Part 11

Among all the insects of the field and swamp none are more familiar than the dragon fly (Fig. 184), which children were once led to believe had a vicious habit of sewing up the eyes and mouth of any one; hence the name "darning needle." These insects are often beautiful, with their rich wings of glistening lace, four in number, their bodies gleaming in tints of bronze, blue, and black. The abdomen is long and slender, like a needle; the head is prominent and armed with powerful jaws; the eyes are large and compound, with several single eyes as well. Some dragon flies are very small. Others are large, as those of the Malay Archipelago, where the natives trap them and use them for food. The dragon flies are hunters, preying upon other insects which they capture on the wing, and large forms have been seen taking very young fishes from the water, swooping down upon them like hawks.

The development of the dragon fly is interesting from the fact that the young lives a long period in the water. The eggs are deposited in the water, hatching out into curiously shaped creatures (Fig. 185), which are among the most ferocious of all the water insects. They pass two years in this form, preying upon other animals and even small fishes. The larva has a proboscis which ordinarily folds over the face and is called the mask (B), but when an insect approaches, this strange appliance with powerful jaws or hooks is shot out (A) with dire results. After the two years have passed the pupa, as it is called, climbs up a stem, leaves the water and casts its skin, appearing as a full-grown dragon fly ready for a life of rapine on land.

In many insects the habits of the young are much more interesting than those of the adults. Not far from my home, in the Arroyo Seco, which leads down from the Sierra Madre, are great deposits or beds of fine sand which I find often covered with little pits (Fig. 186). If a section is made (Fig. 187), it is found to be a perfect bowl almost half an inch in depth, as though a top had been pressed into the sand and taken out. If sand is rolled into the pit, something appears quickly at the bottom and mysteriously tosses it out; and if an ant topples over the edge and rolls down the sides, out comes a fierce pair of jaws and seizes it. If the ant escapes, the unknown creature, still concealed, hurls sand at it, endeavoring to bring it down, often with success. This singular creature is the larva or immature young of the ant lion--itself an attractive, large, lace-winged creature (Fig. 188), resembling a dragon fly. It lays its eggs in dry places. The young are wingless, big-jawed creatures, which for two years live the life of a trapper, each forming a pit and concealing itself beneath the sand at the bottom, the huge jaws being in the center. Ants are the game of this lion, and as they run along they often topple over the sides which, like those of a toboggan, are very slippery. Down the ant goes, its descent being accelerated by the lion which places sand upon its back, and bombards the unfortunate, so adding to its confusion that it rolls down and is seized by the jaws of the lion. At the end of the two years the lion surrounds itself with a ball of sand and silk, and in three weeks appears as the perfect insect.

Unless one is familiar with the eggs of the aphis lion (Fig. 189) he will never find them. They resemble minute plants growing on long stems, fastened to a leaf. These hatch out and become little creatures resembling the ant lion, with huge jaws.

But the most extraordinary changes and series of different individuals are found among the so-called white ants, which are really not ants at all, but among the most destructive of all known insects. The first white travelers in Africa reported the discovery of gigantic ant hills, some of which were twelve feet in height (Fig. 190) and one hundred feet in circumference. Equally large mounds have been found in Australia, large areas of country being dotted with these striking landmarks, among the most remarkable of all animal structures. These mounds are often as hard as rock, and hunters have sometimes escaped from the charges of wild animals by climbing upon them.

They are the work of the so-called white ants. A section made through one of them, as seen in the illustration, shows the singular home of a remarkable community. There are really four kinds of "ants" here, all representing a different phase in the growth of the insect, and all performing a certain work. They are the female, the male, the worker, and the soldier; and there is a winged king. In their lives these insects have many features which resemble those of man. They have a king and queen, which at first have wings; later they lose their wings and the queen grows until she is thousands of times larger than the workers, and is kept in a special chamber in the center of the pile. Here she is attended by the workers, small ants, who carry out the eggs which are laid by millions and placed in nurseries or small cemented cells, designed for the purpose. Sometimes the queen lays as many as eight thousand eggs a day. An army of workers carries them off, builds new nurseries, and adds to the heap. If an enemy appears, the soldiers rush out. These have large heads and enormous jaws, and are well fitted by nature for the work they have to perform.

