Every fall when the weather gets cooler it is a given that a mouse will end up in my house. I understand that this happens probably to most home owners (especially considering the number of trees I have around my house, etc.). But if I wanted to take some action next summer/early fall to prevent mice from entering, what could I do?
This is probably a futile exercise. Mice can squeeze through the smallest of gaps so you'd have to virtually hermetically seal your house to prevent any mouse coming in. Obviously you can block up the largest/most obvious holes and make it generally more difficult.
What you can do is make your house a less welcoming environment.
Make sure that you keep all food sealed in plastic containers etc. so that your house is not a source of food for them. They might still get in, but only for warmth.
When I bought my house it had a big problem with mice. Within an hour of putting the boxes of my stuff in the house, mice had eaten into the cardboard and were attacking any food inside. I had to throw away quite a lot of the food I moved in with. I subsequently found out that the previous owners had tried traps and had put poison all over the place to no effect.
What I did was:
- make sure there was no accessible food
- I checked every place in the house that a mice could hide behind. In particular I found that many mice were living behind some built in cupboards. I removed the cupboards and repaired all the damage to the walls I found. Check under kitchen units, bath, etc, and make sure there is no space with mice in or block access.
- Checked all ways into the house and sealed them, windows, doors, etc. (careful you don't block your ventilation)
- Checked around the edges of every room. I found a couple of places where the carpet had been eaten away near the edges of the walls and there was access through gaps to the area between the floor and ceiling. Blocked all gaps.
Once I had done all this, the number of mice in the house went from (at a guess) over a hundred to a handful in less than a week (I captured quite a lot by putting food in a cardboard box then waiting and then picking up the box and emptying it outside. The remaining few eventually were forced out into the open to look for food. I was actually able to catch several by hand by throwing a box over them! I guess a few died in the house, but I only ever found one body.
Since I got rid of the last of them (nearly 10 years ago). I have only seen one mouse in my kitchen which I think got in due to me leaving the door open.
We live in the country and have a pretty significant mouse problem, we use a pest service and the first piece of advice the guy gave us was to take down (or move FAR away from the house) our bird feeder. Birds eat the seed and spill about 2 seeds for every one they eat, mice LOVE bird feeders for a food source. Oh, and feral cats love to pounce at bird feeders to get the birds ON the feeder, but that ends up knocking a good amount of seed onto the ground.
We had a drop off in mice near our COOP building once a neighbor started feeding neighbor cats.
There are a half dozen cats that show up in the early AM and stay near her home. Not sure if they are also hunting the mice or if the scent has caused the mice to seek other homes.
Sealing basement window cracks with silicone also helped.
Keeping food away is probably the biggest thing you can do to keep mice (and other multi legged critters) away.
You could probably put out poison, but not recommended if you're a pet owner, don't want any secondary poisoning.
As a natural solution, you could attempt to attract hawks, falcons, owls or other birds of prey to the area. I'm not an aviary expert but there's probably some way to attract them. If there are enough mice around, the birds will stick around just for the food source. Not to mention they're rather nice to watch.
But as for keeping them out of your house, ChrisF is right .... it's almost impossible unless you seal your house like a bank vault, mice are the most determined and annoying critters. Just keep the food sealed and off the floor, try to patch/block any obvious holes and keep a few rat traps around just in case.
I've found no solutions to keeping them out, nor will I use poison, as I've no desire to see my dog or our neighbor's cat poisoned too.
You can try to have your house sealed, but unless the seal is virtually hermetic, they will find their way into the warmth of your home. And mice can chew holes in things, so maintaining the perfect seal will be tough.
As much as I dislike the necessity, I find the only solution is to maintain a few traps on top of the rafters in our garage. They will scurry on the rafter tops around the perimeter of our garage at night. The larger spring loaded rat traps seem to work the best. I heat the metal trigger mechanism with a flame from a micro-torch to melt a small piece of american cheese into place. (Note: in the past, I used a dab of peanut butter, which did not work as well as the cheese.)
What I do find is that as long as I maintain a trap or two in the garage, they do not get into the house, as you can hear them scurry around at night if I fail to set the traps.
I was extremely skeptical of electronic pest repellers and I have no idea whether they work with rodents. However, much to my surprise, they work very well against roaches. We live in a very roach-prone area and the usual habit was to have exterminator service twice a year. With these gadgets plugged in in several rooms, no roaches or exterminators for several years. It might be worth it for you to try them against mice.
Frankly, though, I'm so skeptical I still wonder if there's something else at work!