Chapter 24

A GROUP OF CRUSTACEANS1. Common Lobster. 2. Thornback Crab. 3. Land Crab. 4. Hermit Crab.5. Barnacle. 6. Scorpion. 7. Antarctic Trilobite.

A GROUP OF CRUSTACEANS

1. Common Lobster. 2. Thornback Crab. 3. Land Crab. 4. Hermit Crab.5. Barnacle. 6. Scorpion. 7. Antarctic Trilobite.

Crab.—In this class of Crustaceans the abdomen is small and folded under the anterior part of the body. Over two thousand species are known, differing greatly in size, shape, and in other respects. The great majority are marine, but there are a few which spend their entire life on land, only going to the water once a year to lay their eggs. The largest is the great spider crab of Japan, whose legs may stretch out a dozen feet. One species on the Atlantic coast is taken at molting time in great numbers and forms the favorite soft-shell crab of the table. The hermit crabs have the abdomen soft, and to protect this vulnerable part, they insert it in the shell of some dead snail, and carry this about with them wherever they go.

Barnacle.—A family of marine crustaceous animals enveloped by a mantle and shell, composed of five principal valves and several smaller pieces, joined together by a membrane attached to their circumference. They are furnished with a long, flexible, fleshy stalk, provided with muscles, by which they attach themselves to ships’ bottoms, submerged timber, etc. They feed on small marine animals, brought within their reach by the water and secured by their tentacula. Some of the larger species are edible.

Crayfish.—Small, fresh-water crustaceans, which resemble the lobsters in appearance. They usually live in burrows in the banks or bottoms of streams and feed on decaying animal matter. In Europe they form a considerable element in the food supply and are bred in ponds. A large number of species occur in the United States, and are always to be found in the larger markets.

Lobster.—The most important of the crustaceans. One species occurs on our east coast, another on the coast of northern Europe. The body is divided into two regions, the anterior bearing, besides the parts used in taking food, a pair of large pincers and four pairs of walking feet. At the front of the head are two pairs of feelers, which are sensory, and a pair of eyes on the ends of short stalks. The lobsters are fond of decaying fish and are among the scavengers of the sea. They are caught in large traps, called lobster pots, made out of lath and baited with decaying fish. The annual catch on the New England coast is estimated at about thirty million pounds, the average weight of a lobster being between two and three pounds. Farther south on our east coast, in California and the Mediterranean a different animal is called lobster.

Prawn.—Crustaceans nearly allied to shrimps and lobsters, but not exclusively marine. They vary in size from a couple of inches to over a foot in some tropical forms. Many of them are semi-transparent, and exhibit very fine colors. On the approach of night they change to a beautiful blue, but the meaning of this “sunset” coloration is not fully understood. Some of the deep-sea prawns are blind; others possess enormous eyes, and many emit a phosphorescent light. They may be caught in putting nets or in osier baskets, like those used for trapping lobsters. They are esteemed for eating even more highly than the shrimp.

Shrimps.—Small crustaceans allied to the lobster, most of them inhabitants of the sea. In many countries they form an important part of the diet, but with us they are little used with the exception of one or two southern species which are used as a basis for shrimp salad. Shrimps are very abundant off our coast and could be made an important fishery.

In this class of insects the head and thorax are joined together in one mass, on which they have two pairs of jaws, and four pairs of legs.

Scorpions.—These spider-like animals have four pairs of legs and a pair of large pincers, as well as a small pair on the anterior half of the body; while the hinder portion consists of at first a broad region, followed by a narrower one, the whole terminated with a sting, with which a poison gland is connected. The animal strikes by bending the end of this tail over the back. Its sting is very painful, but rarely if ever is it fatal. Scorpions occur as far north as Nebraska, but are more common in the tropics. They bring forth living young and care for their brood for a while.

Spidershave jointed bodies and legs. The bodies are divided into two regions, the anterior of these bearing four pairs of legs and two smaller pairs of appendages. The most anterior of these are the poison claws. They have a poison gland in the base, while the end of the claw tapers to a point. The front of the head has from six to eight simple eyes. The hinder half of the body, the abdomen, is without appendages, save for two or three pairs of very small projections, the spinnerets. Each of these has numbers of openings at the tip, through which a fluid is forced at will. This hardens immediately it comes in contact with the air and furnishes the silk of which the spider’s web is woven. Fine as it is, this silk is really a cable, being made of numbers of finer threads, one for each opening in the spinnerets. They use the silk for making webs, for cocoons for the eggs, nests, and in some cases for parachutes for flying. Each species makes its own type of web.

Spiders breathe by means of sacks—so-called lungs—on the lower side of the abdomen.

Our common house spider is the same as that of Europe; the largest species we see is the one found occasionally in banana bunches.

TheTarantulahas the greatest reputation from the unfounded belief that its bite causes madness which can be cured only by music. So far as is known there is only one species which can cause serious effects by biting man, and even these cases are not sufficiently authenticated.

TheBird Catching Spideris a gigantic spider native to Surinam and elsewhere. It preys upon insects and small birds, which it hunts for and pounces upon. It is about two inches long, very hairy, and almost black; its feet when spread out occupy a surface of nearly a foot in diameter.

Hunter-Spiders.A great many of this species construct no webs, but use their silk merely for lining their dwellings—which are commonly underground—or the construction of protective investments for the eggs. Such forms simply stalk their prey, seizing the victims, when near enough, by a sudden[232]spring. One such type is the tarantula spider described above.

Water Spidersare found in ponds and ditches in this country. They hunt down small crustaceans but do not construct a web. For the protection of the eggs a thimble-shaped nest is woven, moored by threads to stems or leaves, and smeared externally with liquid silk to make it watertight. The nest is filled with air brought down from the surface of the pond in successive bubbles adhering to the hairy body of the spider.

This ubiquitous class includes more species than all the other groups of land animals put together. The bodies consist of a series of rings, divided into three sections: the head, the thorax, and the abdomen. There is an external covering that serves as a protection. The head possesses a pair of antennæ, two large compound eyes (and sometimes several simple eyes as well), and three pairs of jaws, differing greatly in character according to the habits. The thorax bears three pairs of legs, and in most cases two pairs of wings, while the abdomen is entirely or practically limbless. The air-tubes make up an exceedingly complex system, and open to the exterior by a limited number of air-holes.

