The conditions of larval development, especially food quality and larval density, affected appreciably the length of the adult prereproductive period. The isolation of females from males after adult eclosion did not affect this prereproductive period but increased the preoviposition period. The presence of host tissue reduced the prereproductive period of adult females. Presence of non-host plants (wheat broad bean, and pea) did not significantly affect the length of the prereproductive period. The effect of the host on egg production was successfully simulated by exposing females to allyl isothiocyanate, a characteristic constituent of the food plants. The processes regulating number of eggs produced were discussed.