1. 1. Change of ecdysteroid content in whole body and ecdysteroid metabolism in larval and pupal stages were studied in diapause- and nondiapause-destined individuals of Boettcherisca peregrina. 2. 2. In nondiapause-destined animals, a small and large peak of ecdysteroid level were observed 16 and 116 hr after pupariation, respectively. In diapause-destined animals, however, only one peak was detected during larval-pupal transformation, and thereafter ecdysteroid content remained at a very low level over 360 hr of the observation period. 3. 3. Injected radioactive ecdysone was metabolized into ecdysteroids more polar than 20-hydroxyecdysone and very polar degraded products in developing pupae, while in diapausing pupae ecdysone was mainly converted to epimers of ecdysteroid without hydroxylation at C26.