All insects undergo a series of changes (metamorphoses). From the egg first comes the larva (caterpillar, maggot); from the larva after several changes of the outer skin, the pupa is developed; from which, after a longer or shorter period of repose, the perfect insect emerges. In some, such as the dragon flies, the whole course of metamorphosis, or change, is not gone through; for in the dragon flies the larva which comes from the egg resembles the full-grown insect, only it is without wings; but later, without entering the pupa stage, it develops into the perfect insect. There are altogether about two hundred thousand various kinds of insects.

The simplest way of classification is into the following nine orders, though specialists recognize a much larger number: (1) Wingless insects (Aptera); (2) Straight-winged Insects (Orthoptera); (3) Bugs (Hemiptera); (4) Fringe-winged Insects (Thysanoptera); (5) Net-winged Insects (Neuroptera); (6) Beetles (Coleoptera); (7) Moths and Butterflies (Lepidoptera); (8) Flies (Diptera); (9) Membrane-winged Insects (Hymenoptera).

Beetles(Coleoptera).—These include an enormous host of insects. Their horny investment is particularly thick, and they possess strong biting jaws, though these differ in some respects from those described for the cockroach and its allies. The third pair, for instance are much more intimately fused together into a lower lip. The fore wings are modified into hard wing-covers, while the hind wings are membraneous, as in straight-winged insects (cockroaches, grasshoppers, and the like). But there is one marked difference between the two orders in regard to these organs. The hind wings of the latter fold up along a set of longitudinal pleats when they are tucked away under their covers, but in a beetle they are relatively long, and require a transverse fold as well.

The life history of beetles exhibits a well-marked metamorphosis. From the egg a grub hatches out, which, after a time, passes into a motionless pupa stage, and ultimately the investment of this splits open so that the perfect insect may emerge.

Beetles vary in size from a mere point to the bulk of a man’s fist, the largest, the elephant beetle of South America, being four inches long. The so-called “black beetles” of kitchens and cellars are not properly beetles at all, but cockroaches.

The most interesting are the following:

Bombardier Beetle(Brachinus crepitans). This insect is preyed upon by larger beetles of its own family; but when chased, the bombardier ejects an acid fluid from glands situated at the tip of its tail. This acid immediately vaporizes on contact with the atmosphere, and looks like a tiny puff of smoke, while at the same time a distinct report is heard, reminding one of a miniature cannon. The discharge can be repeated several times in rapid succession, and prove very serviceable in keeping the enemy at bay until the little artilleryman is able to find shelter beneath a stone, or in a crevice of the soil.

Cantharis, a genus of blister-beetles, represented by the Spanish fly of Southern Europe. The insects are shaken with gloved hands from the branches of trees (ash, privet, lilac, elder, etc.), the gathering in the south of France taking place in May; they are usually killed in a hot vinegar solution and carefully dried. To retain their medicinal properties they must be kept in stoppered bottles. The blistering principle, or cantharidine, is so powerful that those who gather the insects are apt to suffer, and one-hundredth of a grain, placed on the lip, will raise blisters.

Firefly(Elater).—Some fireflies give forth a steady light, and these may be distinguished as fireflies proper from the glow-worms and “lightning-bugs,” which flash light intermittently.

The most brilliant fireflies are a species most at home in tropical America. One form—Pyrophorus noctilucus—common in the West Indies and Brazil, attains a length of about one and one-half inches, and has a dark, rusty-brown color. On the upper surface of the first rings of the thorax are two yellowish oval spots, which are brilliantly luminous during the nocturnal activity of the beetle, while on the first ring of the abdomen a still brighter organ is situated. Even the eggs are luminous, and excised portions placed in a damp chamber remain functional for two or three days. The pounded debris of the insect is also luminous. The luminous organs are special modifications of the epidermic cells, which are disposed in two layers, of which the outer alone is luminous, while the inner contains masses of waste products, and is riddled by air tubes. The luminosity depends on a process of oxidation; the oxygen is supplied by the tracheæ, and the brilliancy varies with the breathing process of the insect. On the sleeping or entirely passive insect a soft light may be observed; the real light is only exhibited during active respiration, and may be exaggerated experimentally by blowing in an extra supply of oxygen. Experiments seem to show that the fireflies utilize their phosphorescence to guide their steps.

SOME PICTURED MARVELS OF INSECT LIFE

A MOTHER EARWIG PROTECTING HER FAMILY(Seepage 237)CONTEST BETWEEN TWO MALE STAG-BEETLES FOR A MATE(SeePage 234)THE SEVEN SPOTTEDLADY-BUG(SeePage 234)THE VICTORIOUS HERCULES BEETLE HAVING VANQUISHED HIS RIVALS IN COURTSHIPCARRIES OFF HIS MATE IN THIS FASHION.(SeePage 234)THE ENGLISH CRICKETwhose familiar chirp we have all heardin the late autumn (SeePage 237)THE BOMBARDIER BEETLEis an expert artilleryman, and when pursued by an enemy is able successfully to resist the chase. (SeePage 232)

A MOTHER EARWIG PROTECTING HER FAMILY(Seepage 237)

CONTEST BETWEEN TWO MALE STAG-BEETLES FOR A MATE(SeePage 234)THE SEVEN SPOTTEDLADY-BUG(SeePage 234)

CONTEST BETWEEN TWO MALE STAG-BEETLES FOR A MATE(SeePage 234)

THE SEVEN SPOTTEDLADY-BUG(SeePage 234)

THE VICTORIOUS HERCULES BEETLE HAVING VANQUISHED HIS RIVALS IN COURTSHIPCARRIES OFF HIS MATE IN THIS FASHION.(SeePage 234)

THE ENGLISH CRICKETwhose familiar chirp we have all heardin the late autumn (SeePage 237)THE BOMBARDIER BEETLEis an expert artilleryman, and when pursued by an enemy is able successfully to resist the chase. (SeePage 232)

THE ENGLISH CRICKETwhose familiar chirp we have all heardin the late autumn (SeePage 237)

THE BOMBARDIER BEETLEis an expert artilleryman, and when pursued by an enemy is able successfully to resist the chase. (SeePage 232)

Glow-worms(Lampyrides) are to be distinguished from the fireflies. They are nocturnal in habit, and represented by about five hundred species, widely distributed, especially in warm countries. America is very rich in “lightning-bugs,” such asPhoturis pennsylvanicus, and other species.

