Biological control programmes involving Ooencyrtus pityocampae Mercet (Hymenoptera: Encyrtidae) have proved effective at reducing the damage caused by the pine processionary Thaumetopoea pityocampa Denis & Schiffermuller (Lepidoptera: Thaumatopoeidae). In this study, the biological variables that influence the parasitism of O. pityocampae on the new laboratory host Philosamia ricini Danovan (Lepidoptera: Saturniidae) have been investigated. Laboratory experiments were conducted under the conditions of 25 +/- 1 degrees C, 65 +/- 5% R.H (relative humidity) and a photoperiod of 16:8h (L:D=light:dark). The host egg age and parasitoid age are often regarded as being key factors influencing the emergence rate ofO. pityocampae. The optimal age of host eggs for parasitization was 1-2days, and the emergence rate was highest with 5-day-old female parasitoids. Thus, our results define the optimal conditions for the effective and economic rearing of parasitoids as follows: one 5-day-old female parasitoid per 50 (1-2)-day-old host eggs. The development time of O. pityocampae ranged between 19.5 and 22.6days. Parasitoids that were exposed to bio-honey survived 10.5 times longer than those that did not receive supplemental food. O. pityocampae was reared for more than nine generations on the eggs of P. ricini. Consequently, P. ricini has been found as a suitable new laboratory host for the mass rearing of O. pityocampae for the use of biological control programmes against T. pityocampa in future.