Important Stages in the Life Cycle of a Silkworm, Animal Sake

Silk is a valuable fabric that has long symbolized wealth and prosperity. In earlier times, its use was reserved only for kings and monarchs. The metamorphosis of a crawling worm into a moth is one of the most interesting transformations found in nature.

Silk is a biological secretion of a moth named Bombyx mori. This particular moth has become so domesticated over centuries that it has now lost its ability to fend for itself in the wild. Human intervention has had a big impact on this species.

The silkworm metamorphoses into a beautiful moth from its first stage as a tiny egg. The entire life cycle of a silkworm does not last for more than a couple of months.

Life Cycle of a Silkworm

The silkworm life cycle goes through several stages, from egg to adult moth. Each stage is explained in detail below.

Stage 1: Egg

Tiny silkworm eggs laid on a leaf surface, each about the size of an ink dot — Silkworm eggs are barely the size of an ink dot, yet each one holds the start of an amazing journey.

The egg is the first stage of a silkworm's life cycle. The female moth lays an egg about the size of an ink dot during summer or the early fall. The egg stays dormant until spring arrives. The warmth of spring then stimulates the egg to hatch.

Stage 2: Larvae

A tiny silkworm larva crawling on a fresh green mulberry leaf — Newly hatched silkworms are tiny and hairy, but they grow fast on a steady diet of mulberry leaves.

When a silkworm hatches, it is about 1/8th of an inch long and extremely hairy. Young silkworms can only feed on tender mulberry leaves. During the growth phase, however, they can eat tougher mulberry leaves as well.

The larval stage lasts for about 27 days. During this time the silkworm goes through five growth stages called instars. During the first molting, the silkworm sheds all its hair and gains a smooth skin.

Stage 3: Cocoon

Several silkworm cocoons in shades from white to golden yellow, clustered together — Cocoon color ranges from white to golden yellow, the exact shade depends on what the silkworm ate as a larva.

The cocoon is the stage in which the larva spins silk threads around itself to protect against predators. The larva traps itself inside the cocoon in order to pupate. The color of the cocoon varies depending on what the silkworm ate. It can range from white to golden yellow.

The second molting occurs inside the cocoon, when the larva turns into a brown pupa. It takes about 2-3 weeks for the pupa to metamorphose into an adult moth.

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Stage 4: Adult Moth

An adult Bombyx mori silkworm moth with white furry wings spread, freshly emerged from its cocoon — The adult *Bombyx mori* moth lives only long enough to mate and lay eggs, it cannot even eat, as it has no functioning mouthparts.

Once the adult moth comes out of its cocoon, its only purpose is to find a mate. Males are larger than females and more active. They flap their wings rapidly to attract the females. Within 24 hours of mating, the male moth dies, while the female lays abundant eggs, after which she dies as well. A new life cycle then begins.

Silkworms and Silk Production

Normally, there is only one season in a year when silkworms reproduce, giving one generation. However, in countries like India and China, silkworms reproduce continuously throughout the year. When silkworms are bred for commercial purposes, they are kept reproducing all year round.

Commercially, these insects must be raised very carefully. They cannot eat or drink on their own, so everything from their food to their habitat has to be organized by people. Although silkworms feed on mulberry leaves, it is not always possible to find them, especially during fall and winter. Commercial silkworm breeders feed larvae a substance called silkworm chow, which is a good alternative to mulberry leaves.

Silkworm life cycle is short and simple. Yet the stages it goes through during its brief life span are simply mesmerizing.

Term	What It Means
Metamorphosis	The process of transformation from one life stage to another, like a caterpillar turning into a butterfly, or a silkworm turning into a moth.
Instar	One of the five growth stages a silkworm goes through during the larval phase. Between each instar, the silkworm molts (sheds its skin).
Molting	When an insect sheds its old skin to reveal a newer, larger skin underneath. Silkworms molt several times during their larval stage.
Pupa	The resting stage between larva and adult, protected inside the cocoon. Inside, the pupa transforms completely into a moth.
Sericulture	The practice of raising silkworms to produce silk. The word comes from the Latin word for silk, sericum.
Dormant	A resting state where normal activity is paused, like the silkworm egg sitting still all winter, waiting for the warmth of spring to wake it up.

Important Stages in the Life Cycle of a Silkworm