Check into Pure Pep peppermint Oil. My bottle is made fro vitacost. Be sure it is pure. Saturate cotton balls and put them everywhere including under sinks, between floor and basement holes, closets. Check them monthly to be sure they are still saturated. Moth balls don't work. Also, be sure to remove anything they might eat. You could also put some snap traps along under sink areas and walls, just in case. We had good results. One year, I late putting it in and had visitors. Also, it is not poisonous.