The Animal World, A Book of Natural History Part 50

We now come to a very large and important order of insects indeed--that of the _Hymenoptera_. This name means membrane-winged, and has been given to them because their wings are made of a transparent membrane stretched upon a light h.o.r.n.y framework. It is not a very good name, however, for many insects which do not belong to this order at all have their wings made in just the same way. All the _Hymenoptera_, however, have the upper and lower wings fastened together during flight by a row of tiny hooks, which are set on the front margin of the lower pair, and fit into a fold on the lower margin of the upper ones.

BEES

The bees belong to this order, and most wonderful insects they are--so wonderful, indeed, that a big book might easily be written about them.

They are divided into two groups, namely, social bees and solitary bees.

The social bees are those which live together in nests; and our first example, of course, must be the hive-bee.

In every beehive there are three kinds of bees. First, there are the drones, which you can easily tell by their stoutly built bodies and their very large eyes. They are the idlers of the hive, doing no work at all, and sleeping for about twenty hours out of every twenty-four. For six or eight weeks they live only to enjoy themselves. But at last the other bees become tired of providing food for them. So they drive them all down to the bottom of the hive and sting them to death one after another. And that is the end of the drones.

Next comes the queen, the mistress of the hive. You can easily recognize her, too, for her body is much longer and more slender than that of the other bees, and her folded wings are always crossed at the tips.

The other bees treat her with the greatest respect, never, for example, turning their backs toward her. And wherever she goes a number of them bear her company, forming a circle round her, in readiness to feed her, or lick her with their tongues, or do anything else for her that she may happen to want. Her chief business is to lay eggs; and she often lays two or three hundred in the course of a single day.

Lastly, there are the workers. There are many thousands of these, and they have to do all the work of the hive, making wax and honey, building the combs, and feeding and tending the young.

The comb is made of six-sided cells, and is double, two sets of cells being placed back to back. Some of these cells are used for storing up honey. But a great many of them are nurseries, so to speak, in which the grubs are brought up. These grubs are quite helpless, and the nurse-bees have to come and put food into their mouths several times a day.

Fastened to the outside of the combs, there are always several cells of quite a different shape. They are almost like pears in form, with the smaller ends downward. These are the royal nurseries in which the queen grubs are brought up.

Bees feed their little ones with a curious kind of jelly, made partly of honey and partly of the pollen of flowers. This is called bee-bread; and it is rather strange to find that one kind of bee-bread is given to the grubs of the drones and the workers, while quite a different kind is given to those of the queens.

You will want, of course, to know something about the sting of the bee--though perhaps you already know enough of the pain it can give!

This is a soft organ, enclosed in a h.o.r.n.y sheath, with a number of little barbs at the tip. When a bee stings us, it is often unable to draw the sting out again, because of these barbs. So it is left behind in the wound, and its loss injures the body of the insect so severely that the bee very soon dies. The poison is stored up in a little bag at the base of the sting, which is arranged in such a way that when the sting is used a tiny drop of poison is forced through it, and so enters the wound.

Then, no doubt, you would like to know how bees make honey; but that neither we nor any one can tell you. All we know is, that the bee sweeps out the sweet juices of flowers with its odd brush-like tongue and swallows them; that they pa.s.s into a little bag just inside the hind part of its body, which we call the honey-bag; and that by the time the bee reaches the hive they have been turned into honey. But how or why the change takes place no one knows at all.

b.u.mblebees, or humblebees, are also social bees; but their nests are not quite as wonderful as those of the hive-bee, and their combs are not so cleverly made.

One of these bees is called the carder, and you may sometimes find its nest in a hollow in a bank. But it is not at all easy to see, for the bee covers over the hollow with a kind of roof, which is made of moss and lined with wax. And this looks so like the surrounding earth that even the sharpest eye may often pa.s.s it by. When this roof is finished, the bee makes a kind of tunnel, eight or ten inches long and about half an inch in diameter, to serve as an entrance; and this is built of moss and lined with wax in just the same way.

On a warm sunny day in spring you may often see one of these bees flying up and down a gra.s.sy bank searching for a suitable burrow in which to build. Then you may be quite sure that she is a queen. For among b.u.mblebees the drones and workers die early in the autumn, and only the queens live through the winter.

Solitary bees are very common almost everywhere, and you may find their nests in all sorts of odd places. One kind of solitary bee, for example, builds in empty snail-sh.e.l.ls, and another in small hollows like keyholes. A third gnaws out a burrow in the decaying trunk of an old tree, or in the timbers of a barn or house-porch and makes a number of thimble-shaped cells out of little semicircular bits of rose-leaf, which it cuts out with its scissor-like jaws. Haven't you noticed how often the leaves of rose-bushes are chipped round the edges, quite large pieces being frequently cut away? Well, that is the work of the leaf-cutter bee, as this insect is called, and very often not a single leaf on a bush is left untouched.

