CHAPTER XXXII

INSECTS

We now come to the second of the two great divisions of the animal kingdom, namely, the invertebrates, which includes all those creatures which have no bones. This division in its turn consists of a good many classes, just as that of the vertebrates does; and among these is that of the insects, the peculiarity of which is that they must pass through three stages of development before they reach their perfect form, namely: first the egg; then the grub, or caterpillar; and then the chrysalis, or pupa.

You can easily tell an insect when you see it by remembering one or two simple rules.

In the first place, its body is always divided into three principal parts, which are known as the head; the thorax, or chest; and the hind body.

In the second place, it always has six legs. Spiders have eight legs. Centipedes and millepedes have many legs. But an insect never has more nor less than six. And each of these limbs is made up of a thigh, a lower leg, and a foot; while the foot itself has from two to five little joints, the last of which usually has a pair of tiny claws at the tip.

Besides these, there are several other ways in which insects differ from the rest of the vertebrates. We need only tell you about one of them, however, and that is that in some form or other they always have four wings. Sometimes, it is true, you cannot see these wings. That is because they are not developed and cannot be used for flying. But still they are there, and by means of the microscope it is almost always easy to detect them.

These wings, however, take all sorts of forms. The wings of a butterfly, for example, are very different from those of a beetle or a bee; and because of these differences in the wings, insects are divisible into several smaller groups, which we call orders.

BEETLES

First comes the order of the beetles. These are called _Coleoptera_, or sheath-winged insects, because their front wings, instead of being formed for flight, are turned into horny or leathery sheaths, or elytra, which cover up and protect the lower pair while not in use.

At least 150,000 different kinds of beetles have already been discovered in various parts of the world, of which America possesses tens of thousands; and probably quite as many more remain to be distinguished. Of these we can only mention a few of the most interesting.

The tiger-beetles are so called because they are such fierce and voracious insects, spending most of their time in chasing and devouring other insects. The commonest of them is about half an inch long, and is bright green above and coppery below. You may often see it darting about in the hot sunshine, and if you try to catch it you will generally find that it flies away as quickly as a bluebottle.

Ground-beetles are common in gardens. One often seen is about an inch long, and is deep black in color, with a narrow band of violet running round the outer edge of its wing-cases. This, too, is a creature of prey. It cannot hurt you; but if you pick it up it will make your fingers smell very nasty. For it can pour out from its mouth a drop or two of a dark-brown liquid which has a horrible odor.

Then there are a good many beetles which live in streams and ponds, and are called water-beetles in consequence. They can swim and dive very well, and are also able to fly. Almost every night they go for long journeys through the air. And when they want to go back into the pond they hover above it for a moment, fold their wings, and drop into the water with a splash. Only sometimes they fly over the roof of a greenhouse, and mistake that for a pond; and then you can imagine the result!

The cocktails are beetles with short wing-cases and very long, slender bodies, which they carry turned up at the rear end. Some of them are quite large, like the ugly black "coach-horse," but many are very small. Indeed, most of the "flies" which get into one's eyes on warm sunny days in England are really tiny cocktail beetles, and the reason why they make one's eyes smart so dreadfully is that they pour out a little drop of an evil-smelling liquid from their mouths, just like the purple ground-beetle.

SCAVENGERS

The burying-beetles are so called because they bury dead animals. Have you ever wondered why we so seldom find a dead mouse or a dead bird, although these creatures must die in thousands every day? One reason is that as soon as they are dead a couple of "scavengers" are almost sure to come and bury them. They are big black beetles, sometimes with two broad yellow stripes across their wing-cases, and they dig by means of their heads, scooping out the earth from under the carcass till it has sunk well below the surface of the ground. Then they lay their eggs in it, come up to the surface, shovel back the earth till the dead body is quite covered over, and then fly away. And when the eggs hatch, the little grubs which come out from them feed upon the carcass.