The luminous organs consist, like those of the fireflies, of fatty-looking cells round which there is a plentiful supply of tracheæ, affording the necessary oxygen for the rapid production of phosphorescence.

Professor Emery gives a most entertaining account of his observations on the love-lights ofLuciola italica, which he studied in the meadows around Bologna, Italy. By catching females and imprisoning them in glass tubes in the meadows he satisfied himself that sight, not smell, was all important. When the females caught sight of the flashes of an approaching male, in spite of their tantalizing situation, they allowed their splendor to shine forth. The most noteworthy difference is that the luminous rhythm of the male is more rapid and the flashes briefer, while that of the female is more prolonged, at longer intervals, and more tremulous. The attracted males dance round about the female, who, after having captivated one suitor, proceeds to signal other rivals, till she is finally surrounded by a circle of devotees.

Ladybird or Ladybug(Coccinella) is a pretty little beetle, generally of a brilliant red or yellow color, with black, red, white or yellow spots. The form is nearly hemispherical, the under-surface flat, the thorax and head small, the antennæ and legs short. When handled they emit a yellowish fluid, with a disagreeable smell. Adults and larvæ feed chiefly on plant lice, and are thus most useful to hop-growers and other agriculturists. Ladybirds occasionally occur in immense numbers, and from ignorance of their usefulness have sometimes been regarded with superstitious dread.

Colorado Beetle(Chrysomela) is a North American beetle which commits fearful ravages among potatoes. It is an oval insect, of an orange color, with black spots and lines. The antennæ are club-shaped. The larvæ and adults live on the potato-plant, and have sometimes quite destroyed the crop in certain parts of the United States. They pass the winter underground, and emerge from their hiding-places in the beginning of May. The female lays many hundreds of eggs in groups of twelve to twenty on the under side of potato leaves. The larvæ, which emerge in about a week, are reddish and afterwards orange. They grow up quickly and produce a second generation, which may again produce a third in the same summer. Their rate of multiplication is therefore very rapid. The surest remedy in case of attack is said to be a preparation of arsenic known as “Paris Green.”

Scarabæus(Ateuchus sacer), one of the dung-beetles well known for the zeal with which they unite in rolling balls of dung to their holes. The dung serves as food, and a beetle having secured a ball seems to gnaw at it continuously—sometimes for a fortnight—until the supply is exhausted. Sometimes an egg is laid in the ball, and the parents unite in rolling this to a place of safety. There are numerous American species.

By the Egyptians the scarabæus was venerated during its life, and often embalmed after death. Entomologists have recognized four distinct species sculptured on the Egyptian monuments, and gems of various kinds of stones were often fashioned in their image.

Stag-beetles(Lucanus) are nearly allied to the scarabees. The males are remarkable for the large size of their mandibles, the branching of which has suggested stags’ antlers. The common stag-beetle is a large formidable-looking insect, the males being fully two inches long, and able to give a sharp bite with their strong mandibles. It flies about in the evening in the middle of summer, chiefly frequenting oak-woods.

These insects habitually are well known to fight for possession of a coveted mate. For this purpose the mandibles of the male are enormously developed, and frequently there occurs a most amusing tussle, one beetle striving to gain the side of his lady-love, the other balking him. Eventually one suitor admits defeat by turning tail and making off, while the victor marches in triumph to the fair cause of all the trouble, and begins to court her.

The huge Hercules Beetle of South America has been seen to carry off his mate bodily in this way. Other tropical beetles have specially developed forelegs for grasping their spouse, should she prove coy and attempt playfully to run away.

Water-beetles(Ditiscus marginalis) are carnivorous types which have become adapted to life in freshwater, although the adults have not lost the power of flight. In our native great water-beetle the large hind legs are fringed with bristles, and serve as oars, while air can be stored under the wing-covers. There is only a partial metamorphosis.

Weevilis a popular name for a large number of beetles, marked by a beak or proboscis, generally used by both sexes as a boring organ. Among ten thousand described species are the American speciesTrichobaris trinotata, a small black weevil which destroys potatoes, andConotrachelus nenuphar, which lays its eggs in various fruits and is a great pest, and theEntimus imperialis, the diamond-beetle with very brilliant scales.

Wire-wormsare the grubs of skip-jack or click beetles, perhaps the most injurious of farm pests. They are called wire-worms “from their likeness in toughness and shape to a piece of wire;” they are yellowish in color, from one-quarter to one-half an inch in length, with three pairs of legs, and a suctorial appendage below the tail. The eggs are laid near the roots of plants, in the ground or in the axils of leaves; the grub remains for several years (three to five) as such, burrowing in the ground during the frost of winter, but at other times hardly ceasing from voracious attacks on the roots and underground stems of all sorts of crops. Dressing of lime, salt, nitrate of soda, etc., have been recommended as remedies.

THE LIFE HISTORY OF A BEAUTIFUL BUTTERFLYITS STORY IS VERY SIMILAR TO THAT OF THE SILKWORM

In these photographs the transformations of a butterfly are shown: the butterfly’s eggs (highly magnified) laid upon a leaf; the newly hatched caterpillar; and a caterpillar which has finished its growth and has spun a silken pad, to which as a chrysalis it may cling. The chrysalis is also shown, and the newly emerged butterfly waiting for its wings to expand fully and harden. All the figures are enlarged.

