The Role and Setup of Commercial Chawki Rearing Centers

In sericulture, the quality of the final cocoon crop is largely determined in the very first days of a silkworm’s life. The first two larval instars – collectively called the chawki stage – are the most delicate phase of silkworm development. Young larvae are highly sensitive to temperature, humidity, pathogens, and leaf quality. Most small-scale farmers simply do not have the infrastructure to manage these conditions precisely, which is why Commercial Chawki Rearing Centers (CRCs) have become an indispensable institution in modern sericulture. These centers take on the most technically demanding part of silkworm rearing so that farmers can focus on what they do best: late-age rearing and cocoon production.

What is a commercial chawki rearing center? 🔗

According to the Central Sericultural Research and Training Institute (CSRTI), Mysuru, a CRC is a specialized commercial enterprise that rears young silkworms under controlled microclimatic conditions up to the second moult, and then supplies healthy chawki worms to farmers for late-age rearing. Chawki rearing covers the silkworm’s first and second instars – from the moment eggs hatch until the larvae complete their second moult, a period of roughly 9 to 10 days.

Before CRCs became widespread, farmers had to procure silkworm eggs from grainages, incubate them at home, and manage the vulnerable young larvae themselves. This often resulted in improper hatching, unhealthy young worms, and ultimately poor cocoon yields because most farm-level rearing sheds could not maintain the precise conditions chawki worms require. CRCs solve this problem by centralizing the most critical and technically demanding phase of production.

Cocoon productivity from CRC-supplied worms is recorded to be about 20-25% higher compared to worms reared from eggs by farmers themselves. CRCs also save farmers approximately nine days of labor and spare them from the exacting tasks of egg incubation, brushing, and early-instar management.

Why CRCs are the backbone of sericulture 🔗

Research published in Vigyan Varta underscores that CRCs are essential for stabilizing cocoon crop productivity because they offer controlled environments that improve silkworm health, facilitate uniform growth, and significantly raise survival rates, thereby lowering the risk of crop failure. This matters enormously at scale. Around 800 CRCs are registered under the Central Silk Board (Amendment) Act, 2006 across the country, operating in both mulberry and non-mulberry sectors – a number that continues to grow as the benefits of centralized chawki rearing are better understood.

The Karnataka State Sericulture Research and Development Institute (KSSRDI) notes that since most sericulturists in India lack the facilities to conduct chawki rearing on their own, private CRCs play a vital role in providing the required conditions and ensuring crop stability alongside improved cocoon yields. In countries with advanced sericulture industries like China, Japan, and South Korea, as many as 95% of farmers receive silkworms as ready chawki worms rather than starting from eggs – a benchmark India is steadily working toward.

Key requirements for setting up a CRC 🔗

Establishing a functional and profitable CRC requires careful attention to three core pillars: infrastructure, leaf supply, and human resources. Each of these directly determines the quality of the chawki worms produced.

The rearing house and equipment 🔗

The basic requirements for a successful CRC are a suitable rearing house with the necessary rearing appliances, a well-maintained exclusive chawki mulberry garden, and well-trained manpower. The Central Silk Board’s CSRTI, Berhampore specifies that a Mini-CRC set up to rear 1,000 DFLs (disease-free layings) per crop requires a separate rearing house, plastic/HDPE double-wall rearing trays (2′ × 3′), PVC or wooden rearing racks capable of holding at least 100 trays, a leaf chopping machine, dry and wet bulb thermometers, heaters, and humidifiers for microclimate management.

For larger operations, a CRC designed to brush 5,000-6,000 DFLs per batch requires a rearing hall of 30′ × 30′, a leaf storage room of 10′ × 20′, and an ante-room of 10′ × 10′, with adequate ventilation and a continuous water channel along the walls to help regulate humidity.

Microclimate control 🔗

Maintaining precise temperature and humidity is non-negotiable in chawki rearing. The recommended temperature for the first instar is 27-28°C and for the second instar is 26-27°C, with relative humidity maintained at 85-90% throughout. These conditions support rapid, healthy larval development and reduce susceptibility to pathogens.

