All I can say is when and if the really big ones make a try for the house you might want to dispose of them another way, there is nothing more embaressing then calling the Roto ruter guy to remove an animal from the plumbing. Just kidding, seriously though look at your door frames, specifically the handle side (side that moves when you open the door) and your dryer vent tube. These are high trafic areas for little critters. Good luck.