The silkworm is the larva or caterpillar of the domesticated silkmoth, Bombyx mori. It is an economically important insect, being a primary producer of silk. A silkworm’s typical lifespan is about two to three weeks. The silkworm was domesticated from the wild silkmoth, Bombyx mandarina, between 4000 and 3000 BC in China.
Today, there are several commercial species of silkworm besides B. mori: for example, the Italian or Tussah moth (Ailanthus silkmoth), Chinese tussah (Samia cynthia) or Japanese oak Silk Moth (Antheraea pernyi). All these commercially bred insects produce filaments with varying degrees of fineness, but none approaching the quality of B. mori silk – which remains unique among textiles for its combination of strength and extreme delicacy.
Bombyx mori females lay their eggs singly on mulberry leaves; each egg takes about 10 days to hatch into a larva or “maggot”. These maggots feed voraciously on mulberry leaves (up to eight per day), growing rapidly until they are ready to spin cocoons at around 35 days old. They secrete a sticky fluid from their mouths that hardens when it contacts air, allowing them to spin a continuous thread up to 900 m long! Once they have finished spinning their cocoons, the larvae pupate inside them; this process takes another ten days or so.
When fully grown, adult moths emerge from their cocoons by biting through one end with specialised jaws (mandibles); this frees them from the constricting threads and also gives them access to air holes that allow them to breathe during emergence. Adults live for only about a week and do not eat; instead they spend all their time searching for mates using pheromones secreted by males to attract females from up to 10 km away! After mating has taken place, female moths lay hundreds of eggs on mulberry leaves before dying themselves shortly afterwards; thus begins another generation…