How to Get Rid of Mice and Rats: What Actually Works

I've crawled under hundreds of houses. The homeowner usually says "I think I have a mouse." About a third of the time, they have rats. The distinction matters more than most people realize, because mice and rats require completely different strategies. Treat one like the other and you'll waste weeks.

Mice vs Rats: Two Different Animals, Two Different Problems

House mice (Mus musculus) weigh about half an ounce. They're curious, they investigate new things in their environment, and they'll walk right up to a trap the first night you set it. A single female can produce 5-10 litters per year with 6-8 pups each. Do that math and you'll understand why two mice become thirty in a few months.

Norway rats weigh a full pound. They're cautious, suspicious of anything new, and will avoid a trap for days until they get comfortable around it. Rats are also stronger. They can chew through concrete, aluminum, and even soft steel. A mouse can't do that.

Here's the dead giveaway most people miss: droppings. Mouse droppings are the size of a grain of rice, dark, pointed at both ends. Rat droppings look like olive pits. If you're finding droppings the size of a raisin or bigger, that's not a mouse. That changes everything about your approach.

Signs You Have Rodents

Droppings are the most obvious sign, but they're not the only one. Check behind your stove and fridge, inside the cabinet under your kitchen sink, and along the base of walls in your garage. Rodents run the same paths repeatedly.

Grease marks show up on walls where rats travel. Their fur is oily and it leaves dark smudges along baseboards and around pipe penetrations. Mice leave them too, but they're fainter. If you see a distinct brown-black rub mark along a wall, that's a rat highway.

Gnaw marks on wires are a fire hazard that kills people every year. The NFPA estimates rodent-chewed wiring causes around 25,000 house fires annually in the US, and homeowners insurance won't cover the repair unless the fire actually happens. Check the wiring behind your dishwasher and in your attic. If you see tooth marks on wire insulation, you've got an active infestation and a safety issue.

Scratching and scurrying sounds at night, usually in walls or ceilings, between 11pm and 3am. Mice sound like light tapping. Rats sound like something heavy dragging itself through the wall.

Urine smell. If your house has an ammonia-like odor in closed spaces, especially in cabinets, the attic, or crawl spaces, you're past the "a couple mice" stage.

How They Get In

A mouse can fit through a hole the size of a dime. A rat needs a quarter-sized opening. That's it.

The spots I check first on every inspection: pipe penetrations where plumbing enters the house (there's almost always a gap), the rubber seal along the bottom of the garage door, dryer vents with broken or missing flap covers, gaps where the AC line enters the exterior wall, and the junction between the foundation and siding. Older homes with brick veneer usually have weep holes that are open invitations.

Roof rats are a different story. They come in through gaps at the roofline, damaged soffit vents, and where plumbing stacks exit the roof. I've found them entering through gaps as small as the width of my thumb around cable TV lines.

Most people don't know this: your interior doors don't need to be sealed, but every single penetration through an exterior wall does. One unsealed pipe sleeve can keep an infestation going for years no matter how many traps you set inside.

Traps That Work

Victor snap traps. The wooden ones, model M325. About $2 each at any hardware store. They've been around since 1898 and nothing works better for mice. Buy at least 12. Set them perpendicular to the wall with the trigger end touching the baseboard. Mice run along walls, not across open floors.

Bait them with a small dab of peanut butter, about the size of a pea. Smear it into the trigger plate so they can't lick it off without applying pressure. Some exterminators swear by Tootsie Rolls pressed onto the trigger in cold weather. Cheese is a movie myth. It dries out and falls off the trigger.

For rats, you need the bigger Victor rat traps (model M326) or the T-Rex snap trap by Bell Laboratories. Rat traps are serious hardware. They can break a finger. Bait with peanut butter, a piece of hot dog, or a chunk of beef jerky tied to the trigger with dental floss so they have to pull at it.

Set traps in pairs, two feet apart, along known travel routes. For rats specifically, leave them unset and baited for 2-3 nights first. Let the rats get comfortable feeding from the traps before you arm them. This is called pre-baiting and it doubles your catch rate.

What Doesn't Work (and Why)

Glue traps are cruel and mostly useless. A trapped mouse will scream, chew its own leg off, or pull free and drag the trap around your house. Rats are strong enough to pull right off most glue boards. Several states are considering banning them. Skip them.

Poison (rodenticide) indoors is a terrible idea. Here's what happens: the mouse or rat eats the bait, crawls into your wall to die, and you get 2-3 weeks of rotting animal smell that no amount of Febreze will cover. I've had to cut open drywall to remove dead rats for homeowners who used poison. That costs more than hiring an exterminator would have in the first place.

