Staple or nail some fine-mesh hardware cloth over the window wells. You'll need something made of metal--because rodents will just destroy any plastic ones you install. And put down some rodent bait in the window wells--the mice are getting in to search for food and make nests--make sure you don't have anything they can use for nesting material--cloth, paper, cardboard, drywall, etc. near the window wells or in the basement around the windows. Also--clean up any rodent poop you see while wearing rubber gloves. You can get several rodent-borne diseases from this.

It seems as though some rodents are making their way into the basement of my home through the cracks around my basement bedroom window. I've tried filling the cracks, but it only seems to be a few days fix until I go to bed and hear mice scratching in the walls. What I've found out is that there are plenty of mice roaming around my neighborhood due to it being near some wooded areas and quite a few fall into the window well, scratch at the walls and make their way inside. So it seems that if I get a well cover, that should reduce any, hopefully all, mice from making their way into the well and eventually the house as well as frogs that hop in their during storms and such. However I've done some browsing and it seems most covers are just fully plastic and I like having my window open on some nights when its cool though I don't want to give critters the chance to get back into the well. Anyone have suggestions or recommendations on what would be a good window well cover that can keep critters out but also allow me to keep my window open?