That faint scratching or rustling sound inside the wall at night is not the house settling. Mice are active mostly between dusk and dawn, and the sounds of them moving through wall voids, floor joists, and the space between ceiling layers are pretty distinct once you know what they are. The problem with mice in walls specifically is that they are entirely out of reach of most DIY trapping, so people end up addressing only the symptoms rather than the source.
Quick answer
Mice in walls require a two-part fix: trap or bait what is already inside, then find and seal every entry point so no new rodents can get in. Sealing without trapping leaves rodents trapped to die in the wall. Trapping without sealing means the cycle repeats. Both steps matter, and they need to happen in the right order.
Dealing with this right now?
Hearing mice in your walls and not sure where they are getting in? Stampede Pest & Termite handles full rodent exclusion across Houston, Dallas, Cypress, and Austin. Schedule an inspection and we will find every entry point.
How Mice Get Into Texas Homes
House mice need an opening about the diameter of a dime, roughly a quarter of an inch, to squeeze through. Roof rats, which are common in Houston and other Texas cities, need slightly more, closer to half an inch. Neither of those is a gap you would notice during a casual look around the house.
Common entry points include gaps around plumbing and electrical conduit where they pass through the slab or exterior walls, dryer vent openings with damaged or missing louvers, weep holes in brick veneer that are not screened, gaps along the roofline where fascia boards have pulled away, and any crack in the foundation that connects to a void inside the structure.
- Gaps around pipes where they enter through the foundation or wall
- Unscreened weep holes in brick exteriors
- Gaps between the garage door track and the wall
- Damaged or missing dryer vent covers
- Loose or rotted fascia and soffit boards at the roofline
The Right Order of Operations
The instinct is to seal the entry points first, but that is actually the second step. If you seal before trapping, you lock rodents inside the structure where they can die in the walls, creating an odor problem that can last for weeks. Worse, mice that cannot exit will chew through other parts of the structure to find a way out.
Start with trapping. Snap traps placed along the base of interior walls, inside cabinets, and in the garage will reduce the active population. Once trap activity drops off, meaning no new catches for several days, you can move to sealing entry points. At that point you are closing the door on new entrants rather than trapping survivors inside.
Sealing Entry Points That Actually Work
Mice can chew through foam, rubber, and thin plastic, so stuffing a gap with expanding spray foam and calling it done is not sufficient. Effective exclusion materials include copper mesh or steel wool packed into gaps first, followed by caulk or foam over the top. Hardware cloth (quarter-inch galvanized mesh) works well over larger openings like weep holes and vent covers.
Doors and garage doors deserve specific attention. A door with even a half-inch gap at the bottom can admit a mouse. Door sweeps and garage door threshold seals are cheap and make a real difference. Check where the garage door track meets the wall framing on each side, since that gap is almost always present and often overlooked.
Why the Damage Matters Beyond the Nuisance
Mice in walls are not just annoying. They gnaw constantly because their incisors never stop growing, and they will chew through insulation, wood framing, plastic water lines, and electrical wiring. Gnawed wiring is a documented fire risk. The CDC notes that rodents can also spread diseases including hantavirus and salmonellosis through their droppings and urine, which accumulate in wall voids and attic spaces.
Reproduction compounds the problem quickly. A single female can have five to ten litters per year with five to eight pups each. An infestation that starts with one or two mice in the fall can be dozens by spring if it goes untreated through the winter.
When to Bring in a Professional
If you are hearing activity in multiple walls, finding droppings in several rooms, or discovering chewed wiring or gnawed food packages, the infestation is established enough that DIY trapping alone is unlikely to resolve it in a reasonable timeframe. A professional rodent treatment includes a thorough inspection to locate all the entry points, not just the obvious ones, along with a trapping plan and a full-structure exclusion.
Follow-up visits matter too. A professional will return to check traps and verify the exclusion is holding. Sealing one gap only to have them find another nearby is common, and an experienced technician can identify those secondary points before you end up with the same problem in a different wall.