In what month do spring silkworms usually spin silk?

Different kinds have different times. Silkworms can be roughly divided into three types: spring silkworm, summer silkworm and autumn silkworm. Autumn silkworms spin silk 10 month, summer silkworms in July and spring silkworms in April. Silkworms will become pupae after about 4 days of cocoon formation. Silkworm pupa is shaped like a rotating pestle, which is divided into three parts: chest and abdomen. The head is small, with compound eyes and tentacles; The chest has chest feet and wings; There are nine segments in the abdomen. Professional workers can distinguish men and women from the lines and brown spots on the abdomen of silkworm chrysalis. When the silkworm chrysalis is just pupated, its body color is light yellow, the pupa is tender and soft, and it will gradually turn yellow, brown or brown, and the pupa skin will become hard. After about 12 ~ 15 days, when the pupa body becomes soft again, the pupa skin is slightly wrinkled and brown, and it will become a moth.