The larval stage of the silkworm is divided into five ages, marked by four moults.
Approximately the first larval stage lasts 4 days, the second 3, the third 4, the fourth 5 and the fifth between 8 and 9 days.
Between one age and the next the silkworm moults for one day (two for the fourth), during which it is in a state of apparent inertia, in which it remains still with the front part of the body raised. The entire development of the larva occurs in about 28-30 days.