To get rid of mice and keep them gone, the key is to properly seal your home and remove the food that attracts them. To keep mice out, you must secure the openings through which they enter your home and do whatever you can to make the habitat around your home inhospitable to them. You should also keep your house very clean, as food debris trapped underneath the stove or lying in kitchen cupboards acts as an attractant. Once you have sealed your home and made it a place mice don't want to visit, you can trap the mice currently living with you in live traps and release them outside.
Seal Your Home
The only way to keep mice out is to find out how they are getting in and seal the opening. Perform a very thorough inspection of your home, as a mouse needs a hole only 1/2 centimeter (1/4 inch) wide to gain access to the house. Look carefully for possible entry points, and seal them with wire mesh or steel wool and caulk. Remember to seal vents, the area under roof eaves and holes around pipes, as well as foundation cracks and holes in baseboards.
Consider One-Way Doors: If you are sealing your home but think there may still be rodents living in your attic or crawl space, install a one-way door trap over one of the openings. This lets them leave your house, but doesn't let them back in. This is an excellent way to get rid of mice already living in your house without killing them.
Maintain Your Lawn
Keeping your grass mowed and trees and shrubs trimmed away from the house will help deter mice. Long grass and bushy plant growth provide shelter for the mice and serve as a bridge between the lawn and your house. Ivy and other climbing plants should be grown on trellises, rather than allowed to climb outside house walls. Cut overhanging branches that touch the roof—mice use these as bridges. Ideally, you should keep a 2-foot area of rocks or cement around your home's foundation to deter rodents. Remove debris, such as piles of grass or woodpiles, where mice may find shelter from predators.
Take Away the Food and Water
To avoid attracting mice, you must make sure you eliminate food and water sources. Fix leaky pipes, and clean under your stove and refrigerator. Wash your dishes daily, and wipe down your counters each night before bed. Store food in plastic containers or totes to keep mice from feeding on your groceries; they can easily chew through cardboard or paper food packaging.
Set Traps or Get a Cat
Once the house is sealed and mice cannot get in, trap any mice that remain. The most humane traps are live traps that allow you to release the mouse outside once you have caught it. Bait the traps with peanut butter or cheese, and place them where you have seen evidence of mouse activity. You can also set them next to beams, walls and other structures that mice use as highways to avoid running out in the open. Release the mice at least a mile away in a forested or sheltered area where they won't bother the neighbors.
Alternatively, bring one or two cats into the house, or make a space for them in the garage. Because cats are natural predators, the presence of one may be enough to keep the mice away. Those that wander onto your property anyway may find out the hard way that cats are fast and determined hunters.
Do a Deep Clean
If your home is well sealed, mouse activity will decrease as you continue to catch them, and eventually the traps will remain empty. At this point, it's time for a deep clean. Check attic spaces and other areas where mice were living and vacuum up any nesting materials or waste. Mice can carry diseases, such as hantavirus, so you may want to wear gloves and a dust mask during the cleaning process. For extra protection, clean the area with an enzymatic cleaner to eliminate the smell of the mice, which could attract other mice.