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The melon fly, <i>Bactrocera cucurbitae</i> Coquillett (Diptera: Tephritidae), is a quarantine pest that causes considerable economic losses to growers of vegetables and fruits worldwide. <i>Spalangia endius</i> (Walker) (Hymenoptera: Pteromalidae) is a solitary pupal parasitoid of various dipteran hosts. We assessed the impact of the host pupal age (2, 4, and 6 days old), host density (5, 10, 15, 20, 25, and 30), and parasitoid density (1, 2, 3, 4, 5, and 6) on the parasitizing potential of <i>S. endius</i> on <i>B. cucurbitae</i> pupae under laboratory conditions. The effects of different soil depths on the parasitism rate of <i>S. endius</i> and the dispersal behavior of <i>S. endius</i> at distances of 0, 5, and 10 m were also evaluated under field conditions. The results showed that the parasitism rate of <i>S. endius</i> significantly increased with the increase in host density and parasitoid density. The host pupal age did not influence the number of pupae parasitized by <i>S. endius</i> and the progeny sex ratio of <i>S. endius</i> under different host densities. In the fields, different puparium burial depths of <i>B. dorsalis</i> pupae significantly influenced the parasitism and eclosion rates of <i>S. endius</i> but did not influence the eclosion rate of <i>B. cucurbitae</i>. <i>Spalangia endius</i> females could travel up to 10 m to parasitize at a similar rate on <i>B. cucurbitae</i> pupae compared to <i>S. endius</i> placed at 0 m.