Ultrasonic repellers are garbage. Full stop. Multiple university studies including a 2015 study from the University of Arizona confirmed they don't repel rodents. The FTC has gone after companies making false claims about them. Save your $30.

Peppermint oil, dryer sheets, mothballs. None of it works. A mouse will nest inside a box of mothballs if the temperature is right. These are old wives' tales that get repeated on Pinterest.

Exclusion: The Only Permanent Fix

Trapping without sealing entry points is like bailing water without plugging the hole. You'll catch some, but more will come in through the same gaps. Exclusion is the only thing that actually solves a rodent problem long-term.

For mice: stuff steel wool into the gap and seal over it with silicone caulk. Copper mesh (Stuff-It brand, about $10 for a 20-foot roll) works better than steel wool because it doesn't rust. Mice can't chew through either one.

For rats: you need 1/4-inch hardware cloth (galvanized steel mesh). Rats will chew through steel wool, expanding foam, and even aluminum flashing. Hardware cloth screwed over openings is the standard. For larger gaps around pipes, use metal pipe collars or escutcheon plates.

Seal every gap you can find on the exterior of your home in a single day. If you seal some holes and leave others, you're just funneling them to the remaining entry point. The whole perimeter needs to be done at once. Professionals call this a "rodent exclusion" and it's the single most effective service a pest control company can perform. Our pest-proofing guide has the full entry-point checklist with specific products and prices.

When to Call a Professional

If you're hearing rodents in your walls and can't pinpoint where they're entering, call someone. Wall voids are nearly impossible to trap without opening drywall or using bait stations, and a pro with a borescope camera can find things you can't.

If you smell urine or see large quantities of droppings, you're dealing with a colony, not a stray mouse that wandered in. A colony of 50+ mice in an attic or crawl space is a health hazard and requires professional-grade cleanup.

Rats in general warrant a call. They're smarter, harder to trap, and more dangerous than mice. A single Norway rat can contaminate more food and cause more structural damage in a month than a dozen mice. Most homeowners underestimate them.

Real Costs

Basic trapping service (set traps, check weekly for 2-4 weeks): $150-300. This is what you get from most pest control companies on an initial visit.

Full exclusion (sealing all entry points, attic and crawl space inspection, trap-out): $500-1,500 depending on the size of your house and how many entry points need sealing. A 2,000 sqft ranch with a crawl space typically runs $700-900. A two-story colonial with a complex roofline can hit $1,200-1,500.

Attic remediation (removing contaminated insulation, sanitizing, re-insulating) after a severe infestation: $3,000-8,000. This is the bill nobody expects. It's also why you don't ignore a rodent problem for six months.

Most pest control companies offer a warranty on exclusion work, typically 1-2 years. If rodents get back in through a sealed area, they'll come back and re-seal it at no charge. Always ask about this before signing.

Health Risks You Should Know About

Deer mice carry hantavirus. It's rare but serious. You contract it by breathing in dust contaminated with deer mouse droppings or urine. The fatality rate for hantavirus pulmonary syndrome is about 36%. If you find a large accumulation of rodent droppings in a closed space like a shed, cabin, or attic, don't sweep it. Don't vacuum it. Spray the area with a bleach solution (one part bleach, ten parts water), let it soak for 10 minutes, then wipe it up with paper towels. Wear an N95 mask and gloves.

Rats carry leptospirosis, which spreads through their urine and can contaminate standing water. They also carry salmonella. Both mice and rats can trigger allergic reactions and asthma, especially in kids. Rodent allergens have been found in 82% of US homes according to a National Institute of Environmental Health Sciences study.

Don't mess around with cleanup in enclosed spaces. If you're clearing out a heavily contaminated attic or crawl space, the cost of a respirator ($30 for a 3M half-face with P100 filters) is worth every penny.

Quick Action Plan

First, identify what you have. Check droppings. Rice-grain size means mice. Olive-pit size means rats. This determines your entire approach.

Second, set traps immediately. For mice, 12+ Victor snap traps along walls with peanut butter. For rats, T-Rex snap traps with pre-baiting for 2-3 nights. Check traps every morning.

Third, find and seal entry points. Walk the exterior of your home with a flashlight at dusk. Look at every pipe, vent, and gap. Steel wool and caulk for mouse-sized holes, hardware cloth for rat-sized holes.

Fourth, clean up food sources. Store pet food in sealed metal containers (not plastic, rats chew through plastic overnight). Pick up fallen fruit from trees. Move bird feeders 20 feet from the house or take them down entirely during an active infestation.

If trapping and exclusion don't resolve the problem within two weeks, or if you're seeing rats, it's time to call a professional.