Why do silkworms molt? Understanding the reasons for silkworm molting in one article

The silkworm is the larva of the silkworm moth and the main source of silk material. Because it is domesticated and raised indoors, it is also called the domestic silkworm. It holds an important place in human economic life and cultural history. It originated in China, and its main food is mulberry leaves, though gooseweed can also be used as a supplement. In southern mainland China and Taiwan, China, the domestic silkworm is generally commonly called "silkworm baby" or "niangzai." Let us take a look below at why silkworms molt!

Why do silkworms molt?

During the growth and development of a silkworm, the cuticle cannot grow along with the body. When body growth is restricted, it must shed its skin. Silkworm babies live on mulberry leaves. After continuously eating mulberry leaves, their bodies turn white, and after a period of time they begin to molt. Molting takes about one day, during which they neither eat nor move, as if sleeping. After one molt, they become second-instar larvae. Each molt counts as adding one year of age. Larvae molt four times in total to become fifth-instar larvae, then eat mulberry leaves for 8 days to become mature silkworms and begin spinning silk and forming cocoons.

Why do silkworms spin cocoons?

From the physiological perspective of the silkworm, because the proteins that make up the silk glands are composed of amino acids, an excessive amount of amino acids in the silkworm body would poison it, so silkworms need to excrete amino acids by spinning silk to achieve detoxification. From the perspective of natural conditions, as a holometabolous insect, the silkworm is fragile at every stage of life, especially at the pupal stage, when it stops feeding, loses mobility, and is very vulnerable to natural enemies. Silkworms evolved the behavior of spinning silk and forming cocoons, enclosing themselves in a dense cocoon shell. In this way, they can both avoid natural enemies and protect themselves, and safely transform into pupae inside the cocoon, allowing the organs inside the pupa to transform into the form of a silkworm moth, and finally emerge as an adult silkworm moth.

What types of silkworms are there?

1. Mulberry silkworm: The mulberry silkworm feeds on mulberry leaves. Its cocoon can be reeled into silk. Silk is a precious textile raw material, mainly used for weaving silk fabric, and also has wide uses in military industry, electrical appliances, and other fields. The pupae, moths, and silkworm droppings can also be comprehensively utilized.

2. Tussah silkworm: The tussah silkworm is named for its preference for eating oak leaves. Its cocoon can be reeled into silk, mainly used to weave tussah silk. The pupae can be eaten and used as medicinal material. It occurs twice a year, with adults appearing from April to June, and overwinters as pupae inside cocoons.

3. Chinese oak silkworm: The Chinese oak silkworm is a silk-spinning insect of the family Saturniidae in the order Lepidoptera, and is a very rare species in nature. The Chinese oak silk it produces is priceless and is called a green soft gemstone surpassing gold.

4. Camphor silkworm: The camphor silkworm is a wild silk-spinning insect of the family Saturniidae in the order Lepidoptera. Its silk can be made into silkworm gut and high-quality fishing line. In China, it is mostly found in Guangdong, Taiwan, China, Guangxi, Fujian, Jiangxi, Hunan, and other places.

5. Chestnut silkworm: The chestnut silkworm is an economic insect that spins silk and forms cocoons, mainly feeding on walnut leaves and chestnut leaves. It is widely distributed in Japan and in China's "Three North" and central-south regions. Chestnut silk is an expensive natural fiber.

6. Ailanthus silkworm: The ailanthus silkworm is an economic insect that spins silk and forms cocoons, mainly feeding on ailanthus leaves (tree of heaven) and also eating the leaves of Chinese tallow tree, castor bean, holly, Michelia figo, paulownia, phoenix tree, camphor tree, and others. It belongs to the family Saturniidae in the order Lepidoptera and is distributed in China, Japan, India, and other countries.

7. Willow silkworm: The willow silkworm mainly eats the leaves of Chinese wingnut, Fontanesia fortunei, Chinese tallow tree, camptotheca, apple, pear, and others. It is a silk-spinning insect. A high-quality cocoon can be drawn into 300-meter-long silk, which has the advantages of being fine and rot-resistant. It is mainly distributed in East Asia and Southeast Asia.

8. Tiger silkworm: The tiger silkworm is a type of domestic silkworm. During the larval stage, the body has black-and-white stripes. In the moth stage, it is not very different from ordinary white domestic silkworms. During the larval stage, it likes to eat plants of the mulberry family, especially mulberry leaves. Silkworm cocoons are an important raw material for the textile industry.