Among the largest beetles are those called stag-beetles because the jaws of the male look very much like the horns of a stag. Those of the female are much smaller, but are so sharp and strong that they can really give a rather severe bite. These occur in various parts of the world, and are fond of flying slowly about on a warm summer evening, generally about twenty or thirty feet from the ground.

The cockchafer is common everywhere in spring, and if you shake a young birch-tree, or a hazel-bush, three or four of the great clumsy insects will very likely come tumbling down. They are rather more than an inch long, very stoutly and heavily built, and are chestnut brown in color, while their bodies are drawn out into a kind of point behind. The grubs of these beetles live underground, and do a great deal of mischief in fields and gardens, for they feed upon the roots of the plants, and very soon kill them.

Dor-beetles, too, are very common everywhere. You may often see them flying round and round in great circles on warm summer evenings, making a loud humming noise as they do so. They often blunder in at open windows, attracted by the lamplight, and children are afraid of them, but they can do no harm. If you catch one you will find that it is nearly black. You will also see that its front legs are broad and strong, and that they are set with a row of stout horny teeth. With these legs the beetle digs, using them with such address that in the course of an hour or two it will sink a hole in the ground ten or twelve inches deep, in order to lay its eggs at the bottom.

The famous Scarabæus of Egypt, which in days of old some of the people of that country used to revere, because they thought it a symbol of immortality, is really a kind of dor-beetle.

SKIPJACKS AND GLOWWORMS

Skipjacks, too, are beetles. You may know them by their long, narrow, glossy bodies, and by the fact that the head is hidden under the thorax, so that you can hardly see it from above. One very odd thing about them is that they are constantly losing their footing and rolling over on their backs; and their bodies are so shiny, and their legs are so short, that when they do so they cannot get up again in the ordinary manner. But after lying still for a moment they arch themselves into the form of a bow, resting only upon their heads and the very tips of their tails, and suddenly spring into the air, making an odd clicking noise as they do so. And as they fall they turn half round, and so alight upon their feet. For this reason they are often known as click-beetles.

These insects are the parents of the well-known wireworms, which often do such mischief in our fields and gardens, living underground for three or even four years, and feeding upon the roots of the crops, and of such bushes as the currant.

Then the glowworm is a beetle. Perhaps you may have seen its little pale green lamp shining in the grass on a summer evening. The light comes from a liquid inside the hind part of the body, the skin of which is transparent, and forms a kind of window, so that it can shine through; and the insect has the power of turning on its light and shutting it off at will. The lamp of the female beetle is very much brighter than that of the male, and while the male has both wing-cases and wings, and can fly very well indeed, those of the female are so small that one can hardly see them. Indeed, she looks much more like a grub than a beetle.

DEATHWATCHES AND OIL-BEETLES

Deathwatches are small brown beetles which burrow into dead wood and call to one another by tapping with their horny heads. You may often hear them if you happen to be lying awake at night in a room in which there is old woodwork; and in former days people were silly enough to think that when this sound was heard it was a sign that somebody in the house was going to die! That is why these beetles are called deathwatches. They are quite small, and are brown in color, with rather long feelers and legs.

Crawling on grassy banks in the warm sunshine on bright spring days, you may often see a number of oil-beetles. These are large bluish-black insects which have an odd habit, if you pick them up, of squeezing out little drops of a yellow oily liquid from the joints of their legs! This oil has a pungent smell, and no doubt prevents birds, etc., from eating them. You will notice that the female beetles have enormous hind bodies, which they can hardly drag along over the ground. This is because they contain such a very large number of eggs, thirty thousand often being laid by a single beetle. She places them in batches in holes in the ground, and very soon afterward they hatch, and odd-looking little grubs with six long legs come out of them. No sooner have they left the egg-shells than these tiny creatures hunt about for a flower with sweet juices, which is likely to be visited by a wild bee. When they find one, they climb up the stem and hide among the petals. Then, when the bee comes, they spring upon it and cling to its hairy body, and so are carried back to its nest, where they feed upon the food which the bee had stored up for its little ones.

