You found a mouse in the house. Now what?

Richard Durtsche, a Northern Kentucky University biology professor, said this deer mouse was photographed during a vertebrate zoology field trip around 2008.
Richard Durtsche, a Northern Kentucky University biology professor, said this deer mouse was photographed during a vertebrate zoology field trip around 2008.

You first might hear a small scuttle. Then you'll notice a few packages of food have been gnawed open. Before you know it, you scream when you finally see the mouse that has invaded your house.

At least that's my experience.

I started finding mice in my Newport townhouse rental last winter. The critters have already started appearing again as the temperatures drop.

Where are these mice coming from? I know we occasionally leave dishes in the sink, but is my house that dirty? Are my somewhat slob-like tendencies finally catching up to me? I have no idea because I never dealt with mice in my sunny and urban hometown of San Antonio, Texas.

Northern Kentucky University Professor Richard Durtsche weighed in on why mice invade homes every winter and what you can do about it.
Northern Kentucky University Professor Richard Durtsche weighed in on why mice invade homes every winter and what you can do about it.

I had to talk to an expert about this, and because I'm a journalist, I'm sharing my findings with you.

Here's what Richard D. Durtsche, a Northern Kentucky University biology professor, had to say.

Why are there mice in my house every winter?

Long story short, humans are mostly to blame because we've built our homes in mice environments. We use pesticides or other chemicals that affect their food sources and leak into groundwater. We clear vegetation out of our yards that mice would otherwise use to make their nests.

The impact you have on the wildlife in your yard makes a difference. For instance, Durtsche has heard horticulturists encouraging people to mulch their leaves and put them in gardens or greenspaces instead of throwing them away.

"Because they'll decompose, but at the same time, they're providing that refuge for some of these other animals to be able to withstand the winter temperatures," he said.

Much to my relief, he also said finding a mouse in the house doesn't necessarily mean your house is filthy. Mice are small and that works against them in the winter.

"The amount of energy that it expends to keep its body warm is way more than a large mammal, for example … It's called the surface to body ratio. That means that from their body's surfaces, they lose more heat more readily," he said.

It's why they search out places, like your home, to try to keep warm.

Do mice carry diseases or germs that can make me sick?

As long as you don't have a major infestation, you probably don't have to worry about getting sick from mice here in Kentucky and Ohio. But letting things get out of hand with mice is still risky.

Durtsche said mice are known to carry the hantavirus, which can cause deadly disease in humans. It's an aerosolized virus rodents shed in urine, feces, saliva, and sometimes via bite, according to the Centers for Disease Control and Prevention.

But it's pretty rare. The CDC has tracked 850 reported cases in the United States from 1993 to 2021. None have been in Kentucky and Ohio. But two of four reported cases of the hantavirus disease in Indiana have resulted in death.

Durtsche said you're more likely to get the hantavirus if you are breathing in air near mice nests or are exposed to rodent urine and feces for an extended period of time.

"So as long as you keep your house clean, things like that, you're in pretty good shape," he said.

It's also possible for mice to carry fleas and ticks, the latter of which can spread Lyme disease. You probably have a better chance of getting Lyme disease from walking through a grassy area, though, Durtsche said.

Is there anything I can do to keep mice out of my house?

Durtsche is not an exterminator, but he has firsthand experience dealing with mice at the NKU Research and Education Field Station in Melbourne, where he is the director.

He said the most important thing people can do is cover up any holes the mice could be using to get into your homes – either with caulk or mesh wiring. Even if you did that last year, check for holes again because mice can chew through caulking.

If you have a chimney, you should make sure it has a rodent guard over the opening.

Traps are also an option. Durtsche uses live traps at the field station. Those traps are tunnel-shaped and can be taken to another area where trapped mice can be released into the wild. He recommends adding a few cotton balls to the live traps so mice don't get too cold while trapped in there. Snap traps can also work but you will have to clean up the mess of a mouse that's been ... snapped. For bait, he recommends using peanut butter and oatmeal rolled into a ball shape.

You can also try keeping your food in a sealed container. Mice can't chew through metal and, while they can chew through plastic, a thick-walled plastic container could deter them.

What about home remedies?

If it's not science, Durtsche can't professionally vouch for it – but I'm no scientist, so here is my take on a few home remedies.

Ultrasonic mice repellent did nothing to ward off my furry friends. But I can't bring myself to unplug them in my kitchen.

I read in a few online sites that mice hate the smell of mint, so I bought a little satchel of so-called mouse repellent herbs and mint and placed them around my home. In this case, I literally found a mouse using the satchel as a bed underneath my waffle maker. I give it a 0/10.

Here are a few other mouse deterrents I've rounded up from the internet. I've linked to websites where you can find more information.

  • Get a cat if you can. Mice and cats are mortal enemies.

  • Strong scents like bleach, ammonia or vinegar can allegedly repel mice. You'll have to refresh these sources regularly, though.

  • Food products like cinnamon, cayenne pepper and chili powder could cause respiratory problems for mice, but could also cause problems for pets and children.

Is there a mouse deterrent that's worked well for you? Share it in the comments ... please, at least for my sake, share it in the comments.

This article originally appeared on Cincinnati Enquirer: How to get rid of mice in your house