Sericulture Guide: Silk Rearing, Mulberry, and Harvesting

Sericulture, the art and science of rearing silkworms for the commercial production of silk, is a highly remunerative agricultural enterprise in India. As one of the largest producers of silk globally, India has a long history of sericulture, particularly in states like Karnataka, Andhra Pradesh, Tamil Nadu, West Bengal, and Jammu and Kashmir. The industry is unique because it combines agriculture, animal husbandry, and cottage industry elements. Farmers cultivate mulberry plants to produce leaves, which are then fed to silkworms in specialized rearing houses. While mulberry silk accounts for the vast majority of commercial silk production in India, non-mulberry varieties such as Tasar, Eri, and Muga are also cultivated in forest and tribal regions. Sericulture provides a regular income stream throughout the year, with up to five or six cocoon crops harvested annually under irrigated conditions, making it an excellent option for smallholders seeking consistent cash flow.

Successful sericulture requires managing a delicate biological balance, as the farmer must act as both an agronomist and a livestock keeper. Silkworms are highly sensitive creatures that are vulnerable to slight changes in temperature, humidity, and leaf quality. Unlike field crops that can withstand minor dry spells or delayed inputs, a silkworm batch can be completely destroyed by a single day of contaminated feed or poor environmental control. This double dependency on high-quality mulberry cultivation and precise rearing house management makes sericulture a labor-intensive venture. Despite the high labor requirement, the returns per acre of land are generally much higher than traditional field crops like paddy or maize, provided the farmer follows recommended scientific protocols and manages diseases effectively.

Cultivating mulberry plants

The foundation of high-quality silk production lies in the cultivation of healthy mulberry plants, as leaf quality directly determines the health of the silkworms and the quality of the cocoon silk. Mulberry is a hardy perennial shrub that can grow in a variety of soils, though deep, fertile, sandy loam soils with a neutral pH are ideal. Before planting, farmers should carry out a soil test and follow the Soil Health Card recommendations to apply balanced doses of farmyard manure and chemical fertilizers. Popular high-yielding mulberry varieties in India include V1, S36, and G4, which produce thick, moisture-rich leaves suitable for silkworm nutrition. Sowing is typically done using semi-hardwood stem cuttings or saplings planted during the onset of the monsoon in a paired-row system, which optimizes space for weeding and irrigation.

Irrigation management is critical, as mulberry plants require regular water to maintain leaf moisture, which should ideally remain above seventy percent. Drip irrigation is highly recommended to conserve water and apply liquid fertilizers directly to the root zone, and farmers can calculate their water requirements using local irrigation calculators. Regular pruning is necessary to maintain the plants in a bushy form, which makes leaf harvesting easier and encourages fresh vegetative growth. Harvesting is done either by individual leaf picking or by cutting entire branches, depending on the age of the silkworms being reared. Farmers must watch for common pests like mealybugs, thrips, and leaf rollers, and apply biological control measures or safe pesticides under the guidance of local Krishi Vigyan Kendras (KVKs).

Setting up the rearing house

A dedicated, well-ventilated rearing house is essential to protect silkworms from environmental extremes, pests, and disease pathogens. The rearing house should be built on an elevated site with an east-to-west orientation to avoid direct sun exposure on the sidewalls during hot summer days. The building can be constructed using brick masonry with a tiled or asbestos roof, though proper insulation is necessary to regulate indoor temperatures. The height of the ceiling should be at least ten feet, and the room must have sufficient windows fitted with wire mesh to allow cross-ventilation while keeping out predators like lizards, rats, and parasitic flies. Before starting any rearing cycle, the entire house, including all tools and trays, must be thoroughly disinfected using a formalin solution or chlorine dioxide under recommended safety protocols.

Inside the rearing house, silkworms are kept in rearing trays arranged vertically on multi-tier wooden or iron stands to maximize space utilization. Each stand should have four to five tiers, with a spacing of about two feet between tiers to allow easy feeding and cleaning operations. Rearing trays can be circular bamboo trays or rectangular plastic trays, which are easier to clean and sanitize. To protect the silkworms from ants, the legs of the rearing stands must be placed in antwells filled with water mixed with a small amount of oil. Maintaining the correct microclimate inside the rearing room is vital; younger worms require a temperature of twenty-six to twenty-eight degrees Celsius, while older worms perform best at twenty-four to twenty-five degrees Celsius. Humidifiers and heaters must be kept ready to adjust conditions during dry spells or cold winters.

