Chapter IV: Preface (4)

That these crabs have a strong homing sense, or an affection for certain localities, was demonstrated some years ago. Two crab fishermen were following their occupation from the same boat, and each as he caught a crab cut upon its swimming claw a private mark so that they could be claimed by the rightful owners at the end of the day. The boat was overtaken by a storm and the crabs were tipped overboard five miles from where they were caught and lost. The following week the two men again began to fish in the original spot, and to their amazement began to catch the marked crabs, which had returned five miles alongshore to the locality of their choice.

The so-called green crab (Fig. 148) is an attractive and active creature, one that can easily be observed. Its quaint stalked eyes, which turn this way and that, and which can be stowed away in little depressions, and its singular method of walking, are very interesting features. When a crab walks on land it is usually endwise, and when it wishes to change its course it is not obliged to turn about but moves its legs in the opposite direction. It can also move directly ahead. These movements are all performed by six legs, which are pointed, the trail of this crab on the sand resembling pin marks on the hard beach. The two front claws are for tearing food and for general defense, while the last pair, widened out at the end in some, are paddles by which the crab swims when it ventures off the bottom.

At times the crabs appear to migrate. I have seen the bottom of a bay on the Virginian coast so covered that it was impossible to wade without stepping upon a crab. In the island of Jamaica certain land crabs march to the sea to deposit their eggs, at which time they appear more or less indifferent to danger, and move on, despite the attacks of birds and various animals, including man.

The crabs known as fiddlers (Fig. 149) are common up and down the Atlantic coast, especially in the warmer portions. A most interesting colony lived north of Fernandina, Florida. Some years ago a plank walk led across their domain, and one could stand and watch their ludicrous maneuvers. The fiddler is not over an inch in length. It is of a dark ivory hue, and its eyes are perched on long stalks, so that it can bury itself in the mud and thrust its eyes upward, and thus in perfect safety observe everything that is going on. The right claw of this crab is half as long again as its entire body--a colossal weapon framed for an animal five or ten times its size. Indeed, it is so large as to be almost useless, for a large amount of strength is required to operate so gigantic an implement. To emphasize the undue size of this claw, the left one is a dwarf, being too small to act as a defensive weapon. How so small a crab can use so strange a pair of weapons was a puzzle, until by watching them, I discovered that the crab uses its large claw as a bogy, brandishing it fiercely, which gives it a very ferocious appearance. The movement of the claw back and forth is called fiddling, hence the name of the crab, which appears to be constantly fiddling. Where hundreds are seen, all fiddling and menacing one another at the same time, the sight is laughable.

Once while lifting branch coral into my boat on a coral reef, several crabs fell from the olive-hued mass, and like spiders in shape and form, made their way slowly along. Each one was covered with a growth of seaweed. I took a brush and scoured them, producing veritable spider crabs (Fig. 150). The body was pear-shaped; the claws were long and covered with sharp points. These crabs were placed in a tank, and almost immediately began to replace the seaweed which had been rubbed off, evidently being much annoyed at the cleaning process. In redecorating themselves they broke off small bits of seaweed from a branch, placed the broken portion against the mouth, evidently to attach some glutinous matter or animal mucilage, then raising it with an overhand movement, they attached it to the back. This was continually repeated until within a few hours the back of each crab was changed from a smooth surface to a miniature garden. As many times as the seaweed was removed, so many times was it replaced.

The spider crabs range from the beautiful scarlet creatures found in the coral to the giant Macrocheira of Japan, which in large specimens has a spread of legs of twenty feet, some measuring twenty-two feet between the two large biting claws, each of which is ten and a half feet long. This huge crab is very slender, and is slow of movement, its body resembling a rough rock.

Crabs select singular places for homes. One lives in the sea cucumber; others live in corals, which appear to grow over them, forming a gall (Fig. 151). The little oyster crab found in bivalves is a familiar form. But perhaps the most remarkable home for a crab was the bowl of an old tobacco pipe in which a crab I once owned ensconced itself. This was a hermit crab (Fig. 152). The hermits differ from other crabs in having a long, but soft and totally unprotected tail or abdomen, to preserve which they enter empty shells and drag them about wherever they go. The hermits occur in great variety, and there are marine hermits and land hermits. On the Florida Reef they are found in myriads; every shell alongshore conceals a baby hermit; and almost every nook or cranny affords concealment for a score of them, their red and blue claws forming an attractive contrast to the shell.

