I have a cabin up in the mountains. Really up in the mountains. Nowhere near a city for miles and miles. I have mice, rats, ground squirrells and other creatures (muskrats) that want to come in and make messes. I tried for years to do what was though to be correct until I got fed up and went on a rampage to kill them all. Every year when I leave for the winter I put down 5 pounds of "decon" in a stainless steel bowl that is screwed down so it won't tip over and is not too tall for even the smallest mouse to jump in. I even put a brick next to it so all can enjoy. Next I put Parmesan cheese all over it and stir it in with a stick. Lastly I put out an old icebox drawer with 50/50 water and antifreeze out next to the decon, about 5 gallons. For the last 3 years when I come in during the spring to open it up there is less than 10% of the droppings around. All the decon is gone as is the water. I'm thinking of putting twice the amounts out this coming fall, 2014.
You have to remember that a cat is the best deterrent, but I can't leave one all winter at 30 below. Don't leave anything out that you don't want to be rummaged through. Do you part. These critters reproduce so fast, don't ever feel sorry for killing off a few thousand every year, you'll never win the fight. If you have access to your crawl space (if you don't then drill a 3/8" hole in the floor where it's not noticeable and where you can tape over it and put a carpet or something over it) get a funnel from the hardware store and start putting the decon under your home. Just open the packets with gloves on and pour the contents into the funnel. The funnel will put a mound of it under your home. Add in some Parmesan cheese to bring them in and watch them die. You may see them all over the place on their sides trying to breathe their last breath.
Putting it where kids and other 'pets' can't get to the poison is smart and who wants to poison a kid or their own pet. Yeah I know there are some out there that would but I ain't going there.
$100 a year is all it takes.If your neighbors would do the same, you could soon have a rodent free zone for the most part.
Doc