Question

Why are the worms inside the cocoons killed before they are actually grown?

Answer 1

Because there is a worm inside the cocoon so that's why it is boil to kill it . so it will not harm the humans. When the silkworms are still in their cocoons they are boiled out so that they would die inside. After the silkworm dies it becomes easier to unwrap the silk threads

Answer 2

Basically, the cocoon from which we feel the silk is actually a protection for the pupal stage of silkworm.Under natural condition, before pupation, the silkworm spins cocoon and gets converted into pupa inside. When the pupal period is completed ,the pupa metamorphose into adult(moth). As the adult should come out of cocoon for mating (pairing), it releases an enzyme called cocoonase, which help to break the silk filament in cocoon and comes out for mating.

Now, when we rear the silkworm for the production of silk, we need to reel the silk.

Silk is a single continuous thread of up to 1300 m long. This continuity helps us to reel the silk as a thread.When the silk moth come out of cocoon by cutting the cocoon, this continuity is lost, making it impossible to reel the cocoon. Once the cocoon is cut by silk moth to emerge out, it goes for spun silk production which fetches a lower market price.

In order to prevent this, a practice called stifling is practiced wherein, the pupa inside the cocoon is killed before emergence of moth by using hot air or steam or even sun drying.