As noted by the Government of Andhra Pradesh’s Department of Sericulture, maintaining an optimal temperature of 28°C and 85% humidity is simply not possible for most farmers in their own rearing sheds – which is precisely the gap that CRCs fill. Heaters, humidifiers, and proper ventilation systems in the rearing hall are therefore essential investments, not optional additions.

The exclusive chawki mulberry garden 🔗

Leaf quality is as critical as rearing environment. The nutritional requirements of chawki-stage larvae are very different from those of late-age worms. Leaves fed to chawki larvae must be tender, soft, succulent, and rich in protein (around 25%) and carbohydrates (around 14%), with at least 80% moisture content. Standard mulberry cultivation practices are not sufficient to meet these requirements – a dedicated chawki garden with its own package of practices is essential.

Karnataka’s Department of Sericulture recommends dividing the chawki mulberry garden into two plots so that high-quality leaves can be produced at 15-day intervals, facilitating regular brushings throughout the year. With this approach, 24 chawki leaf harvests per year are achievable. Mulberry varieties with high moisture content and nutritional value – particularly G2, V1, and S36 – are recommended for chawki gardens, with G2 capable of yielding up to 38 MT of quality chawki leaves per hectare per year under irrigated conditions.

Location selection for a CRC 🔗

Where you place a CRC matters as much as how it is built. The ideal location balances proximity to rearers, availability of resources, and separation from potential sources of contamination.

A CRC should ideally be situated at the center of a sericulturally active area, close to villages with a significant number of silkworm rearers. This minimizes transportation time and distance for chawki worms after distribution, which is critical since worms should be transported to rearers’ premises during morning hours and fed immediately with fresh leaves upon arrival.

At the same time, the center should be kept well away from commercial rearing houses and any industrial facilities that might be sources of chemical contamination or disease pressure. Proximity to a reliable grainage – a government-licensed facility that produces and supplies disease-free layings (DFLs) – is equally important. Only certified, pebrine-free silkworm hybrid eggs procured from government agencies such as NSSOs (State Silkworm Seed Producing Centers) or Department of Sericulture units should be used to ensure disease-free production from the start.

Recent government initiatives, such as the establishment of 100 CRCs across Jammu and Kashmir under the Holistic Agriculture Development Programme (HADP), reflect the growing recognition that CRCs must be strategically placed within sericulturally active districts to effectively serve local rearing communities.

Egg procurement and the grainage connection 🔗

The quality of chawki worms is directly linked to the quality of the eggs used. CRCs must establish and maintain strong linkages with reputable, government-recognized grainages. Grainages produce industrial seeds – silkworm eggs – on a mass scale for commercial rearing, and the layings they supply are generally certified hybrids that are tested and certified as disease-free. Using anything less puts the entire crop at risk.

After procurement, eggs undergo careful incubation at the CRC. Egg sheets are first dipped in a 2% formalin solution for 10 minutes, air-dried in a cool room, and then incubated at 25°C with 80% relative humidity under 16 hours of light. A black boxing technique – wrapping the developing eggs in black paper or cloth for 24-36 hours once 80% of eggs reach the “blue stage” – is then used to synchronize hatching, ensuring uniform larval development from the very first moment.

Rearing methods used at CRCs 🔗

Two primary methods are used for chawki rearing at CRCs. In box rearing, silkworms are brushed onto paraffin paper in plastic trays, with wet foam pads placed around the bed and paraffin paper covering the top to retain humidity. Trays are stacked one above the other, and the beds are aerated before each feeding. In shelf rearing, bamboo dalas (trays) are used and kept individually on separate racks, allowing for better ventilation and ease of inspection.

Chawki worms are fed three times a day – at 7 AM, 1 PM, and 8 PM – with paraffin paper removed at least 30 minutes before each feeding for proper aeration. Leaf requirements are approximately 15 kg per 100 DFLs for cross-breed and 20 kg per 100 DFLs for bivoltine worms. Proper bed spacing is expanded progressively as larvae grow, and bed cleaning is performed only once – in the second instar, just before the second moult – to minimize disturbance.

