Apanteles cypris Nixon is one of the most important natural enemies of the larvae of rice leaf folder, Cnaphalocrocis medinalis Guenée. Through parasitizing their larvae, A. cypris wasps play a major role in biological control of C. medinalis; parasitized host larvae consume less rice leaf than non-parasitized counterparts, thus causing less damage. Previous studies suggest that some parasitoids using chemical cues to locate their hosts. In a tritrophic interaction system consisting of plants, herbivores, and their parasitoids, chemicals released from plants after herbivory are known to help many female parasitoids find their hosts efficiently. Chemical information associated with herbivory can act as an indirect defense for the plant by attracting natural enemies of the host herbivores. There are several potential sources of infochemicals used by parasitoids: the host plant, direct or indirect cues from the host. This study aims to determine if the host searching behavior of A. cypris is affected by volatiles from C. medinalis-infested and uninfested rice plants and frass produced by larvae of C. medinalis. We found that mated female A. cypris were attracted by the frass of 2nd/3rd or 4th/5th instar C. medinalis larvae but not by C. medinalis-infested and uninfested rice plants. In contrast, male and virgin female A. cypris did not respond significantly to any of the stimuli. These results indicate that the mating status of A. cypris females clearly influences their host-searching behavior in response to herbivory-associated chemical information, and we suggest that female parasitoids forage for hosts depending on their own physiological condition in a tritrophic system. To elucidate which chemicals are used by A. cypris to locate their hosts, we analyzed the chemical composition of frass produced by 2nd/3rd instar C. medinalis larvae using solid-phase micro-extraction (SPME) combined with gas chromatography/mass spectrometry (GC/MS). We collected 23 volatiles from the frass, including terpenoids, alcohols, ketones, amines, aldehyde. Chemical standards of the determined frass components are then tested for the chemotactic effect on mated female A. cypris using Y-tube olfactometer. We found that mated female A. cypris were significantly attracted by 1-undecene and 3-methylbutanal, and suggest that these compounds in the frass of C. medinalis larvae are the kairomones that attract endoparasitoid A. cypris. Our results may prove to be helpful for the agricultural industry through use of these kairomones as control agents for C. medinalis, and are the basis of further study into the tritrophic system of rice -C. medinalis-A. cypris and development of new control methods.