The Life Cycle of Silk Worms

The silkworm is just one part of the life cycle of the silkworm moth. The life cycle of the moth is dependent upon the changing seasons. In areas where summer, fall, spring and winter are clearly discernible, the silkworm moth will reproduce only once annually. In warm climates where the seasons are not discernible, silkworm moths reproduce continuously.

  1. Eggs

    • The female silkworm moth will lay many tiny eggs on mulberry leaves and from these leaves hatches the silkworm or caterpillar. In areas where the seasons change, the moth will generally lay the eggs in late summer or early fall, and the eggs will not hatch until spring.

    Larva

    • The caterpillar or silkworm that emerges from the egg is only about an eighth of an inch long and covered in hair. The caterpillar feeds on the mulberry leaves, going through four separate molts as it matures toward the pupal stage. As it molts, the old skin is shed and a new, larger one is grown.

      After the first molt, the silkworm loses its hairy exterior and remains smooth and soft throughout this stage of its life.

    Pupa

    • After the fourth molt in the larval stage, the caterpillar will spin a cocoon of silk thread around itself. The cocoon is about the size of a cotton ball. Inside the cocoon, the caterpillar becomes a pupa.

    Silk

    • It is at this stage that the silk worm's life cycle ends if the cocoon is taken to make silk thread. The process involves plunging the cocoon into boiling water to kill the pupa and dissolve the glue that holds the cocoon together. The cocoon will be unwound, and the threads used to weave cloth.

      If the pupa is allowed to continue its development, it will change from pupa to moth within the cocoon and emerge as an adult about two to three weeks after going inside the cocoon.

    Adult

    • The silkworm moth has creamy white wings with brown patterns across the front. Today, there are no silkworm moths living naturally. In the four millennia since the silk industry began the species has become so domesticated that it can barely fly, find it own food or defend itself from predators.

      Copulation between adult silkworm moths may last for several hours. Adult silkworm moths do not eat or drink, but mate and die after the female has laid her eggs.