[Objectives]  To identify more effective pesticides, and better application methods, to control chive gnats. [Methods]  We evaluated the effectiveness of eight different pesticides and two different application methods (the single fixed-point irrigation method and the double root irrigation method) against chive gnats. [Results]  Compared with the single fixed-point irrigation method, double root-irrigation was more effective in terms of seedling survival ratio and yield. This method performed best when three kinds of pesticides clothianidin, thiamethoxam and imidacloprid, were either used independently, or mixed with athomin. [Conclusion]  The results of this study identify pesticides, and an application method, that are effective against chive gnats.