How is cocoon formed in silkworms


The silkworm is the caterpillar or larva of the Bombyx mori moth. Silk has been processed in China for at least 5000 years. The moth is essential because it makes the silk, and no longer lives in the natural habit. It is completely dependent on humans. Silkworms ate mulberry leaves and were native to China.

Female silkworm lays about 450-500 eggs. She lays eggs on the blades of mulberry trees. The eggs are coated with a thick discharge by which they cling to the leaves. Female silkworm lays eggs and immediately dies as she does not eat anything. The eggs are kept in a cold place so that they can be cached for a long time. In a favorable condition, they hatch into larva. Larvae are produced in about two weeks from eggs at a temperature of 20 to 25 degrees Celsius.


The cocoon is made of a single thread of raw silk from 1000 to 3000 feet long. The fibers are fragile. About 4,000 to 5,000 cocoons are needed to make a single measure of silk.

If the animal is permitted to survive after spinning its cocoon, it will make a hole in the envelope when it leaves as a moth. This would cut the threads and destroy the silk. Instead, silkworm cocoons are tossed into boiling water, eliminating the silkworms and making the cocoons more accessible to unwind. Often, the silkworm itself is consumed and eaten. Ouch.

The adult silkworms (moths) cannot fly. The silkworm-moths have sides about 2 inches wide and a fair hairy body. Males and females are similarly colored. Adult silkworms have tiny mouths and do not eat.

Cocoon in silkworms- 7 Steps

  1. The silk moth lays 400-500 eggs in a batch. The egg hatch into larvae within ten days.
  2. The larvae experience 4-5 molts and advance into a caterpillar.
  3. Caterpillar is a greedy feeder, and it feeds on mulberry leaves.
  4. After 4-5 days of feeding, the caterpillar becomes lazy, stops eating, and secures a fiber through the mouth from silk glands.
  5. Such caterpillars are isolated and kept in other containers.
  6. These caterpillars within a couple of days present a fibrous cover around themselves. It is known as a cocoon.
  7. A single caterpillar produces 1000-1500 m long, endless fiber. This process of formation of the cocoon is known as spinning.

The science behind Cocoon formation in silkworms

The silkworms secrete an excellent filament made of fibroin protein from 2 glands on its head, hardening after exposure to air, and becoming silk fibers. Through the head’s transition from side to side in the cycle of a figure of eight, the silkworm totally covers itself, forming the cocoon.

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