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Raising Silkworms & Harvesting Cocoons

Silkworms are really not worms at all. silk worms are the larvae of ‘bombyx mori’ moths and silkworms are actually domesticated insects.

Native to china, the silkworm does not longer exist in the wild, after so many centuries of inbreeding the silkworm is incapable of flight, mates quickly after emerging from its crysalis, and dies a day or so after laying its eggs.

Design boom illustrates the several stages of sericulture, which begins with hatching silkworm eggs …

An ounce of silkworm eggs yields about 35,000 worms, during gestation, which lasts approximately three weeks, the eggs must stay between 25 and 31 °C, in a tray with high humidity.

As they hatch, each of the tiny creatures must be carefully moved to a ‘petri dish’, a circular flat bamboo tray, to be fed with fresh mulberry leaves several times a day.

When the baby silkworms emerge from their eggs, they are really tiny, about the size of a lowercase ‘i’, and almost black. From the moment they emerge they start eating with an enthusiasm that never abates.

When design boom entered the farmer’s household we could hear them constantly chewing. The worms are protected from harmful flying insects by wrapping the trays in homespun cotton.

The newly born silkworm only eats mulberry leaves. a silk farmer must have a ready supply of mulberry leaves and fruits close at hand, even one missed feeding can kill the sericulture. there are times of the year when the mulberry leaves are not around… continued food shortages can decrease the quality of silk any survivors make.

If there are shortages anyway, lettuce makes a decent emergency dish, as long as it is well-washed (pesticides kill) and dried thoroughly.

Despite revolutionary changes in methods of manufacture, the ultimate basis of silk remains the tiny, inconspicuous-looking silkworm and the most critical period in silk production comes during the silkworm’s brief life span of around 20/24 days.

Nearly all silkworm-producing moths belong to the family ‘bombycidae’, of which one member, ‘bombyx mori’ is responsible for most of the world’s silk.

At the beginning every few days, the worms need to be moved to a clean tray with fresh food.

Members of the farmer’s household must spend a growing amount of time to their bamboo trays, also because silkworms produce quite a lot of excrement and cleaning the trays is not a job for the weak-stomached.

They continue feeding and moving the silkworms, dividing the colonies when the silkworms are too large or hungry for the numbers in that tray. by the fourth week, the largest of the silkworms will be more than 5 cm. long, fat, and hungry enough that they need to be fed every day.

An easy test confirms their readiness to cocooning. the farmer picks them up and looks between their rear pair of legs, from the underside. if there is a gray mass there, the caterpillar isn’t quite ready, but if it’s milky and translucent, the silkworm has pooped its last and is definitely ready.

The worms suddenly stop eating and raise their heads – another sign that they are ready for the all-important job of spinning cocoons.

At that stage they are removed from their feeding trays.

The ‘bombyx mori’ worms are now inserted in a specially woven circular bamboo scaffolding, which will make the cocoons more uniform in shape and easier to collect.

Again, worms are protected from harmful flying insects by wrapping the trays with fine nets. There seems to be always a few dead silkworms in each tray.

While a dramatic increase in the mortality rate is reason for concern, silkworms are insects, and farmers can expect that less than half of the silkworms will reach full maturity.

Each silkworm now doubles itself up on its back, and by contracting secretes, from an opening under its mouth, a steady stream of liquid silk, coated with sericin, which hardens on exposure to air.

They’re starting to lay out the support strands for their cocoons, although they may not yet be serious about cocooning.

Some of the larger caterpillars are climbing the walls of the tray (they’ve done this before, to shed their skins, but this time their heads are pointing toward the lid) and the busy silkworms are guided by figure of eight movements of their heads, to dispose the liquid silk in layers, forming the cocoon.

After some 36 hours, the worms are sealed within a yellow cocoon, embarked on the process of metamorphosing into a moth.

The worms have spun thousands of gossamer little cocoons.

The satisfactory cocoons are now in a clean tray. see the lustrous, golden color. Care must be taken not to damage them when removing from the old trays.

The entire process, from silkworm egg to complete cocoon, takes about twenty-five days. Silk worms transform themselves, inside the cocoon, into a chrysalis and then into a butterfly…

Most of the cocoons are used for the next step in silk making but some of them leave the cocoon as a butterfly. it usually secretes a liquid onto the silk threads to dissolve them, so it can emerge.

The new moths must be moved to another tray so the mess they make while mating and laying eggs doesn’t get all over the hard-earned silk cocoons. The males (small) will die once the deed is done, while the females will stick around to lay about 200 – 300 eggs each.

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