The Silkworm

by Stefan Chiarantano, Aug 30, 2005 | Destinations: Japan / Tokyo

I am writing about the silkworm. In my travels in Japan, I had seen the remnants of silk farms. When I lived in Maebashi, Gunma, I discovered that it was once a famous silk production center before the Second World War. I have purchased beautiful second hand silk kimonos for friends in thrift shops. But it wasn't until one of my students mentioned recently that she was served silkworm pupae as part of her lunch that got me to find out more about the silkworm.

Did you know that one silkworm cocoon could be unwound into 1,000 meters of silk filament? Silk was first discovered in ancient China. Many legends surround its discovery but credit is attributed to the wife of the Yellow Emperor. Legend has it that she accidentally dropped a cocoon into hot water (tea), fished it out, played with it and in the process discovered that the cocoon would unwind into one long delicate filament. She is also credited with the invention of the silk reel, which joins several fine silk filaments into a thread thick and strong enough for weaving.

There are four stages in a silkworm's lifecycle. The stages are:

1 The egg stage; 2 The silkworm stage; 3 The pupa stage (cocooning); 4 The metamorphosis into a moth.

Silkworms are cultivated in clean environments to prevent the spread of disease. They feed strictly on mulberry leaves. A female silkworm can lay anywhere from 300 to 500 eggs. It takes 20 days for silkworm eggs to hatch. When they hatch, they are the size of an ant and grow to 70 times their original size. It takes them four to five weeks to reach maturity. When they are fully-grown, they stop eating and spin their cocoon. It does this by attaching itself to a twig or a stem by casting a web and then, spins its cocoon, which is the silk filament. It builds its cocoon by swinging its head from side to side in a series of figure-eight movements. The two glands near its lower jaw produces a fluid that hardens into fine silk threads as it comes into contact with the sericin it secretes. The sericin cements the two threads of silk together. It takes about 3 days for a silkworm to spin its cocoon.

They are killed in the pupa stage by placing them in a hot oven. This is done to preserve the cocoon. If the moths were allowed to hatch, they would break the cocoon. The next stage is the reeling of the cocoon filaments into silk thread. This is done by soaking the cocoons into basins of hot water, which dissolves the sericin, the gummy substance that holds the threads together. As a single filament is too fine to be reeled separately, several filaments are threaded together to strengthen the thread. The filaments are drawn together and peeled by pulleys through a tiny porcelain guide. The guide is like the eye of a needle. The melted sericin works to re-glue the several filaments into a single thread, which is wound onto a reel. Once threaded, the silk is removed from the reel and twisted into skeins. This is just the beginning of the process and it doesn't stop until the silk thread is turned into clothing apparel such as kimonos, scarves, ties, dresses, and so on.

As it was a much sought after commodity, silk brought wealth to ancient civilizations and shaped relationships amongst ancient societies.

Japan used raw silk exports to purchase machines and industrial materials to turn itself at the turn of the 19th century into a world power.

Certain key events led to this phenomenon.

At the beginning of the 18th century, in order to cut back on its depletion of gold and silver, which was used to pay for its raw silk imports from China, the Tokugawa government began to provide incentives for people to raise silkworms and produce raw silk domestically.

In the late 1860s, Japan ended its period of relative isolation and opened its doors to the world. Yokohama became an international trading port and raw silk was Japan's key export.

The supply of raw silk in the 1860s was threatened by the outbreak of pebrine disease, which decimated crops in the Mediterranean basin, and by the Taiping Rebellion in China, which disrupted the export of Chinese supplies.

Japan entered the global market for raw silk at just the right moment. By the turn of the century, Japan had become the world's leading exporter of raw silk and in the process turned itself into a powerful nation.

* * * * *