Sericulture Rearing of Silkworm - Explained Process, FAQs

Edited By Team Careers360 | Updated on Jul 02, 2025 04:54 PM IST

Introduction
Silk has been under use by human beings for various purposes since the ancient time. Pure silk is one of the finest and most magnificent natural fibers of the world and is said to be “the queen of fibers”. Silk clothes have a look and feeling of delicacy that no other cloth can have. Due to its immense value and adequacy, there have been many attempts in maximum parts of the globe for the large- scale production of silk.

Rearing of mulberry silkworm

The mulberry silkworm is the most common category of domesticating silkworm. The caterpillar eats leaves of mulberry. All of the silkworm breeds reared till now, belong to the Bombyx mori species, which are known to be ancestors of the Mandarin silkworm, known as Bombyx mandarina.

There are many kinds of mulberry silkworms, namely of Japan, China, Europe or Indian origin based on geographical location.

They are also differentiated on the bases of the number of generations or the number of times they reproduce in a year under natural conditions or also on the number of molts during growth of larval stages.

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Mulberry silk

The silk we get from this kind is yellow or white in coloration. This silk is of the finest quality available around the globe. The silk is made up of single long fibers. It is purified than other kinds of silk. The 100% mulberry silk products are one of the most reliable and deluxe silk goods. Few of the most popular advantages of silk from mulberry is that it is 100% natural, odor free and allergy free. Mulberry silk contains a natural protein which helps get rid of allergies, therefore bedding of mulberry silk is a healthy and right choice for those who are more allergy prone.

Morphology and life cycle of Bombyx mori

Silkworm undergo a process of metamorphosis from egg to the adult stage by two intermediate stages of larva also called as caterpillar and pupa also known as cocoon

Eggs

The egg is round in shape and white in coloration, surrounded by chorion. The egg has only one micropyle situated towards the anterior pole, from where the sperm enters inside. The respiratory channels are in the shape of funnels which become small in size as they go inside, and are distributed in big numbers through the entire surface of the egg except the micropyle. Cytoplasmic surface is known as periplasm and the nucleus is situated in the anterior pole.

Eggs

Larva

The caterpillar after hatching from the egg measures in the length of 5 to 7 mm. Their body surface is quite wrinkled and somewhat dull grayish in color. The larval body is split up into head, thorax and the abdomen.

Larva

Pupa

The pupal stage or more precisely it is also known as inactive or resting stage as in this stage the insect is unable to feed. In this phase, the pupa undergoes a huge number of definite changes which takes place inside the body. In this stage the new form of adult moth take place by the complete revolution of internal organs. Soon after the process of pupation, the pupa is white in color and soft in texture but slowly turns into brown color and the pupal texture becomes rigid or tough.

Pupa

Adult

The adult moth emerging from the pupal stage is not capable of flight. The adult does not eat during its short life span. The body of the moth like that of the larva is composed of three segments same the head, thorax and the abdomen. Just like the butterfly the body is covered by scales. The eyes are situated on either side of the head which are compound. The ocelli are absent. The antennae are large and bi pectinate in appearance.

Adult

Silkworm breeding

Female and male moths mate only for few hours after their birth and start laying eggs. The sexes are separate and the sexual dimorphism is quite clear. The males are smaller in size and tender in texture where as the females are bigger in size and stout. Both the males and females do not feed. The females have a life span of 2 to 3 days, on the other side the males have even less days to live and sometimes die during copulation. There is no need for further mating. One moth lays 400 to 500 eggs depending upon the atmospheric conditions and supply of nourishment.

Process of rearing of silkworm

Rearing by shelf rearing method: rearing of silkworm in round bamboo rearing trays arranged one over the other in tiers on rearing stands is called shelf rearing. A stand can accommodate 10 to 11 trays and therefore, this method provides economy of space but requires more labor for handling so many trays. Larvae are fed on chopped mulberry leaves in this method.

On the basis of selected instar stage, rearing can be done in any of the one stage of development

Young age rearing
Late age rearing

Out of the two, young age rearing is the most preferred one.

Silkworm rearing house

Rearing houses are planned and constructed to maintain and provide proper environmental conditions to ensure good quality of cocoons. The rearing house is designed based on brushing capacity and the method of rearing.