The hermit referred to was first found in a pearly shell and placed in the office, but finally it outgrew this and deserted it for the pipe which some workmen had left on the floor. Every day this old pipe would be clanked and dragged about the room, and once in a while the crab would drag it up a table leg, so reaching the tablecloth and then the table top, where it drank out of a saucer left for the purpose. Later a marine hermit was found in a pipe bowl, proudly dragging the grotesque house about. Anything of this kind would be used by the hermits. One was found in the opening of a spool; and this would roll over and over, carrying the hermit with it. Another took possession of a reed. Among deep-sea sponges the hermits are seen occupying holes in the sponges.

A community of hermits is a laughable sight. They are very pugilistic, and are always fighting. When a hermit outgrows its shell and begins to feel uncomfortable it endeavors to turn out some comrade that has a larger shell, and in the battle arms and claws are often lost. This, however, is not serious, as they grow again. When the hermit finds an empty shell it thrusts in its claws and antennæ, probing it in every direction to see that it is not occupied. When satisfied, it jerks itself out of its own shell, and with the greatest rapidity whisks its soft unprotected body into the new house, where, if it fits, it remains. The shell, when large, is not carried, but dragged about, and when the crab is alarmed or startled it darts backward into the shell, where its large claw and the others constitute almost as good a door as the real operculum of shells. The largest hermits are the marine forms, which enter the large conch shells and drag them about. These hermits are a brilliant red in color. Their claws are very rough.

Closely related to the hermit crabs is the famous cocoanut crab or Birgos of the Spice Islands. This crab is so strong and powerful that, as Professor Van Beneden states, one clinging to a tree, seized a small goat and lifted it from the ground by the ears. The Birgos resembles a huge hermit crab, but has no artificial shell, the soft abdomen being protected by a shell of its own. This large land crab lives mainly on cocoanuts, which it secures by climbing the trees and biting off the stems. Descending, the crab will take the nut and with remarkable discrimination hold it with one claw and with the other tear off the husk, always at the end containing the "eyes." This stripping process, impossible to man without some implement, is remarkable in itself, and tells the story of the muscular strength of the crab. When the "eyes" of the nut are exposed, the crab seizes it by inserting its claws in the holes, and hammers the shell until it is broken. The crabs live at the base of the trees and line their dens with the husk.

In ancient times crablike creatures existed, eight or nine feet in length. These are represented to-day by the quaint horseshoe or king crabs (Fig. 153). They are found in shallow water in Northern waters, and resemble a horseshoe with a long, sharp spike or spine--the tail of this strange animal.

XVII. LUMINOUS CRABS

One of the interesting experiences of Nordenskiöld in the Arctic Ocean was wading through the sludge, as the soft snow water along the beach is called, and seeing each footprint turn into a mass of light, caused by the phosphorescence of a small crustacean called Metridia. The light was bluish white, of great intensity, and although at times the cold was so severe that mercury would freeze, yet everywhere this marvelous light blazed. Even drops and splashes of the water seemed to be molten metal, but were merely alive with this minute light giver resembling Cyclops. In the Pacific, especially in summer, the exhibition of what might be called "crab light" is marvelous, and this is often true in the Atlantic. The light following the splash of an oar, the spray hurled aside by the cut water, the foaming water around a propeller, and the strange shifting specter which follows the rudder, are caused more or less by minute crustaceans which have the faculty of emitting light without heat.

Along the beach beneath seaweed, we shall find Gammarus, a long, very small, but mighty jumper, that at night emits a red light. Many of the near relatives of this little creature are phosphorescent, and perhaps the most beautiful of all is one named Idotea phosphorea. It is a yellowish spotted little creature found in pools alongshore. It darts about among the weed, and would rarely, if ever, be noticed during the day; but at night the entire animal seems permeated with a golden light which marks it in vivid lines against the dark bottom, and flashes and miniature meteors indicate it as it dashes across the little pool, its ocean world.

The most beautiful of all crustaceans is the one known as Sapphirina. I have seen the ocean filled with them; some red, others blue or yellow, purple or green, all known gems being imitated by these matchless gems of the sea, which in daylight vie with the most brilliant iridescence in producing wonderful displays. No more beautiful scene can be imagined than that embracing these living gems, standing out in brilliant tints against the deep blue of the ocean. These gems also have the gift of phosphorescence and at night appear in a new guise.

