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950

TRANSFORMATION OF INSECTS

cular organ for respiration, but their bodies are penetrated in every direction by tubes, through which the air is trans mitted to every part. These tubes communicate externally by openings called spiracles. To serve the purpose of a brain and nervous system, they are furnished with two knotted cords running the length of their bodies. They possess the senses of seeing, tasting, smelling, and feeling; but organs of hearing, if they exist, have not yet been discovered. They are provided with a hard external covering which differs in different species; in some it forms a complete case of a horny or shell-like substance; and in others it consists merely in a tough muscular coat, divided into rings which surround the body. Their heads are furnished with anten'næ or feelers, which are a kind of filaments composed of joints, designed probably as the organs of the sense of touch, or of sensations still more delicate and of a nature totally unknown

to us.

The mouth of insects varies much in construction, according to the nature of their food. Some are armed with a sort of lancet, and others with a trunk or probos'cis, which in the butterflies is capable of being rolled up in a spiral form. Their eyes may be considered among the most surprising of nature's works. They differ much in form and colour in the different insects; but they are not, as might be at first supposed, mere hemispherical bodies of plane simple surfaces, for examination proves them to be composed of an immense assemblage of highly wrought hexagonal facets, each furnished with its proper optic nerve, retina, and other parts necessary for vision: the number of these facets differs in different species; eight thousand have been counted in the eye of the common fly, and twelve thousand in that of the dragon fly.

How sweet to muse upon His skill displayed!
Infinite skill! in all that he has made,
To trace in Nature's most minute design
The signature and stamp of Power Divine;
Contrivance exquisite expressed with ease,
Where unassisted sight no beauty sees;
The shapely limb, and lubricated joint
Within the small dimensions of a point;
Muscle and nerve miraculously spun,

TRANSFORMATION OF INSECTS.

His mighty work who speaks, and it is done.
Th' Invisible in things scarce seen revealed;
To whom an atom is an ample field.

223

COWPER.

The greater part of insects are winged. Those which are not winged, continue, during their whole existence, of the same form and structure as at birth. Those which are winged undergo certain changes of form, which are called their metamorphoses. They differ in number in different kinds of insects. For an example we may take the tribe of the Butterfly. From the egg of this insect is hatched an animal differing entirely from its parent. Its body is long and cylindrical, and divided into numerous rings. It is provided with a large number of very short legs, with jaws, and with several small eyes. It is familiarly known to us by the name of caterpillar. It lives in this state a considerable time, subsisting upon such food as is adapted to its mature. At length it casts off its skin, and appears in another form without limbs. It ceases to feed or to move. It seems to be totally without life. This is called the chrys'alis. After a while, by examining it closely, the imperfect shape of a butterfly may be distinguished through its surface; and finally the envelope is broken and the animal escapes. Its wings are at first short, weak, and moist, but they soon unfold to a greater size, and become strong; and the insect is in a state to fly. It has now six long legs, a spiral trunk, two antennæ, and eyes differing entirely from those of the caterpillar. In short, it is an animal totally different, delighting us by the beauty of its spots and the variety of its colours; and yet these wonderful changes are only the successive unfolding of parts contained one within another in the original em'bryo. In the first state the animal is called the larva; in the second the chrysalis or nympha; and the third is called the perfect state. A considerable portion of the insect tribes pass through these three changes of existence. But many only undergo what is called a demi-metamorphosis. Their larva resembles the perfect insect, except that it has no wings. And the only change they experience is, that in the nymph state they have the rudiments of wings, which finally on casting their skins, are changed into complete ones. Such are grasshoppers and many others.

When about to pass into the chrysalis state, which is a

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1

TRANSFORMATION OF INSECTS.

state of imbecility, insects select the most proper places and modes of concealing themselves from their enemies. Some, as the silk-worm and others, spin silken webs round their bodies, by which the animal form is completely disguised. Others leave the plants upon which they formerly fed, and hide themselves in little cells which they make in the earth. Some fix themselves by a gluten, and spin a rope round their middle to prevent them from falling. Others attach themselves to walls, with their heads higher than their bodies, but in various inclinations. In this state many remain motionless and seemingly inanimate, during the whole winter.

Behold the insect race, ordained to keep
The lazy Sabbath of a half year's sleep;
Entombed, beneath the filmy web they lie,
And wait the influence of a kinder sky.
When vernal sun-beams pierce their dark retreat,
The heaving tomb distends with vital heat;
The full formed brood impatient of their cell,
Start from their trance and burst their silken shell;
Trembling, awhile they stand, and scarcely dare
To launch at once upon the untried air:

At length assured, they catch the favouring gale,
And leave their sordid spoils and high in ether sail.
BARBAULD.

