Abstract: Olfactory responses of the parental generation Spalangia endius wasps to nine treatments were tested using Y-tube olfactometer, and preference of progeny wasps for Musca domestica and Bactrocera dorsalis were measured at (26±2)℃, RH (70±10)% and 14L﹕10D photoperiod. More wasps (46.7%) selected the Y-tube arm with B. dorsalis faeces than the arm with other treatments, showing a responsive rate of 73.3%. Parasitism rate by S. endius decreased with increase in its age from 1 to 6 d. Parasitism rates by 1 d old S. endius against M. domestica, mix group and B. dorsalis were 86.4%, 87.2% and 82.1%, respectively, and by 6 d old S. endius, 61.5%, 49.6% and 22.2%, respectively. With the same age, no significant difference in parasitism rate was found between different generations of the wasp. The data here show that S. endius can be a potential biological control agent against B. dorsalis.