Pesticides threaten the environment and increase amounts of resistance by pests. Ecologically friendly biological control of pests is being considered in scientific and political spheres. Fruit flies cause huge economic losses to more than 81 fruit and vegetable species. They are major pests in tropical and subtropical areas. This study used pupae of melon fly, Zeugodacus cucurbitae (Coquillett), as a host and Dirhinus giffardii (Silvestri) as the parasitoid, the biological control agent. During host-parasitoid interaction at different conditions of exposure, the rate of parasitism of a host by D. giffardii differed significantly in time. Least parasitism was of 1-day-old pupae (13.41 ± 1.10) exposed for 6 hours. Greatest percentage of parasitism was to 3-day-old pupae (43.5 ± 1.12) exposed for 24 hours. Few pupae younger than 3 days old were parasitized. Parasitoid emergence rate from pupae increased from 6 hours (21.49 ± 1.46), to 12 hours (28.30 ± 2.00), and 24 hours (33.93 ± 0.66). Percentage of emergence of 3-day-old pupae was 28.40 ± 0.59 at 6 hours, 29.51 ± 0.45 at 12 hours, and 34.11 ± 0.224 at 24 hours. To maximize in vivo production of parasitoids, 5-day-old female D. giffardii should be provided pupae ≤3 days old. Results contribute to further understanding host-parasitoid interaction important for sustainable and integrated pest management practices throughout the world.