Silk

• Silk is an animal fibre produced by the silkworm.
• Silk fibres are soft and lustrous.
• Like animal hair, silk does not conduct heat, thus keeping us warm in winter.

Life Cycle of Silk Moth:

• The life cycle of silkworm goes through several stages:

Egg:

• Egg is the first stage of a silkworm's life cycle.
• The female silk moth lays about 300 to 400 eggs at a time.
• The female moth lays an egg about the size of an ink dot during summer or the early fall.

Larvae:

• The eggs hatch and the silkworms emerge.
• This is the larva of the silk moth.
• The newly born silkworm feeds on mulberry leaves.

• Young silkworms can only feed on tender mulberry leaves.

Cocoon:

• Cocoon is the stage in which the larva spins silk threads around it, to protect itself from its predators.
• The silkworm deposits filaments in layers, through figure-of-eight movement of the head, forming the cocoon.
• The silkworm takes three to seven days to prepare the cocoon.
• It is formed of about 20-39 concentric layers made up of a single thread.
• Inside the cocoon the silkworm transforms itself into a chrysalis (called the pupa stage in a moth's life cycle) and then into a moth.
• The larva traps itself inside the cocoon in order to pupate.
• Silk threads are obtained from the cocoon of the silkworm.

Adult moth:

• The silkworm, upon hatching, is about 1/8th of an inch and extremely hairy.
• Once the adult moth comes out of its cocoon, its purpose is to find a member of the opposite sex, and mate.
• Males are larger than females and more active.

• Within three to four weeks, it becomes an adult and prepares itself for the next stage in its life cycle.
• The silkworm secretes very fine filaments from two glands on its head.
• The filaments are made of protein which hardens when exposed to air.