THERE is an old German child's story of a little girl who being told that if she could find a place to hide her first silver piece where no eye could see her, and then dance round it three times, she would have her wish. She sought everywhere for such a place, but always some bird or squirrel or mouse or insect was near by, and even when she dug beneath the ground, there too were little crawling creatures watching her.

It may be said that this story was meant to show that animal life is found almost everywhere, and certainly beneath the surface of the ground there are hundreds of kinds of insects working steadily away at their different occupations; for whatever disagreeable things you may find to say about insects, you can never justly call them lazy. The scriptures recognized this fact in the well-known command to the sluggard, and the old nursery rhyme about the "busy bee" emphasizes the same characteristic.

The truest underground insects are those which pass their entire lives beneath the surface of the earth; which are born there, live and grow and die without seeing the light of day. Such, for example, are the true cave insects, a number of forms of which are found in the great caverns in different parts of the world. Some of these insects feed upon the vegetable molds and low forms of plant life found in caves; others feed on dead animal matter and still others upon living insects. Nearly all are of pale colors and are blind or nearly so, for they have no use for eyes in the darkness. All are supposed to be descendants of above-ground forms, which through many generations of life in the darkness have lost their color and their power of sight. The genealogy of these true cave forms may be guessed at with some certainty, for we know insects which are only partly transformed in structure from above-ground forms to true cave species. Such are certain beetles which live in the catacombs of Paris, and certain other insects which have been found in the old and deep burrows of the land tortoise in Florida.

But we do not have to go to caves to find many other true underground insects. Rich, loose soil abounds in such creatures which live upon the decaying vegetation (soil humus or vegetable mold) or upon one another. The most abundant in numbers of individuals are the little spring-tails or bristle-tails, minute creatures seldom more than a sixteenth of an inch in length and which frequently swarm in the ground in such numbers that the earth seems fairly alive. These little creatures are by no means confined to the surface soil, but have been found in great armies at a depth of six feet or more in stiff clay, which they have penetrated by following the deeper rootlets of trees. Certain of these little insects have also become so accustomed to this lightless life that they have lost their eyes.

Other true underground insects are found in the nests of ants, where they fill many different functions. They may be grouped, however as follows: 1. Species which are fed by the ants and from which the ants derive a benefit by eating a certain secretion of the insect. 2. Species which are treated with indifference by the ants and which feed upon the bodies of dead ants and other animal and vegetable debris to be found in ants' nests. The ants are certainly not hostile to these insects and evidently gain some unknown benefit from their presence. 3. Species which live among the ants for the purpose of killing and feeding upon them. The first true ants' nest insect was only discovered and studied at the beginning of this century, but since that time hundreds of other species have been found, and a mere catalogue of their names fills a book of over 200 pages.

Such insects are called "myrmecophilous species" or "ant lovers." The man who has done the most in the study of these interesting creatures is Dr. Wasmann, a Jesuit priest, who lives in Holland, and who has devoted many years to this work, and a difficult task it has been! If one digs into an anthill the inhabitants are at once alarmed and the greatest confusion results, so that it is necessary to study them in artificial nests in glass jars, or in some other way.

Although the most of these "ant-loving" insects are strictly subterranean species, living their whole lives underground, the ants, among which they live, do most of their foraging above ground, and thus may be taken as typical of a second group of underground insects—those which have their homes below ground for protection or concealment, but which themselves live, at least part of the time, above ground. Volumes have been written about the wonderful habits of ants, of their community life, of the division of labor among them, of their slave-making customs, of their courage, patriotism, and indefatigable industry, of their highly developed instinct, which, in fact, becomes real intelligence; so that almost everyone knows the main facts about these wonderful little insects, and we can spend our time to better advantage on those underground creatures about which there is less general information. It will suffice to say that most ants have their nests, consisting of tunnels and chambers, underground; that there their queen lays her eggs and the young are carefully tended by workers until they have reached the adult stage, and there the food is stored for use in the winter months. There is a curious kind of ant in the southwestern states and Mexico called the honey ant. Certain individuals in a colony of these honey ants have enormously distended stomachs and are fed by the other ants with a kind of grape sugar, or honey, during the summer, as they hang suspended by their legs from the roof of an underground chamber. When winter comes the other ants are fed by these honey-bearers, which give put the stored-up honey from their mouths drop by drop.

