Larvae of the noctuid Agrolis segetum were reared on the leaves of cabbage, spinach, sugarbeet or lucerne. Pupal size and weight differed significantly according to the food plant, the largest pupae being produced on cabbage. The pupae were exposed to Pimpla turionellae 23-27'C, 65-70 RH and LD 16:8. The mean development period, adult emergence rate and adult size varied significantly according to the food plant of the host. The shortest development period and the greatest adult emergence occurred in parasitoids from hosts reared on sugarbeet, but the largest adult female parasitoids emerged from hosts reared on spinach. none