QUESTIONS-1. For what are insects remarkable? 2. What have they instead of a heart? 3. What have they to answer the purpose of a respiratory organ? 4. Brain and nervous system? 5. What is said of their senses and external covering? 6. What are antennæ ? 7. Describe the eyes of insects. 8. What are the changes called which winged insects undergo? 9. Give a description of these changes in the example of the butterfly. 10. What is the animal called in its first-second-third state? 11. Describe what is called demi-metamorphosis. 12. What are some of the artifices of insects when about to enter the chrysalis state? [NOTE. All insects have six legs, with the exception of the millepedes, (pronounced millepēdz, or mil-lepe-dez) which have always more, and the number increases also with their age. Aurelia and Chrysalis are synonymous words, both alluding to the metallic or golden splendour of the case in which insects are enclosed during that state. This brilliancy however seems to be confined to the butterfly tribe. The name Pupa has lately been substituted for chrysalis and aurelia, because many insects in this state are thought to resemble an infant in swaddling clothes.

ORDERS OF INSECTS.

225

LESSON 100.

Orders of Insects.

Perforator, a part of some insects with which they bore various substances in order to admit their eggs.

Farina'ceous, mealy, resembling the farina of flowers.

His divisions

LINNEUS divided insects into seven orders. are founded upon the presence or absence of wings, their number, their texture, their arrangement, and the nature of their surface. The first order (colcop'tera) has four wings. The upper pair consist of a hard, crustaceous or horny substance, and cover or defend the under pair, which are of a more soft and flexible texture, and are folded beneath them. This is the most numerous and best known kind of insects and many of them are very remarkable for the singularity of their forms and the beauty of their colours. The various insects known under the name of beetles and winged bugs are included in this order.

The second order (hemip'tera) has likewise four wings; but the upper pair is not of so hard a texture as those of the beetle tribe. They are more like fine vellum, and, at their extremities, terminate with a membranous edge, which resembles the substance of the under pair. They cover the body horizontally, and do not meet in a straight line or ridge, as they do in the first order. Among them are found the grasshopper and the locust.

The third order (lepidoptera) has four wings and comprehends the various kinds of moths and butterflies. Their wings are covered with a farinaceous powder, or rather with scales or feathers, disposed in regular rows, nearly in the same manner as tiles are laid upon the roofs of houses. The elegance, the beauty, the variety of colours, exhibited in their wings, are produced by the disposition and tincture of these minute feathers. When the feathers are rubbed off, the wings appear to be nothing more than a naked and often a transparent membrane.

The fourth order (neurop'tera) has four naked membranous wings, which are so interspersed with delicate veins, that they have the appearance of a beautiful net work. They have no sting. Of this order are the various species of

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ORDERS OF INSECTS.

dragon fly, large and well known insects that frequent lakes and pools of stagnant water; the Ephem'eral flies, which pass two or three years in the states of larva and chrysalis, but whose existence as winged and perfect insects is limited to a single day; and the Ant-lion and Ter'mites, the former celebrated as the destroyer of the common ant, and the latter for the ravages they make in some tropical countries.

The fifth order (hymenoptera) has four naked membranous wings, but destitute of that delicate, netted structure, which belongs to the last order. The females have either a perforator or a sting. In the domestic economy and mode of propagation of some of the species, there are circumstances which excite our admiration and astonishment. The ant, wasp, and bee belong to this order. They live in societies, greater or less in extent and number; and prepare habitations and nourishment for themselves and offspring, with a forethought and provident care, excelled only by man himself. In some of the tribes of this order, there is, beside the males and females, a third sort called neuters, as among the ants and bees.

The sixth order (dip'tera) has only two wings, but beneath them are two cylindrical projections, which seem as if they were the rudiments of another pair. These have been called balancers or poisers, from being supposed to aid them in preserving an equilibrium during their flight. Between them and the wings themselves are found small membranous scales, one upon each side, against which the balancer strikes with great rapidity, whilst the insect is in motion, and causes that buzzing which is then observed. To this order belong some of the most troublesome and annoying of the whole animal creation, such as the various species of gnat, and the common fly. They are found in almost every part of the globe.

The seventh and last order of insects (ap'tera) includes a great variety that are destitute of wings. It is true that in the preceding orders are arranged many sorts of insects that are destitute of wings, but they are so arranged because in their general structure and habits of life they resemble the other members of the order. The Aptera, however, have no such resemblance, and are therefore placed by themselves. Some animals of this order cover the surface of

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