The rice leaf folder (Cnaphalocrocis medinalis) is a major migratory pest of rice. Its frass, retained within rolled leaf chambers, may serve as a persistent herbivore associated signal, yet whether and how frass independently elicits rice immune defenses remains unknown. Using rice (cv. Nipponbare) and laboratory reared C. medinalis, we establish a mechanical wounding plus frass supernatant treatment system. We systematically monitor MAPK phosphorylation, reactive oxygen species burst, jasmonate (JA/JA Ile) accumulation, defense gene expression, callose deposition, and trypsin protease inhibitor activity to dissect the signaling network and temporal dynamics of frass triggered rice defense. Dual choice and no choice bioassays are performed to evaluate larval feeding preference and performance. Furthermore, activity guided fractionation coupled with LC MS/MS is employed to identify and validate candidate protein/peptide elicitors in frass. This study aims to first dissect the independent immunomodulatory function of frass under the leaf rolling ecological context, and to reveal a closed loop regulatory mechanism of "herbivory – frass retention – immunity activation – pest feedback", thereby providing a theoretical basis for unraveling the molecular network of rice induced resistance and discovering novel targets for green pest management.