Life cycle of the Silkworm
Today, the 13th of November, 2008, I took a photo of the silkworms in their different stages.
I will describe the silkworm cycle.
First the silkworm comes out of its egg (this happened in September). It comes out as a tiny caterpillar or larva, which is really, really tiny, and it eats lots and lots of mulberry leaves. At first they don't eat heaps because they are so small, but as they grow, they eat a lot and I needed to change the leaves each day.
In their brain, messages are sent to tell the larva to make a new skin (cuticle) and not to become an adult. The new cuticle develops and the old cuticle comes off. The larva moults a number of times which might take from 1-3 months. Some of our silkworms took a long time before they began making their cocoon.
Then the juvenile hormone which stopped it becoming an adult, is reduced so that it doesn't send anymore messages to the brain about not becoming an adult. It then spins its cocoon and the pupa inside starts changing.
This only happens when the juvenile hormone stops altogether. Then the pupa changes and develops wings, antennas, eyes, legs and new organs.
Then after all the changes the adult breaks through the cocoon. Then the silk moth comes out, finds its mate (they can't fly), mates with their abdomens together and then they lay heaps of eggs and the cycle begins again in the next spring.