The cunning and intelligence of white ants are well displayed in their attacks upon houses. Having decided to enter a house, they begin to tunnel some distance away, and finally reach the corner post or some timber that enters the ground. With remarkable speed the workers enter this, hollowing it out, until it is nothing but a shell. They eat to the very surface, leaving only a faint ghost of a partition, and what appears to be a solid block is really so thin that a finger can be thrust through it. So clever are these little ant miners that they have been known to come up through the floor directly beneath the leg of a chair, and burrow and eat up through it, so completely devastating it that when the owner moved it the small hole in the floor appeared and the chair fell in pieces.

In the Isle of France a new building was ruined by these insects in a few months; and at Colombo a large house suddenly fell in over the heads of the occupants, the beams being crushed like egg shells. The work they accomplished in this way would hardly be credited were it not for the substantiated statements collected by the authorities in the countries where they are mostly found.

The so-called caddis worms (Fig. 191) are merely the larvæ of the caddis fly which incloses itself in a case that is often decorated in a singular way. The cases of a number of the worms placed together display a striking variety of designs. Some roll up leaves; others spin a silken thread from the mouth and bind pieces of leaves together, attaching other pieces to it.

XXII. SOME MIMICS

All insects have a continual struggle for life. They constitute the food of many birds, and very few of the young escape these watchful creatures and attain mature life.

To enable the insects to escape, nature has given many a strange protective garb, which is called mimicry or a protective resemblance. Sometimes it is color, an insect mimicking a leaf in color; or again, the insect imitates a twig or leaf in shape, and so escapes attention. We find examples of this in many families, but particularly among the insects now under consideration. The mantis (Fig. 192) belongs to a group in which the insects resemble twigs in shape and color, and nothing could be more striking than these strange, slow-moving creatures. They have an uncanny, weird appearance, and look as though they might have been originally of wood. I have seen them in the tropics passing slowly along a limb, lifting one leg at a time, moving it with all the halting deliberation of an automaton; but when the mantis perceived me, it stopped just as it was, the foot that was in the air remaining as though it had been frozen in the act. Some are a vivid green, and in them the resemblance to twigs is very striking. I once encouraged a number to live in my preserves, where I watched and studied and often fed them. They would take a fly from my hand by a very rapid movement of the cruel, fore hands or claws, which were toothed. When food was scarce the insects would devour one another in the most deliberate fashion, then assume the quaint, supplicating position with claws up, from which the insect is called the praying mantis. My specimens deposited their eggs in a curious case about an inch long, resembling a trilobite, which they attached to the fence and colored the exact hue of the latter. The fence was not painted, and varied in color, yet the nests always agreed more or less exactly with the shade or tint of the plank or base to which it was attached.

In South America is found a huge mantis so powerful that it captures birds by grasping them in its terrible claws. The insect is described by Burmeister as crouching on the limb, imitating it so closely that the bird approaches it without fear. In Java a beautiful pink mantis is so perfect in its mimicry of a pink orchid that insects alight upon it and are caught. A Philippine Island mantis is remarkable for its resemblance to a dried and withered leaf.

The chief characteristic of this insect is its cool, deliberate ferocity--devouring its mate with indifference, lunching calmly upon its young, while they are dining among themselves. When fighting they have the characteristics of the bulldog, with many times its endurance. A mantis will continue a combat even when part of its body is cut away. I have seen one deprived of all its legs cling to a limb with one claw and continue to reach for its foe with the other.

