the temperature of an oven, we shall call a halt; there is a fine harvest to be gathered here. This tropical land is the native soil of a host of Wasps and Bees, some of them busily piling the household provisions in underground warehouses—here a stack of Weevils, Locusts or Spiders, there a whole assortment of Flies, Bees, or Caterpillars,—while others are storing up honey in wallets or clay pots, cottony bags or urns made with pieces of leaves.

With the Bees and Wasps who go quietly about their business, mingle others whom we call parasites, prowlers hurrying from one home to the next, lying in wait at the doors, watching for a chance to settle their family at the expense of others.

It is something like the struggle that goes on in our world. No sooner has a worker by means of hard labor gotten together a fortune for his children than those who have not worked come hurrying up to fight for its possession. To one who saves there are sometimes five, six or more bent upon his ruin; and often it ends not merely in robbery but in black murder! The worker’s family, the object of so much care, for whom that home was built and those provisions stored, is devoured by the intruders. Grubs or insect-babies are shut up in cells closed on every side, protected by silken coverings, in order that they may sleep quietly while the changes needed to make them into full-grown insects take place. In vain are all these precautions taken. An enemy will succeed in getting into the impregnable fortress. Each foe has his special tactics to accomplish this—tactics contrived with the most surprising skill. See, some strange insect inserts her egg by means of a probe beside the torpid grub, the rightful owner; or else a tiny worm, an atom, comes creeping and crawling, slips in and reaches the sleeper, who will never wake again, because the ferocious visitor will eat him up. The interloper makes the victim’s cell and cocoon his own cell and cocoon; and next year, instead of the mistress of the house, there will come from below ground the bandit who stole the dwelling and ate the occupant.

Look at this one, striped black, white, and red, with the figure of a clumsy, hairy Ant. She explores the slope on foot, looks at every nook and corner, sounds the soil with her antennæ. She is a kind of Wasp without wings, named Mutilla, the terrible enemy of the other Wasp-grubs sleeping in their cradles. Though the female Mutilla has no wings, she carries a sharp dagger, or sting. If you saw her, you might think she was a sort of sturdy Ant, gayer in dress than other Ants. If you watched her for some time, you would see her, after trotting about for a bit, stop somewhere and begin to scratch and dig, finally laying bare a burrow underground, of which there was no trace outside; but she can see what we cannot. She goes into the burrow, stays there for a while, and at last reappears to replace the rubbish and close the door as it was at the start. The abominable deed is done: the Mutilla’s egg has been laid in another’s cocoon, beside the slumbering grub or larva on which it will feed.

Here are other insects, all aglitter with gleams of gold, emerald, blue, and purple. They are the humming-birds of the insect-world, and are called the Golden Wasps. You would never think of them as thieves or murderers; but they, too, feed on the children of other Wasps. One of them, half emerald and half pale-pink, boldly enters the burrow of a Fly-hunting Wasp at the very moment when the mother is at home, bringing a fresh piece of game to her babies, whom she feeds from day to day. The elegant criminal, the Golden Wasp who does not know how to dig, takes this moment when the door is open to enter. If the mother were away, the house would be shut up, and the Golden Wasp, that sneak-thief in royal robes, could not get in. She enters, therefore, dwarf as she is, the house of the giantess whose ruin she is planning; she makes her way right to the back, never bothering about the Wasp, with her sting and her powerful jaws. The Wasp-mother either does not know the danger or is paralyzed with terror. She lets the strange Wasp have her way.

Next year, if we open the cells of the poor Fly-hunting Wasp, we shall find some which contain a russet-silk cocoon, the shape of a thimble, with its opening closed with a flat lid. In this silky covering, which is protected by the hard outer shell, is a grub of the Golden Wasp. As for the grub of the Fly-hunter, that grub which wove the silk and encrusted the outer casing with sand, it has disappeared entirely, all but a few tattered shreds of skin. Disappeared how? The Golden Wasp’s grub has eaten it.