WEEVILS AND OTHER BEETLES

A great many beetles have a long beak in front of the head, with the jaws at the very tip. These are called weevils, and many of them are very mischievous. Grain of various kinds, for example, is destroyed in enormous quantities by the wheat-weevil and the rice-weevil, while the nut-weevil is the cause of those "bad" nuts which no doubt most of you know only too well. The mother beetle bores a hole through the shell of the nut while it is small, and the little grub which hatches out from the egg she leaves inside it feeds upon the kernel, leaving nothing behind but a quantity of evil-tasting black dust.

One of the handsomest of European insects is the musk-beetle, which you may often find sunning itself on the trunks and leaves of willow-trees in England in July. Often you can smell it long before you find it, for it gives out a strong odor much like that of musk. This beetle is sometimes nearly an inch and a half long, with long legs and still longer waving black feelers. In color it is rich golden green with a tinge of copper. But if you put one of its wing-cases under the microscope, it looks like a piece of green velvet studded all over with diamonds, and rubies, and sapphires, and emeralds, and topazes, which seem to turn into one another with every change of light.

The grub of this beetle lives inside the trunks of dying willow-trees, and feeds upon the solid wood.

Then there are the turnip-fleas, little black beetles with a yellow stripe on each wing-case, which skip about just as fleas do, by means of their hind legs. They are only too common in turnip-fields, and often do most serious mischief, nibbling off the seed-leaves of the young plants as soon as they push their way above the surface of the ground, and so destroying the greater part or even the whole of the crop.

And, lastly, there are the ladybirds, common everywhere. But perhaps you did not know that they are among the most useful of insects. The fact is that both as grubs and as perfect insects they live upon the green blight, or greenfly, an aphis which is terribly mischievous in fields and gardens, and destroy it in thousands of thousands. Indeed, if it were not for ladybirds, and for one or two other insects which help them in their task, we should find it quite impossible to grow certain crops at all.

EUPLEXOPTERA

Next after the beetles comes the order of the _Euplexoptera_, which means beautifully folded wings. This order contains the earwigs. We do not know much about these insects in the United States; but they are so constantly spoken of in books about England, where they are numerous, that it will be well to describe them.

Perhaps you did not know that earwigs have wings; and certainly one does not often see these beetles flying. But nevertheless they have very large and powerful wings, only, during the daytime, while they are not being used, these organs are folded away in the most beautiful manner under the tiny wing-cases. By night, however, earwigs often fly; and when they settle, they fold up their wings most cleverly by means of the horny pincers at the tail-end of their bodies, and then pull the wing-cases down over them!

That is the real use of the pincers, although the earwig is able to give quite a smart pinch with them if it is interfered with.

Another very curious fact about the earwig is that the mother insect heaps her eggs together into a little pile, and sits over them until they are hatched. If you turn over large stones early in the spring you may often find a mother earwig watching over her eggs in this odd manner, and she will allow herself to be torn in pieces rather than desert her charge.

ORTHOPTERA

Next comes this order, the name of which means straight-winged insects, so-called from the way in which the wings are folded. This order contains many very well-known insects.

There is the cockroach, for example, which is so common and so mischievous in our houses. It is often called the black beetle, although it is not a beetle at all, and is not black, but dark reddish brown. It is remarkable for several reasons. One is that while the male has large wing-cases and broad, powerful wings, those of the female are very small indeed, so that she cannot possibly fly. And another is that the eggs are laid in a kind of horny purse, about a quarter of an inch long, with a sort of clasp on one side. These little purses are hidden away in all sorts of dark corners, and if you open one you will find two rows of little eggs inside it, arranged rather like the peas in a pod.

The crickets, too, belong to this order.

