Life Cycle of Silkworm – History of Silk, Life Cycle of Silkworm, Processing of Silk, Practice Problems and FAQ

The rich beauty and unmatched range of patterns and hues of Indian silk sarees are well-known. The majority of Indian ladies typically choose these sarees as their wedding attire. Without the opulent and pricey sarees made of pure silk, no wedding is complete.

Nevertheless, how are these silk sarees made?

The cloth is spun by a silkworm that has been bred to create silk. Silk is an example of an animal or natural fibre.

On this concept page, we will get to know more about the life cycle of silkworms and the processing of silk!

TABLE OF CONTENTS

• History of silk
• The life cycle of silkworm
• Processing of silk and Sericulture
• Practice Problems
• Frequently Asked Questions – FAQ

History of Silk

Substances comprised of thin, continuous threads are referred to as fibres. Natural fibre and synthetic fibre are the two types of fibres. While synthetic fibres are produced by humans, natural fibres are derived from plants and animals. Natural fibres include things like cotton and silk, whereas synthetic fibres include things like nylon, polyester, etc.

Around 3500 BC, silk was discovered in China. Silk was traded for a very long time and sent to different regions of the world. Manufacturers may now generate various varieties of silk from various silkworms based on lustre and texture thanks to technological improvements and new discoveries. The most popular silkworm is the mulberry silkworm. Sericulture is the practice of raising silkworms.

The Life Cycle of Silkworm

A silkworm's entire life span is between 6 and 8 weeks. In general, a silkworm will finish its life cycle faster in warmer climates. However, other elements like humidity and sunlight exposure are equally crucial. The ideal environment for silkworms includes 12 hours of daylight, 12 hours of darkness, a temperature of 23–28°C, and humidity levels of 85–90%. The eggs should hatch in 7–10 days under these circumstances. Without an incubator, it is quite difficult to create these conditions, thus it is customary to just adapt to the local climate. The life cycle of the silkworm begins when a female silk moth lays eggs. The caterpillar or larvae are produced after the silk moth's eggs hatch. The pupa is created by silkworms while they consume mulberry leaves. To keep itself contained when in the pupa stage, the silkworm spins a net around itself. Then it twists its head and spins a fibre made of proteins that will eventually become silk fibre. The collective term for the barrier that numerous caterpillars develop around the pupa is the cocoon. The silk thread is made from the silk moth's cocoon (yarn). Here is a thorough explanation of the life cycle of the silkworm.

Stage 1: Egg

The egg is the first stage of the silkworm's life cycle. The egg is laid by the female moth, which is primarily the size of a tiny dot. At one time, a female moth can lay up to 350 eggs. Due to the warmer air in the spring, the eggs hatch. This procedure happens once a year.

Stage 2: Silkworm

The cracked eggs release a hairy silkworm. At this time, the silkworms start to expand. They eat a lot of mulberry leaves for roughly 30 days before moving on to the next stage.

Stage 3: Cocoon

The silk moth reaches this stage after 30 days. At this stage, the silkworm often turns translucent and yellowish in colour. The silkworm is now beginning to enclose itself in a layer of defence. This protective coating or covering is known as a cocoon. The cocoon is made up of a single silk thread that is almost as little as a tiny cotton ball. The cocoon takes around two days to develop completely.

Stage 4: Pupa

The silkworm is only completely motionless during the pupa stage. When they are in the pupa stage, people kill the pupa by dipping the cocoon into the bubbling water to unwind the silk thread.

Stage 5: Moth

The silkmoth must spend 10 to 14 days in the cocoon stage before emerging. The life cycle is finished when the pupa transforms into a silkmoth.

As soon as it is fully formed, the silk moth begins its search for a mate. The silk moth creates substances known as pheromones to attract mates for mating. Following mating, the female silk moth lays 350 eggs on the surface of mulberry leaves. These eggs each begin their life cycles independently.

Processing of Silk and Sericulture

Sericulture is the practice of raising or producing silkworms. The domestic industry of many countries heavily depends on the manufacturing of silk. India and China are the two nations that produce the most silk worldwide. Three processes are typically involved in sericulture: Moriculture, raising silkworms and reeling silk. The practice of cultivating mulberry leaves is known as moriculture. The process of promoting the growth and development of silkworms is known as silkworm rearing. The process of removing silk fibre from silkworm cocoons is known as reeling.

The term "silk processing" describes a method of obtaining silk from the cocoon. Typically, sunlight is used to break the silk thread free from the cocoon. The silk thread is unravelled from the cocoon once silk reeling is completed. Bleaching is done to the silk threads that are extracted from cocoons. The spinning of silk fibre into threads takes place after the silk has been bleached. To create the silk yarn, the silk threads are further stacked. This is how silk is extracted from the silk moths' cocoons.

Practice Problems

1. Which of the following is a natural fibre?

1. Silk
2. Nylon
3. Rayon
4. All of these

Answer: A

Silk is a natural fibre since the silkworm spins it as a cocoon. The silkworm creates a cocoon around itself to use as a nest, which is eventually removed to produce the silk used in the fabric. Silk is a popular fabric in the textile business and is regarded as a luxurious material. The best kind of silk is thought to be larval silk. The other fibres given in the options are synthetic fibres.

So, option A is the correct answer.

2. Which of the following is sericulture?

1. Fish rearing
2. Silkworm rearing
3. Bird rearing
4. Cockroach rearing

Answer: B

Insect management and breeding for the purpose of producing silk is known as sericulture. Mulberry silk, also known as cultivated silk, and non-mulberry silk, sometimes known as wild silk, are the two main forms of silk.

So, option B is the correct answer.

3. Which of the following is not a silk city in India?

1. Jaipur
2. Kanchipuram
3. Bhagalpur
4. Pochampally

Answer: A

India, the second-largest producer of raw silk in the world, accounts for about 18% of global production. Cities like Kanchipuram in Tamil Nadu, Pochampally in Telangana, and Bhagalpur in Bihar are responsible for the expansion of the silk industry. In each state, they are known as silk cities. Jaipur is not called the silk city, it is rather called the ‘pink city’.

So, option A is the correct answer.

4. Silk is produced by

1. Cocoon
2. adult moth
3. Larva
4. larva and adult moth

Answer: C

Fibroin, a macromolecule produced by cocoone-making insect larvae, makes up the fibre of silk. The known silk is made from cocoons made by mulberry silkworm moth larvae that are raised in captivity (sericulture).

So, option C is the correct answer.

Frequently Asked Questions – FAQ

1. How long can silkworms live without food?
A. Once the silkworms have gone through a few moults, we can cease feeding them every day. They might go for a week or longer without eating (depending on temperature and size). The "hold" period can be extended by feeding them every few days to keep them hydrated and healthy.

2. Does a silkworm turn into a butterfly?
A. The larva undergoes changes for two to three weeks before becoming a pupa and eventually a white butterfly, however, we are unable to see what takes on inside the cocoon. Despite the cocoon's construction from a sturdy silk thread, the butterfly secretes a yellowish liquid.

3. How long does a silkworm take to complete its life cycle?
A. The life cycle of the silkworm lasts about 6 to 8 weeks. When the female silk moth lays eggs, the life cycle of the silkworm begins.

4. What happens to silkworms after silk is extracted?
A. Peace silk is produced using moral farming practices. This indicates that the silkworms will be allowed to develop into mature Bombyx mori moths. They emerge from their cocoons on their own will and pass away peacefully.

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