The performance of biological control agents (BCAs) is strongly regulated by ambient temperature. Understanding the thermal biology of BCAs is a crucial first step for manipulation of their thermal performance, which could be a potential avenue to improve biological control efficacy. In this study, the effects of temperature on several life history parameters (longevity, fecundity, development time, wing size) of the commercialised egg parasitoid Trichogramma achaeae Nagaraja & Nagarkatti (Hymenoptera: Trichogrammatidae) were examined. First, parasitoids were reared at 23°C and tested in the laboratory at four constant temperatures (15, 20, 25 and 30°C) to generate thermal reaction norms. Results demonstrated that temperature significantly affected all investigated parameters. Second, developmental acclimation was applied to investigate the phenotypic plasticity of the same traits. Parasitoids were allowed to develop at either of the above four temperatures and their performances were compared at 23°C. Results showed that developmental acclimation had a significant impact on fecundity, development time and wing size but not on female longevity. Our results have implications for improving the performance of T. achaeae in mass production and potentially for its application for biological control under different thermal conditions.