Qualitative and quantitative effects of dietary components on the reproduction of mated females of Pimpla turionellae L. were investigated by using chemically defined synthetic diets. It was found that the synthetic diet must contain at least 7.0% sucrose for normal survival of the insect. Sucrose levels higher than 7.0% affected only the egg hatchability. Diets without amino acid mixture or water-soluble vitamin mixture reduced significantly the egg production and hatchability. The effects of these two mixtures depended on their levels in the diet. Egg production was significantly increased by the addition of 0.0015% vitamin E to the diet. Neither single omission of lipid mixture, cholesterol or inorganic salt mixture for the diet nor their levels tested had any significant effect on the reproduction. none