Closely allied to the mantis, and even more remarkable as mimics, are the walking sticks (Phasma) (Fig. 193). I have kept them alive, and often have been unable to see them when I knew they were directly beneath my eyes, so remarkable is the mimicry. They have no biting claws, merely long antennæ, a long, sticklike body, and straight-jointed, sticklike legs. Some are green. The most remarkable are those which seem to imitate dead wood. I have seen a walking stick that was a perfect imitation of a moss or lichen-covered twig, the body and legs of the insect being covered with peculiar growths. The largest walking stick I have seen was twelve inches in length, and one of the most perfect imitations of a green twig that could be imagined. This was from the Malay country, where they grow to a length of fourteen inches. They stretch out upon long tendrils, extending the limbs or holding them up, the poseurs of the insect world.

The walking leaves (Phyllium) (Fig. 194) are clever mimics, resembling leaves. Even the veins and midrib of the leaf are imitated, and the insect, when crouching on a limb, is a virtual leaf, so far as appearance goes, the disguise being absolutely perfect. Some resemble green leaves; others dried and withered specimens. Even the legs of these insects are supplied with a singular growth. Most of these strange mimics are found clinging to trees; but one common in Brazil spends most of the time during the day under water in streams, where it clings to the pebbles. In Nicaragua there are several species that resemble leaves in all stages of decay. The movements of some of these insects resemble those of leaves. I saw one in the Sierra Madre range come down from a tall sycamore, and supposed it a leaf, as it dropped slowly, zigzagging down. I should not have discovered the mistake had not my dog recognized it.

XXIII. THE GRASSHOPPERS AND LOCUSTS

These forms may be considered the musicians of the insect world. None of the insects can produce vocal sounds, that is, they have no voice, but they have certain appliances which enable them to produce sounds which can be heard a long distance. On hot days in summer is heard the constant and shrill zee-zeeing of the locust, while countless varieties lend their aid in producing a volume of sound.

The "instruments" in the locust are (Fig. 196) minute teeth, arranged along the thighs; these are rubbed against the fore wings, producing the remarkable sounds. The locusts are commonly called grasshoppers. They have two pairs of net-veined wings, and hind legs adapted for leaping, by which they send themselves sprawling through the air, almost invariably using this method of escape instead of unfolding their delicate wings. All are mimics. The common ground locust resembles the dusty road and the dried foliage which it affects. Others, which live on plants, are a vivid green. Some which I find in my garden resemble closely the tender shoots of the passion vine, upon which they feed.

The locusts (Acridiidæ) have short antennæ, large glassy eyes, and ears at the base of the abdomen. The female is provided with an appliance called the ovipositor, four sharp points with which the grasshopper digs holes in the ground; later these are used as a guide or funnel for introducing the eggs into the burrow. The mouth is supplied with parts adapted to biting. When a grasshopper (Fig. 195) is caught it exudes a peculiar fluid resembling molasses, a secretion of the salivary glands. The eggs are deposited in masses from sixty to one hundred. The young resemble the parent, but at first have no wings. The grasshopper in making its metamorphosis, or change from one stage to another, casts its skin in a manner calling to mind the crabs; in a word, it molts several times (Fig. 197). In accomplishing this, it often climbs a spear of grass and there shuffles out of its old skin and jumps away, leaving the hollow skin clinging to the grass.

At times they appear in vast numbers, and in clouds rise into the air, so that from a distance they might be taken for smoke or a tornado. This cloud is made up of starving locusts which devastate the countries they infest. They alight upon a wheat field, and an hour later hundreds of acres appear as though a fire had swept over the ground. Every spear of grass, every leaf, has been devoured by this insatiate throng, which can not be destroyed or even checked. In Africa swarms have been swept by the wind out over the ocean, to be washed in in such vast numbers that they formed a line fifty miles long and three or four feet high alongshore, creating an odor which drove people from that region. Jægar, the naturalist, rode through a swarm in Russia for four hundred miles where they were two feet deep. The entire country was devastated by this band of locusts, and tens of thousands of human beings were threatened with starvation. The government troops were ordered to the place and warfare declared against the locusts, the soldiers being armed with shovels instead of guns. A line of thirty thousand men moved slowly forward, covering the insects with earth or digging them under, while in various localities huge fires were built to burn the ground and destroy the eggs. Despite this, thirty thousand people starved to death, the direct result of their raids. Almost every portion of the world away from the poles has been threatened by these raiders. There are many references in the Bible to these insects, and their ravages have been carried on from the earliest times known to man. In America the Rocky Mountain locust is the most destructive, and many of the Western states have been ravaged by them.

