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Some demographic parameters of the indigenous parasitoid, Aphidius matricariae Haliday (Hymenoptera: Braconidae) parasitizing the greenbug, Schizaphis graminum (Rondani) (Hemiptera: Aphididae), were estimated at 3 different temperatures (20, 25, and 30 ± 1 °C; 70 ± 5% RH; 16 L:8D). According to age-specific theory, the demographic parameters of the parasitoid were computed by related formulas. The results showed that duration of mummy's formation to adult emergence and oviposition to adult emergence were significantly prolonged at 30 °C. The high temperature (30 °C) markedly shortened the longevity and lifespan of the wasp. The lowest value of fecundity (6.35 ± 0.85) significantly occurred when the female wasps were exposed to 30 °C. The estimated values of rm were remarkably high when the female wasps were exposed to 20 (0.320 ± 0.011) and 25 °C (0.310 ± 0.009). The lowest and highest values of the R0 significantly occurred at 30 (6.167 ± 0.754) and 20 °C (55.306 ± 6.316). The λ, T, DT, and rw values were noticeably decreased at high temperature, and there was non-significant difference between the two other temperatures. High temperature decreased the number of females produced per female per day (mx) and survival rate (lx) of the parasitoid wasp. The highest mx and lx happened at 20 and 25 °C, respectively. Therefore, the results showed that the parasitoid wasp was sensitive to the high temperature, as its low reproduction, survival, and short adult longevity were recorded. Considering the characteristics, the wasp appeared to be well-adapt with the temperatures below 30 °C. Understanding the optimal temperatures for the life history traits of A. matricariae could promote the performance of the parasitoid wasp in different climatic regions, and this might advance the mass production of the parasitoid applied in IPM program for successful biological control of S. graminum. [ABSTRACT FROM AUTHOR]