Part 50

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=

=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 as _Photuris 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 of _Luciola 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.

=Weevil= is 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 species _Trichobaris trinotata_, a small black weevil which destroys potatoes, and _Conotrachelus nenuphar_, which lays its eggs in various fruits and is a great pest, and the _Entimus imperialis_, the diamond-beetle with very brilliant scales.

=Wire-worms= are 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.

=BUTTERFLIES AND MOTHS= (_Lepidoptera_)

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 BUTTERFLIES DEVELOP

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 BUTTERFLIES FROM 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 MOTHS HAVE 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 OF BUTTERFLIES

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) The _Erycinidæ_ is represented by the Duke of Burgundy fritillary.

(3) The _Lycænidæ_ include 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) The _Pieridæ_ include 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) The _Papilionidæ_, 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 family _Hesperidæ_, 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 giant OWL-MOTH of 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 under Domesticated Animals.

=STRAIGHT-WINGED INSECTS= (_Orthoptera_)

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, 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, is _Pachytylus migratorius_.

=ANTS, BEES AND WASPS= (_Hymenoptera_)

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.