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.
[Illustration]
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.
[Illustration]
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?
[Illustration]
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.
[Illustration: “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!
[Illustration]