"Onward they came, a dark, continuous cloud of congregated myriads, numberless. The rushing of whose wings was as the sound of a broad river, headlong in its course. Plunged from a mountain summit, or the roar of a wild ocean, as the autumn storm, Shattering its billows on a shore of rocks." --SOUTHEY.

Some years ago a flock settled in Colorado Springs, the streets and roofs being covered with them, so that they were swept and shoveled about like snow. Some American swarms have been traced for several hundred miles, and settling on railroads, have stopped the trains by making the tracks slippery. Alighting in a cornfield the rustling sound of their depredation can be heard for some distance; and when they rise, a fire might have swept over the fields, so far as appearances go. The swarm, a black, portentous cloud, sweeps on, flying at a rate of thirty miles an hour to reach some new field, where they dig burrows with their curious ovipositors, and deposit their eggs by millions. Then they move on, leaving an unborn swarm to develop and later constitute another army to spread devastation abroad in the land.

The crickets (Fig. 198) are familiar forms with cylindrical bodies and large heads placed vertically, the ovipositor often being as large as the entire body. The female often deposits three hundred eggs in the ground. The note of the cricket is produced by the male, and is a decidedly musical chirp, varying in the different kinds. The close observer may easily find the cave house of the little singer that is often seen sitting at the entrance, singing, not at the top of its voice, but with the full force of its wings, the sound being produced by using the fore wings, as bows and the hind wings as fiddles, and sawing with great rapidity.

The crickets are found in the greatest variety. Some live in the ground, others affect houses, and in the tropics beautiful tree crickets are found. The snowy tree cricket has a peculiar note, te-reat, te-reat, te-reat. The broad-winged tree cricket has a call which resembles a dog whistle. Another has a piping note resembling the thrilling musical sound made by rubbing the edge of a glass with one's finger. The singular cave cricket is wingless, and has antennæ several times the length of its body. The Western cricket does great damage to the crops of the farmer, and when bands are seen marching over the country, ditches are often dug into which the crickets plunge, where, in default of food, they begin to devour one another. The cry of this cricket is harsh and disagreeable, the "musical instrument" being on the dorsum or back of the shield which seems to cover the fore part of its back. The curious mole cricket, which burrows underground and is provided with enormous jaws, is a menace to the gardener. In the outer Florida Keys I found that it was almost impossible to rear plants, so plentiful and ravenous were these fierce root eaters.

XXIV. THE BEETLES

The beetles (Fig. 199) are insects having their fore wings thickened to constitute sheaths or covers for the lower pair, used in flight. Their mouths are adapted for biting, and they pass through a complete metamorphosis. There are about ninety thousand species, ranging from minute creatures to huge, lumbering goliaths. When walking the beetle presents a trim appearance, enveloped in a gleaming armor of the highest polish, and often ablaze with metallic tints, but when it flies the elytra, or wing covers, are thrown up, and a pair of soft, silken wings flutter out, stiffen, and bear the beetle away.

The head of the beetle is small and adapted for biting (Fig. 200); the digestive apparatus is simple. The most noticeable feature of many are the antennæ (Fig. 201), which often are very long and ornamental. The eyes are compound. The legs are strong and powerful. The beetles spend little time in flying, many being flesh eaters and continually searching for game under refuse and in dark places. They lay eggs which are deposited in the ground, or in special cavities made in wood, which hatch into larvæ (Fig. 202). In the tiger beetle the larvæ resemble white worms. In the rose beetle they look like grubs. These in time change to helpless pupæ.