Each rearing house should have

A main rearing hall and
Leaf preservation room

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Generally, three types of rearing are known: shelf rearing, shoot rearing, and floor rearing. In shelf rearing, rearing trays of consecutive sizes are arranged on stands with 8 to 10 tiers. Shelf rearing is economical best method because in less area, maximum number of eggs can be reared.

It is a rat proof building with net all around to prevent rats from entering the building. The building should have good amount of light and proper ventilation.

The rearing house is partitioned into four convenient rooms, out of which one must have high temperature and humidity for rearing of the young age silkworms.

The rearing houses are designed for effective disinfection, like smooth surface of walls, use of lime white wash, facility for the making building airtight, less reactive to disinfectants and

washable smooth floor.
Silkworm rearing house

Silkworm rearing equipment

Rearing stands: rearing stands are made of wood or bamboo and are portable for transportation. The trays are arranged on the shelves and each stand can accommodate 10 rearing trays. 6 stands are sufficient for each rearing room.

Ant wells: ant wells stop ants crawling on to trays and attacking the silkworms. They are made of concrete or stone blocks and each block bears groove at center. Water is poured in to groove to stop the ants. Each stand leg must be put on ant well.

Rearing trays: these are reared to rear silkworm and are usually made of bamboo so they are light and easy to handle.

Paraffin paper: this is thick craft paper coated with paraffin wax with a melting point of 55oC. It is used to rear early- stage silkworm.

Chop sticks: these are made of bamboo approximately 17.5 cm long, thin and tapering to one end. Direct handling of the young age silkworm is to be avoided for hygiene reasons.

Feathers: bird feathers are used for brushing the delicate newly hatched worms on the rearing bed.

Chopping board: chopping knives are used for the cutting of mulberry leaves. Now a days power operated chopping machines are used.

Leaf chamber: mulberry leaves are stored in leaf chamber made from wood. The chamber is covered on all the sides with wet gunny cloth to prevent leaf withering.

Cleaning nets: these are made of cotton thread or nylon. They have different sized meshes to suite the size of larvae.

Montage: these are used as a support for the silkworms to spin cocoons. They are made from bamboo strips and mat. The ripe worms, who are about to spin cocoons are transferred on this mat.

Silkworm cocoon extract

When the silkworm is fully grown its appetite fails and starts moving restlessly finding a place for spinning the cocoon. At this stage worms should be mounted on chandrica. Extreme care is necessary during mounting as it will affect reeling qualities of cocoon. Overcrowding of the worms on the mat should be avoided. The rooms should be well ventilated and its temperature should be kept between 70 to 75oF for spinning. The proper relative humidity is between 60 to 70%.

Silkworm egg storage

The period of incubation for eggs begins when the eggs are taken out of cold storage. Maintenance of proper temperature and humidity is extremely important during incubation. The optimum temperature for incubation of eggs is about 73.5 to 77oF. Required humidity for all the eggs is 75 to 80%. For incubation, the eggs are spread on piece of paper in the rearing tray. In order to stimulate eggs to hatch all the same time, they are regularly and evenly stroked with feather a day before they are due to hatch.

Also check-

NCERT Chemistry Notes:

Frequently Asked Questions (FAQs)

1. Name the procedure used for rearing the silkworm for obtaining the silk?

The rearing of silkworm for obtaining the silk is called sericulture.

2. What is meant by rearing of silkworm?

Rearing of silkworm means to rear or develop or looking after of the silkworm insects to get economically profitable silk is known as rearing of silkworm.

3. How we get silk from silkworm?

Silk is extracted from the cocoons of the silkworm, after their development is complete and is able to spin out the cocoons.

4. Name the silkworm tree?

The mulberry tree leaves are used to feed the silkworm insect therefore the mulberry tree is also called as silkworm tree.

5. What is the scientific name of silkworm?

The scientific name of silkworm is Bombyx mori.

6. What is the rearing of silkworm called?

The rearing of silkworm is called sericulture.

7. What is the purpose of the cocoon in a silkworm's life cycle?

The cocoon serves as a protective shell for the silkworm during its pupal stage. Inside the cocoon, the silkworm undergoes metamorphosis, transforming from a larva into an adult moth. The cocoon is made of a single continuous silk fiber, which is what makes it valuable for silk production.

