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OF THE MOTHS IN GENERAL*.

The Moths are only to be seen flying abroad in the evening and during the night, which are their times of feeding. The larvæ or caterpillars are in general smooth, and more or less cylindrical: they are active creatures, and prey with great voracity on the leaves of plants. Their chrysalids are either concealed in the ground, or protected from the inclemency of the weather by a silky covering, spun by the larvæ around their bodies. In this state they are either simple, or have a kind of hook at their extremity.

THE SILKWORM †.

The Silkworm is found, in a native state, on mulberry-trees, in China and some other eastern countries, whence, in the reign of the emperor Justinian, it was originally introduced into Europe. It is, however, at this time become, in a commercial view, one of the most valuable of all insects; affording those delicate and beautiful threads, that are afterwards woven into silk, and manufactured into garments in almost all parts of the world.

In the warmer climates of the east, the Silkworms are left at liberty upon the trees; where they are hatched, and on which they form their coccoons: but in cooler countries, where these animals have been introduced, they are kept in a room with a south aspect, built for the purpose, and are fed every day with fresh leaves.

*The antennæ gradually taper from the base to the tip. The tongue is spiral, and the wings, when the animals are at rest, are generally deflected.

+ See Plate xviii. Fig. 8, 9, 10, 11. SYNONYMS. Phalana (bombyx) mori. Linn.-Bombyx mori. Fabricius.

The eggs are of a straw-colour, and each about the size of a pin's head. At its birth the larva or worm is entirely black, and about as long as a small ant; and it retains this colour eight or nine days. The worms are put on wicker shelves, covered first with paper, and on this with a bed of the most tender of the mulberryleaves. Several ranges are placed in the same chamber, one above another, about a foot and a half apart. The scaffolding for these ranges should, however, be in the middle of the room, and the shelves not too deep. The worm continues feeding during eight days after its birth, when it becomes about the fourth of an inch in length: it then experiences a kind of lethargic sleep for three days, during which it casts its skin. It now feeds for about five days, and is considerablly increased in size, when a second sickness comes on. In the next ten days it experiences two other attacks; by which time it has attained its full growth, and is somewhat more than an inch in length, and two lines in thickness. It then feeds during five days, with a most voracious appetite; after which it refuses food, becomes transparent, with a tinge of yellow, and leaves its silky traces on the leaves that it passes over. These signs denote that it is ready to begin the coccoon, in which it it is to undergo its change into a chrysalis. The animals are then furnished with little bushes of heath or broom, stuck upright between the shelves; they climb up the twigs, where, after a little while, they begin the foundation of their lodge, and are five days in spinning the coccoon. They generally remain in this state about forty-seven days.

The retreat which they thus form, is a cone or ball of silk, spun from two longish bags, that lie above the intestines, and are filled with a gummy fluid of a marigold colour. The apparatus, with which the animal is furnished for spinning the silky threads, that principally compose this bag, resembles, in some measure, a wiredrawer's machine, in which gold or silver threads are drawn to any degree of fineness; and through this the

animal draws its thread. As every thread proceeds from two gum-bags, it is probable that each supplies its own; they, however, are united as they proceed from the animal's body. If we examine the thread with a microscope, it will be found flattened on one side, and grooved along its whole length. Hence we may infer, that it is doubled just upon its leaving the body, and that the two threads stick to each other by the gummy quality they possess.

In a state of nature, the Silkworm, previously to the spinning of its web, seeks out some convenient place to erect its cell without obstruction. When it has found a leaf, or a chink, fitted to its purpose, it begins to writhe its head in every direction, and fastens its threads on every side to the walls of its retreat. These, being continued, form at length the little oval ball, in which it is to undergo its change.

The exterior of the coccoon is composed of a kind of rough cotton-like substance, called floss; within this the thread is more distinct and even; and next to the body of the aurelia, the apartment seems lined with a substance of the hardness of paper, but of a much stronger consistence. The thread which composes the coccoon, is not rolled regularly round, but lies upon it in a very irregular manner, and winds off first from one side, and then from the other.

In the course of six or seven days, all the coccoons are generally formed: they are then taken from places where they had been deposited, and divided into classes. The best are strong, and of a pure, unspotted colour. Some are white, and others yellow. The good ones are firm and sound, of a fine grain, and have both ends round and strong. Those of a bright yellow yield more silk than the others. But the pale ones are preferred, because they take certain colours better, and because, since they contain less gum than the others, they lose less than those in boiling.

Five or six days after the coccoon has been detached, the birth of the moth is prevented, as the insect would

otherwise pierce the shell, and thereby render the coccoon useless. To prevent this, the coccoons are put into long, shallow baskets, covered up, and baked for about an hour, in a heat equal to that of an oven from which the bread is just drawn.

After the baking, they are disposed in a proper manner on osier shelves, distributed into stories, two or three feet distant from each other.

The whole thread, if measured, will be found about three hundred yards long; and it is so fine, that eight or ten threads are generally rolled off into one. For this purpose the coccoons are put into small coppers or basins of water, each over a small fire. The ends of the threads are found by brushing them over gently with a whisk made for the purpose; and, in the winding, they are each passed through a hole, in an horizontal bar of iron placed at the edge of the basin, which prevents them from becoming entangled.

A fortnight or three weeks generally elapse before the insect within the coccoon is changed into a moth; but no sooner is it completely formed, than, having divested itself of its aurelia skin, it prepares to burst through its prison. For this purpose it extends its head towards the point of the coccoon, and gnaws a passage through its cell, small at first, but enlarging as the animal increases its efforts for emancipation. The tattered remnants of its aurelia skin are left in confusion within the coccoon, like a little bundle of dirty linen.

The animal, thus set free, appears exhausted with fatigue, and seems produced for no other purpose than to transmit a future brood. The male dies immediately after its conjunction with the female; and she only survives him, till she has laid her eggs, which are to be hatched into worms in the ensuing spring.

In many parts of Italy, the inhabitants contrive to have two silk-harvests in the year. They keep the eggs in very cool places; and, when the mulberry-trees (after having been stripped entirely of their leaves for

former worms) begin to bud a second time, they expose the eggs to be hatched.

During the whole time in which the animals continue in a worm state, the utmost care and attention are requisite, as they are extremely susceptible of cold, dampness, and unpleasant smells.

THE GOAT MOTH*.

The Caterpillar of this moth inhabits the interior of decayed trees, particularly that of the willow and poplar, and continues in this state for three years, before it undergoes its change to a chrysalis. The parent moth deposits her eggs on the bark of the tree; and the larva, as soon as it is hatched, gnaws its way, through the bark, into the interior. Its jaws are extremely powerful.

This is one of the species of Lepidopterous Insects, which possess properties injurious to mankind during the larva state. They do considerable damage by their boring, in various directions, into the trunks of young willow trees, and there feeding upon the wood and pith; often weakening the tree so much as to cause its easy overthrow by the first storm that afterwards

occurs.

In this state they have a strong and disagreeable odour, occasioned by an oily liquid, which they emit from their mouth. It is supposed that this liquid is of use in moistening the wood, and thus preparing it for the operation of the insect's jaws.

The insect changes into a chrysalis in the interior

* DESCRIPTION. The wings of this moth are of a deep and clouded grey-colour, marked with a great number of small blackish waves. The thorax has an angulated band of black on its posterior part.

SYNONYMS. Phalana (bombyx) cossus. Linn. Bombyx cossus. Haworth.-Cossus ligniperda. Fab.-La Rongeuse de Bois. Cuvier.

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