The effect of gossypol on the growth and development of Heliothispunctigera and H. armigera was investigated by incorporating gossypol in an artificial diet. Increased gossypol concentrations resulted in a decrease in the weights of larvae, pupae and adults, and an increase in the larval development period of both species. Increased gossypol concentrations extended the duration of the pupal stage of H. punctigera but slightly reduced that of H. armigera. Low gossypol concentrations had little effect on survival, but high concentrations resulted in high mortality of both species.