Silkworms

We have been raising silkworms this Spring.

A friend gave us a couple of eggs and soon after they hatched into tiny little silkworms.  Can you see the tiny black worms?

 And they grew and grew and we needed to feed them a constant supply of mulberry leaves.  We don't have a mulberry tree so every few days we picked lots of leaves from the boys' grandparents house and kept the leaves in the fridge.  This way the leaves stayed fresh.

 

We soon found we had tubs and tubs full of growing silkworms and we cleaned out the droppings and old leaves every other day.  These chaps are serious eating machines! Some are all white and others have black stripes. Once a silkworm has gone through four moults and are fully matured; this growing stage from tiny black worm to mature worm takes approximately 6 weeks.

The worm then begins to slowly sway its head back and forth to show that it is time for the next stage - spinning a cocoon.

The silk is hardened silkworm saliva. It comes out of the mouth.  The silkworm has a small spinneret on its lip, through which the silk emerges. The single strand of silk that forms the cocoon is about one mile long!  

The silk cocoons are beautiful - bright yellow, pale yellow or white.  It takes a silkworm about 72 hours to complete this process.  Each cocoon is about two inches long.

Once encased in the cocoon, the silkworm becomes a pupa.  And then it slowly changes into a moth from within the pupa.  Three weeks later the moth is ready to emerge. The new moth secretes a special spit which dissolves the silk and then it pushes out of one end of the cocoon.  The wings are crumpled to begin with but soon straighten.  Within minutes the silkmoths start searching for a mate.  The females are larger than the males.  After mating for about a day, the female lays a big batch of eggs and dies after 5 days.

And then we keep all the eggs safely until the next hatching.  The empty cocoons cannot be used to make silk thread as it has a hole in the end breaking the continuous thread.  Silk farmers use heat to kill the pupa whilst still in the cocoon and then unravel the unbroken silk thread intertwine it with several others to thicken the thread to produce silk.

We have been reading this book,  a legend of how the Chinese first discovered silk.

I used to keep silkworms as a child and the boys now find it great fun keeping silkworms too!