Larvae do not resemble adults. Undergo a series of molts , increasing in size at each instar . B. Stages represent different functional periods. C. Ecdysone or molting hormone. Chemical structure was determined from extracts of 4 tons of silkworm pupae.
Insects are incapable of synthesizing the steroid ring.
Obtain plant sterols in the diet. Produced and secreted by prothoracic gland . Located in the first thoracic segment. Ecdysone secreted during larval and pupal stages. Gland regresses in adult.