Silkworm rearing process

The rearing process begins with sourcing high-quality, disease-free layings (DFLs) from registered government or certified private grainages. DFLs are silkworm eggs that have been tested and certified free from hereditary pathogens, particularly the deadly pebrine disease. The eggs are incubated at a constant temperature of twenty-five degrees Celsius and eighty percent relative humidity until they are ready to hatch. When the eggs show a blue-dot stage, they are covered with black paper for a day to ensure uniform hatching when exposed to light the next morning. The newly hatched tiny black larvae, called ants, are carefully brushed onto rearing trays using tender, finely chopped mulberry leaves in a process known as brushing.

Silkworms grow at an astonishing rate, increasing their body weight by about ten thousand times during their thirty-day life cycle. This growth period is divided into five distinct stages called instars, separated by four molting periods. During a molt, which lasts for twenty to twenty-four hours, the silkworm stops feeding, remains motionless, and casts off its old skin to allow its body to expand. Farmers must stop feeding the worms completely as soon as they see the first signs of molting, which include a raised head and shiny skin. Feeding should only resume once all the worms in the tray have successfully cast off their skin. The first two stages are known as the young age or chawki stage, which is often managed in specialized chawki rearing centers before being handed over to commercial farmers for the late-age rearing of the remaining three instars.

Feed management for worms

Silkworm feed management requires matching the maturity of the harvested mulberry leaves with the specific growth stage of the larvae. Young chawki worms have delicate mouthparts and require tender, moisture-rich leaves from the top sections of the mulberry plant, chopped into small pieces to facilitate feeding. Late-age worms in the fourth and fifth instars have strong mandibles and require mature, nutrient-dense leaves from the middle and lower branches. Feeding is typically done three to four times a day at regular intervals to ensure continuous nutrition. Sourcing leaves during hot summer afternoons should be avoided, as harvested leaves wilt rapidly and lose their moisture content, making them unpalatable and less nutritious for the worms.

Bed sanitation is a critical aspect of feed management, as accumulation of leftover leaves, fecal matter, and dead worms creates a humid environment that promotes fungal and bacterial growth. Bed cleaning must be done regularly using plastic cleaning nets of appropriate mesh size for each instar. To clean the bed, fresh leaves are spread over the net; the healthy worms crawl up through the net to feed on the fresh leaves, allowing the farmer to lift the net and remove the underlying waste. Dry bed disinfectants like Vijetha or Ankush powder should be dusted over the worms after each molt to keep the bed dry and kill surface pathogens. Keeping the rearing beds dry and clean reduces the incidence of infections and ensures that the worms spin high-quality silk.

Preventing silk diseases

Preventing diseases is the most challenging task in sericulture, as silkworms are highly vulnerable to viral, bacterial, fungal, and protozoan infections that can wipe out an entire crop. The most dreaded of these is pebrine, a systemic protozoan disease caused by Nosema bombycis, which is transmitted from the mother moth to the eggs. Pebrine causes irregular growth, black spots on the larval body, and failure to spin cocoons. Because there is no cure for pebrine, prevention through strict screening of mother moths and purchasing certified DFLs from authorized grainages is the only defense. Any batch found infected with pebrine must be destroyed immediately, and the rearing house must undergo rigorous disinfection.

Other common diseases include grasserie, a viral disease that causes the larvae to become swollen, pale yellow, and secrete turbid body fluid, and flacherie, a bacterial infection associated with poor leaf quality and high humidity. Fungal diseases like muscardine turn the dead larvae into chalky white or green mummified bodies. Managing these diseases requires maintaining a dry rearing environment, avoiding overcrowding, and applying recommended bed disinfectants after every molt. Farmers must consult their local sericulture extension officer or nearby KVK for advice on regional disease outbreaks and approved sanitization products. Implementing strict biosecurity, such as washing hands and feet in a disinfectant solution before entering the rearing house, is essential.

Mounting and cocoon harvesting

At the end of the fifth instar, which lasts for seven to eight days, the silkworms stop feeding, change from a greenish-white to a translucent golden-yellow color, and begin to search for a place to spin their cocoons. These mature worms must be quickly transferred to mountages, which are specialized frames that provide support for cocoon construction. Traditional bamboo mountages, known as Chandrikas, are widely used in India, though plastic corrugated mountages and rotary mountages are also popular due to their durability and ease of harvesting. The density of worms on the mountage must be monitored carefully; overcrowding leads to double cocoons, where two worms spin a single cocoon together, which cannot be reeled commercially and fetches a much lower price.