These are among the highest orders of insects. For beauty and variety of coloration they are quite unrivaled, and their attractive appearance is primarily due to the fact that the four wings are covered with overlapping scales of different kinds. The mouth parts are specialized to constitute a suctorial organ, which is made up of the second jaws, while the first and third jaws are greatly reduced. Each second jaw has become a half-tube, and the two are hooked together to make up a proboscis, sometimes of great length, which can be separated into its halves.

HOW BUTTERFLIESDEVELOP

The life-history exhibits a very typical and familiar metamorphosis. From the egg, which is often very beautifully sculptured, a larva known as a caterpillar hatches out, possessing not only the three pairs of jointed legs characteristic of the class, but also a varying number of unjointed pro-legs terminating in suckers. After feeding voraciously for some time by means of its powerful biting first jaws, and undergoing a number of moults, the caterpillar passes into the motionless pupa stage, here called a chrysalis, which may or may not be invested in a protective cocoon. The skin of the chrysalis ultimately splits, and the perfect insect makes it way out.

HOW TO DISTINGUISH BUTTERFLIESFROM MOTHS

Butterflies are typically distinguished from moths by the club-shaped thickenings at the ends of their antennæ, and by the fact that when settling, the wings are folded together over the back. In moths the antennæ may be of various form, but very rarely club-shaped, and the rest-position of the wings is horizontal or sloping downward, while in some instances they may be more or less wrapped round the body.

WHY BUTTERFLIES AND MOTHSHAVE BEAUTIFUL COLORS

Some butterflies are dingy, others uniform, but in contrast to moths the majority are beautifully colored. This is especially the case with tropical forms. How the colors are variegated and contrasted in spots and bands, how the hues are embellished by metallic shimmer, every one knows; what exactly the color means is, however, still obscure. A few general facts may be first noticed: (1) The color is in many cases subject to variation—it cannot be said to be absolutely constant for a species; (2) in some instances, at any rate, it is influenced by external conditions, for different forms at different periods of the year, is known in many kinds; (3) sometimes the color and markings, especially of the under surface of the wings, are obviously of use for the protection of the resting butterfly; (4) in some cases this protective adaptation is so pronounced as to deserve to be called mimicry; (5) in many cases the coloring is in direct connection with the physical constitution of the species, and is usually most marked in the males.

CHIEF CLASSES OFBUTTERFLIES

Of the families representing more than five thousand species, the chief are the following:

(1)Nymphalidæ, the largest, containing between four and five thousand species. They have a relatively simple type of coloration, and are interesting because of their disposition to mimic other species. They are distasteful to birds. They include the red admiral, the tortoise-shells, the peacock, and so on, as well as the fritillaries and the purple emperor. In it are also included the remarkable leaf butterflies in which the under surface, in shape, color and markings, closely resemble a dead leaf, while the upper surface is brightly colored. On alighting only the under surface is visible.

(2) TheErycinidæis represented by the Duke of Burgundy fritillary.

(3) TheLycænidæinclude the “blues,” so commonly seen flitting near the ground along muddy roads, so called from the color of the upper surface, but many are also copper, white and yellow.

(4) ThePieridæinclude the white cabbage butterflies. They are remarkable for the prevalence of white, yellow, and orange colors, and for the fact that these tints are due to uric acid, or derivatives of this substance, stored in the wings as a pigment.

(5) ThePapilionidæ, or swallow-tails, contain perhaps the most beautiful forms. The females are strikingly different from the males, and though larger, do not display the same beauty of coloration. The members of the family are widely distributed.

(6) The familyHesperidæ, or skippers, includes insects very different from other butterflies, both in structure and habits. The adults have in many cases a very rapid but jerky method of flight, and the larvæ in their habits resemble moths rather than butterflies.

Moths(Heterocera).—The antennæ of moths are bristly, gradually lessening from base to tip; when sitting the wings are turned down; and its flight is nocturnal. What the owl is among birds, the moth is among insects: it is a night-insect, carrying on its pursuits, and exercising all its activity amid the gloom of darkness. So numerous is the variety of moths, that there are upward of five hundred species.

The giantOwl-Mothof Brazil (Thysania agrippina) measures nearly a foot across from tip to tip of expanded wings, while the smallest are hardly visible to unaided eyes. The larvæ or caterpillars feed mostly on living plants, and in this connection are very familiar; others of these ravaging forms ruin clothes, furs, and the like. Almost the only directly useful form is the silk-moth.

Silkworm Moth.See underDomesticated Animals.

The fore wings are either parchment-like or membraneous; the hind wings always membraneous. The wings cover the body horizontally, and do not meet in a straight line or ridge, as they do in the beetles. This order of insects undergoes only a partial metamorphosis, being produced from eggs in a wingless condition. The Cicadas, however, are an exception,[237]as they live in the ground frequently for years in the larva state. In this order are included the locust, cricket, grasshopper, cockroach, scale insect, plant-lice, and many kinds of bugs.

Crickets(Gryllus) are akin to grasshoppers. They have long feelers, a rasping organ on the wing-covers of the males, wings closely folded lengthwise, but often along with the wing-covers degenerate, great powers of leaping, and a retiring, more or less subterranean habit of life. Many of the species are wingless, and it is the males only which make a chirping sound. They are widely distributed, and all are herbivorous. The field cricket, house cricket and the common mole-cricket, are well-known representatives of the family.

Earwigs(Forficula) have two pairs of wings, very dissimilar, the anterior pair being short and horny, the posterior pair folded longitudinally and transversely; the mouth parts are well developed and suited for biting; the antennae are thread-like; there is no true metamorphosis in the life-history. The common earwig is best known for the pincer-like organ at the end of the abdomen.

Earwigs avoid the light, and do most of their work in the dark. They feed, as gardeners well know, on petals and other parts of flowers, on fruit, seeds and leaves, nor is animal debris refused. They are usually and readily caught in artificial shelters provided for their destruction.

The eggs of the common species are laid in spring, fifteen to twenty, in some convenient cavity. These are carefully watched, and even after the birth of the young earwigs, the mother still tends them as a hen does her chicks.

Grasshopper, a name given to numerous insects forming the locust family. They usually live among vegetation, in woods and thickets or in the open field. Most of them feed on flies and caterpillars, in catching which they use their powerful fore-legs, but many affect plants, and some combine both diets.