Disinfection and hygiene protocols 🔗

Strict hygiene is what separates a reliable CRC from a risky one. Disinfection is conducted twice for each batch: first, 2-3 days before brushing, and again after completion of every batch, using 5% bleaching powder solution and NIRMOOL as general room disinfectants. Workers must wash their hands thoroughly before entering rearing rooms, and all rearing appliances are sanitized between batches.

Before worms are distributed to farmers, a chawki certification check is carried out during the second moult. This involves verifying that missing larvae are fewer than 5%, undersized larvae are below 15%, and that the weight of 100 larvae falls within acceptable ranges – 3.4-3.8 g for bivoltine and 2.2-2.6 g for cross-breed worms. Pebrinized (disease-infected) chawki worms are never distributed.

The economic opportunity for entrepreneurs 🔗

CRCs are not just an agronomic tool – they represent a genuine business opportunity. A study of 45 CRCs across Tamil Nadu found that large-sized CRCs achieved a benefit-cost ratio of 2.83, with net returns of over ₹7.23 lakhs per annum, demonstrating strong profitability at scale. The shorter production cycle of 12-14 days, compared to 35-40 days for full cocoon production, enables faster capital turnover and reduced exposure to seasonal risks.

Research from the University of Mysore on CRCs in Karnataka’s Kanakapura Taluk found benefit-cost ratios ranging from 1.72 in smaller CRCs to 1.92 in larger ones, confirming that CRCs with greater mulberry acreage tend to be more profitable. Commercial CRCs are being operated by individual entrepreneurs, self-help groups (SHGs), and NGOs – making this a model accessible to a range of stakeholders, not just large investors.

The KSSRDI offers a 45-day classroom and practical training program, along with field-level exposure training, for entrepreneurs who wish to register and establish CRCs. Central Silk Board registration under the 2006 Amendment Act is mandatory for commercial operation, and financial assistance has been made available through schemes like the Catalytic Development Programme (CDP).

Farmers’ gains from CRC-reared chawki 🔗

Farmers who adopt chawki rearing technology receive 5-6 kg more cocoon yield compared to those who conduct self-chawki rearing, in addition to being freed from approximately 10 days of intensive early-stage rearing work. Cocoon production costs are reduced, crop timing becomes synchronized across a village or cluster, and the technology encourages cooperative behavior among farming communities – all of which have measurable social and economic benefits.

The relationship between CRCs and cocoon farmers is essentially symbiotic. Healthy chawki worms mean better cocoons, better cocoon yields mean higher incomes, and higher farmer incomes drive continued demand for quality chawki – making a well-run CRC a stable and growing business in any active sericulture region.

What do you think? With growing government support and proven profitability, what do you see as the biggest barrier to expanding CRC coverage in India’s newer or less-developed sericulture regions? And how important is the link between a CRC and a certified grainage in determining the final quality of cocoons produced by farmers?

References

1. http://www.csrtimys.res.in/sites/default/files/ebooks/2015-1.pdf
2. https://www.researchgate.net/publication/384812522_Chawki_Rearing_Centers_The_Backbone_of_a_Thriving_Sericulture_Industry
3. https://kssrdi.karnataka.gov.in/page/Contributions/Silkworm+Crop+Improvement/en
4. https://www.csrtiber.res.in/Brochure_pamphlets/Publications/91%20Pamphlet%20(Chawki%20Rearing_English).pdf
5. http://www.csrtimys.res.in/sites/default/files/phamplets/en-00-rh.pdf
6. https://westgodavari.ap.gov.in/sericulture/
7. https://karunadu.karnataka.gov.in/Sericulture/english/Pages/Chawki-Rearing.aspx
8. https://risingkashmir.com/dir-sericulture-lays-foundation-stone-for-chawki-rearing-centre/
9. https://www.slideshare.net/slideshow/ento-332lec-no10grainage-and-chawki-and-late-age-rearingpptx/251597771
10. https://www.chemijournal.com/archives/2024/vol12issue2/PartA/12-2-4-330.pdf
11. https://www.extensionjournal.com/article/view/1254/7-10-47