Bingowings said:

But a few spiders or a few mice, even a few rats?

Just pick them up and put them outside.

Are you joking? A few mice or rats isn't a minor problem. Have you ever experienced mice or rat problems? This isn't a Disney cartoon, they don't just run up to you while they sing about your mean stepmother and let you pick them up. They're dirty, mean, and can be quite dangerous. I guess you can use humane traps, but once you dump them outside, they're likely to find their way back into your house again.