Where I live, surrounded by woods and fields there are field mice everywhere. I can't keep up with them. Having horse and chicken feed around doesn't help either. Two years ago, I figure the mice cost me in the neighborhood of $2000. They ate the wiring on my horse trailer, pick-up truck and two ATV's. Heck the bill might be even more then that. I forget now. If a mouse can get just his nose through an opening, then he can and will get the rest of his body through it.