Complete Guide to Silkworm Rearing | Mulberry Leaves, Temperature Management, Cocoon-Making, and the Joy of Raw Silk Experiences | ブリちょく
Insects| ✍️ BreederDirect Editorial
Complete Guide to Silkworm Rearing | Mulberry Leaves, Temperature Management, Cocoon-Making, and the Joy of Raw Silk Experiences
Detailed explanation of silkworm (silkworm moth) rearing methods. A complete guide to silkworm rearing that beginners can enjoy, covering mulberry leaf sourcing, temperature management, growth management at each instar, cocoon-making, and raw silk experiences.
Key Takeaways
Detailed explanation of silkworm (silkworm moth) rearing methods. A complete guide to silkworm rearing that beginners can enjoy, covering mulberry leaf sourcing, temperature management, growth management at each instar, cocoon-making, and raw silk experiences.
Silkworms (Bombyx mori) are fully domesticated insects that humans have reared for over 5,000 years, and they can no longer survive in the wild. Selectively bred to produce silk, silkworms are popular as educational insects in schools, and their appeal lies in providing rewarding rearing experiences for children and adults alike. This article provides a detailed explanation of silkworm rearing methods.
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Silkworms are a type of moth (family Bombycidae) and are completely domesticated insects that cannot fly as adults and cannot survive without human care. They undergo complete metamorphosis: egg → larva (silkworm) → cocoon → adult (moth). During their larval stage, they feed on mulberry leaves, grow, and eventually spin cocoons.
Key pleasures of silkworm rearing:
- Observing the mystery of life as they rapidly develop through five instars (1st through 5th instar)
- Observing cocoon-spinning behavior (silk spinning)
- Experiencing traditional craftsmanship by hand-reeling raw silk using a silk wheel
- Handcrafting silk products (embroidery, dyeing, etc.)
- Use as an educational material for SDGs and agricultural education in schools and homes
Required Rearing Supplies
Rearing Containers
Cardboard boxes or plastic containers: A4 to B4-sized cardboard boxes are standard when rearing many larvae. Larger containers are recommended as they grow in size as development progresses
Lids and nets: Avoid direct lids as they cause moisture buildup. Instead, use paper or breathable fabric (complete sealing is not permitted)
Poor ventilation leads to moisture buildup, mold, and bacterial growth, so always ensure the container can be properly ventilated
Food
Mulberry leaves (essential): Mulberry (marberry) leaves are the only food for silkworms.
Collect them if there are mulberry trees nearby
They may be available at roadside stations, agricultural cooperatives, or included in silkworm rearing kits
If mulberry leaves are difficult to obtain, artificial feed (commercially available silkworm food) can be used as a substitute
Always provide fresh mulberry leaves. Dried or discolored leaves result in poor feeding and nutritional deficiencies. Freshly collected leaves can be stored in the refrigerator for 3 to 5 days when wrapped in moistened paper towels.
Artificial feed: Available from agricultural e-commerce sites and silkworm rearing kits. It's convenient for urban areas where obtaining mulberry leaves is difficult. However, growth may be slightly slower compared to natural mulberry leaves.
Other Tools
Spray bottle (for maintaining leaf moisture)
Tweezers or chopsticks (for moving larvae)
Thermometer
Folded paper for cocoon-spinning (mabushi) or cardboard partitions
Temperature and Humidity Management
Optimal Temperature
The optimal rearing temperature for silkworms is 25-28°C.
Below 20°C, development becomes significantly slower
Above 30°C, there is a risk of heat stress
Maintaining a consistent temperature is key to stable growth
When rearing at home, use air conditioning (set to 27-28°C) in summer and heaters or heating mats in spring and fall. Especially during the late 5th instar (before cocoon formation), a slightly cooler temperature (24-26°C) is preferable.
Humidity
Humidity should be around 60-70%. Excessive dryness can lead to molting problems, while high humidity increases the risk of disease (such as polyhedrosis). Since adequate moisture is typically supplied from mulberry leaves, special humidification is often unnecessary, but attention is needed during dry winter periods.
Growth Stage Management
1st to 3rd Instar (Early Stage)
Newly hatched larvae are extremely small (several millimeters) and fragile, so they must be handled carefully.
Food preparation: Feed finely chopped fresh mulberry leaves (whole leaves can also be used)
Density management: Move them to larger containers as needed to prevent overcrowding
Feces removal: Clean out old leaves and frass (silkworm droppings) every 1-2 days
Molting (sleep): At the end of each instar, there is a pre-molting resting period called "sleep" (min). Do not disturb larvae in this resting state.
4th to 5th Instar (Late Stage)
From the 4th instar onward, they grow rapidly (reaching 4-5 cm) and their appetite increases significantly.
Amount of feed: Large quantities of mulberry leaves are needed (especially in the 5th instar, when they consume large amounts daily)
Container expansion: Move them to larger containers as needed based on population size
Hygiene management: The 5th instar produces more frass, requiring daily or every-other-day bedding changes
Rearing density: Overcrowding increases the risk of disease spread. Maintain adequate spacing.
Late 5th Instar and Cocoon-Spinning
In the late 5th instar, they stop eating and their bodies become translucent and yellowish (a state called "mature silkworm"). This signals they are ready to spin cocoons.
Mabushi setup: Place mature silkworms in a mabushi (a compartmentalized cocoon frame made from cardboard or folded paper). Commercial compact frames can also be used.
Observing cocoon-spinning: They spin their cocoons over 3-5 days. Watching them release silk (shaking their heads in a figure-eight pattern while spinning) is a highlight of observation.
Cocoon Harvesting and Raw Silk Experience
Raw silk can be extracted from completed cocoons within approximately 2-3 weeks (while the pupa is still inside) through a process called cocoon cooking and silk reeling.
Boiling the cocoon in hot water (80-90°C) softens the sericin and reveals the silk thread end
Find the thread end and slowly pull it out
Wind the silk onto a silk wheel or chopstick to create a hank of raw silk
A single cocoon yields 1,000-1,500 meters of silk
Raw silk extraction is highly valuable as an educational experience for children, helping them understand the connection between nature and industry by extracting silk from silkworms they have raised themselves.
Observing Adults (Moths) and Egg-Laying
Silkworm moths (adults) that emerge from cocoons have degenerate mouthparts and cannot eat or drink. One to two days after emergence, males and females mate, and females subsequently lay 300-500 eggs.
Since adults cannot fly, they can be managed in smaller containers
By allowing them to mate and lay eggs, and storing the eggs in a refrigerator over winter, you can rear them again the following season
Eggs laid on paper can be refrigerated and hatched the following spring
Diseases and Precautions
Silkworms are susceptible to disease, and special attention is needed for the following:
Nuclear Polyhedrosis Virus (NPV): A frightening viral disease where the silkworm's body dissolves and dies. Caused by overcrowding, high humidity, and unsanitary conditions. Remove infected individuals immediately and maintain a clean environment.
Muscardine disease (Flacherie): A bacterial disease that softens the body and causes death.
Basic prevention: Sterilizing containers (with hot water or alcohol), ensuring ventilation, and regular bedding changes are the fundamental preventive measures.
Conclusion
Silkworm rearing is a unique form of insect rearing with multifaceted appeal: observing the complete metamorphosis life cycle, experiencing raw silk production, and understanding traditional industries. As long as mulberry leaves can be obtained, it is relatively simple to enjoy and is ideal for children's summer vacation projects. Through br-choku, you can connect with insect breeders and access a variety of rare insects.