Of course you have often heard the big black cricket chirping merrily away in the fields; and in Europe they have a kind called the house-cricket, which comes into the house, and is often spoken of as "the cricket on the hearth" in the kitchen. It is not correct, however, to speak of the "note" or "song" of this insect, for it is not produced in the throat at all, but is caused by rubbing one of the wing-cases upon the other. You will notice, on looking at a cricket, that in each wing-case there is a kind of stout horny rib, which starts from a thickened spot in the middle. Now in the right wing-case this rib is notched, like a file, and when it is rubbed sharply upon the other the loud chirping noise is produced.

The feelers of the cricket are very long and slender, and at the end of the body of the male are two long hairy bristles, which seem almost like a second pair of feelers, warning the insect of danger approaching from behind. At the end of the body of the female is a long spear-like organ, with a spoon-like tip. This is called the ovipositor, and by means of it the eggs are laid in holes punched in the soil.

Crickets have large wings, and fly rather like the woodpeckers, rising and falling in the air at every stroke.

Another kind of cricket lives in holes in the ground, which it digs by means of its front legs. These limbs are formed almost exactly like the fore feet of the mole, and for this reason the insect is known as the mole-cricket. It is generally found in sandy fields, and scoops out a chamber almost as big as a hen's egg at the end of its burrow, in which to lay its eggs and where it lies, showing only its jaws and great front legs until some small creature comes near upon which it may pounce for food.

GRASSHOPPERS

Right here has come a mixing up of names between the English, as spoken and written in Great Britain, and that used in the United States. When an Englishman speaks of a grasshopper he means the related insect which we call a cicada, or katydid, and this _we_ call a locust; but when _he_ says "locust" he refers to what _we_ call "grasshopper." We suspect he is nearer right than we are, who have unfortunately fallen in with the mistake of some ignorant early settler. At any rate the locusts of which we read in the Bible, and in books of travel in desert regions, are all of the same race as our grasshoppers. None of the cicada tribe could ever do so much damage.

Grasshoppers (to stick to our own name) abound in all warm countries, especially in those which in summer, at least, are hot and dry, such as Egypt, or Syria, or parts of India. They feed exclusively on leaves, blades of grass, and the like, and are strong fliers; and in countries that are favorable to them, where they are always very plentiful, certain species sometimes become excessively abundant, and then spread over the land, and swarm away to neighboring countries, in such immense numbers that they devour every green leaf and every blade of grass, or spear of grain, until they leave the ground as bare as if it had been swept by fire.

Nor is this the worst, for wherever they go the females push quantities of eggs down into the ground. The following summer these eggs hatch, and the devastation of the previous year is repeated, for where before dense clouds of flying grasshoppers descended from the sky, now enormous armies of grubs march over the ground, climb all the plants and bushes, and devour all that has newly sprung up.

Millions may be killed by fire or other means, but it has little effect, and the farmers and grazers of a region so visited are all but ruined--perhaps wholly so.

When, in the last century, men began to settle on the prairies of the far West, they met this plague; and between 1870 and 1880 the gardens and farms and young orchards of Kansas, Nebraska, and other western districts, were ruined again and again. The government sent out several of the wisest entomologists it could employ to study the insects, and they found that these destructive red-legged grasshoppers had their home in the dry foothills of the Rocky Mountains, especially toward the north. They learned a great deal about the habits of the insects, and reported that there seemed no remedy just at hand; but that the more the West was settled and cultivated, the more grass and other food would be provided for the grasshoppers, so that they would not have to make those wide flights, and the more the plowing of the land and burning of rubbish would destroy their eggs, so that gradually the pest would become less and less, until finally it would cease to be troublesome. This has turned out to be true, and already the fear of grasshoppers has departed. The same thing is taking place in Egypt and some other improving countries, which no longer suffer from the plague of locusts as they used to do.

The wonderful walking-stick and the leaf-insects also belong to this order. They are so marvelously like the objects after which they are named that as long as they keep still it is almost impossible to see them. They seem to know this perfectly well, and will remain for hours together without moving, waiting for some unwary insect to come within reach, for they are among the insects of prey. They are found in all the warmer parts of the world.