8. What is sericulture?

Sericulture is the process of cultivating silkworms to produce silk. It involves rearing silkworms, growing mulberry plants as food for the silkworms, and extracting silk from their cocoons. This ancient practice combines agriculture and textile production to create one of the most luxurious natural fibers.

9. Which species of silkworm is most commonly used in sericulture?

The most commonly used species in sericulture is Bombyx mori, also known as the domesticated silkworm. This species has been selectively bred for thousands of years to maximize silk production and is entirely dependent on humans for survival and reproduction.

10. What do silkworms eat?

Silkworms primarily feed on mulberry leaves. The Bombyx mori species is monophagous, meaning it exclusively eats mulberry leaves. This diet is crucial for their growth and the quality of silk they produce. Some wild silkworm species may eat other plants, but cultivated silkworms are raised on mulberry leaves.

11. How long does it take for a silkworm to complete its life cycle?

The life cycle of a silkworm typically takes about 6-8 weeks. This includes the egg stage (10-14 days), larval stage (about 25-30 days), pupal stage (10-14 days), and adult moth stage (5-10 days). The exact duration can vary depending on environmental conditions and the specific silkworm species.

12. How does humidity affect silkworm rearing?

Humidity is crucial in silkworm rearing. The ideal relative humidity is between 70% to 90%. High humidity helps prevent the mulberry leaves from drying out too quickly and aids in the molting process. However, excessive humidity can promote the growth of harmful molds and bacteria, potentially leading to disease outbreaks among the silkworms.

13. What is the difference between mulberry silk and wild silk?

Mulberry silk comes from domesticated silkworms (Bombyx mori) that feed exclusively on mulberry leaves. It's characterized by its uniform color and texture. Wild silk, also known as Tussah silk, comes from several species of wild silkworms that feed on oak and other leaves. Wild silk is typically coarser, stronger, and more varied in color than mulberry silk.

14. What is the ideal temperature for rearing silkworms?

The ideal temperature for rearing silkworms is between 20°C to 28°C (68°F to 82°F). Temperature plays a crucial role in silkworm development and silk quality. Temperatures that are too high or too low can negatively affect the silkworms' growth rate, cocoon formation, and silk quality.

15. How many times does a silkworm molt during its larval stage?

A silkworm typically molts four times during its larval stage. These molting periods are called instars, and the silkworm grows significantly between each molt. After the fourth molt, the silkworm enters its fifth and final instar, during which it spins its cocoon.

16. Why are most silkworms killed before they emerge from their cocoons?

Silkworms are usually killed before they emerge from their cocoons to preserve the continuous silk fiber. If the moth were allowed to emerge naturally, it would secrete enzymes to break down the silk fiber, creating a hole in the cocoon. This would result in shorter, broken silk fibers, which are less valuable for textile production.

17. What is the chemical composition of silk?

Silk is primarily composed of two proteins: fibroin and sericin. Fibroin is the structural protein that forms the core of the silk fiber, while sericin is a gummy substance that coats the fibroin, helping to bind the fibers together. Raw silk is typically about 75-80% fibroin, 20-25% sericin, and small amounts of fats and waxes.

18. How do silkworms breathe?

Silkworms breathe through small openings along the sides of their bodies called spiracles. These spiracles connect to a network of tubes called tracheae, which distribute oxygen throughout the silkworm's body. This respiratory system is common among insects and allows for efficient gas exchange without the need for lungs.

19. What is the purpose of the sericin in silk?

Sericin, also known as silk gum, serves several purposes:

20. What is the difference between raw silk and processed silk?

Raw silk is the silk as it comes directly from the cocoon after reeling. It still contains sericin and may have a slightly yellow or off-white color. Processed silk has been treated to remove the sericin, which gives it a softer texture and more lustrous appearance. Processed silk may also undergo additional treatments like dyeing or finishing.

21. How has genetic engineering impacted sericulture?

Genetic engineering has had several impacts on sericulture:

22. What is degumming in silk processing?

Degumming is the process of removing sericin (silk gum) from raw silk fibers. This is typically done by treating the silk with warm soapy water or mild alkaline solutions. Degumming softens the silk, increases its luster, and makes it more comfortable to wear. However, it also reduces the weight of the silk by about 25% as the sericin is removed.