In the grasshopper the head is placed vertically; the slender antennae are longer than the body; there are hemispherical eyes, but rarely eye-spots; wings and wing-covers are generally present. The right (and occasionally also the left) wing-cover of the male bears a clear, round membrane stretched on a ring, which produces the well-known “chirp” when set in vibration.

The females have a long egg-positor. The eggs are laid by means of it either in the earth or in some dry stem. From these, in spring, larvæ are developed, which are virtually like the adults, but molt at least six times before they become full-grown.

Katydid, a name applied to numerous American insects, nearly related to grasshoppers. They frequent trees, shrubbery, and grass, and are well concealed in the foliage by their green color. In their general habit,e. g.in the song to which the syllables “kat-y-did” refer, and in the egg-laying accomplished by the long egg-positors of the female, these lively insects resemble grasshoppers.

Locusts(Acrididae) are large, ground-loving insects, of world-wide distribution, famous for their voracious vegetarian appetite. In size they vary from one-quarter inch to five inches in length. They have strong hind-legs with great leaping powers, large heads with formidable mouth-organs, shorter antennæ and robuster bodies than grasshoppers. Both winged and wingless forms occur, the former with strong powers of flight. The females have strong egg-positors by which they bore holes for their eggs. The numerous eggs are laid in holes drilled in the ground; the young when hatched generally resemble the parents except in the absence of wings. From the first they are gregarious, and excessively voracious except during their repeated molts; they devour all green things, and even one another, and are often forced by stress of hunger and excessive multiplication to migrate in great swarms.

Their ravages sometimes cause widespread famine and ruin. One of the most famous and destructive forms is the Rocky Mountain Locust (Caloptenus spretus); the most abundant migratory species of the East, so often mentioned in the Scriptures, isPachytylus migratorius.

On the left is shown a Leaf Insect which, having given up the habit of flight, has yet retained its likeness to the leaves upon which it feeds to protect itself from its enemies. On the right is shown a grasshopper depositing her eggs in a nest under the ground. (Seeabove).

These membrane-winged insects are the most intelligent of their kind. They are readily recognized by the presence of four transparent wings traversed by a comparatively small number of veins, the hinder ones being much smaller than the others, to which they are in many instances attached during flight by means of a row of minute hooks. The posterior end of the body in the female is commonly provided with a piercing apparatus, which may either serve for boring holes, in which eggs are laid, in which case it is called an “ovipositor,” or may have been modified into a poisoned sting, useful for offense and defense. The black and yellow or black and red bands of wasps and bees are “warning colors,” indicating their stinging powers.

The larvæ either resemble caterpillars or are pale, helpless maggots, devoid of limbs, for the welfare of which more or less elaborate provisions are made by the mother insect. Later on a pupa stage is reached, from which the winged adult ultimately emerges. The highest members of the order live in communities comprising several casts.

Ants(Formicidae).—These familiar and intelligent diminutive creatures are perhaps the most interesting of all insects, owing to the extraordinary way in which they have become adapted to a great variety of modes of life. All are social, and a community typically consists of males, females, workers (of one or more kinds), and, it may be, soldiers. The first two are generally provided with wings, though those of the females are soon shed, but exceptions to this occur, and some species may have both winged and wingless individuals of one sex or the other. The first pair of jaws (mandibles) are well or even excessively developed, and possess unusually free powers of movement in accordance with the varied functions they have to perform. In many cases the females (including the workers) are provided with a sting.

Ants hatch out as helpless, limbless larvæ, which have to be fed and carefully attended, either by the fertile females or the workers, as the case may be. Feeding is rather a curious affair, for the nurse possesses a sort of pouch (crop) connected with her gullet, and this is used as a store from which nutriment can be squeezed up into the mouth. Adults can feed one another in the same way, as also the little beetles and other insects which are often found as guests in their communities.

WANDERING ANTS OFTHE TROPICS

These ants are of highly carnivorous habits, and move about in large armies, devouring everything of animal nature that comes in their way. The fact that they are blind, or practically so, does not seem to interfere with their devastations. Some of the forms are common in the hotter parts of South America, while others, the “driver” ants, are well known in Africa, where criminals, it is said, are sometimes tied up in their path, to perish miserably, if speedily.

SLAVE-HOLDING ANTS ANDTHEIR SLAVES

Some ants press weaker species of their kind into unmerited captivity. In one familiar instance the relatively large oppressor (Polyergus rufescens) is of reddish color and well endowed in the matter of jaws, while the enslaved species (Formica fusca) is small and dark. Regular slave raids are made from time to time, when, after stubborn resistance, the pupæ and older larvæ of the weaker form are carried away to lead a life of bondage, to which, indeed, they take very kindly. This kind of social economy has indeed become an absolute necessity to the slavers, which have quite lost the power of feeding their own young, while some such species cannot feed themselves.

A most extraordinary state of things occurs in the case of a small kind of ant (Anergates) which possesses no workers of its own, but lives within the communities of another species (Tetramorium cæspitosum) entirely made up of workers.

Some ants, such as the little black species (lasius niger) common in gardens, use as part of their food a sweet fluid that exudes from plant lice (aphides), and keep these insects as we keep kine. The captives are fed, sheltered, and jealously guarded. Fenced enclosures are constructed for them on plants in the vicinity of the nest, with which they are connected by covered roads. During winter the fragile eggs of the plant lice are taken underground and sedulously cared for.

THE HARVESTER ANTS OF EUROPE, NORTHAFRICA AND NORTH AMERICA

A number of ants are known that construct extensive underground dwellings, in which they store seeds of various kinds. Some of the American species (Pogonomyrmex) may be even said to winnow their grain, for they carefully strip off the husks and deposit these on rubbish-heaps outside the nest.

Some of the seed-storing ants almost deserve the name of maltsters on account of the way they deal with their harvest. The human method of making malt is to allow the barley grains to germinate to a certain extent until the contained starch is converted into malt-sugar, when the process is arrested by scalding. In similar fashion ants permit germination to go on to a certain point, and then kill the seedlings by biting away the little shoots and roots. In this way a supply of the sweet food they love is secured.

