ORDER ORTHOPTERA.
Including the Grasshoppers, Locusts, Crickets, Cockroaches,
Earwigs, and their Allies.
The Orthoptera include all those forms of insects which have four wings, the anterior pair being of a leathery nature. They are mandibulate; that is, their mouths are formed for biting, and they undergo an imperfect metamorphosis.
The insects comprised in this order are extremely numerous and destructive in the tropical parts of the world (Kirby gives their number as about 7,000), but they are only represented in the British Isles by about sixty species, few of which are really abundant. They include the cockroaches, crickets, grasshoppers, locusts, earwigs, etc.
All these insects may be divided into three sub-divisions or tribes—namely, the Runners or Cursoria, the Leapers or Saltatoria, and the Earwigs or Euplexoptera.
The following table will show at a glance the outlines of the proposed arrangement:—
Tribe I., Cursoria.—Hind wings with veins radiating from the base. Hind legs formed for running.
Tribe II., Saltatoria.—Hind wings with veins radiating from base. Hind legs formed for leaping.
Tribe III., Euplexoptera.—Hind wings with veins radiating from the apex of a horny piece occupying the base of the anterior margin.
The Euplexoptera, or Earwigs, are regarded by some authors as a separate order. They are thus treated by Westwood in his "Introduction to the Modern Classification of Insects," but the modern tendency is to revert to the Linnæan system, and retain them among the Orthoptera.
TABULAR VIEW
OF THE
PRINCIPAL FAMILIES OF THE ORTHOPTERA.
| Tribe I.—Cursoria. | ||
| Family | 1. | Blattidæ or Cockroaches. |
| Family | 2. | Mantidæ or Praying Insects. |
| Family | 3. | Phasmidæ or Stick and Leaf Insects. |
| Tribe II.—Saltatoria. | ||
| Family | 4. | Achetidæ or Crickets. |
| Family | 5. | Gryllidæ or False Locusts. |
| Family | 6. | Locustidæ or True Locusts and Grasshoppers. |
| Tribe III.—Euplexoptera. | ||
| Family | 7. | Forficulidæ or Earwigs. |
We will now proceed to describe each of these families in turn.
Tribe I.—Cursoria.
The insects constituting this group are distinguished by having their hind legs adapted for walking or running. They are subdivided into three families.
Family 1, Blattidæ.—This family includes the numerous species of cockroaches, or "black bats" as they are often called by uneducated persons. They are represented in all parts of the world, but are most abundant within the tropics, and especially in central and southern America, where also the largest and finest species are to be found. Many curious forms are also to be met with in India and different parts of Africa.
They are very active creatures, and run with considerable rapidity, but their activity is chiefly nocturnal, and during the day they generally remain quietly concealed in some obscure retreat. Their diet consists of both vegetable and animal matter, and offal of every description. They are most useful in hot climates, acting the part of scavengers, and by these means preventing the outbreak of malaria and other pestilential diseases.
The best-known species in this country is the common Cockroach (Blatta orientalis), which, by-the-bye, is not a native of Europe, having been introduced from the East several centuries ago, and to have made its home here.
Other species besides this are met with occasionally in different parts of the country, having been introduced in like manner at different times from foreign parts. The Giant Cockroach (Blaberus giganteus) is one of these. Its native home is South America and the West Indies, and in the latter place it is commonly called the "drummer." It measures nearly three inches in length. The Zoological Gardens in London is a favourite resort of this species.
Family 2, Mantidæ.—The Mantidæ may be at once distinguished from the insects comprising the other two families of the Cursoria by the structure of the forelegs, which are converted into powerful raptoral organs.
The body of these insects is more or less elongated, and the head, which is triangular or heart-shaped, is attached to the thorax by a distinct neck.
The Mantidæ, or Praying Insects, are celebrated for their habit of resting on their four hind legs, and with their front legs raised in the air, in what was formerly supposed to be an attitude of devotion, but really in an observant attitude, and on the alert for their prey.
None of these insects are met with in the British Isles, but several species are rather abundant in the south of France. Two species, Mantis pauperata and Mantis religosa, measure about two or two and a half inches in length. A third species, Mantis oratoria, is also common but somewhat smaller in size.
Family 3, Phasmidæ.—These insects very much resemble the Mantidæ in general appearance, to which also they are very closely allied.
They are among the most peculiar insects in existence. Their appearance is comical in the extreme. Many of them resemble sticks, either green growing trees or brown and withered branches, and hence the name of stick insects commonly applied to them is very appropriate. On account of their skeleton-like forms they have also been likened to ghosts and spectres.
Some few species mimic leaves of trees and various plants, and these are often called "leaf insects."
The number of species of this family is not very large, and by far the greater part of these are inhabitants of the warmer regions of the earth, and they seem to increase in size, especially the nearer their home lies to the Equator.
Among the more interesting species we may mention Cyphocrania semirubra from Brazil, with short greenish elytra and pink wings.
Bacillus rosii is a brown, wingless form found in Italy and the south of France.
Some of the tropical species are among the largest insects known. A winged Australian species attains the length of ten inches.
Lopaphus cocophagus is a common species in the South Sea Islands, and sometimes commits great ravages in the plantations of cocoa-nut trees. When this insect is alarmed it squirts out a highly acrid fluid, which causes great pain, and sometimes blindness if it reaches the eye.
We may remark that no species of Phasmidæ are known to inhabit the British Isles.
Tribe II.—Saltatoria.
The principal character of the insects belonging to this tribe consists in the adaptation of the hind legs to the purpose of leaping.
The males of most of the species possess the faculty of producing loud chirping sounds, but the means by which this is effected vary in the different families.