But the commonest of all the solitary bees burrows into the ground. As you walk along the pathway through a meadow in spring, you may often see a round hole in the ground, just about large enough to admit an ordinary drawing-pencil. That is the entrance to the burrow of a solitary bee; and if you could follow the tunnel down into the ground you would find that it was about eight or ten inches deep, and that at the bottom were four round cells. In each of these cells the bee lays an egg. Then it fills the cells with flies, or spiders, and caterpillars, or beetles, for the little grubs to feed upon when they hatch out. For solitary bees do not nurse their little ones, as social bees do, and feed them several times a day. But at the same time the grubs are quite helpless, and cannot possibly go to look for food for themselves. So the mother bee has to store up sufficient to last them until the time comes for them to spin their coc.o.o.ns and pa.s.s into the chrysalis state. These are only a few examples of a large number of interesting ways in which the solitary bees in various parts of the world provide for their young.

WASPS

Wasps make nests which are almost as wonderful as those of the hive-bee.

That of the common yellow-jacket wasp is generally placed in a hole in the ground, or in a cavity under a stone, and is made of a substance very much like coa.r.s.e paper, which the wasps manufacture by chewing wood into a kind of pulp. You may often see them sitting on a fence, or on the trunk of a dead tree, busily engaged in sc.r.a.ping off shreds of wood for this purpose. When the nest is finished it is often as big as a football, and of very much the same shape; and inside it are several stories, as it were, of cells placed one above another, and supported by little pillars of the same paper-like material. These cells are six-sided, like those of the hive-bee, but they are squared off at the ends, instead of being produced into pointed caps, and they always have their mouths downward. In a large nest there may be several thousands of these cells, and very often three generations of grubs are brought up in them, one after the other.

The hornet, which is really a kind of big wasp, makes its nest in just the same way, but places it on a beam in an out-house, or in a hole which the sparrows have made in the thatched roof of a house, or in a hollow tree, or perhaps hangs it in the open air to the bough of a tree.

ANTS

Even more wonderful than bees and wasps are the ants, which sometimes do such extraordinary things that we are almost afraid to tell you about them, for fear that you might not believe us. There are ants, for example, which actually take other ants prisoners and make them act as slaves, forcing them to do all the work of the nest, which they are too lazy to do themselves; and there are ants which keep large armies, sometimes more than one hundred thousand strong; and there are many ants which harvest grain and store it away in underground barns! Many ants, too, keep little beetles in their nests as pets, and fondle and caress them just as one might pat a dog, or stroke a favorite cat. They even allow them to ride on their backs; while, if the nest is opened, the first thing they think of is the safety of their pets which they pick up at once and hide away in some place of safety, even before they carry off their own eggs and young. They also pet tiny crickets and small white wood-lice in just the same way.

Then ants have little "cows" of their own, which they "milk" regularly every day. These are the greenfly or aphis insects which do so much harm in our gardens and fields, plunging their beaks into the tender shoots and fresh green leaves of the plants, and sucking up their sap unceasingly. And as fast as they do so they pour the sap out again through two little tubes in their backs, in the form of a thin, sticky, very sweet liquid which we call honeydew. Now the ants are very fond of this liquid, and if you watch the greenfly insects which are almost always so plentiful on rose-bushes, you may see the ants come and tap them with their feelers. Then the little creatures will pour out a small quant.i.ty of honeydew from the tubes on their backs, which the ants will lick up. That is the way in which ants milk their little cows, and they are so fond of the honeydew that they will carry large numbers of these aphides into their nests and keep them, like a herd of cattle, all through the winter, so that they may never be without a supply of their favorite beverage!

Ants, like bees and wasps, almost always consist of drones, queens, and workers. Only the drones and queens have wings, and these are seldom seen until the end of August. But then they make their appearance in vast swarms, which are sometimes so dense that from a little distance the insects really look like a column of smoke. They only take one short flight, however, and when this is over they come down to the ground and snap off their wings close to their bodies, just as termites do.

One of the most curious of all these insects is the parasol-ant, of South America, which makes enormous dome-shaped nests of clay. But as the clay will not bind properly by itself, the insects work little pieces of green leaf up with it. These pieces of leaf are generally obtained from an orange plantation, perhaps half a mile distant. And when the ants are returning from their expedition, each holds its little piece of leaf over its head as it marches along, just as if it were carrying a tiny green parasol!

Another very famous ant is the African driver, which owes its name to the way its vast armies drive every living creature before them.