Among the most interesting of ants are leaf-cutting forms (Atta) native to tropical America. They are associated in huge communities occupying complex underground dwellings, the sides of which are marked by mounds that may measure as much as forty yards round. The chief food consists of a kind of fungus (Rozites gongylophora), cultivated on bits of leaf, and treated in such a way that little white elevations are produced. It is these that the ants desire.

The chief duty of one set of workers is to collect the pieces of leaf required. To facilitate their operations, roads, largely underground, are constructed, which lead to suitable trees, and may be as much as twenty yards long, or more. Curved pieces of leaf are bitten out and carried back to the nest, where they are handed over to[239]another set of workers, by them to be reduced to smaller fragments and made into mushroom beds.

WHERE AND HOW THE HOMES OFANTS ARE BUILT

Ants live in dwellings of the most varied kind, many being underground. In a large number of species ant-hills are constructed of various loose materials, our common native wood-ant (Formica rufa) being a good example of this. An Asiatic ant (Oecophylla) constructs a summer-house of leaves in a curious fashion. The larva possesses silk-glands from which a sticky fluid exudes, hardening quickly on exposure to the air. Advantage of this is taken by the workers, for they hold larvæ in their jaws, and employ them as living gum-bottles, while the leaf-edges to be cemented are held in position by other workers.

Some South American ants construct hanging nests in trees, by which protection against floods is secured. Other ants in the same part of the world make curious homes which well deserve the name of “hanging gardens,” for they are mainly constructed of living plants, some of which have never been found in any other situation. The plants are cultivated and tended by the ants with which they are associated. The soldiers of certain ants (Colobopsis), which tunnel out homes in the wood of trees, play the part of living front doors. Every entrance to the nest is guarded by one of these hall-porters, its huge head not only exactly filling the aperture, but closely resembling the adjacent bark in appearance. If this curious door be touched by a bit of stick or a feather, it remains shut, but is immediately opened when stroked by the antennæ of a worker.

CURIOUS ANT GUESTSAND ASSOCIATES

Not only may ants of two or more kinds be associated together in the same dwelling, but a nest may also be tenanted by peculiar species of beetles (and other insects), spiders, mites, or other creatures. Many of these, especially the beetles, are fed and cared for by the ants, some of them for the sake of a substance which exudes from their bodies; others, perhaps, to serve as pets. The beetle-grubs are looked after as well as the adults; at least in the case of certain blind species.

On the other hand, certain ant-beetles not only steal food from the ants, but also devour their young. There can be no doubt that these curious associations are very ancient ones, for many species of beetles are found nowhere else. A kind of bristle-tail that lives in ants’ nests is a thief pure and simple. It has been seen to steal the drops of honey being passed from the mouth of one worker to another, afterwards retreating at full speed.

The common red ant (Myrmica rubra) shelters and feeds a curious kind of blind mite, which lives on the bodies of its hosts. By stroking its entertainers with its legs it makes known its need of nutriment, and such requests are never refused. Not impossibly some return may be made for these good offices.

One of the Indian ants (Sima rufo-nigra) lives on the bark of trees with a species of wasp (Rhinopsis ruficornis) and a kind of spider (Salticus), both of which closely resemble it in appearance. The three associates appear to be good friends, while wasp and ant sometimes engage in a friendly wrestle.

AN ANT AT ITS MORNING TOILETA remarkable observation made by a student of insect life while examining ants under the microscope.

AN ANT AT ITS MORNING TOILET

A remarkable observation made by a student of insect life while examining ants under the microscope.

HOW ANTS COMMUNICATE WITHONE ANOTHER

The complex life of an ants’ nest is a striking instance of order among apparent disorder. Each of the innumerable individuals discharges its special tasks without hesitation, unless unusual circumstances prove a hindrance. It would seem, therefore, that there must be some means by which any one can convey information to others. When two meet they frequently stroke one another with their feelers, and this perhaps serves the purpose of language.

THEIR REMARKABLE HABITSOF CLEANLINESS

Some wonderful facts are recorded concerning matters of personal cleanliness among ants, and has shown incidentally that these insects perform amazing feats of acrobatic skill without the least effort, and quite as matters of course. For example, an ant will often hang from a grass stem by the claws of one leg, while it combs its antennæ, cleanses its five remaining feet, or bends its head upwards to lick its abdomen and furbish the joints of its armor. Indeed, thanks partly to the wonderful flexibility of its “waist,” and still more to the tenacity of its muscles, an ant is able to assume and maintain almost any position that the need or fancy of the moment may prompt.

Many stingless ants, when fighting, first bite their adversary with their jaws, and then[240]bringing the tip of the abdomen beneath the body, squirt formic acid into the wound.

Bees.—SeeDomesticated Animals.

Bumble-bees.—These common bees are large, somewhat clumsy-looking insects which live in communities including workers or imperfect females as well as ordinary members of the two sexes. The nests are constructed in holes in the ground or other sheltered places, and the establishment of a community is due in the first instance to the labors of a queen in early summer. She makes a number of waxen cells, stores them with honey and pollen, and afterwards feeds the larvæ when they have devoured these provisions. From the first (and several other), batches of larvæ workers are chiefly produced, which undertake the constructive and nursing work, until at last the queen has nothing to do but lay eggs. Males and other queens are reared from some of the eggs laid in late summer and early autumn.

Wasps, like bees, are either solitary or social, and it is only in the latter that workers exist. Solitary wasps construct small nests of clay and little stones, or else make burrows. They possess the curious habit of storing up immature—for example, caterpillars—or mature insects, or even spiders, for the benefit of their larvæ when these hatch out. The kind of victim depends upon the species of the wasp concerned, but in any case it is killed or paralysed by stinging.

Social wasps somewhat resemble social bees in their habits, but their building material, instead of being wax, is a kind of paper made of chewed wood mixed up with saliva. In some instances the nest is suspended from a bush or tree, and is provided with a kind of overhanging roof by which rain is drained off.

