Every year, the mice try to move in. Rather, they DO move in- for awhile. Its not safe to live in my house if you are a mouse. (ask my daughters hamster). The mice come in where the waterpipes go out- under my floor in the utility room. I know, because that is where the cats sit and stare. I just scooped up an armful of dirty clothes off the floor (gotta love kids) and found myself nose to nose with a half-beheaded little dead mouse. Most of my cats are lazy, would probably befriend a mouse- simply because it would require too much energy to actually catch one. There are a couple however, that thrive on that hunt. It just seems that the mice would give up.