Visceral organs and metabolic substances. Silkworm pupa is a state in the life history of silkworms, insects will have a digestive tract, so the black stuff inside the pupa is internal organs and metabolic substances. Silkworm chrysalis, synonym of small bee child, original chrysalis, late chrysalis, silkworm chrysalis is a silk spit cocoon in the cocoon into the pupa, silkworm chrysalis is not only delicious, nutritious, or a valuable source of animal protein, but also the extraction of a variety of raw materials for chemical drugs.