Silkworms are unique, polymorphic silk-producing insects. After four molting stages, they develop into five larval instars and take about 26 to 28 days to mature. During this time, each silkworm consumes over 20 grams of mulberry leaves. Mature silkworms are white in color, weighing between 1.8 to 2.3 grams, with a cocooning rate of around 20% to 23%. The silk produced can be as long as 1,000 to 1,400 meters, with a thickness ranging from 2.6 to 3.2 deniers. Typically, one species is raised with 18,000 to 20,000 silkworms per batch, consuming 50 to 600 kg of mulberry leaves and producing 30 to 40 kg of silkworms. Modern breeding techniques include the following key steps.
Strict disinfection and disease prevention are essential for maintaining healthy silkworms. Seven days before rearing, silkworm eggs are disinfected using a 1% available chlorine solution or a 3% formaldehyde solution. The eggs are kept at 25°C for 30 minutes. The rearing room must be clean, and after spraying the disinfectant, doors and windows should be closed for 2 to 3 days before ventilation. Silkworm nets and tools should be boiled for sterilization.
Centralized hatching is an effective method to ensure uniform emergence. After hatching, silkworms are placed in a controlled environment to emerge on a specific day. This process, known as "qing qing," involves using wooden boxes measuring 1m x 0.35m x 0.5m, with small holes for ventilation. A layer of wet sand is placed at the bottom, and 40 to 50 mulberry eggs are hung inside. The temperature is gradually increased from 20°C on day one to 25.5°C by day 11.
Ant silkworm rearing helps streamline the process. Newly hatched silkworms are collected and fed mulberry leaves in a controlled setting. A non-toxic plastic sheet is placed in a sterilized container, followed by a layer of fresh mulberry leaves. The eggs are placed on top, and after 20 minutes, the silkworms crawl onto the leaves. The container is sealed and opened the next day. Mulberry leaves are prepared according to the silkworm's age, with 1- to 2-day-old silkworms fed 3 to 5 times daily at 26°C–27°C, and 3-day-old silkworms maintained at 25°C–26°C with 80% humidity.
Feeding larger silkworms requires careful management. On the fourth and fifth days, silkworms are distributed to households for further growth. They consume 80% of their body weight in mulberry leaves daily, and their size increases up to 300 to 10,000 times that of ant silkworms. It’s important to expand the feeding area regularly to avoid overcrowding and disease.
As silkworms mature, they begin to spin cocoons. By the end of the fifth day, they become less active, their bodies shrink, and their feces turn soft. They move to designated areas like new pods, clusters, or firewood stacks. The cluster room should maintain a temperature of 25°C initially, then drop to 24°C, with 75% humidity. Proper ventilation ensures even light distribution and prevents clustering. Any unripe silkworms are removed, and once the cocoons are formed, they are carefully collected and stored in a cool, ventilated place to avoid heat damage.
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