Rat and mouse articles · Updated
Dead rat or mouse smell: how to find it and get rid of it
The smell comes from a rat or mouse that died in a wall, the attic or under a floor, often after eating poison. Follow the odor and any flies to the spot, remove it with gloves and disinfectant, and seal the gaps so it doesn't happen again. Left alone, the smell can last weeks.
A sweet, heavy, rotten smell that's strongest in one room, gets worse on hot afternoons and wasn't there last week. That's almost always a dead rodent. In Plano it often follows poison that someone put in the attic, or a rodent that got trapped in a wall void.
The smell will fade on its own eventually, but in a Texas summer attic that can take a long time. Here's how to find it, remove it and keep it from happening again.
How long the smell lasts
It depends on the size of the animal, the temperature and the airflow. A mouse in a cool wall may fade in a week or two. A rat in a hot attic can last much longer. Plano attics get very hot from June through September, which speeds up decay and makes the smell stronger while it lasts.
Finding the source
Your nose is the best tool. Walk the house and find the room where it's strongest, then the wall, then high or low. Other clues:
- Flies gathering at a window, a light fixture or a wall vent
- A stain spreading on the ceiling drywall
- The smell getting stronger near a can light, bath fan or return grille
- Noise that stopped suddenly a few days before the smell started
- Recent poison use in the attic or walls
Something in the attic or the garage?
Want a local rodent technician to look at it? Same-day appointments are often available. (972) 325-9652
If it's in the attic
Look from the hatch first, with a flashlight, along the runways near where the smell is strongest. Deep blown-in insulation can hide a carcass a few feet away. Houses with several attic sections over the garage, porch or bonus room may need each one checked. If you go in, stay on the joists and wear gloves and a mask.
If it's in a wall
Walls are harder. Sometimes the carcass can be reached through an outlet, a vent, an access panel or from the attic above. If not, a small hole in the drywall at the right spot is often the cleanest fix, and it's easy to patch. A technician can narrow down the spot before anyone cuts. See dead rodent removal.
Removing it safely
Follow the CDC's general guidance for rodents and their waste. Wear rubber or plastic gloves. Spray the carcass and the area around it with a disinfectant or a bleach solution until soaked, and let it sit about five minutes. Pick it up with a plastic bag turned inside out, seal it, bag it again and put it in the trash cart. Clean the spot with disinfectant, then wash your gloved hands, remove the gloves and wash your hands with soap and water.
Getting rid of the odor
Once the source is gone, the smell fades as the area dries out. Air out the room. Replace soiled insulation if a rodent died on it. Enzyme-based odor products made for organic odors can help on hard surfaces. Air fresheners only cover it up. If the smell lingers after removal, there may be a second carcass or soiled nest material nearby. Check the insulation and any stored boxes close to where you found the first one.
Flies after a dead rodent
A few days after a rodent dies in a wall or attic, flies often show up: big, slow flies at a window or a light in one room. They're hatching from the carcass. They're a clue to where it is, and they'll keep coming until it's removed or dries out. Vacuum up the dead flies, wipe the window sills and don't spray insecticide around food. Once the source is gone, they stop.
Pets and poisoned rodents
If poison was used, a dying rodent may wander into the open, where a dog or cat can find it. Pick up any dead rodent you see with gloves right away. If you think your pet ate a poisoned rodent or bait, call your vet immediately and tell them what product was used if you know it. That's one more reason many homeowners ask providers to skip poison inside and near the house.
When to call for help
Call if you can't find the source after a day or two, if the smell is coming from a wall you can't reach, or if it's in a hot attic you'd rather not crawl through. A technician can narrow down the spot, remove the carcass with as little wall damage as possible, treat the area and check whether more rodents are still in the house.
Preventing the next one
Most dead rodents in walls trace back to poison used indoors or in the attic. If bait was put out inside, remove it and switch to traps. Then close the gaps so live rodents can't get back in. The why rats come back article explains the common gaps. Entry point sealing handles the roofline.
Something in the attic or the garage?
Ready to have the gaps found and closed? Call and describe what you're hearing or finding. (972) 325-9652
Common questions
Is the smell harmful?
It's unpleasant more than dangerous, but the carcass and the flies it attracts carry germs. Remove it with gloves and disinfect the area.
Why did the rodent die in the wall?
Often poison. Rodents don't reliably leave a building after eating bait.
Should I just wait it out?
You can, but it may take weeks in hot weather, and flies can become a second problem.
Can a dead rodent attract other pests?
Flies, yes. Beetles and other scavengers too, over time.
Will opening windows help?
Airing out the room helps while you look for the source. The smell won't really go away until the carcass is removed or dries out.