One of these splendid-appearing, criminal Golden Wasps is dressed in lapis-lazuli on the front part of the body and in bronze and gold on the abdomen, with a scarf of blue at the end. When one of the Mason-wasps has built on the rock her heap of dome-shaped cells, with a covering of little pebbles set in the plaster, when the grubs have eaten up their store of Caterpillars and hung their rooms with silk, we see the Golden Wasp settle on the outside of the nest. Probably some tiny crack, some defect in the cement, allows her to insert her probe and lay her egg. At any rate, about the end of the following May, the Mason-wasp’s chamber holds a cocoon which again is shaped like a thimble. From this cocoon comes a Golden Wasp. There is nothing left of the Mason-wasp’s grub; the Golden Wasp has gorged herself upon it.

Flies, as we have seen, often act the part of robbers. They are not the least to be dreaded, though they are weak, sometimes so feeble that one cannot take them in his fingers without crushing them. One species called Bombylii are clad in velvet so delicate that the least touch rubs it off. They are fluffs of down almost as frail as a snowflake, but they can fly with wonderful quickness. See this one, hovering motionless two feet above the ground. Her wings vibrate so rapidly one cannot see the motion at all, and they seem to be in repose. The insect looks as though it were hung at one point in space by some invisible thread. You make a movement, and your Fly has disappeared. You look about for her. There is nothing here, nothing there. Then where is she? Close by you. She is back where she started, before you could see where she went to. What is she doing, there in the air? She is up to some mischief; she is watching for a chance to leave her egg where it will feed on some other insect’s provisions. I do not know yet what sort of insect she preys upon, nor what she wishes for her children, whether honey, game, or the grubs themselves.

I know more about the actions of certain tiny, pale-gray Flies, called Tachinæ, who, cowering on the sand in the sun, near a burrow, patiently wait for the hour at which to strike the fell blow. When the different Wasps return from hunting, one kind with her Gad-fly, another with a Bee, another with a Beetle, another with a Locust, at once the Gray Flies are there, coming and going, turning and twisting with the Wasp, always behind her and never losing her. At the moment when the Wasp huntress goes indoors, with her captured game between her legs, they fling themselves on her prey, which is on the point of disappearing underground, and quickly lay their eggs upon it. The thing is done in the twinkling of an eye; before the Wasp has crossed the threshold of her home, the food for her babies holds the germs of a new set of guests, who will feed on it and starve the children of the house to death.

Perhaps, after all, we should not blame too much these insects which feed on others, or on the food of others. An idle human being who feeds at other people’s tables is contemptible; we call him a parasite because he lives at his neighbor’s expense. The insect never does this; that is to say, it does not live on the food of another of the same species. You remember the Mason-bees: not one of the Bees touches another’s honey, unless the owner is dead or has stayed away a long time. The other Bees and Wasps behave in the same way.

What we call parasitism in insects is really a kind of hunting. The Mutilla, for instance, is a huntress, and her prey is the grub of another kind of Wasp, just as the game of this other kind of Wasp may be a Caterpillar or a Beetle. When it comes to this, we are all hunters, or thieves, whichever way you look at it, and Man the greatest of all. He steals the milk from the Calf, he steals the honey from the children of the Bee, just as the Gray Fly takes the food of the Wasps’ babies. She does it to feed her children; and Man helps himself to everything he can find to feed his.

CHAPTER XII
FLY SCAVENGERS

There are various kinds of insects that perform a very useful work in the world, for which they do not always receive credit. When you pass a dead Mole in the fields, and see Ants, Beetles and Flies on it, you shudder and get away from the spot as quickly as possible. You think they are horrid, dirty insects; but they are not; they are busy making the world a cleaner place for you to live in. Let us watch some of these Flies at work, and we shall get an idea of the wonderful things they do in this connection.

You have seen the Greenbottle Flies. They are a beautiful golden-green which shines like metal, and they have red eyes, set in a silver border. They scent dead animals from far away, and rush to lay their eggs in them. A few days afterward, the flesh of the corpse has turned into liquid, in which are thousands of tiny grubs with pointed heads. This is very unpleasant, perhaps you think; but, after all, it is the best and easiest way for dead things to disappear, to be absorbed in the soil and pass on to another form of life. And it is the little Greenbottle worms that produce this liquid.

