THE HAIRY SAND-WASPS

A SLENDER waist, a slim shape; an abdomen tapering very much at the upper part and fastened to the body as though by a thread; black raiment with a red sash across the belly: there you have a short description of the burrowing Sand-Wasps, who hunt Caterpillars.

The Sand-Wasps choose for their burrows a light soil, easily tunneled, in which the sand is held together with a little clay and lime. Edges of paths, sunny banks where the grass is rather bare—these are the favorite spots. In spring, quite early in April, we see the Hairy Sand-Wasp there.

Its burrow is a straight up-and-down hole, like a well, about as thick as a goose-quill and about two inches deep. At the bottom is a solitary cell, to hold the egg. The Sand-Wasp digs by herself, quietly, without hurrying, without any joyous enthusiasm. As usual, the front feet serve as rakes and the jaws do duty as mining-tools. When some grain of sand is very hard to remove, you hear rising from the well a sort of shrill grating sound made by the quivering of the insect’s wings and of her whole body. Every little while the Wasp appears in the open with a load of dirt in her teeth, some bit of gravel which she usually flies away with and drops at a distance of a few inches, so as not to litter the place.

Some of these grains the Sand-Wasp does not treat as she does the rest. Instead of flying off and dropping them far from the work yard, she removes them on foot and lays them near her burrow. She has a special use for them. When her home is dug, she looks at this little heap of stones to see if there is any there to suit her. If there is not, she explores the neighborhood until she finds what she wants, a small flat stone a little larger in diameter than the mouth of her hole. She carries off this slab in her jaws and lays it, as a temporary door, over the opening of the burrow. To-morrow, when she comes back from hunting, the Wasp will know how to find her home, made safe by this heavy door; she will bring back a paralyzed caterpillar, grasped by the skin of its neck and dragged between her legs; she will lift the slab, which looks exactly like the other little stones around, and which she alone is able to identify; she will let down the game to the bottom of her well, lay her egg and close the house for good by sweeping into the hole all the rubbish, which she has kept near by.

The Hairy Sand-Wasp hunts a particular sort of prey, a kind of large Caterpillar called the Gray Worm, which spends most of its time underground. How does she then get hold of it? We shall see. One day I was returning from a walk when I saw a Hairy Sand-Wasp very busy at the foot of a tuft of thyme. I at once lay down on the ground, close to where she was working. My presence did not frighten the Wasp; in fact, she came and settled on my sleeve for a moment, decided that her visitor was harmless, since he did not move, and returned to her tuft of thyme. As an old stager, I knew what this tameness meant: the Wasp was too busy to bother about me.

The insect scratched the ground at the foot of the plant, where the root joined the stem, pulled up slender grass rootlets and poked her head under the little clods which she had lifted. She ran hurriedly this way and that around the thyme, looking at every crevice. She was not digging herself a burrow but hunting the game hidden underground; she was like a Dog trying to dig a Rabbit out of his hole.

Presently, excited by what was happening overhead, a big Gray Worm made up his mind to leave his lair and come up to the light of day. That settled him: the Wasp was on the spot at once, gripping him by the skin of his neck and holding tight in spite of his contortions. Perched on the monster’s back, the Wasp bent her abdomen and deliberately, without hurrying, like a clever surgeon, drove her lancet-sting into the back surface of each of the victim’s rings or segments, from the first to the last. Not a ring was left without receiving a stab; all, whether with legs or without, were dealt with in order, from front to back.

The Wasp’s skill would make science turn green with envy! She knows by instinct what man hardly ever knows; she knows her victim’s nervous system and exactly what nerve centers to strike to make it motionless without killing it. Where does she receive this knowledge? From the power that rules the world, and guides the ignorant by the laws of its inspiration.

I will tell you about another encounter of a Sand-Wasp with a Gray Worm which I witnessed. It was in May, when I detected a Sand-Wasp giving a last sweep of the rake to her burrow, on the smooth, hard path. She had paralyzed her Caterpillar, probably, and left it a few yards away from the home while she made ready the entrance. At last the cave is pronounced spick and span, and the doorway thought wide enough to admit the bulky prey. The Sand-Wasp sets off in search of her captive.

She finds it easily. It is a Gray Worm, lying on the ground: but, alas, the Ants have found it, too; they have already invaded it. The Wasp now scorns it. She will not have anything to do with a Worm which she must share with Ants. To drive them away is impossible; for each one sent to the right-about, ten would return to the attack. So the Wasp seems to think; for she goes on with her hunting, without indulging in useless strife.

She explores the soil within a radius of ten feet from the nest, on foot, little by little, without hurrying; she lashes the ground continually with her antennæ curved like a bow. For nearly three hours, in the heat of the sun, I watch her search. What a difficult thing a Gray Worm is to find, for a Wasp who needs it just at that moment!

It is no less difficult for man. I have a plan. I wish to give the Wasp a Worm in order to see how she paralyzes it.

Favier, my old soldier friend, is there, gardening. I call out to him:

“Come here, quick; I want some Gray Worms!”

I explain the thing to him. He understands at once and goes in search. He digs at the foot of the lettuces, he scrapes among the strawberry-beds, he inspects the iris-borders. I know his sharp eyes and his intelligence; I have every confidence in him. Meanwhile, time passes.

“Well, Favier? Where’s that Gray Worm?”

“I can’t find one, sir.”

“Bother! Then come to the rescue, you others! Claire, Aglaé, all of you! Hurry up, hunt and find!”

The whole family is put at work. All its members become very active. But nothing turns up: three hours pass and not one of us has found the Caterpillar.

The Sand-Wasp does not find it either. I see her hunting persistently in spots where the earth is slightly cracked. She wears herself out in clearing-operations; with a great effort she removes lumps of earth the size of an apricot-stone. These spots are soon given up, however. Then a suspicion comes to me: perhaps the Gray Worm, foreseeing a gathering storm, has dug its way lower down. The huntress Wasp very well knows where it lies, but cannot get it out from its deep hiding-place. Wherever the Sand-Wasp scratches, there must a Gray Worm be; she leaves the place only because she cannot dig deep enough. It was very stupid of me not to have thought of this earlier. Would such an experienced huntress pay any attention to a place where there is really nothing? What nonsense!

I make up my mind to help her. The insect, at this moment, is digging a tilled and absolutely bare spot. It leaves the place, as it has already done with so many others. I myself continue the work, with the blade of a knife. I do not find anything, either; and I leave it. The insect comes back and again begins to scratch at a certain part of my excavations. I understand:

“Get out of that, you clumsy fellow!” the Wasp seems to say. “I’ll show you where the thing lives!”

I dig at the spot she indicates and unearth a Gray Worm. Well done, my clever Sand-Wasp! Did I not say that you would never have raked at an empty burrow?

Following the same system, I obtain a second Gray Worm, followed by a third and a fourth. The digging is always done at bare spots that have been turned by the pitchfork a few months earlier. There is absolutely nothing to show the presence of the Caterpillar from without. Well, Favier, Claire, Aglaé, and the rest of you, what have you to say? In three hours you have not been able to dig me up a single Gray Worm, whereas this clever huntress supplies me with as many as I want, once that I have thought of coming to her assistance!

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!