Oviposition, development and searching behavior of Cotesia flavipes Cameron and Cotesia sesamiae (Cameron) on aestivating Chito spp. and non-aestivating Chilo partellus (Swinhoe) larvae were investigated. Oviposition experiments indicated that parasitoids readily accepted aestivating and non-aestivating larvae for oviposition under laboratory conditions. The development times of C. flavipes from egg to adult emergence in aestivating compared with non-aestivating host larvae were not significantly different. Field-cage studies demonstrated that C. flavipes and C. sesamiae were unable to locate and parasitize aestivating Chilo spp. larvae in dry maize stems. Parasitization of non-aestivating C. partellus larvae was significantly higher in cages where C. flavipes was released (26.21%) than in cages where C. sesamiae was released (11.32%).