Mythimna separata (Lepidoptera: Noctuidae) is a notorious migratory pestand has caused significant damage in NortheastAsia including South Korea. For this reason, predicting occurrence time and distribution area considered to be an importantfor establishing early control plan. Because it cannot survive during the winter in South Korea and occurs seasonallydue to invasion from the southeast of China, general application of CLIMEX may not be adequate. Therefore, we appliedCLIMEX for analyzing seasonal occurrence M. separata of based on its growth index (GI) predicted in accordance withclimate. As a result, GI in southern region of South Korea began to occur at the earliest time and showed the highestvalue from the end of April to the beginning of September.

• Dae-hyeon Byeon
• Jae-Min Jung
• Sunghoon Jung
• Wang-Hee Lee