The production of silk – also known as sericulture – has a rich history that most people aren’t aware of. The west wasn’t even aware of how silk was produced, and who it was produced by, for a very long time. The Roman historian Pinny wrote in Natural History in 70BC that silk was using water to remove the down from leaves. The Chinese closely guarded the secret of silk and kept it to themselves for over two thousand years. Silk was one of the most closely guarded secrets in all of human history.
The Origins of Silk and the Legend of Lady His-Ling Shih
According to Chinese legend, Lady His-Ling Shih was the Goddess of Silk. Lady Hsi-Ling-Shih was the wife of the legendary Yellow Emperor, who supposedly ruled China around 5,000 years ago in 3000 B.C. She was said to have introduced silkworm rearing to China and invented the loom. Half of a silkworm cocoon was discovered in the loess soil by the Yellow River in Shanxi Province in China in 1927. The cocoon was dated back to around 2,600 to 2,300 BC. Another discovery dating back to around 3,000 BC was that of ribbons, threads, and woven fragments discovered at Qianshanyang in the Zhejiang province. There have been more recent discoveries that suggest silk farming, if not agriculture as a whole, dates back even further; a small ivory cup adorned with a silkworm design was discovered along the lower Yangzi River, as well as silk thread, fabric garments, and spinning tools that are thought to be up to 7,000 years old.
Silkworms and the Family
There are plenty of species of silk moths found across the world. The secret behind how China was able to produce silk and dominate silk production and promotion can all be linked to one single solitary species of silk moth; the flightless and blind Bombyx Mori silk moth. This moth typically lays over 500 eggs in the span of four to six days before dying. The eggs are practically weightless; 100 eggs weighs just one gram. One ounce of eggs produces around 30,000 worms. These worms eat through a ton of mulberry leaves to produce around 12 pounds of natural raw silk. The original wild ancestor of the Bombyx Mori silk moth is believed to be the Bombyx Mandarina Moore silk moth. This moth, unique to China, lives on white mulberry trees. The silkworms of this species are known to produce a thread with a finer, smoother, and rounder filament than other species of silk moths. Across thousands of years, a time when the Chinese practiced and perfected sericulture using all the silk moths they could find, the Bombyx Mori evolved and became the silk producing species we know today; a moth that lost the power to fly and is now only able to mate and produce eggs for another generation of silk producers.
The Secrets Behind Sericulture
The production of silk is a long and lengthy process that requires constant attention. There are two conditions to producing the highest quality silk – preventing moths from hatching out and feeding the silkworms the best diet. The Chinese developed their own methods for achieving both of these conditions.
- Eggs must be kept at 65 degrees Fahrenheit, with the temperature being increased gradually to 77 degrees, which will cause them to hatch. The newly hatched baby worms feed constantly every half hour on a diet of fresh, hand-picked, chopped mulberry leaves to fatten them up. A constant temperature must be maintained during this time. Thousands of these worms are kept on trays which are stacked on top of each other. A room full of feeding worms sounds similar to heavy rain crashing against a roof. The newly hatched silk worms keep feeding and they can multiply their weight by around 10,000 times in just a month, shedding their skin and changing their color a number of times in the process.
- Silkworms continue feeding until they have the energy to begin their metamorphosis and become cocoons. They must be protected from drafts, loud noises, strong smells like fish, meat, and sweat during their growth period. When the time comes to build cocoons, the worms will create a jelly-like substance within their silk glands. This substance hardens upon contact with the air. Silkworms can spend around four days spinning their cocoons around themselves. A silkworm in a cocoon resembles a small, puffy white ball.
- After around 9 days in a warm and dry environment, the cocoons can be unwound. They are first baked or steamed to kill the worm or pupa inside. The cocoon is then dipped in hot water to loosen the filaments. A spool is used to unwind the once-tight filament. Cocoons are made from filaments that are between 600 and 900 meters long. Around five to eight of those super-fine filaments are joined together to form one thread.
- The final step is for the silk threads to be woven into cloth or used directly for embroidery. The clothes made from silk are lightweight and beautiful, while still being warm in the colder months and cool in the hotter months.
Literary sources like the Book of Rites and The Book of History provide extra details about sericulture. Reeling and spinning silk were considered to be household duties women performed, while embroidery and weaving were done at workshops as well as in the home. The daughters, mothers, and grandmothers in silk-producing provinces spent most of their day, for six months, feeding, tending, and supervising silkworms and unravelling, spinning, weaving, dying, and embroidering silk. Six Chinese provinces, at the very least, were producing silk by the fifth century BC. Every spring, the empress herself would inaugurate the silk-raising season as silk production truly was the work of women across China. That included even the empress. China kept the secrets of sericulture guarded by Chinese authorities. Anyone who was caught revealing these secrets or smuggling silkworms and their cocoons outside of China was punished, and the penalty for this crime was death.