What to Do When There’s a Dead Mouse in Your Wall

dead mouse in the wall

Photo by Fenners1984 / CC BY

One of the worst odors that can show up in a home is the smell of a dead mouse. If the critter dies inside your living space, it isn’t fun, but you can easily find and dispose of the carcass. If it dies inside the walls, the solution is going to be a little more complicated.

One day, my ex-wife called me, crying and frantic. I was distraught for a moment until I realized what had happened. “Oh, my god!” she started. “It’s terrible. I can’t stand it. You have to help me! Ooooh!” You know my response, right? Calm down, take a breath, tell me what happened. “Ooooh, there’s a dead mouse in my wall!”

What Do You Do Now?

After a little bit of crying and nose-blowing (on her part), I was able to walk her through some options. If you face the same problem, the options will be the same for you.

Time Heals A Broken Heart – And It Eliminates The Smell Of A Dead Mouse.

The option of last resort is to wait out the smell. Once the mouse is desiccated or decomposed, the odor will diminish and disappear. Depending on the size and the number of dead rodents, you will have to put up with the smell for a couple of weeks, at least.

While you wait it out, you can mask the odor with disinfectants and odor neutralizers. A friend of mine said he put a dehumidifier in the room where the smell was the worst. I asked him if he thought that helped. He shrugged. “I don’t know, but Angel thinks I’m doing something about it.”

Call a Professional Exterminator

My experiences with a dead mouse and professional exterminators were not positive. They shook their heads like mourners at a funeral. Then, they set up fans and dehumidifiers. Afterward, they tried to push mouse-exterminating services. It looked good and cost a lot, but the mouse continued to stink.

Put On The DIY Shoes!

Yep. Sometimes, you have to do it yourself if you want it done right.

Zero In On The Smell

If you can accomplish this first step, you’ll probably get it all done. If not, then you’re either going to have to wait it out or take that Jamaican vacation now instead of later.

I know the smell is terrible. Some people can’t take it and gag. Some people get nauseated and need fresh air. The smell permeates any mask or filter. This task is not for the faint of heart or the weak of stomach.

Finding the room with the dead mouse in the wall is easy. Pinpointing where it may be in the walls of that room is tougher. Here’s a tip. If the smell is located in one room, chances are the mouse is in an exterior wall. If you smell it in more than one room, chances are good the mouse is in the interior wall shared by the two rooms.

You need to pretend you’re a bloodhound. You are looking (smelling) for the one place, probably located somewhere along the baseboard, where the most potent odor is. If you are lucky enough for the spot to be obvious, somewhere behind the wall in that area is where the mouse died.

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Cut A Hole In The Wall

Before you unsheathe your knife, it might help to locate the studs in the area. You can use the studs to pinpoint the odor source if you are uncertain. Is it coming from this side of the stud or that side of the stud?

You decided. Put your finger on it. It’s right there. Maybe. But you know where to start, in any case. Use a box knife or an Exacto knife with a sharp blade. Use a straight edge to guide your blade. Cut out a rectangle in the wall about 6 inches high and an inch or so wider, right in the middle of two studs, starting about 9 to 12 inches above floor level.

The hole needs to be big enough for your fist to fit into easily and wide enough that your arm can move from side to side within it. Error on the side of discretion. Bigger is better.

Use your knife blade to score along the cut lines several times. Cut all the way through, if you can. Then, tap the cut square until it falls through. Be gentle. Try not to break the cut-out square. You can use it later to patch things up. Reach in and carefully pull the piece out.

Let’s Go Exploring

Put on latex gloves and have a plastic bag ready. If you are lucky, the stench coming out of the hole will let you know you hit the bullseye. Reach in the wall. Explore along the bottom from stud to stud. Whatever you feel, pull it out. There may be a nest in the wall, and in that case, you may find more than one mouse. It may be a single carcass. The worst-case scenario is you find nothing.

If you come up empty, explore as high as you can. A mouse can die and lie on top of a pipe or an electrical line. If you still can’t find it, cut more holes and explore the other sides of the two studs if you think it is worth it.

I’ve been able to find the dead mouse each time I did this, although I once had to cut several holes. An extended family had died behind the wall. There is no guarantee this will work, but if you know how to patch holes in drywall, I think it’s worth a shot.

“Did You Get It? Did You? Oh, Please Tell Me You Found It!”

That was my ex after I triple-bagged the dead mouse, wrapped it in old newspaper, and sealed it up with duct tape. She was delighted to think she wouldn’t have to smell the rotten rodent again.

I had to tell her we hadn’t got to the happily ever after part yet. Dead mice stink. Even after the stinking little bodies are gone, the place still stinks. The smell permeates everything and lingers.
The smell will go away before pigs fly, but I like to help it go away sooner.

I toss baking soda around inside the wall, crush some charcoal briquettes and throw that in the wall, or set down an odor-neutralizing product inside the wall. I use whatever is available, but some decent products are on the market to help neutralize odors. And wait to patch up the hole(s). Let things air out first.

One Last Thing

Everything, including mice, must die, so occasionally, a mouse might die in a wall from natural causes. That usually isn’t the case with a dead mouse in the house.

People like to put out poison pellets or blocks without thinking it through. The mice will eat the poison, and the mice will die, and the live mouse running across the kitchen floor late at night is going to be replaced by a dead one stinking in the walls all day and night long.

There are lots of other options besides poison. Traditional mousetraps work. I use peanut butter as bait on them. There are sticky glue sheets that don’t let go of the mouse. There are all kinds of live traps where the mouse can be released (and die in someone else’s walls). There are electronic devices meant to repel mice from an area. Cats also work sometimes too.

An ounce of prevention is worth a pound of cure for dead mice in the walls. Think about how your rodent extermination strategy may create problems before going ahead with it. Good luck!

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  • With his grandpa and dad as carpenters, Forest grew up loving the process of building, and through the years, he’s done it all. Concrete wrecking crew member, building maintenance supervisor, one-time Indiana-licensed asbestos abatement supervisor, moving company crew runner . . . Needless to say, he’s very, very familiar with power tools.

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