catherine, some mice are BIG! I know, we have plenty of them. They amuse the cats, who only want to play, and get into all sorts of crap. We have a big old farmhouse, and I don't see any way we'll ever seal it to keep them out. They are industrious, inquisitive little buggers. And maybe not as smart as rats, but smart enough. They don't bother me all that much, we've mouse-proofed most all the cupboards and keep most foodstuffs that they can reach in metal containers. I raised mice as a kid, so I have sort of a soft spot for them, I guess. I really prefer mice to bugs!!