What are they made out of? I use metal cans to store my bird seed and dog food. The mice can't/don't get in those. If they are wood, could you put a metal edge around the bottom and a little way up the sides? I'm thinking maybe even aluminum foil might confound them. I know they won't chew through steel wool b/c I stopped a hole with that once and ended the problem of them getting into the house. Seems aluminum would prevent them from chewing their way into your boxes. Just a thought.

Hi cyn,
All the deck boxes are made out of plastic of some type (Rubbermaid). They are made in sections, so the mice are getting in through those little openings. Also, the lids get a bit warped over the years and there are spaces. They're pretty hard to outsmart.

I think you could try stuffing steel wool in the openings. I know the mice won't chew through that. Metal seems to be the only thing that keeps those little pests out! Good luck.

use Critter Ritter - it is a spray and you can spray around anywhere the mice get in.