Abstract: We reported the discovery of a Lepidopteran larva in the aecia of Cronartium ribicola, within the town of Baicaopo, Jinyang County, Sichuan Province. The larva, approximately 3-5 mm in length, has a cylindrical, segmented body covered with long setae. Its head width ranges from 0.3-0.5 mm, is elliptical in shape, and is equipped with a masticatory type mouthpart featuring prominent mandibles in a serrated configuration. Morphological and molecular biological identification of the species belonged to the Arthropoda, Lepidoptera, Carpophoridae, Bondia. After dissecting its digestive tract and excreta, it was found that they contained rust spores of Cronartium ribicola. This study provides a basis for further exploring the feeding characteristics of Lepidoptera insects in the aecia of Cronartium ribicola and whether they have the potential for biological control.