Peppermint oil on cotton balls inside of small pill bottles in basements, under sinks, and in the area under drawers. Drill holes in the pill bottles. Keeps the mice at bay and it also makes the coach smell nice. Plus I have a Black & Decker Ultrasonic Pest Repeller in every room and each basement compartment. And to tell if this is working or not, I have set a couple traps. The traps have not caught anything so far, so it appears that the Peppermint Oil and ultrasonic repellers are working. This is the first year I've tried this method. Time will tell!