THE TIGER-MOTH.

(METAMORPHOSES OF INSECTS.)

IT is a universal rule in nature that nothing comes to its perfection at once, but has to pass through a series of changes. Sometimes these changes glide imperceptibly into each other, but mostly each stage of progress is marked clearly and distinctly.

Such is the case with the insect which we are now about to consider; and when we have examined the development of the tiger-moth through its phases of existence, we have the key to that of other insects.

After an insect has left the egg, and entered upon the world as an individual being, it has to pass through three stages, which are called larva, pupa, and imago.

The word "larva," in Latin, signifies "a mask," and this word is used because the insect is at that time "masked," so to speak, under a covering quite different from that which it will finally

assume.

In the present instance, the tiger-moth is so effectually masked under the woolly bear that no one who was ignorant of the fact would imagine two creatures so dissimilar to have any connection with each other.

The word "larva" is usually understood to signify the first of the three states of insect life, whether it be a "caterpillar," a caterpillar," a "grub," or a

"" 'worm."

In its next stage the insect becomes a "pupa,' which word means a "mummy," or a body wrapped in swaddling clothes. This name is employed because in very many insects the pupa is quite still, is shut up without the power of escape, and looks altogether much like a mummy wrapped round in folds of cloth.

In the moths and butterflies the insect in this stage is called a "chrysalis," or "aurelia," both words having the same import, the first Greek and the other Latin, both derived from a word meaning "golden."

Several butterflies-that of the common cabbage

butterfly, for example-take a beautiful golden tinge on their pupal garments, and from these individual instances the golden title has been universally bestowed.

The last, and perfected state, is called the "imago," or image, because now each individual is an image and representative of the entire species.

The woolly bear, then, is the larva of the tigermoth; and if any inquiring reader would like to keep the creature, and watch it through its stages, he will find it an interesting occupation. There is less difficulty than with most insects, for the creature is very hardy, and the plant on which it mostly feeds is exceedingly common.

Generally, the woolly bear is found feeding on the common blind nettle, and the amount of nutriment which one caterpillar will consume is perfectly astounding.

I once had nearly four hundred of them all alive at the same time, and they used to be furnished with nettles by the armful. Of course so large a number is not necessary for ordinary purposes; but this regiment was required for the purpose of watching the development and anatomy of the creature through its entire life.

As the skins of caterpillars are not capable of growth, and the creature itself grows with singular rapidity, it is evident that the skins themselves must be changed, as is the case with many other animals of a higher class, such as the snakes, newts, &c.

For this purpose the skin of the caterpillar splits along the back of the neck, and by degrees the creature emerges, soft, moist, and helpless. A very short time suffices for the hardening of the new envelope; and as the caterpillar has been obliged to fast for a day or two previously to changing the skin, it sets to work to make up for lost time, and does make up effectually.

In the case of the woolly bear, and several others, the cast skin retains nearly the same shape and appearance as when it formed the living envelope of the caterpillar; and consequently, if any number of these insects are kept, the interior of their habitation soon becomes peopled with these imitation caterpillars. Each individual changes its skin some ten or eleven times, each time leaving behind it a model of its former self, so that caterpillars seem to multiply almost miraculously.

We will now watch it as it prepares for its next state of existence.

Hitherto it has been tolerably active, and if alarmed while feeding, it curls itself round like a hedgehog and falls to the ground, hoping to lie concealed among the foliage, and guarded from the effects of the fall by its hairy armour, which stands out on all sides, and secures it from harm. But a time approaches wherein it will have no defence and no means of escape, so it must find a means of lying quiet and concealed. This object it achieves in the following manner :

It leaves its food, and sets off on its travels to

find a retired spot where it may sling its hammock and sleep in peace. Having found a convenient spot, it sets busily to work, and in a very short time spins for itself a kind of silken net, much like a sailor's hammock in shape, and used in the same It is not a very solid piece of work, for the creature can be seen through the meshes; but it is more than sufficiently strong to bear the weight of the enclosed insect, and to guard it from small foes.

manner.

It casts off its skin for the last time, and, instead of being a hirsute and active caterpillar, becomes a smooth and quiescent chrysalis. In this state it abides for a time that varies according to the time of year and the degree of temperature, and at last bursts its earthy holdings, coming to the light of the sun a perfect insect.-Wood.

LEARN:-
:-

Met-a-mor'-pho-ses, changes of form or | A-chieves', brings about, accomplishes.

Im-per-cept'-i-bly, so trifling as not to Nu'-tri-ment, that which nourishes or

be observed.

Dev-el'-op-ment, unfolding, coming out of one state of existence into another.

feeds the body.

An-d'-to-my, the science which treats of the structure of animal bodies.

Swad'-dling, swathing, or rolling in a Mesh'-es, the openings in network.