Cotesia ruficrus is one of the main larval parasitoids of the rice striped-stemborer (SSB) Chilo suppressalis and rice leaf folder (RLF) Cnaphalocrocis medinalis in rice field habitat. The behavioral response of the wasp to the volatiles emitted from herbivores, rice plants and herbivore damaged rice plants were studied with a Y-tube olfactometer. Female wasp was attracted to the volatiles from rice plants, larvae of the two species of herbivores and their trass. The volatiles from rice plants being damaged by herbivores were more attractive to the female wasps than those from the healthy plants. However, after the larvae and larval trass were removed from the damaged plants, the volatiles were no longer more attractive than that from the mechanically damaged plants. The rice plants mechanically damaged or treated with the regurgitant of herbivore larvae were not induced to release attractive volatiles. These results indicated that the volatiles from rice plants, herbivore larvae and their trass were used by C. ruficrus to locate the host habitat and host larvae and the volatiles from herbivore larvae and their frass were used by the wasp to discriminate the rice plants being damaged from healthy ones. Of the two species of herbivores, the volatiles from RLF larvae, rice plants being damaged by RLF and frass of RLF were more attractive. Nutrition; Diet; Parasites diseases and disorders; Parasites; Insect parasites; Hosts; Insect hosts Chilo suppressalis; Cnaphalocrocis medinalis (Pyralidae ); Food plants; Rice; Hymenopteran parasites; Cotesia ruficrus; Host seeking, role of volatiles from host & host damaged plants Cotesia ruficrus (Braconidae); Lepidopteran hosts; Chilo suppressalis & Cnaphalocrocis medinalis; Host seeking, role of volatiles from host & host damaged plants none