Supporting Sericulture Farms in Decline

In Japan, sericulture farmers reverently call silkworms—kaiko—“Okaiko-san.” In decades past, many rural households engaged in sericulture. The larvae, a valuable revenue source, shared the family’s living space. The number of sericulture farms in Gunma prefecture peaked in 1970 at 66,200. As prices for cocoons plummeted, that number dropped to just 1,930 farms by 1999.
As of 2017, a mere 121 farms remained. With only 336 farms left nationwide now, the fate of the silk industry in Japan rests largely on Gunma. To this end, the prefectural government off ers support to new entrants.

Four years ago Miyama Zenshoku fi nanced operations at an abandoned sericulture farm. The fi rst order of business was to secure the proper temperature, humidity, and ventilation of the rearing house. When we visited in September, preparations were underway for the mature silkworms’ fi fth and fi nal molt, when they build cocoons. The larvae are placed in rotating wooden frames split into 12-centimeter square compartments. These are stacked in groups of ten and suspended from the ceiling. In due time each silkworm fi nds and occupies the highest spot available and begins to spin its nest.

In the last week before cocooning, the silkworms are fed mulberry leaves four times a day, from morning to night. They eat ravenously, increasing their weight 10,000-fold in just seven days. A small truckload of the leaves, which are grown without the use of pesticides, is brought in for each feeding.

Usui Raw Silk Company, Japan’s largest silk mill, is nestled in the low foothills surrounding Annaka. The craggy peak in the background is Mount Myogi, renowned for its striking rock formations. The Usui River flows behind the mill. This abundant source of water allows the company to operate without burdening the environment.

Gunma Silk is Environmentally Friendly

Usui Raw Silk Company in Annaka, Gunma, is Japan’s largest silk mill. In 1970 there were 106 silk mills operating in the prefecture.
Now, Usui is the only one left. It is the last bastion of support for sericulture farms producing high-quality cocoons in Gunma.
Each cocoon is spun of a single strand of silk. The reeling, or extraction, process unravels those individual fi laments and spins them together to make one much thicker thread. A huge reeling machine—like something you might imagine from the Machine Age of the early 20th century—is used for this. Nothing is computerized. With people operating the reeler and carefully tending the process, the silk rendered is of far higher quality.

Silk making at Usui is environmentally conscious. Sustainability is emphasized; waste is minimized. The mill obtains cocoons only from sericulture farms that use no chemical pesticides in cultivating their mulberry trees. Once the silk fi lament has been harvested the expired pupae are used as food for monkeys at the Japan Monkey Centre, and for carp. Silkworm feces are collected and returned to the earth as fertilizer. No formalin or other disinfectants are used in the reeling process. Waste yarns are graded for quality and repurposed as spun silk. Such sustainable measures taken throughout the production process heighten the intrinsic quality and appeal of Gunma silk.

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