To consider the appropriate methods to conserve the double gardenia, Gardenia jasminoides form. ovalifolia, around Mt. Tasuda-yama, we compared oviposition and feeding preferences of the pellucid hawk moth, Cephonodes hylas, between the double gardenia and the common gardenia, G. jasminoides. Through the field observation, the number of eggs (total of eggs and hatched larvae) oviposited per surface area of the tree crown was significantly larger on the double gardenia. Oviposition on the leaf of both gardenias reached over 75% and was especially abundant on the young leaf. For feeding preference, we compared the areas of leaves fed by a larvae released for 24 hours into the plastic box containing each five leaves of both gardenias but the feeding rate were not differed. We also compared the presence of feeding by a larvae released for 1 hour on the plastic tray containing each leaf with the same size of both gardenias but no preferences observed. These results suggested the moth preferred the double gardenia to the common gardenia for the oviposition but the larvae had no feeding preferences. We discussed the importance to control the moth for in/ex situ conservation of the double gardenia.