Equally curious, too, is the praying-mantis, which also is very much like a leaf. It has very long front legs, with a row of sharp teeth running along their inner margin, and when it is hungry it holds these limbs over its head, in very much the attitude of prayer. That is why it is called the praying-mantis. Then when an insect comes within reach it strikes at it, and seizes it between the upper and lower parts of these limbs, so that the long spike-like teeth enter its body and hold it in a grip from which there is no escape. These occur in various parts of the world, including the warmer parts of America.

DRAGON-FLIES AND MAY-FLIES

The dragon-flies belong to another division of the _Orthoptera_. You must know these insects very well by sight, with their long slender bodies and their broad gauzy wings; for they are common in almost all parts of the country, and you can hardly go for a ramble on a sunny day in summer or autumn without seeing them in numbers. There are a good many different kinds. Some have yellow bodies, some blue ones, and some red ones, and the loveliest of all perhaps are the graceful demoiselles, whose wings are rich metallic purple. You may sometimes see these beautiful insects flitting to and fro over streams and ditches.

All the dragon-flies spend the earlier part of their lives in the water. The grubs are very curious creatures and catch their prey in a curious way. Underneath the head is an organ called the mask. This consists of two horny joints, which fold upon one another while not in use. At the end of the second joint is a pair of great sickle-shaped jaws, and when the grub sees a victim it swims quietly underneath it, unfolds the mask, reaches up, and seizes it with the jaws. Then it folds the mask again, and by so doing drags the prisoner down against the true jaws, by means of which it is leisurely devoured.

This grub swims, too, in a singular manner. At the end of its body you will notice a short sharp spike. Now this spike really consists of five points, which can be opened out into the form of a star; and in the center of this star is a small round hole, which is really the entrance to a tube running right through the middle of the body. And the grub swims by filling this tube with water, and then squirting it out again with all its force, so that the escaping jet pushes, as it were, against the surrounding water, and drives the insect swiftly forward by the recoil.

Dragon-flies are voracious, and always seem to be hungry. They feed entirely upon other insects, and spend almost all their time in chasing and devouring them.

The May-fly, or June-fly, also belongs to this order. One sometimes sees it in thousands, dancing, as it were, up and down in the air toward evening on warm spring days, in the neighborhood of water. You can always tell this insect by the three long thread-like bristles at the end of its body.

Most people think that this insect only lives for a single day. This, however, is not strictly true, for in damp weather many May-flies live for three or four days. Before they become perfect flies, however, they have lived for nearly two years in the muddy banks of rivers and ponds, in the form of long slender-bodied grubs. These grubs always make their burrows with two entrances, in the form of the letter U turned sideways, so that they can easily leave them without having to turn round.

TERMITES

The most wonderful of all the insects which belong to this order, however, are the termites. Often these creatures are known as white ants, and although they are not really ants, they are certainly very much like them. In Africa they make marvelous nests of clay, which are often twelve or fourteen feet high, and are so very large that a church, a parsonage, and a schoolroom have been built of clay slabs cut from the walls of a single termites' nest! These nests are made up of a wonderful series of chambers and galleries, and in the middle is the royal cell, in which the "king" and "queen" live. For in every termites' nest there is one perfect male and one perfect female, which are treated with very great respect, and have a kind of palace, as it were, all to themselves. And the rest of the insects in the nest are either imperfect males, which are called soldiers, or imperfect females, which are called workers.

The "king" is quite a handsome and graceful insect, with broad and powerful wings; and the "queen," at first, is very much like him. But they never take more than one flight in the air, and as soon as that is over they actually break off their own wings close to their bodies! Then they burrow into the ground and begin to form a nest. Before long, the workers build the palace for the royal couple; and as soon as they have been shut up inside it the body of the queen swells to a most enormous size, so that she can no longer walk at all. This is because of the vast number of eggs, developing within her body, which she at once begins to lay at the rate of many thousands in a single day. As fast as she lays them they are carried off by the workers, which also take care of the little grubs that hatch out from them, just as bees do.

