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which they possess after their growth is completed. The whole order of aptera, which comprehends all. the different kinds of spiders, come under this denomination. The viviparous insects, in like manner, appear from the first under their most perfect form. Some kinds, without undergoing all the changes of the silk worm, or that of the common butterfly, after having grown for a certain period, deposit a tunic in which their wings were inveloped, and ascend into the air. Previous to this change, however, such insects enjoy the power of locomotion by means of their limbs, and in this state are distinguished by voracity and activity: of this description are all the different species of locusts. Flies, wasps, and bees, constitute another class, which, after leaving their vermicular form, and passing into their chrysalis state, display their limbs and wings without being capable of using them. The most complete example of transformation is displayed, as we have already observed, in the class of moths and butterflies.
One of the most wonderful circumstances in the economy of insects, is the different preparations which they make, and the expedients to which they have recourse, for their preservation, in their chrysalis or aurelia state. Many dig a hole in the earth, where they remain during the whole period of their inactivity. Such is the invention of all the coleopterous insects.
The gnats, on the other hand, dive into the water, where they remain till the period of their winged state arrives. Some eat their way into seeds and fruits, where they undergo the different changes previous to their entomized appearance. Many lodge themselves in animal bodies on the approach of their transformation; several of the aquatic tribes bury themselves among sand, encrusted with a glutinous substance; while the numerous race of phalænæ wrap themselves up in the leaves of trees, the bombyces, or larger kinds, constituting for themselves a
silken web to protect them during that trying vicissitude of their lives.
Each owns his error in his later cares,
In general, all insects provide for their security before their helpless state arrives, by retiring from their usual haunts into some sheltered retreat. It is thus that the worm of the butterfly provides for its safety, by betaking itself, while it has yet the power of motion, to the hole of a wall, or the eave of an incumbent roof. In this situation, some are suspended by a thread, which nature assists them in providing; some hang by the head, others by the opposite extremity, and many by the middle. The crustaceous covering with which they are then clothed, affords another instance of the attention paid by nature to the preservation of her offspring, during a period in which they are not able to avoid external injury by flight. Thus protected by the munificence of Providence, myriads of animals sink annually into a state of torpor so profound, as appears to threaten the extinction of every vital power. At the return of spring, however, all nature seems again to quicken into life; her countless tribes awake from their torpid state, and enter upon new functions with enlarged powers.
The fulness now of circling time arrives;
But something than corporeal more refined,
Habitations and Food. It has been asserted by Aristotle, that every kind of quadruped and bird is inhabited by its peculiar insect; and this assertion, which has never been contradicted, seems to admit of being much extended. Salmon, cod, and most other fishes, are, at certain seasons, infested with insects parasitic to them : animals of other kinds afford food and residence to other insects; and the same is the case with plants. As the same quadruped is often seen to feed upon a great many different plants, so the same plant often supports a variety of insects. The oak in this country affords sustenance to twenty or thirty different genera; and there are varieties of this tree in warmer climates that serve for food to a far greater number.
Plants afford the most general and copious pabulum for this division of the animal kingdom. Wherever any insect is found indigenous in a country, there will always be found in it plants accommodated to its wants. There are many insects attached uniformly to one plant; the silk-worm always gives a decided preference to the mulberry, but will live, though less vigorously, upon common lettuce. Hence Linnæus has frequently given them names from the plants upon which they feed; a method often fallacious, however, since perhaps the greater number reside indiscriminately upon several plants, and support themselves upon a variety of different vegetable foods. Some are asserted to be capable of residing in the human intestines, and of undergoing their transformations there, being ejected from the stomach in their winged state.
The most poisonous herbs afford food to insects equally with those that are salubrious: the waterhemlock, almost as poisonous a plant as any we know, is frequented by many tribes of these animals, and seems to constitute a favourite nourishment.
In the different stages of their lives, insects are distinguished by various degrees of voracity; many of them in the state of larves are most insatiable : the different species of the butterfly and silk-worms are then endowed with teeth, with which they make great havoc among leaves, even though of a pretty strong consistency; their stomachs being capable of dissolving these harder substances. The same animal, when a chrysalis, not only loses all appetite for food, but the instruments that were employed in comminuting it. The teeth are deposited with its first covering; and the inner coats of the stomach are voided, it is said, along with the excrements, a short while before the first transformation. After being liberated from the last state of confinement, the butterflies are still inferior in voracity, and in the powers of digestion. Their food is now a thin liquid substance collected from the leaves of plants, and devoured only in small quantity.
The same is the case with the different species of locusts; some of which in their larve state are the most voracious of all animals, and desolate entire provinces. It is not till they arrive at their winged and more perfect form that their depredations cease, and mankind are relieved from one of the heaviest calamities which fall upon them in sultry climates. It is by insects in their larve state that the roots of corn are perforated and devoured in more northerly countries. If the season prove cold and wet, they
continue long under ground in the same state; and the crop in the mean time is so completely eaten away, that in some instances scarcely a tenth stalk survives the depredation. In a more genial spring, these animals are expedited into their more perfect form, and the damage done by them is proportionably less; their destructive operations below ceasing as soon as they are enabled by their wings to rise into the air, and go in quest of sustenance in another element.
All insects, even when furnished with wings, take food in a greater or less quantity; though some, as the may-fly and gad-fly, are so short-lived, as in the opinion of one or two naturalists to require no sustenance, and to be destitute of mouths for eating : it is at least true, that the mouths of these insects have no mandibles. But to assert that they never eat, requires a more accurate examination than has hitherto taken place. The smaller and more delicate insects find, perhaps, various particles of matter floating in the air that serve for their support: the effluvia continually emitted by animal and vegetable substances in a state of putrefaction probably support many of them. We know, at least, that numerous tribes of fishes are capable of living upon earthy or other particles found floating in the purest water; and if animals of so superior a size be thus supported, there can hardly be any room to doubt that insects, many of whom are scarcely perceptible, may find abundant subsistence in the air, impregnated as it is with effluvia of various kinds.
Uses of Insects. The economical uses of insects, and their noxious effects upon the various objects of human industry, have already been considered; it only remains that we point out the purposes which they serve in the