Simple laboratory methods to select candidate Trichogramrna strains for use in biological control were tried. 17 strains were screened for their suitability against the codling moth Cydia pomonella L. as well as the 2 summer fruit tortrix moths Adoxophyes orana F.R. and Pandemis heparana Schiff. In one set of experiments, the capacity of Trichogramma to parasitize each of these target pests was examined, in another set, the preference of Trichogramma to contact and parasitize the target pests compared to the standard mass rearing host Sitotroga cerealella was assessed in choice experiments.A strain of Trichogramma dendrolimi from the People's Republic of China was found to have the highest fecundity with all the 4 hosts tested. In choice experiments, however, this strain was shown to have a near equal preference between the target tortrix pests C. pomonella, A. orana and the replacement host S. cerealella, il local Trichogramma strains collected from fruit orchards and vineyards in different locations in the Federal Republic of Germany were reared separately. Four of these local strains, one identified as T. embryophagum, showed clear preference to the tortrix pests C. pomonella and A. orana compared to S. cerealella. The preference of one of these strains was particularly strong and amounted to a near total rejection ofS. cerealella eggs in the presence of any of the 2 tortrix pests.The remaining 12 strains had weaker parasitization capacity and/or less preference to the target pests. Four of the strains tested in these experiments, including T. dendrolimi and T. embryophagum, were mass reared and released in apple orchards between 1984 and 1986. The results of these field experiments are planned to be published in this journal.