In our commonest species, an underground site is chosen, and a series of combs constructed from above downward, the whole being enclosed in several layers of wasp paper. Adjacent combs are held together by little pillars. The young are at first fed upon fruit-juice, nectar, and other vegetable matter, for which a more stimulating diet of chewed insects is afterwards substituted.

TheHornet(Vespa crabro) is a social wasp which commonly nests in hollow trees or constructs elaborate nests out of wood fibers, suspended from boughs. The females have formidable retractile stings. The hornet is represented in the United States by the white-faced hornet (V. maculata), also a large species.

There are some thirty or forty thousand species of flies known, while no other order has so many individuals as this. This enormous assemblage of insects, most of which are small or even minute, includes many species that have earned an undesirable reputation as bloodsuckers and pests. Except in fleas and a few others, such as sheep-ticks, there are two membraneous front wings, the hinder pair serving as sensory structures. The mouthparts of the female are very often piercing and sucking organs of great efficiency, the first and second jaws being in the form of slender lancets protected above and below by the upper and under lip respectively.

But in other types, such as the house-fly (Musca domestica), the jaws are modified into a proboscis used for sucking juices, and devoid of powers of perforation.

THEIR UNCLEANLY AND DEATH-CARRYING HABITS

This fly lays its eggs in manure or other refuse, these hatching out, passing through all their stages and emerging as perfect insects in a few days. Their uncleanly habits make the house flies most efficient agents in the carriage of different diseases, especially typhoid fever and others which attack the digestive tract. Flies are therefore not merely a nuisance to be deplored, but a positive danger to mankind. Among other flies are the carrion flies, black flies, the gnats and the mosquitoes, all troublesome to man, while others attack various plants.

THE LARGE VORACIOUSFLEAS

Of these the breeze-flies or gad-flies possess powerful piercing mouth-parts, with which they torment both stock and human beings. A well-known species is the long brown clegg (Hæmatopota pluvialis), often met with in woods. In some tropical kinds the jaws are of enormous length.

Robber-flies are voracious and insatiable forms which prey upon other insects, even wasps and tiger-beetles being among their victims.

Hover-flies are swift and elegant insects which have already been mentioned in connection with flowers. Some of them closely resemble bees in appearance.

The dreaded tsetse fly (Glossina morsitans), so fatal to horses in parts of South Africa, belongs here. Germs of the fly-sickness (Nagana) are introduced into the blood of the victims, Tsetse flies of other species are responsible for “sleeping sickness,” which makes parts of tropical Africa uninhabitable.

THE PESTIFEROUS MOSQUITOSAND GNATS

These are particularly notable for the blood-sucking propensities of the female. Some tropical mosquitoes disseminate the germs of such diseases as malarial fever. Wholesale destruction of the early stages, by pouring petroleum on the surface of the stagnant water in which they live, has been employed with conspicuous success at Havana and in the Panama Canal zone as a preventive measure against yellow fever and malaria.

Midges are very minute gnats, of which the aquatic larvæ are known as blood-worms.

THE WINGLESS FLEASAND OTHER PESTS

Fleas are wingless members of the order, and their agility fully compensates for the loss of the power of flight. There are many species, infesting different mammals and birds. The females of the tiny sand-fleas, or chiggers (Sarcopsylla penetrans), of America deposit their eggs in the feet of human beings (or other animals), and unless the painful swellings thus brought about are carefully treated they are apt to fester dangerously.

STRANGE ANIMAL FORMS FOUND IN THE SEA

Echinoderms, or hedgehog-skinned animals differ from all the forms so far considered in the nature of their symmetry. Instead of being two-sided, with a well-marked distinction between right and left and front and back (bilateral symmetry), they resemble a star or regular flower in shape. The skin is hardened by the deposition of salts of lime, and the body is often covered with spines, as more particularly in sea urchins.

Five existing subdivisions are recognized: (1) Sea-lilies and feather-stars (Crinoidea); (2) Starfishes (Asteroidea); (3) Brittle Stars (Ophiuroidea); (4) Sea urchins (Echinoidea); and (5) Sea-cucumbers (Holothuroidea). All are marine.

Sea Cucumbersare sort of second cousins to the sea urchins and rather more distantly related to the starfish. As the name indicates, they are shaped like a cucumber, and hundreds of little feet on the side heighten the resemblance, as they recall the spines on the vegetable. Inside they have a coiled intestine, usually filled with mud and the contained vegetable and other debris. With us no use is made of the animals, but they are taken in great numbers in the South Seas, and sent to China, where, as trepang, they form an ingredient in soups.

Sea-liliesare deep-sea animals, once numerous and flourishing, but now comparatively rare, and only to be obtained by dredging in the deeper parts of the ocean. They are fixed by a long, jointed stalk bearing circlets of sensitive threads and terminating in a cup, in the center of which the mouth is situated. Radiating from the edges of the cup are five branching, feather-like arms, all of which are grooved above, the grooves uniting, and finally converging to the mouth. They are beset with cilia, and minute organisms are conducted inward along them to serve as food.

Sea Urchinsare radiated animals which are usually shaped like a flattened sphere. They have a mouth, surrounded by five chisel-shaped jaws at one pole, while the whole outer surface is covered with slender, movable spines. Between the spines are numbers of slender, flexible, tubular feet, which pull the body along, while the spines act more like true feet. The animals feed mostly on seaweeds. They have no economic value with us, but in Europe the eggs of some species are eaten, forming part of thefrutti di mareof every Italian seaport.

Starfishes.—Starfishes are among the most familiar objects of the seashore, and the commonest kinds, such as the five-finger (Asterias rubens) and the comb-star (Astropecten aurantiacus) possess five radiating arms. The mouth is in the center of the under side, and leads into a capacious stomach, of which the first part can be protruded from the body to surround such prey as mussels and oysters.

A starfish crawls slowly by means of numerous tube-feet, which are lodged in five grooves radiating from the mouth, and make up a part of the water-vascular system, so called because it is full of sea-water. At the end of each arm is an unpaired tube-foot acting as a feeler, while on its under side there is an orange-red eye-spot.