There is an interesting class of underground insects which, in their early stages, hide in especially dug pits and lie in wait for their prey, but which, when full grown, live above ground. Such are the ant-lions and the tiger-beetles. The young ant-lion is a heavy-bodied, clumsy-looking creature, with very long and sharp jaws, which digs for itself a funnel-shaped pit in loose, dry sand, using its flat head and jaws as a spade in digging. Then it hides itself at the bottom of the pit, its body completely covered with the sand, and waits until some unlucky little insect comes along and stumbles over the edge of the hollow. The side of the hole is made at such an angle that the sand slips down with the weight of even an ant and carries it towards the open jaws of the ant-lion. Every struggle which the poor creature makes to escape causes the sand to slide down faster, and the ant-lion at the bottom jerks up a shower of sand with its head, which hastens the miniature avalanche until the poor victim is within reach of the powerful jaws and is devoured. The adult ant-lion is a beautiful, gauzy-winged creature, not at all like its blood-thirsty larva.

The young tiger-beetle, or "doodle bug," as it is called in the South, digs a straight burrow in hard soil, such a hole as would be made by pushing a small lead pencil into the ground. This creature, like the young ant-lion, has a clumsy body and powerful jaws, and on its back are two projections armed with hooks which help it to climb up and down in its burrow. It waits for its prey at the mouth of its hole, which it closes with its head, thus making a sort of trap-door. The little insect which steps upon this trap-door doesn't have time to say its prayers before it is devoured by the voracious "doodle." Should a large, strong insect walk over the burrow, the tiger-beetle larva retreats precipitately to the bottom of its hole, which is sometimes eighteen inches below the surface of the ground.

There are many other insects which, when young, live below ground, and become above-ground flying creatures, when full grown, which have not the carnivorous tastes of the forms we have just mentioned. Many of these species live on the roots of plants and others upon the vegetable mold of rich soils. The large white grubs so often found in the soil of grass lands belong to both of these classes. They are the larvÆ, or young, of several kinds of the clumsy beetles known as scarabs. The larvÆ of the common brown May-beetles, for example, are root-feeders, living mainly on grass-roots, and they are sometimes so abundant and destructive as to destroy valuable lawns. The roots are sometimes so uniformly eaten off by these white grubs that the sod may be rolled up like a roll of carpet. The white grubs of the beautiful large green beetles, known as June-beetles, or fig-eaters, in the South (they do not occur in the more northern states), although they look almost precisely like the May-beetle larvÆ, are not injurious and feed only upon the vegetable mold of the soil. The wire-worms, which are the young of the click-beetles, or "snapping-bugs," feed upon the roots of plants; there are plant lice which live underground and suck the sap from plant roots, like the famous grape-vine phylloxera; there are caterpillars which live almost entirely underground and feed upon living roots; there are maggots which have the same habit; and there are even bark lice or scale insects which live attached to rootlets in the same way that the other species live above ground on the limbs and twigs of trees.

Other insects living above ground all their lives hide their eggs underground. Most grasshoppers, for example, do this, and many of the closely related crickets not only hide their eggs in this way, but live underground themselves in the day time, and come forth at night to feed, or to collect grass leaves, which they carry into their burrows and eat at leisure. Other insects also hide below ground during the day and feed only at night. The full grown May-beetles do this, and the cut-worms also. The cut-worms are soft-bodied caterpillars and are greedily eaten by birds and carnivorous insects, so it is essential to their safety that they conceal themselves as much as possible. There is an interesting cut-worm which occasionally becomes so numerous that it has to migrate in great armies in search of food, and these great masses of caterpillars hurry on, driven by hunger, by day as well as by night, followed by flocks of birds and other enemies until the majority of them are destroyed. This cut-worm is generally called the "army worm."

Other caterpillars, while living above ground and feeding on the leaves of plants, instead of spinning cocoons for their protection when they transform to the helpless chrysalis or pupal condition, burrow beneath the surface of the ground and there transform without a cocoon. Hundreds of species do this and sometimes these brown pupÆ are so abundant that they are turned up in numbers with every spadeful of earth.

We are now able to say that the insects found beneath the surface of the earth are as follows:

1. Insects which live underground during their whole lives, feeding (a) on roots and rootlets; (b) on dead and decaying vegetable matter; (c) on other insects.

2. Insects which live in the nests of ants.

3. Insects which have their nests underground, but which get their food elsewhere.

4. Insects which live underground only in their younger stages of life.

5. Insects which hide their eggs or pupÆ underground.

6. Carnivorous insects, and insects which feed on decaying animal matter, which occasionally burrow underground in search of food.

I hope it will be clear from what we have said that insects must take an important part in the changes in the character of the soil which are constantly going on, quite as important indeed as do the earthworms about which Darwin wrote.