If the corpse were left undisturbed, it would dry up and take a long while to disappear. The Greenbottle grubs, and the grubs of other Flies as well, have a wonderful power of turning solid things into liquid. When I give the Greenbottle grubs a piece of hard-boiled white of egg to feed upon, they turn it at once into a colorless liquid which looks like water. They have some sort of pepsin which comes out of their mouths and does this work. It is like the gastric juice in our stomach, which dissolves and renders digestible the food we eat. The grubs or worms live on the broth they make in this way until it has all disappeared.

Other Flies whose worms do this work are the Gray Flesh-flies and the big Bluebottles, whom you often see buzzing about the window-panes. Do not let them come near the meat for your dinner, for if they do they will surely make it uneatable. Out in the fields, however, they are in their right element. They give back to life, with all speed, the remains of that which has lived; they change corpses into an essence which enriches our foster-mother earth.

CHAPTER XIII
THE PINE CATERPILLAR

In my piece of waste ground stand some pine-trees. Every year the Caterpillar takes possession of them and spins his great purses in their branches. To protect the pine-needles, which are horribly eaten, I have to destroy the nests each winter with a long forked stick.

You hungry little Caterpillars, if I let you have your way, I should soon be robbed of the murmur of my once so leafy pines. But I am going to make a compact with you. You have a story to tell. Tell it to me; and for a year, for two years or longer, until I know more or less about it, I will leave you undisturbed.

The result of my compact with the Caterpillars is that I soon have some thirty nests within a few steps of my door. With such treasures daily before my eyes, I cannot help seeing the Pine Caterpillar’s story unfolded at full length. These Caterpillars are also called the Processionaries, because they always go abroad in a procession, one following closely after the other.

First of all, the egg. During the first half of August, if we look at the lower branches of the pines, we shall discover, here and there on the foliage, certain little whitish cylinders spotting the dark green. These are the Pine Moth’s eggs; each cylinder is the cluster laid by one mother. The cylinder is like a tiny muff about an inch long and a fifth or sixth of an inch wide, wrapped around the base of the pine-needles, which are grouped in twos. This muff has a silky appearance and is white slightly tinted with russet. It is covered with scales that overlap like the tiles on a roof. The whole thing resembles somewhat a walnut-catkin that is not yet full-grown.

The scales, soft as velvet to the touch and carefully laid one upon the other, form a roof that protects the eggs. Not a drop of rain or dew can penetrate. Where did this soft covering come from? From the mother Moth; she has stripped a part of her body for her children. Like the Eider-duck, she has made a warm overcoat for her eggs out of her own down.

If one removes the scaly fleece with pincers the eggs appear, looking like little white-enamel beads. There are about three hundred of them in one cylinder. Quite a family for one mother! They are beautifully placed, and remind one of a tiny cob of Indian corn. Nobody, young or old, learned or ignorant, could help exclaiming, on seeing the Pine Moth’s pretty little spike,

“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 geometrical regularity. Is it not strange that a tiny Moth should follow the laws of order? But the more we study nature, the more we realize that there is order everywhere. It is the beauty of the universe, the same under every sun, whether the suns be single or many, white or red, blue or yellow. 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, the result of brutal, uncontrolled forces? It seems hardly likely. Is there not Some One back of it all, Some One who is a supreme lover of beauty? That would explain everything.

These are very deep thoughts about a group of Moth-eggs that will bear a crop of Caterpillars. It cannot be helped. The minute we begin to investigate the tiniest things in nature, we have to begin asking “Why?” And science cannot answer us. That is the strange part of it.

The Pine Moth’s eggs hatch in September. If one lifts the scales of the little muff, one can see black heads appear, which nibble and push back their coverings. The tiny creatures come out slowly all over the surface. They are pale yellow, with a black head twice as large as their body. The first thing they do is to eat the pine-needles on which their nest was placed; then they fall to on the near-by needles.

From time to time, three or four who have eaten as much as they want fall into line and walk in step in a little procession. This is practice for the coming processions. If I disturb them, they sway the front half of their bodies and wag their heads.

“When winter is near they will build a stronger tent.”

The next thing they do is to spin a little tent at the place where their nest was. The tent is a small ball made of gauze, supported on some leaves. Inside it the Caterpillars take a rest during the hottest part of the day. In the afternoon they leave this shelter and start feeding again.

In less than an hour, you see, after coming from the egg, the young Caterpillar shows what he can do. He eats leaves, he forms processions, and he spins tents.

