The life cycle of a silkworm goes through four stages: egg, larva, pupa, and adult.

The life of a silkworm refers to the entire journey of the silkworm (Bombyx mori) from hatching from the egg to the death of the adult. The silkworm is an insect with complete metamorphosis, and in its lifetime it passes through four stages in sequence: egg, larva, pupa, and adult. The whole process takes about a month or more, and the exact duration varies with temperature and rearing conditions.

Silkworm eggs are tiny, like sesame seeds. When first laid they are relatively light in color, then gradually turn grayish-green or purplish-brown. When the ambient temperature is suitable, the larva breaks out of the egg; because it is extremely small and covered in dark brown, resembling an ant, it is called an ant silkworm. The larval stage is the only feeding stage in a silkworm's life, feeding mainly on fresh mulberry leaves, and its appetite keeps growing as it develops.

During growth, the larva undergoes four molts, and each molt adds one instar. After entering the fifth instar, the silkworm eats the most, its body color turns bluish-white, and its body gradually becomes plump and stout. At the end of the fifth instar, the silkworm's body becomes translucent and its droppings soften, indicating that it has matured and is beginning to spin silk and form a cocoon. The mature silkworm first spins out silk threads to fasten itself to the silkworm mount, then wraps layer upon layer, weaving an oval cocoon in about two or three days, after which it pupates inside.

After the pupal stage ends, the silkworm moth breaks out of the cocoon. The adult no longer feeds, its whole body covered in white scaly hair; although it has wings, it is not good at flying. After the male and female mate, the female moth lays silkworm eggs, and soon after completing its reproductive mission it dies, and the silkworm's life ends here.

Although the silkworm's life is short, it has high economic and cultural value. Silkworm cocoons can be reeled for silk, and silk is an important raw material for making silk fabric. China has a very long history of sericulture and silk reeling, and the ancient Silk Road originated from this. Nowadays many schools also have students raise silkworm babies to observe its complete transformation from egg to moth, making it a very intuitive material for nature observation.