Three laboratory experiments were performed to assess parasitization of freeze-killed house fly puparia, buried 0 to 6 cm in media, by Muscidifurax raptor Girault & Saunders, Muscidifurax raptorellus Kogan & Legner, Muscidifurax zaraptor Kogan & Legner, Trichomalopsis sarcophagae (Gahan) and Urolepis rufipes (Ashmead) (Hymenoptera: Pteromalidae). Virtually no parasitization occurred at depths greater than 1 cm in large arenas (988 cm²) with densities of 0.3 puparia and 0.008 female parasitoids per cm². Parasitization was observed at depths as great as 4 cm for three of five species in small arenas (3 cm²) with densities of 6.4 puparia and 1.0 female per cm². Combined across experiments, M. raptor achieved the highest level of parasitization, followed by M. zaraptor, M. raptorellus, U. rufipes, and T. sarcophagae. The greatest number of F₁ females was produced by the gregarious species T. sarcophagae (834♀♀) and M. raptorellus (708♀♀), and then by the solitary species M. raptor (530♀♀), M. zaraptor (365♀♀) and U. rufipes (163♀♀). High parasitization by M. raptor and high production of offspring by T. sarcophagae identify these species as being particularly attractive as biological control agents.