Insects, reptiles, antelopes, monkeys, even man himself, must give way before the advancing hosts of the drivers; for it is certain death to stand in their path.

SAW-FLIES

The saw-flies also belong to the order of the _Hymenoptera_. These flies are so called because the female insects have two little saws at the end of the body, which work in turns, one being pushed forward as the other is drawn back. With these they cut little grooves in the bark of twigs, or in the midribs of leaves, in which they place their eggs by means of the ovipositor between the saws.

Some of these insects are extremely mischievous. The grub of the turnip saw-fly, for instance, often destroys whole fields of turnips, while the currant saw-fly is equally destructive to currants and gooseberries. One often sees bushes which it has entirely stripped of their leaves.

You may always know a saw-fly grub by the fact that it has no less than twenty-two legs--three pairs of true legs on the front part of the body, and eight pairs of false legs, or prolegs, as they are often called, on the hinder part.

There is one little family of saw-flies, however, which are quite unlike all the rest, for instead of having saws at the ends of their bodies, they have long boring instruments, very much like brad-awls. With these they bore deep holes in the trunks of fir-trees, in order to place their eggs at the bottom; and the grubs feed, when they hatch out, on the solid wood.

These insects are known as horn-tailed saw-flies, and one, which is very common in pine woods, is very large, sometimes measuring an inch and a half from the head to the tip of the tail, and very nearly three inches across the wings, while the boring tool is fully an inch long. It is a very handsome insect, and looks rather like a hornet, the head and thorax being deep glossy black and the hind body bright yellow, with a broad black belt round the middle. The feelers are also yellow, and the legs are partly yellow and partly black.

GALL-FLIES

Another group of the _Hymenoptera_ consists of the gall-flies.

These are all small insects, which lay their eggs in little holes which they bore in roots, twigs, and the ribs and nervures of leaves. In each hole, together with the egg, they place a tiny drop of an irritating liquid, which causes a swelling to take place, on the substance of which the little grub feeds. Sometimes these galls, as they are called, take most curious forms. The pretty red and white oak-apples of course you know; and no doubt, too, you have often found the hard, woody, marble-shaped galls which are so common on the twigs of the same tree.

Then some galls look like bunches of currants, and some look like scales, and some look like pieces of sponge. And if you cut one of them open you will find perhaps one little grub, or perhaps several, curled up inside them.

[Ill.u.s.tration: LEAF-EATING INSECTS OF SHADE-TREES.

TUSSOCK MOTH: 1, caterpillar (black and yellow, head red); 2, male moth (mottled gray); 3, wingless female laying eggs on her recently vacated coc.o.o.n; 4, coc.o.o.ns; 5, cast skins of young caterpillars; 6, work of youth caterpillars under the surface of a leaf; 7, male pupa; 8, branch girdled by caterpillar; 9, broken end of girdled twig.

FOREST TENT-CATERPILLAR: 10, female moth (buff); 11, male moth (rust-red); 12, egg-belt; 13, fully grown caterpillar, or "maple-worm" (dull blue, red-streaked); 14, coc.o.o.n in leaf; 15, pupa; 16, cast skins.]

ICHNEUMON-FLIES

This is the last group of _Hymenoptera_ that we can mention. These insects lay their eggs in the bodies of caterpillars or chrysalids, and sometimes in those of spiders, boring holes to receive them by means of their little sting-like ovipositors. Before long the eggs hatch, and the little grubs at once begin to feed upon the flesh of their victims. For some little time, strange to say, the unfortunate creature seems to suffer no pain, or even discomfort, but goes on feeding and growing just as before, although hundreds of hungry little grubs may be nibbling away inside it. Sooner or later, however, it dies; and then the little grubs spin coc.o.o.ns and turn to chrysalids, out of which other little flies appear in due course, just like the parents.

Millions of caterpillars are destroyed by these little flies every year.

Out of every hundred of those which do so much damage to our cabbages and cauliflowers, for example, at least ninety are sure to be "stung."

Indeed, if it were not for ichneumon-flies we should find it quite impossible to grow any crops at all, for they would all be eaten up by caterpillars.

LEPIDOPTERA

Next we come to the b.u.t.terflies and moths, which are called _Lepidoptera_, or scale-winged insects, because their wings are covered with thousands upon thousands of tiny scales. If you catch a b.u.t.terfly, a kind of mealy dust comes off upon your fingers, and if you look at a little of this dust through a microscope, you find that it consists simply of little scales, of all sorts of shapes. Some are like battledores, and some like masons' trowels, and they are nearly always most beautifully sculptured and chiseled. These scales lie upon the wing in rows, which overlap one another like the slates on the roof of a house. And sometimes there are several millions on the wings of a single insect.