Family 4, Achetidæ.—The most familiar British insect belonging to this family is the common House Cricket (Acheta domestica). Living, as it does, in the immediate vicinity of the fire, it seems to be totally independent of the changes of the seasons, and may usually be found of all ages at all periods of the year. Crickets are particularly abundant in bakehouses, being extremely partial to warmth. The chirping noise which they produce at night-time is sometimes almost deafening, and it is really surprising from what a very long distance the sound may be heard.
Their food consists of bread crumbs and scraps of meat and vegetables which have been allowed to accumulate during the daytime. The best way, therefore, to get rid of the insects is to take proper care in clearing away all the refuse after meals, for if this were not there the crickets could not subsist, and would soon quit the house. They are, however, generally objected to only by weak-nerved people, and do very little harm, if any whatever. It is a question whether they are not very useful in acting as scavengers.
A nearly allied British species is the Field Cricket (Acheta campestris), which is rather larger than the house cricket. It is comparatively rare and local in this country, but abounds everywhere on the Continent.
A third British species is the Wood Cricket (Nemolicus sylvestris), which is considerably rarer than either of the preceding. It is found abundantly among dead leaves in woods in France and other parts of the Continent, but is very rarely found in England.
The Mole Cricket (Gryllotalpa vulgaris) is perhaps the most interesting member of the family. It is a large, robust insect, about an inch and a half in length and of a very dark brown colour. It is remarkable for the peculiar shape of its front legs, which exactly resemble those of the mole.
It burrows in loose soil, and, like the mole, it passes along close beneath the surface of the ground, and often raises a small ridge as it advances. It frequents gardens, especially near the banks of canals, and is also fond of damp meadows and other localities in the vicinity of water.
The eggs to the number of 200 or 300, are deposited in a chamber of considerable dimensions, and enclosed in a sort of cocoon-like envelope.
The larvæ when first hatched are white, and are said to be three years in arriving at a state of maturity. The mole cricket is found chiefly in the south of England.
Family 5, Gryllidæ.—The most conspicuous insect belonging to this family in Britain is known as the great Green Grasshopper (Phasgonura viridissima), which measures nearly four inches in expanse of the wing, and is therefore nearly as large as the migratory locust which sometimes visits us.
The great green grasshopper is not, however, a very common insect in this country, being principally confined to the south of the island.
Another European and British species, Decticus verrucivorus, is of about the same length. It receives its name from the custom prevailing among the Swedish peasants of making it bite their warts. This insect, in common with many others of the same family, when at all roughly handled, emits from the mouth a brownish fluid, which is said to possess acrid qualities, and the introduction of this into the warts is supposed to cause their disappearance.
Family 6, Locustidæ.—This family, which includes the grasshoppers and true locusts, is easily distinguished from both the preceding families by the character of the antennæ, which are comparatively short.
The common English Grasshopper (Rhammatocerus biguttulus), whose song must be familiar to every one who has walked through the fields during the summer time, is produced by the friction of the hinder thighs against the wing-cases.
The locusts have been celebrated from the dawn of history on account of the terrible ravages which they have committed in various parts of the world; and although many different species have made their appearance in our own country at various times, the climate, fortunately, seems unsuitable for them to live in, and they have, therefore, not been known to breed here.
The Migratory Locust (Ædipoda migratoria) is perhaps the best known in this country on account of its visits, many stray individuals of which have visited us at different periods.
Locusts are known all the world over, in fact, nearly every country has a species peculiar to itself. The most extraordinary accounts are on record of the vastness of the swarms which every now and again invade particular districts. They are said sometimes to absolutely darken the sun.
They clear off everything from the surface of the ground as completely as if the place had been visited by fire.
In many eastern countries locusts are relished as articles of food.
The distinctive character of the insects comprised in this group is found in the structure of the wings. The anterior pair are of a horny or leathery consistence, but always much shorter than the abdomen. The hind wings, on the contrary, are of large size, and are composed of a very delicate membrane. There is only one family.
Tribe III.—Euplexoptera.
Family 7, Forficulidæ.—The insects of this family present a great uniformity of structure. They are, for the most part, of nocturnal habits, concealing themselves during the day in crevices under the bark of trees, or in the ground under stones and leaves, etc.
Their food consists almost exclusively of vegetable substances, and are sometimes very injurious to flowers and fruit.
It has been said, however, that they also feed largely on plant lice or aphides, which, if true, give them a very redeeming quality.
The female earwig deposits her eggs under a stone in some cavity in the ground often dug out by her own labour.
Unlike most other insects, the female does not perish as soon as she has laid her eggs, but lives to behold her offspring, brooding over them almost like a hen. But it is distressing to learn that if the mother should die she is immediately devoured by her progeny.
The Euplexoptera are widely distributed over the surface of the earth. The tropical regions, however, can hardly claim any great predominance over more temperate climates as regards either the number or size of the species.
The largest European species (Forficesita gigantea), which is an inhabitant of some parts of England, measures about an inch in length of the body.
Our common Earwig (Forficula auricularia) is not only found all over Europe, but apparently throughout the greater part of the eastern hemisphere.
Another British species, viz., the little Earwig (Labia minor), is also of wide distribution.
The earwig derives its name from its occasionally creeping into the human ear in search of concealment. This has been denied by many authors, but we have personally known instances of earwigs entering the ears of persons lying asleep in fields in the summer time. The insect can be driven out immediately by pouring a little oil into the ear.
Some writers have attempted to prove that the name earwig is a corruption of "earwing," in allusion to the shape of the hind wings; really a very ingenious idea, but incorrect nevertheless.