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.