mice deterrents can help prevent mice from both entering and returning to either your house or your yard and garden. Even if you don't actually see the mouse, you'll hear sounds in the walls, see chewed up stuff, and see the droppings... sometimes the pitter-patter of little feet is something you really don't want to hear.
Indoors, you obviously don't want mice contaminating food and other items, or chewing through walls, insulation, or wiring. If you've had mice in the house before, there are many preventive pest control measures that can be taken to remove their access to warmth, shelter, food, and water, the things they're searching for when they enter homes. Assuming you've taken these measures already, here are a few more deterrents you can try.
Use scents that mice hate. Dribble peppermint oil onto cotton balls, or make tiny sachets of cayenne pepper and place in areas where there were previously mouse problems. The idea is that the mice will leave on their own.
DO NOT USE PEPPERMINT OIL IF YOU HAVE CATS! Cats are very sensitive to it and can become ill.
You can also buy commercial mouse repellents. There are many different types available. Some are a mix of natural scents, others are supposed to smell like the urine of predators. Lots of people have said that the 'predator urine' scents don't work very well (a few people have reported actually using real urine - where they got it, who knows - it did not work and the smell wasn't pleasant to have inside the house either!).
While using 'mouse-unfriendly' scents is a relatively quick and easy thing to try, there are two potential problems: first, scents have to be replaced/refreshed every so often; and second, the smell may be too strong for people or pets. Figuring out how to get rid of house mice isn't easy so you may need to try one or more products or a combination of them.
Try using sounds or vibrations that mice find annoying. There are plug-in or battery-operated ultrasonic devices that emit sound waves or vibrations that are very unpleasant for mice, causing them to leave the area.
Once again, there are mixed reviews on whether or not these really work, and again, there are problems with their use as well. One problem is that even though the sounds these devices make are supposed to be undetectable to humans, they are not undetectable to pets, whose hearing is much more sensitive then ours.
Another problem is that the sound waves can't penetrate walls or go around corners, so placement of the device is important. Multiple devices may be necessary.
Yet another issue is that rodents can eventually become habituated to the sound and will ignore it - so if it's something you wish to try, look for a device that varies the sound patterns to try to prevent mice from quickly getting used to it.
Try to scare them away, or use a natural predator. A barn owl is a fantastic way to get rid of mice naturally - they are prolific rodent hunters! The key is to make your property attractive to a barn owl so that they'll choose to hang around.
If you're not keen on a real live owl living near your house, try using a owl statue or deterrent instead. For more realism, look for one that moves its head (or wings) or lights up its eyes. Make your yard (and home) unpleasant for mice and they'll look for somewhere else to go.
You might wonder why bother fighting to keep mice, rats, and other rodents out of the yard or garden areas. Rodents, through their urine and feces, can transmit disease to humans. Plus when the weather turns cold they will be looking for a place to stay warm - and your house may look like a great temptation to them. The goal is to control the rodent population outdoors to lessen the chance that they might try to get into your home.
Contrary to popular belief, cats and dogs are not necessarily good mouse deterrents. In some cases, the smell of a dog or cat may be enough to keep mice away but not always. Cats are also not natural born mousers - some dogs are much better at it! And there are both cats and dogs that could not care less if a mouse was running through the house.
Also remember that being 'toyed with' by a pet can't exactly be classified as humane pest control.
Mouse deterrents aren't foolproof. You will find that some work better than others, and that even some brands of the same type of product will work better than others. Keep trying until you find a combination that works for you. Many homeowners would agree that it's worth the time, effort, and even the cost, to deter or repel mice before they become a much bigger, costly, and difficult problem.