Recently we are facing increased frequency of the vespa encounters not only in the natural forested area but also in the residential area. These could be partly from the increased population sizes of diverse vespa species as well as the expansion of their nest habitats from mountainous environments to the human residences, resulting occasional casualty or sting damages. In terms of the risk management, we studied hornet attack and defense behaviors relative to the visual or physical disturbance. Four species of vespa showed strongest aggressiveness to the black colored target with high rate of bumping and stinging followed by red color. In most case, vespa showed behavioral change to the high alerts and hover-flying surveillance out of the nest entrance when people approached ap. 10 m close to the nest. When the nest was disturbed by the stick beating, then swarm of defensive force moved out and begin to showed the defensive behavior including stinging or propelling poison. The defense boundary was related to the nest colony size with larger defense line for larger colony. But it was between 15 to 25m from the nest location.

• Dongwon Kim(Agriculture Science Technology Research Institute, Andong National University current address: National institute of Agricultural Sciences, RDA)
• Chuleui Jung(Department of Plant Medicals, Adong National University)