TRANSFORMATION OF INSECTS. His mighty work who speaks, and it is done. 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 nature. 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 224 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 At length assured, they catch the favouring gale, 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 mil'lepēdz, or mil-lep/e-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. LINNEUS divided insects into seven orders. His divisions 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 226 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 ORDERS OF INSECTS. 227 plants so completely as to produce the appearance of a discoloured change of structure. The family of spiders (ara'nea) is not always arranged among insects, and strictly speaking their structure is different in some important particulars. They are distinguished from all other insects by the absence of the antennæ. They have generally eight legs, and are furnished with six or eight eyes, which enable them to see objects in several different directions at once. They are nourished generally by living prey, which they secure by means of a web, spun with much ingenuity. The threads, of which the web is composed, are produced from six little fleshy bunches, or muscular instruments, each of which contains about a thousand tubes, or outlets of threads, so extremely minute that many hundreds of them must be united before they form one of those visible ropes, of which the spider's web is composed. By means of their webs, many species of spiders, particularly when young, are able to transport themselves to a considerable distance through the air. In order to effect this, they ascend some eminence, and throw out a number of webs. These are raised up and carried along by the wind, and the animal being buoyed up by them is conveyed sometimes to a great height. In order to alight, they have only to disengage themselves from a part of their web, and suffer themselves to descend gradually to the ground. It is probable that they have recourse to this expedient, in part at least, for the purpose of catching insects for food. In autumn, the air is often full of the cobwebs which have been made use of for this singular mode of conveyance. This fine filmy substance is called Gossamer; and it is seen not only in the air, but is more observable in stubble fields, and upon furze and other low bushes. Those who have ascended eminences for the purpose of observing the phenomenon, have frequently seen spiders floating by in the air, supported in the manner which has been described. To the Insect of the Gossamer:-BY C. SMITH. Float'st on a sunbeam. Living atom, where |