One of the singular long-legged spider crabs of the deep sea, Colossendeis, is said to be phosphorescent. Giglioli, the Italian naturalist, describes a crab which gives a golden purple light, the latter appearing from the thorax. The little shrimp, Mysis, which carries its young in a pouch, from which it is called the opossum shrimp, is not phosphorescent, but its young in what is called the zoëa stage are luminous. The odd-shaped little creature, which is the mantis shrimp in one of its stages, is brilliantly luminous, not over its entire body, but in the eyestalks. Some of the deep-sea crabs have luminous eyes, strange monsters wandering in the abysmal regions of the deep sea.

While most of these crabs have the light in only one place, one discovered by Sir Joseph Banks was luminous over its entire surface. Exactly what the luminous matter is, is not known, but in some instances it can be scraped off and will render the hands luminous when rubbed upon them. According to A. M. Norman, naturalist of the _Porcupine_ expedition, the crustacean Ethusa, found at a depth of eighteen hundred feet, is blind, its eyestalk being spiny, and the eye replaced by a smooth, round termination which is supposed to be a light-emitting organ. Aristeus has phosphorescent eyes, which blaze with the yellow fire of a cat's eye, and this is true of many other crustaceans. Some have luminous backs; others have fiery bands upon the legs, while almost every portion of the body of some species is the seat of this wonderful light. That the lights are of some use there can be little doubt. In one little creature Dr. Gunther found a brilliant light stationed between its eyes, which certainly was a light to illumine its way in the deep, dark bed of the ocean.

XVIII. THE INSECTS

Among the best-known and attractive members of the lower animal kingdom are the insects, represented by the gorgeous butterflies, the iridescent beetles, the fierce spiders, and many others. The crustaceans may almost be called the insects of the ocean, as in general appearance they closely resemble these animals; but the real insects are higher forms.

The skeleton (Fig. 154) of an insect is divided into three distinct parts instead of two. The head is distinct from the body, as in the crabs, and the skeleton, like that of the crabs, is external, and formed of a horny substance called chitin. As in the crabs, the body is made up of rings, or segments: four in the head generally, three in the thorax, and ten or eleven in the abdomen. It is interesting to glance at the various parts of insects, and later on, in reading about the many species, to note the many different purposes to which each is adapted.

The mouth is a very complicated organ in the crabs, and equally so in the insects. It is generally separated into four distinct parts: the upper lip, labrum, the jaws, or mandibles, a second pair of jaws smaller than the above, and the lower lip or jaws, labium. These are formed into sucking organs in the mosquito, biting organs in the ant, and tremendous graspers in the centipede, all displaying the most remarkable variety.

The eyes of insects are wonderful organs, being both simple and compound. In the grasshopper (Fig. 155) the two are easily seen, the compound eye being the larger. The fly has a remarkable compound eye (Fig. 156), and in the center of the two eyes are three simple ones. The compound eye in the fly is made up of vast numbers of six-sided eyes crowded together, appearing under a glass like a honeycomb; yet each of these facets is a complete eye. In a sectional view of the eye of a beetle (Fig. 157) we can see the nerve that reaches every one. In using the eyes hundreds of images of the same object must reach the brain of the insect, yet the image of but one is seen.

Attached to the head of insects are various sense organs, feelers, or antennæ, which are very ornamental, as in the beetles. The central portion of the skeleton bears the wings. In the beetle the wing covers are formed of hard chitin. When its wings are not in use this insect stores them away in covers provided for the purpose.

The third or last part of the skeleton, the abdomen, often bears a weapon of defense, as a sting or a drill for boring holes in trees, or machines for making silk, as in the spiders. Here also we find a remarkable variety of tails, ranging from that of the dragon fly to the long tail of the scorpion with its dangerous sting or dagger.

The feet of insects would make an interesting chapter alone, ranging from the curious, sucking, padded foot of the fly (Fig. 158) to the claws of others. The anatomy of insects is more or less complicated. The method of breathing is particularly interesting. It is very natural to imagine all animals breathing by the mouth or nostrils, but insects breathe by a singular system of air tubes (Fig 159), or tracheæ, some having lungs as well. The air tubes are wound with threads upon the inside. This preserves their shape and keeps them open. If we examine a grasshopper (Fig. 160), we shall see along the sides openings, which under a powerful microscope resemble eyelike organs (Fig. 161). These are air holes, windows, or spiracles, which lead to the air tubes, and by minute thread-lined tubes reach all over the body. To obtain air, or to breathe, the bee keeps its abdomen continually in motion, forcing air through the body, carrying oxygen to the blood tissues.

