Stock cultures of Trichogramma spp. were obtained from Missouri for crossbreeding studies, including a culture of topotypic T. minutum Riley. Altogether, 15 cultures (based on host egg, host plant, host locality, and color of adults) were obtained, including 2 cultures of Trichogramma from California; T. pretiosum Riley (reference stock culture) which was originally obtained from Heliothis zea Boddie eggs collected from tomato near El Toro, and Trichogramma sp. obtained from Laspeyresia pomonella (L.) eggs collected from apple in Riverside. The cultures were isolated individually in separate rooms and maintained on eggs of Trichoplusia ni (Hübner). A total of 42 crosses was conducted, with each cross and reciprocal cross being replicated 20 times and each check cross (84 total), 10 times. The results show that 4 species of Trichogramma were obtained from Missouri, including T. pretiosum which occurs also in California. Two of the species from Missouri and one from California did not cross with either T. minutum or T. pretiosum, and apparently they are undescribed species.