The initial soil penetration of Premise 75 and Termidor SC, containing imidacloprid and fipronil, respectively, were tested in laboratory columns of five different soils, Three combinations of application concentration and volume were used: double the recommended active ingredient concentration at one half the recommended volume (DR), the full concentration and volume (FR), and one half the concentration and twice the volume (HR), In all three cases, the same total amount of active ingredient (0.01 g of imidacloprid for Premise and 0.012 g of fipronil for Termidor) was applied to the same soil surface area (45.36 cm²), Regardless of soil or application method, the concentration of active ingredient was highest in the top 1 cm of soil. Within each soil, the concentration in the top 1 cm was highest in the DR treatment and lowest in the HR treatment. At each depth below 1 cm, active ingredient concentration was highest in the HR treatment and lowest in the DR treatment. The DR treatment therefore results in a thinner barrier of higher initial concentration in the top 1 cm, whereas the HR treatment results in a thicker barrier but of lower initial concentration in the top 1 cm.