The nymph grows slowly. Under the influence of ecdysone hormone, its cuticle peels off. Molting is called moulting. Abandoned shells are called exuvium. The period between two moults is called stodium or instar. Their body consists of wing pads. Nymphs and wing pads grow larger after each moult. After changing the shell 11-12 times, the nymph turns into imago.