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Silk is an animal fibre obtained from the secretions of the silk moth. It is obtained from the cocoon of the silkworms.
Silkworms are insects that feed on the leaves of the mulberry plants.
 
Silkworms are insects that live for only two months which is a brief period. During their life period, the silkworm pass through four different development stages known as the life cycle of silkworm.
The life cycle of silkworm:
The life cycle of a silkworm comprises \(4\) stages. They are eggs, caterpillars, cocoons, and adult moths.
  • The life cycle of a silk moth starts when the female silk moth lays eggs.
  • The eggs hatch into caterpillars or larvae that are known as silkworms.
  • These silkworms feed on the mulberry leaves giving rise to pupa.
  • During this stage, a weave is netted around by the silkworm to hold itself.
  • After this, the cocoon swings its head, spinning a fibre made up of protein and developing into silk fibre.
  • The protective layer around the pupa and this covering is known as a cocoon.
  • The silk thread (yarn) is obtained from the silk moth's cocoon.
Stages in the life cycle of silkworm:
 
1. Egg:
It is the first stage in the life cycle of a silk worm. The female moth lays eggs during the springtime.
 
2. Silkworm:
This a stage during which the egg cracks and gives rise to a hairy silkworm. These worms feed on the mulberry leaves to reach the next stage.
 
3. Cocoon:
During this the silkworms spin a protective cocoon around themselves. The cocoon is made up of a single silk thread and is the size of a cotton ball.
 
4. Pupa:
It is a motionless stage in which people kill the pupa by placing them in boiling water so that the silk thread can be unwound.
 
5. Moth:
It is a stage in which the pupa changes into an adult moth. During this stage, the female moth lays eggs, and the lifecycle begins again.
 
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Lifecycle of silkworm
Reference:
https://www.vecteezy.com/vector-art/304113-silkworm-life-cycle-diagram