The eggs develop into the silkworm lava, grub or caterpillar. They eat for 20-30 days, consuming large amounts of mulberry leaves The caterpillar moults through four changes of skin
The silkworm spins a cocoon for protection, to permit the development of the pupa or chrysalis. The cocoon takes about three days to be fully complete and is a similar size to a peanut shell.
The chrysalis emerges from the cocoon as a moth. In cultivated silk, the grub is terminated while still inside the cocoon so that the long filaments are maintained.
The colour of the silk is determined by the diet of the lava and seasonal influences. Mulberry leaves produce the preferred lighter coloured cocoons, but in the wild silk worms will eat other plants, producing all variety of colours, as shown.
The moths mate and the female lays more than 350 eggs. The moths then die
In the wild this cycle occurs once a year, but under scientific breeding it can occur up to three times in a year.
It is slow and difficult process to produce silk fibre. There are many factors which can influence the quality and amount of the end product. Around 12 x kilos of cocoons will only produce about 1 x kilo of reelable silk (long fibres) and 1 x kilo of unreelable spinning silk (short fibres).