If a mature silkworm doesn't spin silk, its body will be black, and its head will swing from side to side to find a cocoon.

If there are cocoons that don't spin silk, you can see that the mature silkworms in the cocoons are yellow or yellow-white, and there will be some black or colorless situations when they start spinning silk.

If the pupa doesn't spin silk, its body will turn brown or light brown, and its head will swing from side to side, looking for a cocoon.

It should be noted that if the mature silkworm fails to find a cocoon in time, it may die because of excessive consumption of its own physical strength, and the silk will also break.

In addition, if the ambient temperature is too low or the air is too dry, mature silkworms will not be able to spin silk normally. If mature silkworms don't spin silk because of environmental factors, appropriate measures can be taken to adjust the environmental temperature and humidity to help mature silkworms cocoon smoothly.

In short, in any case, if mature silkworms don't spin silk, it may lead to silkworm death. Therefore, in the process of sericulture, it is necessary to provide suitable environment and conditions to help mature silkworms cocoon smoothly.