Photo/IllutrationBagworm silk (Provided by Kowa Co. and the National Agriculture and Food Research Organization)

  • Photo/Illustraion

Researchers said they have developed a method to collect bagworm silk--considered the strongest natural fiber--for possible use in products ranging from golf clubs to bulletproof vests.

Under the joint project, Nagoya-based drugmaker Kowa Co. and the National Agriculture and Food Research Organization (NARO), based in Tsukuba, Ibaraki Prefecture, said they have applied for a patent on the technology that can extract silk thread several hundred meters long from a single bagworm larva.

Bagworm silk is a protein fiber emitted by a bagworm moth larva for its cocoon and other purposes. With a thickness of only 0.01 millimeter or so, the silk is thinner than human hair.

Bagworm silk is stronger than spider silk, which had been viewed as the toughest of all natural fibers, according to the researchers.

Kowa and NARO officials said their studies found that bagworm silk is five times more resistant to snapping than silkworm silk, and twice as strong as the silk of Araneus ventricosus, an orb-weaving spider species.

“This type of silk has various potentials,” Kowa President Yoshihiro Miwa said. “We hope to explore its applications.”

Bagworm silk can be used to make fiber-reinforced plastic, which is both strong and light, for airplane and car bodies, among other products, the officials said.

The silk begins to decompose at a temperature of 340 degrees, relatively high for a natural fiber, they added.

Kowa and NARO said their silk-collection method does not kill the bagworms.

Kowa currently breeds several tens of thousands of bagworms of two species that are native to Japan. The company plans to work with a materials manufacturer to mass-produce bagworm silk and reduce the production cost to levels on a par with that for silkworm silk.