Short of scientific procedures, such as X-ray imaging, it is impossible to determine silkworm gender in the larva or pupa stage. In the adult moth stage, females can be distinguished from the males because of their larger size.
Male silkworms produce more silk in their cocoons and a higher quality silk than females. In the silk business, gender is therefore an important factor in farming silkworms.
Scientific research has recently discovered the genetic factor in determining gender in developing embryos. Research has proven successful in finding ways to genetically modify specific genes and proteins in developing embryos so that scientists can produce more males than females.