This work was carried out to study the effect of different photophase (L): scotophase (D) combination (11 L: 1 3D, 1 2L: 121), 1 3L: 11 D, 14L: 1 OD) on Trichogramma galloi Zucchi biology, the most important parasitoid ofDialraea saccharalis (Fabr.)eggs in the state of São Paulo.There was no effect of the photoperiod on the life cycle (egg-adult), mortality and parasitism capacity, when T. galloi was reared on the natural host, D. saccharalis (sugarcane borer).However, the females life span was shorter at 14L: 101) when compared to 1211213 photoperiod.