THE STORY OF THE SILKWORM.
A silkworm is not a real worm, but an insect. True worms remain worms during the whole of their life history. The common earthworm which you see upon the ground after a rain is a real worm.
The life history of an insect is not at all like that of a worm. Each of the eggs of an insect hatches into a little worm-like animal, or caterpillar. After living a number of days the caterpillar changes into a pupa or chrysalis. In this condition it has a hard case and is helpless. Now it undergoes a slow change and after a time emerges as a perfect insect with wings.
Thus we see that the insect during a part of its life looks like a worm, but during another part like a very different creature.
The hairy little caterpillar which you one day watched crawling over the ground may have been the same insect which, at a later time, as a pretty butterfly, you chased over the meadows.
Have you not seen the prettily marked cases, from one half to three fourths of an inch long, hanging from a board or limb? If you happen to find one at just the right time you will see the insect break the case and come out a perfect moth or butterfly.
In a short time its wings, which were tightly folded in the case, will be expanded, and it will fly away through the air.
This butterfly will lay eggs which will, in time, hatch into other caterpillars. Is not this a strange story? The silkworm came from China. It has been known there for hundreds and perhaps thousands of years. It is now raised in many parts of the world where the weather is not too cold.
The larva or young insect is a little caterpillar.
In the earlier part of its life it is hairy, but as it grows it loses its hair and looks more like a worm. This is the reason it is called the silkworm.
The caterpillars, or larva?, are given all they can eat of the soft green leaves of the mulberry tree. Where silkworms are raised many such trees have to be cultivated to supply the necessary amount of leaves.
The larvae are always hungry and very great eaters. During their growth they shed their skins several times. The skin does not grow with the body of the caterpillar, and when it becomes too tight, it cracks and comes off, a new one having formed under it.
When fully grown the caterpillar spins a cocoon of silk about itself, the silk being taken from the lower jaw.
It wraps itself up in about one thousand yards of very fine thread. In this way is formed a whitish or yellowish case which is about one inch in length. In this case, snugly tucked away, the insect goes to sleep, until after having undergone a slow change, he awakes as a moth and bursts the cocoon.
When the cocoons are to be used for their silk, they are not allowed to hatch. At a certain time the insect is killed and the silken threads are unwound. This work is done by the aid of machinery.
You can see that it must take many cocoons to make one yard of silk cloth. The different colors of the silk are given the threads before they are woven into cloth.