Most of ants seem to be beneficial, whereas some of them are annoying or harmful. Among harmful creatures red imported fire ants have been notorious for not only destroying farm plants and domestic animals but also biting and killing human beings. The red imported fire ants, Solenopsis invicta Buren and Solenopsis richiteri Forel, will feed on the buds and fruits of numerous crop plants. Large nests located in fields interfere with and damage equipment during cultivation and harvesting. They respond rapidly and aggressively to disturbances, and ant attacks inhibit field worker activities. A single fire can sting its target repeatedly. Young and newborn animals as well as humans are especially susceptible to the stings’ venom. These pests can damage the environment by displacing native ant species and reducing food sources for wildlife. In Korea Solenopsis invicta Buren were found for the first time in Busan Gamman port in 2017. Then they were found in Incheon port, Pyongtaek port, North Daegu, Ansan in 2018 and Gwangyang in 2021. Once they invaded and occupied the terrestrial area, we have no proper solution to prevent them. I can assume that they have been successfully enlarging their colonies toward inland since they can move freely by flight. Therefore, I strongly suggest that we need to study ants in order not only to control harmful ants properly but also to preserve and use beneficial ants in this country.