Silkworm Moth

Bombyx mori is the domesticated silkworm moth, a species that no longer exists in the wild. Its wild ancestor, Bombyx mandarina, still flies in northeast Asia, but B. mori has been bred so intensively for at least 5,000 years that the modern moth has lost its ability to fly, cannot evade predators, and cannot find food without human care. The larva — the 'silkworm' itself — feeds exclusively on mulberry leaves and spends roughly five weeks growing through five instars before spinning a cocoon. The cocoon is constructed of a single, continuous silk thread up to 900 meters long. To extract the silk, sericulturists kill the pupa inside (typically by steaming) and unwind the entire thread; it takes roughly 2,500 cocoons to make one pound of silk. The species was domesticated in China around 3,000 BCE; for centuries the secret of silk production was the most closely guarded trade secret in the world, and the species' export was illegal under Chinese law. Smuggling silkworm eggs out of China — most famously by Byzantine monks in the 6th century — broke the monopoly and triggered the spread of silk production into the Middle East and Europe. The Silk Road, the trade network that connected East and West for over a millennium, owes its name and existence to this single species.