In twenty-four hours the little tent has become as large as a hazel-nut, and in two weeks it is the size of an apple. But it is still only a temporary summer tent. When winter is near, they will build a stronger one. In the meantime, the Caterpillars eat the leaves around which their tent is stretched. Their house gives them at the same time board and lodging. This is a good arrangement, because it saves them from going out, and they are so young and so tiny that it is dangerous for them to go out yet awhile.

When this tent gives way, owing to the Caterpillars having nibbled the leaves supporting it, the family moves on, like the Arabs, and erects a new tent higher up on the pine-tree. Sometimes they reach the very top of the tree.

In the meantime the Caterpillars have changed their dress. They now wear six little bright red patches on their backs, surrounded with scarlet bristles. In the midst of these red patches are specks of gold. The hairs on their sides and underneath are whitish.

In November they begin to build their winter tent high up in the pine at the tip of a bough. They surround the leaves at the end of the bough with a network of silk. Leaves and silk together are stronger than silk alone. By the time it is finished it is as large as a half-gallon measure and about the shape of an egg, with a sheath over the supporting branch. In the center of the nest is a milk-white mass of thickly-woven threads mingled with green leaves. At the top are round openings, the doors of the house, through which the Caterpillars go in and out. There is a sort of veranda on top made of threads stretched from the tips of the leaves projecting from the dome, where the Caterpillars come and doze in the sun, heaped one upon the other, with rounded backs. The threads above are an awning, to keep the sun from being too warm for them.

The inside of the Caterpillars’ nest is not at all a tidy place; it is full of rags, shreds of the Caterpillars’ skins, and dirt.

The Caterpillars stay in their nest all night, and come out about ten o’clock in the morning to take the sun on their terrace or veranda. They spend the whole day there, dozing. Motionless, heaped together, they steep themselves deliciously in warmth and from time to time show their bliss by nodding and wagging their heads. At six or seven o’clock, when it grows dark, the sleepers awake, bestir themselves, and go their several ways over the surface of the nest.

Wherever they go, they strengthen the nest or enlarge it by the threads of silk that come out of their mouths and trail behind them. More green leaves are taken in, and the tent becomes bigger and bigger. They are busy doing this for an hour or two every evening. So far, they have known nothing but summer; but they seem to realize that winter is coming. They work away at their house with an ardor 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!”

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. Let us work!

After the day’s work comes their dinner. The Caterpillars come down from the nest and begin on the pine-needles below. 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 branch bend under the load. The diners, all motionless, all poking their heads forward, nibble in silence, placidly. Their broad black foreheads gleam in the rays of my lantern. They eat far into the night. Then they go back to the nest, where, for a little longer, they continue spinning on the surface. It is one or two o’clock in the morning when the last of the band goes indoors.

The Pine Caterpillars eat only three kinds of pine: the Scotch pine, the maritime pine, and the Aleppo pine; never the leaves of the other cone-bearing trees, with one exception. In vain I offer them other foliage from the evergreens in my yard: the spruce, the yew, the juniper, the cypress. What! Am I asking them, the Pine Caterpillars, to bite into that? They will take good care not to, in spite of the tempting resinous smell! They would die of hunger rather than touch it! One cone-bearing tree and one only is excepted: the cedar. They will eat the leaves of that. Why the cedar and not the others? I do not know. The Caterpillar’s stomach is as particular as ours, and has its secrets.

To guide them as they wander about their tree, the Caterpillars have their silk ribbon, formed by threads from their mouths. They follow this on their return. Sometimes they miss it and strike the ribbon made by another band of Caterpillars. They follow it and reach a strange dwelling. No matter! There is not the least quarreling between the owners and the new arrivals. Both go on browsing peacefully, as though nothing had happened. And all without hesitation, when bedtime comes, make for the nest, like brothers who have always lived together; all do some spinning before going to rest, thicken the blanket a little, and are then swallowed up in the same dormitory. By accidents like these some nests grow to be very large. 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 anything. But there are hundreds and hundreds of them in the spinning-mill; and the result of their tiny contributions is a stuff belonging to all, a thick blanket splendidly warm in winter. In working for himself, each works for the others; and the others work for him. Lucky Caterpillars that know nothing of property, the cause of strife!