Knowledge of the thermal requirements of Trichospilus diatraeae (Hymenoptera: Eulophidae) is important if it is to be used successfully in to control Diatraea saccharalis (Lepidoptera: Crambidae) in sugarcane plantations. In the current study, the development of T. diatraeae was investigated in the pupae of D. saccharalis incubated at different temperatures. Seven T. diatraeae females were placed with host pupae for 24 h in tubes within chambers at 16, 19, 22, 25, 28 and 31 °C with 70 ± 10% RH and 14:10 h L:D. The life cycle duration of T. diatraeae decreased as the temperature increased, although no development was recorded at 31 °C. The number of T. diatraeae progeny per female ranged from 264.8 ± 40.7 (at 16 °C) to 385.1 ± 36.3 (at 25 °C), but no significant difference were recorded among temperature treatments (P > 0.05). The base temperature (T_b) and thermal constant (K) of T. diatraeae were 9.37 °C and 257.60 degree-days, respectively. The estimated average numbers of generations per year of T. diatraeae in pupae of D. saccharalis were 18.5, 19.93 and 17.73 for Dourados, Ivinhema and Ponta Porã municipalities of Mato Grosso do Sul State, Brasil, respectively.