The insects, with some exceptions, deposit eggs, and the young pass through many strange changes, or metamorphoses, before the full-grown form is attained. The eggs of beetles hatch into larvæ (Fig. 162), which may live weeks or months or even years in the ground. The eggs of other insects, as moths, may become caterpillars, which finally spin a cocoon, as in the case of the silkworm, and from this cell-like room appears the perfect moth. These changes, so infinite in their variety, are among the most interesting features of insect life, and are never failing sources of wonder and amazement on the part of those who devote time to the study.

XIX. LOWER FORMS OF INSECTS

In the previous chapter we have by the aid of illustrations glanced at the structure of insects, and noted some of the features which distinguished them from the crabs. Now we may take up some of the more important and interesting groups and observe how Nature has adapted them to their peculiar surroundings, and for the various offices they fill in the world.

In examining the various families of insects it is interesting to note that many produce certain results or accomplish certain ends in totally different ways. The highly organized spider by drawing silk from the spinning machines at the tip of its abdomen builds a web so strong that it sometimes captures birds. I recently found a living humming bird hard and fast in a web at the corner of my house, and released it just in time to save it from the spider. In the very lowest groups of insects we find the Peripatus (Fig. 163), which spins a weblike structure from glands in its mouth, ejecting the secretion at the insect it wishes to catch. This appears to crystallize in the air and hold the victim despite its struggles. The Peripatus, found in Africa and Central America, resembles a large caterpillar, having a long, soft, cylindrical body with many pairs of feet, sometimes sixty-six; the latter are soft and armed with claws. It is remarkable for the possession of many legs, but is outdone in this respect by the millipeds, as some (Fig. 164) have as many as two hundred. These insects, when placed upon their backs, present an extraordinary appearance, clawing the air; yet they are among the slowest of walkers. They live in the ground, are harmless, feed on vegetable matter, and deposit their eggs in the earth, which hatch out little creatures at first resembling crickets.

The centipeds, on the other hand (Fig. 165), are animal feeders, and those found in the tropics are formidable creatures from six to ten inches in length, supplied with many claws and terrible fangs. They live a life of rapine and destruction, and the appearance of a large specimen almost a foot in length, dashing along with great rapidity by the aid of its fifteen or twenty pairs of feet, is sufficient to demoralize the stroller through the dark glades of the tropical forests. They have two pairs of foot jaws (Fig. 166) which grasp an enemy with wonderful tenacity. The second pair is perforated, and from it pours a poison dangerous to man in some tropical species and fatal to small animals. Several of these hideous creatures are luminous at times. Many centipeds have long antennæ. The eyes are very small, and in groups. The ordinary centiped of the North is harmless, despite the tales related of its ferocity.

Among the very small, though destructive insects, are the mites, found in cheese and sugar; they are parasitic in cattle and various other animals. In California certain forms (Fig. 167) cling to the bushes.

In remarkable contrast to the round-bodied mites are the scorpions (Fig. 168), in which the tail is sometimes two inches in length and armed with a sharp, daggerlike sting, provided with a poison apparatus. The scorpions of the largest size are often found in the tropics in the same locality with centipeds, under board piles and in dark places, coming out at night to prey upon small insects, which they seize with their crablike claws and tear apart. If the insect struggles violently, the scorpion raises its tail over its back and pierces it with its dagger, paralyzing it. In striking at other enemies the scorpion whirls about, keeping its tail toward them, repeatedly striking down and using its jointed tail with marvelous ingenuity. A few years ago these scorpions were common on the Florida Reef and were frequently killed in my own house at night. The pain resulting from the sting was about as disagreeable as that occasioned by a wasp. These scorpions were about three inches in length, but in Ceylon very much larger ones have been seen, and known to catch birds. The young scorpions are born alive and cling to the mother. The little book scorpion, the large whip scorpion, and the daddy longlegs, or harvestman, a harmless and sociable insect, are related to the true scorpions.

XX. THE SPIDERS

A little insect half as large as a grain of corn, finds itself on a limb high above ground and is desirous of reaching another, five feet away. It is not a jumper, at least it could not hope to cover this distance; neither has it wings. But it has a marvelous silk-manufacturing apparatus, known as spinnerets (Fig. 169), and elevating its abdomen it reels off a thread which the wind carries across the chasm where it lodges. Across the single cord the spider runs, the act being suggestive of the intelligence of these insects.

