A material which is composed of thin and continuous strands is known as fiber. A fiber can be of two types: natural fiber and synthetic fiber. The fibers which are obtained from plants and animals are known as natural fibers whereas synthetic fibers are man-made fibers. Examples of natural fibers are cotton and silk whereas examples of synthetic fibers are: nylon, polyester, etc. Silk is a type of natural fiber or animal fiber. Silkworm is responsible for spinning of silk and it is reared to obtain silk.

History of silk

Silk was discovered around 3500 BC in China. For a long period of time, silk was shipped to other parts of the world through trade. Technological advancement and new developments have enabled manufacturers to produce different types of silk from different silkworms on the basis of luster and texture. Mulberry silk is the most common silk moth that is used for producing silk. Rearing of the silkworm is known as sericulture.


The life cycle of silkworm

The life cycle of silk moth starts when a female silk moth lays eggs. The caterpillar or larvae are hatched from the eggs of the silk moth. The silkworms feed on mulberry leaves and give rise to pupa. In pupa stage, a weave is netted around by the silkworm to hold itself. After that it swings its head, spinning a fiber made of a protein and becomes a silk fiber. Several caterpillars form a protective layer around pupa and this covering is known as the cocoon. The silk thread (yarn) is obtained from the silk moth’s cocoon. The life cycle of silkworm is explained below in details.

Life Cycle of Silkworm

Stage 1: Egg

An egg is the first stage of the life cycle of silkworm. The egg is laid by a female moth which is mostly the size of small dots. A female moth lays more than 350 eggs at a the springtime, the eggs hatch due to the warmth in the air. This procedure happens once in every year.

Stage 2: Silkworm

A hairy silkworm arises after the eggs crack. In this stage of silkworms, the growth happens. they feed on mulberry leaves and consume a large amount of these leaves for around 30 days before going to the next stage.

Stage 3: Cocoon

In this stage, silkworms spin a protective cocoon around itself. It is the size of a small cotton ball and is made of a single thread of silk.

Stage 4: Pupa

Pupa stage is a motionless stage. In this stage, people kill the pupa by plunging the cocoon into boiling water and unwind the silk thread.

Stage 5: Moth

In this stage, the pupa changes into an adult moth. The female moth lays eggs after mating and thus the life cycle of silkworm begins again.

Processing of  silk

Extracting silk from the cocoon is known as the processing of silk. Silk is separated from cocoon by exposing it to sunlight. After that reeling of silk is done, the process of unwinding silk from a cocoon. Silk thread is then bleached. Silk fiber is then spun into silk threads.

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Practise This Question

Pollution in rivers like the Ganga is caused by which of the following factors?