Potato tuber moth (PTM), Phthorimaea operculella (Zeller), is a serious pest of potato (Solanum tuberosum L.) plants in the fields from warm temperate to tropical climates, and tubers stored under ambient temperatures post-harvest. In recent years, concerns on PTM occurrence and damage to potato are increasing due to climate change resulted in global warming. To search potent natural enemies of PTM, we collected >150 PTM larvae from potato fields in Jeju-do in May, 2009 and then reared in the room until wasp adults emerging, which was identified by Lee J.W. as Diadegma fenestrale (tentative Korean name, 감자뿔나방맵시벌). This is the first report in Korea. When supplied 10% sugar solution on adults to rear, the longevity was 12.2±2.0 day, which was much longer than supplied with only water (5.0±1.4 day) or none (3.1±1.1 day). When the 2nd larvae of PTM, 10 days after hatch, dwelled in potato tubers were supplied to parasitoid adults for parasitization, the developmental periods from egg oviposition to adult emergence was 24.0±2.9 day, and the sex ratio of newly emerged adults was 0.27. The parasitization ratio indoor showed a kaleidoscopic characteristics, ranged from 30.0% to 71.4%. It represented that many factors might be related for the successful parasitization to PTM larvae.