An outbreak of Ussur Brown Katydid, Paratlanticus ussuriensis, occurred in the orchard areas of central Korea in 2006 and 2007. These crickets occur widely in Korea but before 2000 they were not regarded as an agricultural pest and were confined mainly confined to wooded hillsides. In an attempt to understand this change in feeding behaviour, we have conducted an ecological study of the affected areas. This has revealed small differences in the structure of vegetation in the area of the outbreaks compared to the other regions. There was also evidence that the density of predatory magpies was lower in the outbreak areas than in non-affected regions. It seems possible that higher temperature and low predator populations are associated with enhanced egg survival during winter. The high temperature seems to affect on the lifecycle of Katydid. The Katydid spends two years in egg stage in Korea. But if they are exposed to high temperature on early egg stage, they emerge next year just after spending a winter. As the using of detail ecological study, it was tried to impact assessment of this katydid on climate change with CCGIS Program under Climate Change Scenario which was released by IPCC. There are several specific area in Korea will be damaged in future and expected area are deeply related with distribution of the vegetation and temperature factor.