The duty of the soldiers, as their name implies, is simply to fight, and if a hole is broken in the side of the nest they hurry to the spot at once, and begin to snap with their jaws at the foe. And these jaws are so sharp and so powerful that they can really give a very smart bite. The workers are a good deal smaller, and they have to build the nest and keep it in repair, to find food for the grubs, and take care of them, and wash them, and feed them, and do everything else that is necessary for the welfare of the colony.

The grubs of these insects are fed upon dead wood, which is generally obtained from the trunks and branches of trees. But termites are sometimes very troublesome in houses, for they will devour the woodwork and the furniture and the books, leaving nothing but a thin shell of wood or paper behind them.

There are a good many different kinds of these wonderful insects, and they are found in warm countries in all parts of the world.

The North American termites do not build great clay hills or houses above ground, but some species make extensive galleries beneath the surface, while others hollow out a dead stump, or the dying branch of a tree, or even an old fence-post or telegraph pole, until it becomes a mere sponge, with a thin outside shell.

NEUROPTERA

The _Neuroptera_, or nerve-winged insects, form an order whose wings are divided up by horny nerves, or nervures, into such numbers of tiny cells, that they look as if they were made of the most delicate lace.

The caddis-flies belong to this order--brownish insects with long thread-like feelers and broad wings, which are folded tentwise over the body when they are not being used. They are very common near ponds and streams, in which they pass the earlier part of their lives, living down at the bottom in most curious cases, which cover them entirely up with the exception of their heads.

These cases are made of all sorts of materials. Some caddis-grubs merely fasten two dead leaves together, face to face, and live between them. Others make a kind of tube out of grains of sand, or tiny stones, or little bits of cut reed, all neatly stuck together with a kind of glue which resists the action of water. But the oddest case of all is made of tiny living water-snails, and you may sometimes see fifteen or twenty little snails all trying to crawl in different directions, while the grub is unconcernedly pulling them along in another!

The grubs never leave these cases, but drag them about with them wherever they go. And when they find that their odd little homes are becoming too small, they just cut off a little piece at the end and add a little piece on in front, rather larger in diameter. And so they always manage to keep their homes of exactly the proper size.

Most likely, too, you have heard of the ant-lion fly, which is a rather large fly with a slender body and four long narrow wings, and is found in many parts of the south of Europe, as well as in America. But the interest lies in the grub, or "ant-lion" proper, which has a most singular way of catching its insect victims. It digs a funnel-shaped pit in the sand, about three inches in diameter and two inches deep, by means of its front legs and its head. Then it almost buries itself at the bottom, and lies in wait to snap up any ants or other small insects which may be unfortunate enough to fall in. And if by any chance they should escape its terrible jaws and try to clamber up the sides, it jerks up a quantity of sand at them, and brings them rolling down again to the bottom, so that they may be seized a second time.

A relation of the ant-lion is called the lacewing fly, and is a pretty pale-green insect with most delicate gauzy wings, over which, if you look at them in a good light, all the colors of the rainbow seem to be playing; and its eyes glow so brightly with ruby light that one can scarcely help wondering if a little red lamp is burning inside its head. You may often see it sitting on a fence on a warm summer day, or flitting slowly to and fro in the evening.

This fly lays its eggs in clusters on a twig, or the surface of a leaf, each egg being fastened to the tip of a slender thread-like stalk. The result is that they do not look like eggs at all; they look much more like a little tuft of moss. When they hatch, a number of queer little grubs come out, which at once begin to wander about in search of the little greenfly insects upon which they feed. And when they have sucked their victims dry, they always fasten the empty skins upon their own backs, till at last they are covered over so completely that you cannot see them at all!