The silkworm takes about two to three days to complete the spinning of its cocoon, which is made of a single continuous silk filament held together by a natural gum called sericin. Once spinning is finished, the larva transforms into a pupa inside the protective cocoon shell. Harvesting should be done on the fifth or sixth day after mounting, allowing the cocoon shell to harden fully. Harvested cocoons must be sorted immediately to remove defective ones, such as stained, double, thin-shelled, or deformed cocoons, which are sold separately at lower prices. The selected high-quality cocoons are packed in loose gunny bags and transported to the silk market within two to three days of harvest to prevent the pupa inside from emerging as a moth and breaking the silk thread.

Marketing cocoons

Cocoons are sold in government-regulated silk cocoon markets, such as the famous Ramanagara market in Karnataka or similar regional auction yards in Andhra Pradesh and Tamil Nadu. The price of cocoons is determined through an open bidding process or e-auction, based on quality parameters like shell ratio, filament length, and defective cocoon percentage. Because live pupae will eventually emerge as moths and damage the cocoons, buyers must kill the pupae using hot air dryers or steam chambers in a process called stifling. Stifled cocoons can be stored for several months without damage to the silk filament. Cocoon prices are subject to market volatility influenced by international silk import rates, local textile demand, and seasonal supply fluctuations.

To secure stable prices and protect themselves from middlemen, farmers should organize into sericulture cooperative societies or self-help groups. Selling directly to registered silk reelers or through official government channels ensures transparent weighing and immediate payment. Farmers must monitor cocoon price trends and plan their rearing cycles to align with peak demand seasons, which often coincide with festival and wedding periods in India. Proper transport, avoiding compression of bags, and keeping cocoons ventilated during transit are simple steps that prevent damage and maintain the market value of your hard-earned produce.

Subsidies and credit

Starting a commercial sericulture unit requires capital investment for constructing a rearing house, preparing land, establishing mulberry plantations, and purchasing rearing equipment. To assist farmers, the Central Silk Board, along with state sericulture departments, offers various financial assistance and subsidy schemes. Subsidies are typically provided for rearing house construction, purchasing drip irrigation systems, and buying quality rearing tools. These subsidies are routed through official channels, and farmers should visit their local sericulture office or verify the guidelines on the official Central Silk Board portal to check eligibility and application procedures. It is essential to secure approval before beginning construction to ensure compliance with subsidy rules.

In addition to subsidies, commercial banks, regional rural banks, and cooperative credit societies provide short-term crop loans and term loans for sericulture. The Kisan Credit Card (KCC) scheme covers working capital requirements for purchasing DFLs, disinfectants, fertilizers, and hiring labor. When preparing a loan application, farmers should submit a detailed project report including a training certificate from an agricultural university or state training center. Lenders look for formal training as it reduces the risk of crop failure. Always consult your local bank branch manager to understand the interest rates, repayment schedules, and security requirements before finalizing your credit plans.

Frequently asked questions

What is sericulture?

Sericulture is the commercial rearing of silkworms for the production of raw silk.

Which state is the largest producer of silk in India?

Karnataka is the leading producer of mulberry silk in India, followed by Andhra Pradesh.

What is the main food of silkworms?

Silkworms feed exclusively on the fresh leaves of the mulberry plant.

What is a chawki rearing center?

A chawki rearing center is a specialized facility that rears young silkworms during their first two delicate stages before handing them over to farmers.

How long is the life cycle of a commercial silkworm?

The larval life cycle from hatching to cocoon spinning takes approximately twenty-five to thirty days.

What is a DFL in silk farming?

DFL stands for Disease-Free Laying, which are silkworm eggs certified free from hereditary pathogens.

What is pebrine disease?

Pebrine is a fatal protozoan disease in silkworms that is transmitted from the mother moth to the eggs.

What is a Chandrika in sericulture?

A Chandrika is a traditional circular bamboo tray with spirals used to support silkworms while they spin their cocoons.

How is the price of silk cocoons determined?

Cocoon prices are determined through open bidding or e-auctions in government-regulated silk markets based on shell quality parameters.

What is cocoon stifling?

Stifling is the process of killing the pupae inside the cocoons using steam or hot air to prevent them from emerging and breaking the silk filament.

Can sericulture be done in dry regions?

Yes, sericulture can be practiced in dry zones if drip irrigation is available to maintain the mulberry fields.

What temperature is ideal for rearing adult silkworms?

Adult silkworms perform best at a room temperature of twenty-four to twenty-five degrees Celsius.

How many crops can be harvested in a year?

Under irrigated conditions, farmers can harvest five to six cocoon crops within a single year.

Does the government provide subsidies for sericulture?

Yes, the Central Silk Board and state sericulture departments provide subsidies for rearing house construction and drip irrigation.

Can I get a KCC loan for sericulture?

Yes, KCC crop loans cover the working capital requirements for silkworm rearing, including eggs, disinfectants, and labor.