23. How do different species of silkworms produce different types of silk?

Different silkworm species produce silk with varying characteristics:

24. What is the economic importance of sericulture?

Sericulture has significant economic importance, particularly in countries like China, India, and Brazil. It provides:

25. What are some alternatives to traditional sericulture?

Some alternatives to traditional sericulture include:

26. What is the process of reeling silk from cocoons?

Reeling silk from cocoons involves several steps:

27. How does the structure of silk fibers contribute to its properties?

The structure of silk fibers contributes to its unique properties:

28. What are some non-textile applications of silk?

Silk has various non-textile applications:

29. How do silkworms communicate with each other?

Silkworms have limited communication abilities, but they do interact through:

30. What are the main challenges facing the sericulture industry today?

The sericulture industry faces several challenges:

31. How is silk extracted from the cocoon?

Silk is extracted through a process called reeling. The cocoons are first treated with hot water or steam to soften the sericin (silk gum) that holds the silk fibers together. Then, the loose ends of silk from several cocoons are combined and wound onto a reel. This process unravels the cocoons, creating one long, continuous thread of raw silk.

32. What is sericulture's environmental impact?

Sericulture has both positive and negative environmental impacts. On the positive side, it promotes the cultivation of mulberry trees, which can help in soil conservation and provide a habitat for various species. However, the intensive use of water in silk processing and the chemicals used in dyeing can have negative environmental effects if not managed properly.

33. How many silkworms are needed to produce one pound of silk?

It takes approximately 2,500 to 3,000 silkworms to produce one pound of raw silk. This is because each silkworm produces only a small amount of silk – the cocoon of a single silkworm yields about 1,000 to 1,200 feet of silk filament, but this weighs only about 0.0008 ounces.

34. What is the role of the adult silk moth in sericulture?

In commercial sericulture, the primary role of adult silk moths is reproduction. Selected moths are allowed to emerge from their cocoons, mate, and lay eggs. These eggs then become the next generation of silkworms. However, most silk moths do not reach adulthood as their cocoons are harvested for silk production.

35. How do silkworms produce silk?

Silkworms produce silk through specialized glands called silk glands or sericteries. These glands secrete a protein-rich fluid that hardens when exposed to air. As the silkworm extrudes this fluid through openings called spinnerets, it solidifies into a continuous silk filament. The silkworm uses head movements to weave this filament into its cocoon.

36. How long can a single silk fiber be?

A single silk fiber from one cocoon can be incredibly long, typically ranging from 300 to 900 meters (1,000 to 3,000 feet). However, the usable length is usually less, around 600 to 900 meters, as some of the outer silk is often damaged or of lower quality.

37. What factors affect the quality of silk produced?

Several factors affect silk quality, including:

38. How do silkworms know when to start spinning their cocoons?

Silkworms begin spinning their cocoons when they reach maturity, typically after their fifth instar (final larval stage). This process is triggered by hormonal changes in the silkworm's body. Environmental factors like temperature, humidity, and the amount of light can also influence when a silkworm starts cocoon spinning.

39. How does the diet of silkworms affect the quality of silk?

The diet of silkworms significantly affects silk quality. Mulberry leaves are the primary food source, and their quality directly impacts the silk. Leaves with higher protein content generally result in better quality silk. Factors like the mulberry tree variety, leaf age, and growing conditions all play a role in determining the nutritional value of the leaves and, consequently, the quality of the silk produced.

40. What are some common diseases that affect silkworms?

Some common diseases affecting silkworms include:

41. How does the silkworm's nervous system control silk production?

The silkworm's nervous system plays a crucial role in silk production:

42. How do silkworms adapt to different environmental conditions?

Silkworms have limited ability to adapt to environmental changes due to their domestication. However, they can:

43. What role does photoperiod play in silkworm development?

Photoperiod, or the duration of light exposure, influences several aspects of silkworm development:

44. How do silkworms defend themselves against predators?

Domesticated silkworms have few defenses against predators due to centuries of selective breeding. However, they retain some basic defensive mechanisms:

45. What is the role of mulberry cultivation in sericulture?

Mulberry cultivation is crucial in sericulture:

46. How does the silk industry address ethical concerns about silkworm treatment?

The silk industry addresses ethical concerns through: