Silkworms were first brought from Asia to Byzantium around A.D. 550. Legend has it that two monks hid silkworm eggs inside a bamboo pole to smuggle them out of China, where they were guarded as closely as state secrets. The monks then presented the eggs to Byzantine Emperor Justinian I in Constantinople, where he created a thriving silk industry. Silkworms reached Italy through Sicily in the 12th century, and by the 13th century, silkworm cultivation—or sericulture—had migrated north to the Po River Valley. By the 16th century, sericulture had been introduced to the Como area.
Silkworm farming was a brutal job. Since silkworms require a constant, mild temperature, entire sections of farmhouses were turned over to them and whole families would often pitch in, stoking round-the-clock fires to maintain the proper warmth. Some even "gave the worms the house and slept outside in the stalls with the animals," says Ester Geraci, an official at Como's Educational Silk Museum.
The process began with the 10-to 14-day incubation of silkworm eggs, which are produced by the mating of adult silkworm moths. According to the Silk Museum, keeping the tiny, delicate eggs (about the size of a pinhead) at just the right temperature was "the task of the women, who often carried small bags of eggs in direct contact with their skin. . .sometimes between their breasts." Once hatched, the worms, only about one millimeter long, had to be fed mulberry leaves night and day. From a birth weight of only half a milligram, they would grow 10,000-fold to a final weight of around five grams and a length of 8 to 9 centimeters (3 inches) in just 30 to 32 days. Then, in the final three days of their larval stage, the worms would start to spin their cocoons out of one continuous thin filament—up to 1,200 meters (or 4,000 feet) long—which they emitted from a "spinneret" located near their mouths. The filament, formed primarily of a substance called fibroin manufactured in two glands on the underside of their jaws, hardened instantly when it came in contact with the air.
After about a week, the cocoons were placed briefly in a hot, dry oven to kill the adult moths inside. (If allowed to emerge from a cocoon, an adult moth would ruin the silk, so just enough adult moths were allowed to fully mature to maintain the reproduction cycle.) The cocoons were then put in hot water to facilitate the difficult and tedious task of extracting the silk. The minute end of the cocoon's silk filament had to be located and threaded onto a reel, which then unwound it from the water-warmed cocoon. The silk thread was then cleaned, twisted (to prevent filaments from separating) and woven into fabric.
Como's silk companies now buy most of their undyed raw silk (both fabric and yarn) from China.