The recently described Mexican parasitic wasp Eurytoma sivinskii Gates and Grissell (Hymenoptera: Eurytomidae), attacks Anastrepha obliqua (Diptera: Tephritidae) pupae in the soil. The life cycle (egg to adult) is completed in 23.1 (± 2.1) d (mean ± S.E.) at 27 ± 2°C. Females were capable of superparasitism and laid 1-8 eggs per host (2.59 ± 1.56, mean ± S.E.), but invariably only 1 adult parasitoid emerged. Oviposition occurred primarily in the medial and posterior portions of the host. Eurytoma sivinskii is ectoparasitic since 100% of the eggs are laid within the internal cavity of the puparium and on the surface of the pupa of the host fly. In no case were first and second instars parasitized. However, 1 third-instar out of 625 fly pupae exposed, yielded a single parasitoid per host. Eight-day-old pupae yielded the most parasitoids although females laid eggs in 1-d- to 14-d-old pupae. There were no significant differences in rates of parasitism among female E. sivinskii of different ages. Adults derived from eggs laid in the posterior region developed more rapidly, but adult sex ratio and percent of emergence were the same in both posterior and medially laid eggs. Regardless of oviposition location, adults were more likely to emerge through the middle of the puparium.