the tiny larvae embark on an almost nonstop eating binge, plowing their way through layer after layer of white mulberry leaves, their food of choice. In a breeding room,where hundreds of thousands of worms are feeding, it is said that the sound is like that of a steady rain on a tin roof. After thirty-two days, when the caterpillar has multiplied its weight by ten thousand and shed its skin four times, it begins to spin a cocoon by moving its head from side to side in a figure-eight pattern, extruding from two glands under its jaw a liquid that—in an amazing trick of chemistry—becomes solid as soon as it hits the air. The larva spins continuously for three days, shrinking as it constructs its white, multilayered oval pod.
Left alone, the moth would soon break out of the cocoon and the cycle would begin again. But when harvesting high-quality silk is the goal, the moth must be killed inside the cocoon before it damages the mile-long silk filament. This is usually done by boiling it to death. Animal-rights advocates have pushed for humane silk-harvesting practices. There is a small market for Ahimsa, or Peace, silk, made from the broken fibers of cocoons after the moth has been allowed to emerge naturally, but the silk is less lustrous and far more expensive than silk produced in the traditional way. Scientists have also been studying how to get at silk produced by wild caterpillars, whose cocoons have a hard coating that makes unraveling almost impossible.In 2011, researchers from England and Kenya discovered a way to remove that mineral layer without damaging the fibers using an acidic solution—something that could help open the door to a lucrative industry in poor countries where there is a large population of wild caterpillars.
Silkworms are extremely sensitive; expose them to cool temperatures, drafts, loud noises, humidity, tobacco smoke, even the smell of sweat or extra-sweet perfume, and they may produce inferior silk or no silk at all. Few creatures have been studied as extensively as the
Bombyx mori
. In the past several decades, researchon silkworms and moths has led to major discoveries about genetics, heredity, the brain, and the mysteries of sexual attraction. Pheromones, for instance, were first isolated and identified when scientists realized that one sexually ready female silkworm moth could attract every male moth within a mile, just by giving off a minuscule amount of scent through the nanotunnels in her antennae.
More recently, researchers have blasted silkworms with an electric field to induce them to spin more durable silk, fed them dyed leaves to coax them to produce colored silk, and even implanted them with spider genes to get them to spin a hybrid version of Kevlar-strong spider dragline silk. (Since spiders are cannibalistic, raising them in groups for raw silk has so far proved to be an exercise in futility.) Researchers at Tufts University have applied their knowledge of caterpillars to design soft-bodied robots. Taiwanese engineers have used silk proteins in transistors to increase the page-turning speed of e-books.
For more than two thousand years, the Chinese guarded the secret of silk. Anyone who dared to smuggle eggs, worms, or moths over the border was executed. Eventually, the secret leaked out, first to Korea, then to Japan, Persia, India, and Arabia. Sericulture made it to the West in the middle of the sixth century, when two monks, sent by the Byzantine emperor Justinian, sneaked silkworm eggs and seeds from the mulberry tree across the border by hiding them in hollow bamboo walking staffs. Four hundred years later, King Roger of Sicily captured Greek silk weavers, brought them back to Palermo, and set them up in a silk-making operation in his palace. From Sicily, silkworm breeding moved to Northern Italy, where forests of white mulberry trees were planted in order to ensure a constant food supply for the voracious larvae. In a bid to boost an economy dragged down bythe faltering
Left alone, the moth would soon break out of the cocoon and the cycle would begin again. But when harvesting high-quality silk is the goal, the moth must be killed inside the cocoon before it damages the mile-long silk filament. This is usually done by boiling it to death. Animal-rights advocates have pushed for humane silk-harvesting practices. There is a small market for Ahimsa, or Peace, silk, made from the broken fibers of cocoons after the moth has been allowed to emerge naturally, but the silk is less lustrous and far more expensive than silk produced in the traditional way. Scientists have also been studying how to get at silk produced by wild caterpillars, whose cocoons have a hard coating that makes unraveling almost impossible.In 2011, researchers from England and Kenya discovered a way to remove that mineral layer without damaging the fibers using an acidic solution—something that could help open the door to a lucrative industry in poor countries where there is a large population of wild caterpillars.
Silkworms are extremely sensitive; expose them to cool temperatures, drafts, loud noises, humidity, tobacco smoke, even the smell of sweat or extra-sweet perfume, and they may produce inferior silk or no silk at all. Few creatures have been studied as extensively as the
Bombyx mori
. In the past several decades, researchon silkworms and moths has led to major discoveries about genetics, heredity, the brain, and the mysteries of sexual attraction. Pheromones, for instance, were first isolated and identified when scientists realized that one sexually ready female silkworm moth could attract every male moth within a mile, just by giving off a minuscule amount of scent through the nanotunnels in her antennae.
More recently, researchers have blasted silkworms with an electric field to induce them to spin more durable silk, fed them dyed leaves to coax them to produce colored silk, and even implanted them with spider genes to get them to spin a hybrid version of Kevlar-strong spider dragline silk. (Since spiders are cannibalistic, raising them in groups for raw silk has so far proved to be an exercise in futility.) Researchers at Tufts University have applied their knowledge of caterpillars to design soft-bodied robots. Taiwanese engineers have used silk proteins in transistors to increase the page-turning speed of e-books.
For more than two thousand years, the Chinese guarded the secret of silk. Anyone who dared to smuggle eggs, worms, or moths over the border was executed. Eventually, the secret leaked out, first to Korea, then to Japan, Persia, India, and Arabia. Sericulture made it to the West in the middle of the sixth century, when two monks, sent by the Byzantine emperor Justinian, sneaked silkworm eggs and seeds from the mulberry tree across the border by hiding them in hollow bamboo walking staffs. Four hundred years later, King Roger of Sicily captured Greek silk weavers, brought them back to Palermo, and set them up in a silk-making operation in his palace. From Sicily, silkworm breeding moved to Northern Italy, where forests of white mulberry trees were planted in order to ensure a constant food supply for the voracious larvae. In a bid to boost an economy dragged down bythe faltering
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