Lab experiments were conducted to study the effect of two different artificial diets on some biological and economical parameters of two silkworm Bombyx mori L. races during two rearing seasons, Spring and Autumn. First diet (T1) had the same components as prepared by (Tsuchida and Yoshitake, 1983), second one (T2) by adding propolis material as natural antibiotic and anabolic agent. Feeding young larvae (first, second and third instars) on the diet containing   propolis (T2) resulted in shortened larval duration and increasing most of the economic characters with preference of Autumn rearing season than Spring one.