My shop sat unused for many years. When we bought the house, I was told by my neighbor that thete were very likely field mice living in it. I found some very old droppings at the rear of the shop, and put out traps throughout. 6 months later, no dead mice and no fresh droppings. However, squirrels serm to have tsken up residence in some fiberglas pipe on the shop roof. I've nailed a couple with a pellet gun, but more keep moving in. I've sealed off as many potential entries into the shop as I can find, hope it keeps all the critters out. My neighbor's cat has been very helpful. She's passed through out yard carrying 5 or 6 mice.