The common garden spider (Fig. 170), which may illustrate the group, is seen to differ very materially from the scorpion. The abdomen is not ringed or made up of segments, but is large and plump, and connected with the thorax by a delicate cord or pedicel.

The spiders, as we have seen, have a spinning arrangement by which they form beautiful webs or nets to capture prey. By this silken cord they can lower themselves from great heights. The single thread which supports them is made up of a number of minute threads (Fig. 171). The webs are formed in endless variety and with all the skill of a bridge maker, being guyed, supported, and braced in a manner which, if the work of man, would be said to be the result of endless study. They are perfect in their arrangement, and each web is a study in geometry, yet the spider builds it with the greatest rapidity, never hesitating in the making or repairing.

By my door is a huge spider similar to the one shown in Figure 172. It has a beautiful web which covers a space two feet square, but the spider rarely occupies it. Near by it has a covering formed of a leaf of a fern which it has pulled down each side and fastened, forming a little room just the size of its body. Wondering how the spider would discover a victim caught in the web, I examined it carefully, and then placed a grasshopper in the web. Instantly the spider noted the disturbance, having what to all intents and purposes was a private telephone line. This was a single guy line leading from the center of the web to its retreat, where one of the spider's claws rested upon it, holding it, so that the slightest swaying of the web lifted its foot. When an insect became entangled, the spider darted at it, and by skillful manipulation of its hind pair of legs reeled off its silken cord and attached it to the victim at every point, in a short time literally binding it in a roll. If it was likely to escape, the spider would bite it, using its poison fang (Fig. 173), which paralyzed it. The biting mandibles (Fig. 174) are terrible weapons, from which there is no escape. The inner jaws (Fig. 175) are equally sharp and effective. The eyes of the spider are very brilliant, and in a bright light can be seen to gleam and glisten like points of steel or fire. They are minute dots, seen just above the mandibles.

The male and female spiders often present a very different appearance, the male being smaller. The spiders deposit eggs which are inclosed in silken balls or nests of various kinds, in which they remain until the young are hatched. Some are concealed in the web; others are placed underground; and some are perched upon a stalk resembling a plant.

There appears to be no limit to the uses to which the marvelous silk of spiders is put. Some spiders form balloons with which they sail away through the air. I have seen scores of these aëronauts in the air at one time. Another form constructs a raft of leaves bound together with silk. Some build nets for small game, as gnats. The silken cord made by others is so tough that it can be used as thread.

By partly destroying a web and suspending a black cloth behind the locality, the operations of the spider in building and repairing can be plainly seen. It is well to place the spinnerets beneath a microscope, under which they appear to be made up of many points. Touch one of these and a glutinous secretion adheres, which when stretched is seen to be silk, and each point provides a separate thread which joins with the others, producing one cable. The spinnerets are to some extent movable. They can be turned to the right or left, and wherever they touch, the silk remains glued fast. This explains why the spider moves and works so quickly and accomplishes so much. The amount of silk secreted is astonishing, and some idea of it can be obtained by walking over the country in spring, early in the morning. On the slopes of the Sierra Madre, in the San Gabriel Valley, I have seen the surface of the ground for a great distance covered with webs which caught the rays of the sun as it rose, presenting a most beautiful appearance. This fabric covered hundreds of acres in a fairy maze of web, so many traps for unwary small fry of the insect world. With a small stick I have wound a large amount of silk from the spinnerets of a spider, there apparently being no diminution of the supply. Professor Burt Wilder wound from the large spider known as Nephila plumipes several miles of silk. Some spiders have long, slender legs and are rapid runners. Others, as Salticus, are very deliberate, but powerful leapers, jumping upon their prey like a cat. Perhaps the most remarkable leaping spider is one from Australia, called the flying Attus, having singular flaps or winglike extensions upon its sides. One of the spiders not only runs over the surface of the water readily, but spends a part of its time under the surface, carrying down a bubble of air for its supply of oxygen, the bubble acting as a diving bell.

The spiders are very solicitous of their young, placing every safeguard about them, and resenting any attack by a fierce rush. Several large spiders (Fig. 176) carry their young upon their backs. The little spiders are rubbed or scraped off when they become too great a burden. The spiders are natural hunters and trappers, and a volume could be written on their methods and adventures in running down prey. Once as I was crawling through the almost stifling brush of one of the Florida Keys I came to a little opening about five feet wide, across which was a large, conspicuous, and powerful web. In the center of this web clung a huge and most remarkable spider, colored a vivid yellow and black. I watched it for a few moments while resting, and then touched the web, whereupon the spider began to swing, by raising and depressing its body, increasing its speed rapidly, until I could with difficulty see it. A moment later it disappeared almost entirely before my eyes. For half a minute the spider kept up this motion, then it slowly came to a standstill, having demonstrated that it could easily disappear from any bird enemy without running away. I have seen the daddy longlegs perform the same feat in California.

