[Background] The wasp Spalangia endius Walker is an important parasitoid of the pupae of flies. It can parasitize various fly species, such as Musca domestica, Bactrocera cucurbitae, B. dorsalis and B. tau. Studying the selectivity of S. endius to hosts and its development on different hosts can help to enhance the use of the parpasitoid.[Method] The impact of S. endius on the pupae of B. cucurbitae, B. dorsalis, and B. tau was determined by measuring the rates of parasitism and development, and parasitoid longevity. Rearing conditions were (26±1)℃, (70±5)% RH and 14 h (L):10 h (D) photoperiod.[Result] The results showed that S. endius could lay eggs and develop to adult in the three flies. The selection coefficient (0.37) and the parasitic ratio (55.33%) of S. endius to B. cucurbitae pupae were significantly higher than those of the other two flies. In non-choice tests, the number of S. endius emergence was the highest and the development duration of the wasps was the shortest in B. cucurbitae pupae. On the same host pupae, the development duration and longevity of females were significantly longer than those of males. The weights of female wasps were significantly higher than the weights of male.[Conclusion and significence] Based on these results, S. endius can be used to control B. cucurbitae. The pupae of B. cucurbitae are the suitable host for rearing S. endius.