What Is a Silkworm?

Silkworms are also known as the domesticated silk moth, or Bombyx mori, Latin for "Silkworm of the Mulberry Tree." They are the insects from which silk is produced. One of the first products in the world to earn the "Made in China" tag is silk! Silk has been cultivated in China from ancient times and traded worldwide ever since.

The biological classification of the silkworm breaks down like this:

  • Kingdom: Animalia, a multi-cellular eukaryotic organism
  • Phylum: Arthropoda, invertebrates with appendages and an exoskeleton
  • Class: Insecta, three-part body, compound eyes, and antennae
  • Order: Lepidoptera, undergoes complete metamorphosis through a four-stage life cycle
  • Family: Bombycidae, shares all the traits of the moth family
  • Genus: Bombyx, the mulberry silk moth group

Life Cycle

The silkworm life cycle follows the larva, cocoon, moth stages typical of most moth-like insects. Here are some of the most interesting facts about silkworms and their life cycle.

Silkworm eggs are laid about 300 to 400 at a time and generally take about ten days to hatch. Once the eggs hatch, the larvae (the baby silkworms) eat non-stop. They are always hungry.

Silkworms prefer eating white mulberry tree leaves, because they are attracted to a mulberry scent chemical called cis-jasmone. They will also feed on all other varieties of mulberry leaves.

Silkworm larvae (Bombyx mori) clustered on mulberry leaves
Silkworm larvae (Bombyx mori) feeding on mulberry leaves. The larvae eat constantly and shed their skin four times before spinning their cocoon.

The silkworm larvae shed their skin four times in a row. After the fourth shedding, the bodies of the larvae turn slightly yellow and the skin becomes tighter. This is the sign that the cocoon stage is coming.

The larvae then enclose themselves in a shell of raw silk produced by their salivary glands. Inside this protective layer, they enter a motionless pupal state. It is at this stage that silk can be extracted from them. If left undisturbed, the cocoon is eventually broken open and a young adult moth emerges.

A single white silkworm cocoon resting in a child's palm, showing the fine silk fibers
A single silkworm cocoon. The raw silk fibers that make up its walls are about 10 micrometres in diameter, finer than a strand of human hair.

If the raw silk of a single cocoon is unfolded, it contains a thread of about 300 to 900 meters in length. The raw silk fibers are about 10 micrometres in diameter, very fine and very lustrous. To make one pound of silk, about 3,000 cocoons are boiled in water. Boiling kills the silkworms and makes it easier to extract the threads.

The adult silk moth cannot fly.

Frequently Asked Questions

What is the scientific name of a silkworm?

Bombyx mori, meaning 'Silkworm of the Mulberry Tree' in Latin.

How much silk thread does one cocoon produce?

About 300 to 900 meters of raw silk thread.

How many cocoons are needed to make one pound of silk?

About 3,000 cocoons.

Can the adult silk moth fly?

No, the adult silk moth cannot fly.

What leaf do silkworms prefer to eat?

White mulberry tree leaves, because of a chemical called cis-jasmone that attracts them.

Test Your Silkworm Knowledge!

5 quick questions about the world's most famous silk-spinner.

Uses of Silkworms

Here are some facts about the uses of silkworms.

The primary use of silkworms is in the production of silk. Every year, 70 million pounds of raw silk is produced, after about 10 billion pounds of mulberry leaves are consumed by silkworm larvae! The total length of that 70 million pounds of fabric could easily cover about 300 round trips to the Sun.

Silkworms are also part of the cuisine in both Koreas and China. A popular snack food called beondegi is made from boiled and seasoned silkworm pupae. Chinese cuisine also includes roasted silkworm pupae.

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An adult silk moth (Bombyx mori) with pale wings and cream-white body, showing the final stage after the cocoon
The adult silk moth, Bombyx mori. Unlike most moths, the adult cannot fly, thousands of years of domestication have made it completely dependent on humans.