How to prevent the occurrence of small silkworms, "Fusangyi" silkworms and lost silkworms

The level of silkworm cocoon yield is not only related to the weight of a single cocoon, but also depends to a large extent on the number of silkworms per sheet of eggs. Therefore, effective measures should be taken during rearing to prevent the occurrence of small silkworms, "Fusangyi" silkworms and lost silkworms. The specific measures are as follows:

1. Carefully select good leaves. For collecting newly hatched silkworms and for the leaves used for 1st to 2nd instar silkworms, choose mulberry leaves that are suitably mature but on the tender side, fresh in leaf quality, and with a moisture content of no less than 75%. Avoid using old leaves and immature leaves, otherwise small silkworms are easily formed. During the middle feeding stage and the peak feeding stage, fresh and relatively tender mulberry leaves should also be chosen to feed the silkworms.

2. Suitable temperature and humidity. The optimum room temperature for 1st to 2nd instar silkworms is 26.7-27.8°C, with a wet-bulb depression of 0.5°C; the room temperature for 3rd instar silkworms is 25-26°C, with a wet-bulb depression of about 1°C; the room temperature for 4th instar silkworms is 24-25°C, with a wet-bulb depression of 1-1.5°C. Temperatures that are too high or too low, or that fluctuate suddenly, as well as low temperature with high humidity, all easily lead to the occurrence of "Fusangyi" silkworms.

3. Keep the silkworm bed sparse, even and flat. An even and appropriately sparse distribution of the silkworms can not only promote individual development, but also make overall development neat and the silkworm bodies robust. According to the standard, for 1st, 2nd, 3rd and 4th instar silkworms, the silkworm bed area per sheet of silkworm eggs should reach 1.1, 2.2, 5 and 5.18 sq m respectively, to prevent excessive density of silkworms from affecting their feeding on mulberry leaves. The size of cut leaves and the amount of mulberry leaves given must both be appropriate. If the cut leaves are too large or too many mulberry leaves are given, "Fusangyi" silkworms are easily produced, and silkworms feeding on leftover mulberry leaves will also become weak and small. At the same time, when expanding the bed, the silkworm bed must be kept flat, especially when expanding the bed before molting. Do not disturb the silkworm bed, to prevent silkworms from falling through gaps to the lower layer, feeding insufficiently on mulberry leaves, and becoming small silkworms or "Fusangyi" silkworms.

4. Pick out the green-headed silkworms in batches. After more than 95% of the silkworms have settled down for molting, for the small number of green-headed silkworms, burnt chaff can be used to stop feeding, and nets can be added to pick out the green-headed silkworms for separate rearing, preventing the silkworms from becoming weak and small due to molting while hungry.

5. Feed at the proper time. If feeding after molting is too early, because newly molted silkworms begin feeding at different times, the silkworms easily develop unevenly. The leaves used for feeding after molting should be fresh and on the tender side, and the leaves should be fed evenly, to prevent the formation of weak and small silkworms.

6. Expose to light and ventilate. Half an hour before feeding mulberry leaves, uncover the silkworm film (that is, the moisture-proof paper) to expose the silkworms to light and ventilate, and at the same time do a good job of swapping the silkworm trays from top to bottom and from inside to outside, striving for even light. On cloudy and rainy days, turn on lights for illumination, to prevent the occurrence of "Fusangyi" silkworms and lost silkworms.

7. Commonly use burnt chaff and lime. In the rearing of 1st to 2nd instar silkworms, before feeding mulberry leaves, often use three-to-seven burnt chaff (that is, three parts fresh lime and seven parts burnt chaff). Under humid conditions, it not only has a drying effect, but also achieves the purpose of disinfection and disease prevention, and at the same time can prompt the silkworms not to eat leftover mulberry leaves, reducing "Fusangyi" silkworms.

In addition, cleaning during molting and cleaning after molting must be carried out carefully to reduce lost silkworms. If the silkworms develop unevenly, the silkworm droppings after cleaning following molting should be temporarily spread on the ground, and silkworm blocks or mulberry leaves should be used to lure out the late-molting silkworms for separate careful rearing.