Silkworm moths spin silk for humans to make cloth out of. But what’s more interesting is their lifetime. From egg to moth is an amazing journey called metamorphosis and it has four phases.
The first phase of metamorphosis is the egg stage. When the larva is in its egg and ready to hatch, it bites a hole in its egg and crawls out. When the larva is born it is three millimeters long. It has a large head and a very hairy body.
Before the silkworm becomes a moth, it is a caterpillar it is called a larva. During this phase, it molts four times and goes through five instars, or “periods before or after the different molts.” The larva has to molt, which means it has to shed skin, and before it does that, it stops eating for a whole twenty-four hours.
When the larva is ready to become a moth, it makes a cocoon made of shiny silk. It takes six hours for the larva to make its cocoon. Then, it starts its transformation into a moth. When the moth is ready to come out of the cocoon, it makes a chemical that comes out of its mouth and dissolves a hole in the cocoon. When the moth comes out of the cocoon is a grown up moth.
After fifteen minutes of clinging to its cocoon, its wings open completely, but its wings are too small too fly. When the moth’s wings are open all the way, they are two inches across. Their wings are white with tiny white scales on them. Their antennas are long and feathery.
Even though it is not the same in each of its life stages, the silkworm is an interesting creature that we can use to make strong and shiny silk fabric.
Silkworms by Silvia A. Johnson
Diagram from: http://edoc.hu-berlin.de/dissertationen/kusnaman-djeimy-2004-07-29/HTML/kusnaman_html_19b3c0cc.gif