The water-vascular system assists in breathing. It was probably first evolved in the interests of respiration, and this is its chief use in the sea-lily. Some of the spines are formed of little, two-bladed pincers, which clean the surface of the body.

Starfishes are remarkable for their powers of restoring lost parts. A detached arm can grow a fresh disc and another four arms.

Several groups of the lower animals are collectively known as Worms, though most of these groups are but remotely related. Ringed worms are elongated creatures in which the body is made up of a considerable number of rings or segments, most of which are, on the whole, much alike. There is often a well-marked head, but no distinct thorax and abdomen, as in an insect or crayfish. Two subdivisions are recognized: (a) Bristle-worms (Chætopoda) and (b) Leeches (Discophora).

Bristle-wormsinclude a host of marine worms, together with some that live in fresh water, and also the earthworms. Their average characters are best understood by examining one of the commonest shore-worms, known as the sea-centipede (Nereis). Here the segments are very clearly seen, and almost every one of them bears a pair of unjointed conical foot-stumps, used for crawling.

Imbedded in the foot-stumps of the sea-centipede are bundles of strong bristles, which give a hold on the underlying surface and prevent slipping. The head-region is fairly distinct, and bears a number of feelers of various kinds, as well as four simple eyes. Sea-centipedes and many of their allies are highly carnivorous, and seize their prey by means of a pair of horny jaws which can be protruded at will.

Earthwormsare found in all parts of the world, though naturally they do not thrive in arid tracts; and their effect upon the fertility and drainage of the soil can hardly be calculated. Burrowing into the ground, they cast up the earth they have swallowed, and so pursue a constant and thorough system of ploughing. Though eyeless, they evade the light and only come out of their burrows at dusk, often remaining, even then, with their tails in the holes and their bodies working round and round.

Darwin long since demonstrated, the earthworm is one of the farmers’ best friends. Its burrows drain and aerate the soil, while the earth which has passed through its body is finely divided and constantly being brought to the surface from lower levels.

Not far from the front end of an earthworm a thickening will be seen, often erroneously supposed to be the result of injury. From it exudes a fluid which hardens into the egg-cases.

Leecheslive in the sea, fresh water, or even in damp, tropical forests. The flattened body of the leech is divided by grooves into a number of narrow parts, several of which go to make up a segment. Foot-stumps and bristles are entirely absent, and progression is effected by means of suckers, one at each end. They effect a looping movement, but the animal can also swim by undulations of its body. The freshwater leech is a bloodsucking parasite. The mouth is situated in the middle of the front sucker, which serves to fix the animal to its victim. Three saw-edged jaws are then brought into play, a three-rayed cut being made, and a fluid poured out which prevents the blood from clotting. Digestion is slow, and the food is stored in a large crop, drawn[243]out into numerous pairs of pouches. The head possesses eye-spots, but no feelers.

ANIMALS LIKE PLANTS(Cœlenterata) of which sea-anemones, corals, and jelly-fishes are examples, are distinguished by the ray-like symmetry of starfishes and their kind, though here, as a rule, it is more perfect. In structure they are much simpler, than any of the animals so far considered. For such a creature is to all intents and purposes simply a stomach, the wall of which is made up of two layers of cells, one (ectoderm) external, and the other (endoderm) internal. In higher animals a third layer (mesoderm) is interposed.

Sea Anemonesare common between tides and lower on all coasts. They are cylindrical animals, with a mouth surrounded by tentacles at one end. Inside there is a single cavity which serves as a stomach and whose branches run to all parts of the body, thus distributing the food like a blood vessel. The colors, especially in the tropics, are variable, and often gorgeous.

Coral-polypsare closely related to sea-anemones, but differ from them by secreting a hard, limy skeleton in the base of the body. They are either simple or compound. The well-known mushroom coral may be taken as an example of the former. Its skeleton is a shallow cup, exhibiting numerous radiating plates. If we look at the upper surface of such a coral in the living state we shall see a mouth surrounded by circlets of tentacles, much as in a sea-anemone.

A compound coral consists of a number of individuals, relatively small in size, connected together by a common flesh, and formed by the budding or splitting of a single original polyp, the results of the process remaining united.

Many corals branch, while others form compact masses, as in the kind above described, and also in the brain coral, where the boundaries between the individuals are not clearly marked.

Corals are widely distributed, some living even in cold latitudes, and others on the floor of the deep sea. Coral reefs, however, made up of the skeletons of such animals, are only found in the warmer parts of the ocean, where the water is clear, particularly favorable conditions being afforded by the Pacific and Indian Oceans. (See alsoCoral ReefsandIslands).

Jelly-fish(Medusæ).—All agree in having a more or less bell or umbrella shaped body, with a proboscis hanging down in the place of the handle of the umbrella or the tongue of the bell. The mouth is at the end of the handle and leads into a stomach which divides and sends out branches, like the ribs of the umbrella, to the margin. The common name is due to its gelatinous consistency. Most of the species start in life as buds from attached animals, which later separate and henceforth lead a free existence, swimming by opening and closing the bell.

SPONGES(Porifera) are animals of peculiar structure, which resemble zoophytes in many respects, but possess neither tentacles not thread-cells. Some are simple, but most of them are compound. A simple sponge may be compared to a cup or vase with a wall perforated by numerous small holes, through which currents of sea-water stream into the central cavity, to make their exit by the main opening. They are set up by ciliary action.

Venus Flower-basket.—In the majority of cases the skeleton of a sponge is mostly or entirely made up of sharp needles of lime or flint, which may be welded together, as in this form. Often the opening of the vase is provided with a convex perforated covering. Another elegant form is the Glassrope Sponge native to the Japanese seas. It is rooted in the mud by a bundle of long, glassy spicules, which are slightly twisted.

Most sponges are marine, and, despite their fixed habit and apparent helplessness, are pretty free from the attacks of most other creatures, partly because of the innumerable sharp spicules they contain, and partly because their taste and smell are unpleasant. These deterrent qualities are often associated with bright warning colors, generally red, yellow or orange.

Most of us little realize that the sponges we see or use daily are in reality dead animals.

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