The spiders which build webs, from plain geometrical traps to conelike affairs, are interesting; but the trapdoor spiders and those which dig burrows are among the wonderful artisans and engineers of the insect world. One of the most perfect doors, in hinge, fit, beauty of interior, finish, and quality of its outward defense is built by a spider (Fig. 177). In the illustration, the den and its trapdoor is shown, and in Figure 178 a sectional view of the same is seen; but the door is never found open, the spring or hinge being so devised as to remain closed. I have found many of these dens in southern California sometimes a foot or more in length. The spider is not the large one shown in the cut, which is a tarantula, but is very much smaller, though a large spider. The genera, Cteniza and Nemesia, are best known for their cunning and skill as builders. The California spider begins its den when very small, and I have found many the size of goose quills, with door complete, in the vicinity of a large den.

In forming the burrow the spider carries out the clay bit by bit, and when it reaches a point below the surface it begins to line the sides with a silken tapestry. The door is an upper extension of this lining. It is round, about the size of a silver quarter, or a little larger, and is formed of silk so woven and interwoven that it becomes a pad of seeming satin, which by continued manipulation is made to fit with marvelous perfection. The spring or hinge is so adjusted that the door always closes, and with a snap. The exterior of the door is covered with clay, and is made to simulate the surroundings so exactly that only the sharpest eye, and one skilled in the work, can distinguish it. In some of the European spiders of this kind the door is carefully covered with moss and plants. The work of building is done at night. The spiders feed at night, and in returning to the burrow they can lift the lid instantly, dart in, and turn about to seize the cushion or pad of the door with their fangs, and hold it so tightly by bracing back that some little strength is needed to force it. I have often lifted the door with the blade of my knife and seen the spider rush up and seize it. In all the doors little round holes can be seen where the mandibles or fangs hold. The spider can be caught by pouring water into the burrow and forcing it out. In the island of Timos there is a trapdoor spider which does not hunt, but combines the methods of other spiders. It comes out at night, fastens back its door by a thread, then builds a web near by and waits for its victims to become entangled.

The largest spiders are called tarantulas, though the term is applied to some forms not so large. They are hideous creatures, and are very common in southern California. They are five or six inches across the legs, and the body in some forms is as large as a small mouse, and is covered with reddish hair. They form deep burrows, but not trapdoors, the entrance being open or covered by a web. They are supposed to be very poisonous. Mygale Hentzii is the name of the common American species found in the southwest (Fig. 177). They hunt at night for grasshoppers, crickets, and other small game, and can often be seen lumbering along over the roads at sunrise, returning from a hunt. Sometimes these huge spiders migrate in a body, such a movement having been observed in southern California.

A South American species has been known to attack and capture small birds, though this may be considered rather the exception than the rule, their food consisting of large insects and small lizards. Of all the spiders, the Tarantula turricula (Fig. 179) is the most remarkable, as it not only makes a deep burrow, but erects above it a chimneylike structure with all the skill of a human workman. Indeed, the structure, in neatness and perfection of design, is far superior to many of the chimneys seen among the poorer classes of some countries. The spider lays the miniature timbers across with the precision and exactness of a skilled carpenter and after the manner of human log-cabin builders. The female carries her young upon her back, as shown in the illustration.

XXI. SOME SIX-LEGGED INSECTS

One of the great divisions into which the insects are divided relates to their possession of six legs (Fig. 180). This includes a marvelous array of creatures. Among them we find the singular little glacier flea (Fig. 181) and the springtail, a prodigious jumper (Fig. 182). The latter is found in damp places, and when touched will release a forked spring which is held in place by a hook, and this sends the insect flying into the air like an acrobat. These humble little creatures present a strange contrast to the lace-winged insects which are among the most beautiful of the tribe.

The May flies (Fig. 183) are well known for the wonderful exhibitions they sometimes make, the air being filled with them, a joyous, beautiful throng, destined to live but a few hours. In South America they occur in such vast numbers that they are collected and used as guano. The young pass through a strange change, having little resemblance to the parent, and live in the water, where they breathe by means of several plumelike gills.

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.