Exterminators get rid of mice in walls through a combination of inspection, trapping, and sealing entry points, a process that typically costs $150 to $550 depending on the size of the infestation. The work focuses on cutting off access to wall voids rather than simply killing mice already inside, because new mice will keep entering through the same gaps if the structure isn’t sealed.
The Inspection Comes First
Before setting a single trap, a professional will walk through your home looking for evidence of how mice are getting into the walls and where they’re traveling once inside. This inspection covers both the interior and exterior of the house, and it’s more systematic than what most homeowners do on their own.
Inside, exterminators check behind refrigerators at the baseboard level, around water supply lines under sinks, and where dryer exhaust ducts pass through exterior walls. They look at every point where pipes and wires enter through the subfloor, especially if you have a crawl space. These utility penetrations are some of the most common entry points because they’re rarely sealed tightly during construction.
Outside, the inspection starts at ground level along the foundation on all four sides. Key spots include where the sill plate meets the concrete or brick, gaps around exterior pipe and conduit penetrations, and any foundation cracks wider than a quarter inch. Mice can squeeze through openings as small as a dime, so even minor gaps matter. The exterminator will also look up at soffit vents and roof vents for torn mesh screens, rust holes, or loose edges a mouse could push through. Damaged weatherstripping on exterior doors and garage doors is another frequent culprit.
Signs of activity guide the inspection too. Droppings, grease marks along baseboards, gnaw marks on wood or wiring, and the musty smell of urine all help pinpoint which wall cavities the mice are using as runways.
Trapping Inside Wall Voids
Once the exterminator knows where mice are active, the next step is removing them. Snap traps are the standard tool for mice inside walls. Professionals place them along known travel routes, often at the base of walls, near entry points, or in areas where droppings are concentrated. When mice are clearly entering and exiting through a specific hole, traps are positioned right at that opening so mice encounter them immediately.
In some cases, exterminators will cut small access holes in drywall to place traps directly inside the wall cavity. This sounds drastic, but it’s often the fastest way to deal with mice that are nesting deep in a wall void. The holes are small and easy to patch afterward.
Exterminators generally avoid using chemical baits (rodenticides) for mice inside walls. The reason is straightforward: a poisoned mouse often crawls deeper into the wall to die, and a decomposing mouse creates a lingering odor that can last several weeks. Orkin specifically notes that indoor rodent bait use is not recommended for this reason. When baits are used at all, they’re typically placed in tamper-resistant stations outside the home or in areas like garages and basements where a dead mouse can be retrieved.
How Tamper-Resistant Bait Stations Work
If your exterminator does use bait, they’ll place it inside locked plastic stations designed to keep children and pets out. The EPA requires tamper-resistant bait stations to meet specific safety criteria: they must be strong enough to resist a child under six using hands, feet, or objects to break in, and they must be lockable and anchored to the floor or wall so they can’t be shaken to spill bait.
Some stations use a two-chamber design that forces rodents to make a 90-degree turn to reach the bait, which prevents larger animals from accessing it. Others use baffles or distance to keep the toxicant out of reach. The EPA classifies these stations into four tiers based on how much protection they offer. Tier 1 stations resist children, dogs, and outdoor weather. Lower tiers offer less protection and are meant only for indoor use in controlled settings. A professional will choose the appropriate tier based on whether you have pets, small children, or outdoor placement needs.
Sealing Entry Points (Exclusion)
This is the most important part of the process and the step that separates professional work from a DIY approach. Exclusion means physically sealing every gap, crack, and hole that mice use to enter the structure. Without it, trapping is just a temporary fix.
Exterminators use a few core materials. Copper mesh is the go-to for small holes and cracks because it’s flexible enough to stuff into irregular openings, resistant to rust, and impossible for rodents to chew through. Steel wool works similarly and costs less, though it can corrode over time in damp areas. For larger or irregular gaps, professionals use expanding foam sealants that harden into a rigid barrier resistant to gnawing. The best results come from combining materials: stuffing copper mesh or steel wool into a gap first, then sealing over it with foam so rodents can’t pull the mesh free.
The work targets every category of entry point found during inspection. Foundation cracks, roofline gaps, attic penetrations, basement openings, vents, utility lines, and gaps under doors all get sealed. The mesh or wool needs to be packed tightly so mice can’t grip it and pull it out. Foam sealants need time to cure fully before they reach their final hardness.
Exclusion is often offered as an add-on service. While it increases the upfront cost, it’s the only way to prevent the same problem from recurring a few months later.
What the Timeline Looks Like
The initial inspection and trap placement usually happen in a single visit lasting one to two hours. The exterminator will return to check traps, typically every few days for the first week or two. Most mouse infestations in walls take two to four weeks to fully resolve, depending on how many mice are present and how accessible the wall voids are.
Exclusion work can sometimes be done during the first visit for minor issues, but extensive sealing, especially if it involves roofline work, crawl space access, or multiple foundation repairs, may require a separate appointment. Some companies schedule exclusion after trapping is complete to avoid sealing mice inside the walls.
What It Costs
Most homeowners pay around $350 for professional mouse extermination, with the typical range falling between $150 and $550. The price depends on how severe the infestation is, the size and layout of your home, and what treatment methods are needed. Some exterminators charge per visit, usually $75 to $125, rather than a flat project fee.
Whole-home fumigation, which is rare for mice and usually reserved for extreme cases, can run $2,000 or more. Exclusion services add to the base cost but tend to save money long-term by preventing repeat infestations and repeat service calls.
Why Wall Infestations Are Harder to Solve
Mice in walls are more difficult to deal with than mice in open living spaces for a few specific reasons. Wall voids give mice a protected highway system that runs vertically and horizontally through your home, connecting the attic to the basement with minimal exposure. They can nest in insulation, which provides warmth and nesting material, and travel to food sources in the kitchen without ever crossing an open room where you’d notice them or where a trap could reach them.
The sounds you hear, scratching and scurrying, especially at night, are mice running through these voids. A single pair of mice can produce a litter of five to six pups every three weeks, so what starts as a minor scratching noise can become a serious infestation within a couple of months. This is why professionals focus so heavily on exclusion: the reproductive math means that trapping alone can’t keep pace if new mice keep entering from outside.