Controlling rats and mice starts with figuring out which rodent you’re dealing with, sealing the gaps they use to get inside, and then trapping or eliminating the ones already there. The order matters: if you skip exclusion and jump straight to traps or poison, new rodents will keep replacing the ones you remove. Here’s how to handle the full process yourself and when it makes sense to call a professional.
Rats vs. Mice: Why It Matters
Mice and rats require different control strategies because they behave differently around traps and live in different parts of your home. A house mouse measures two to four inches long, has large floppy ears relative to its body, and a triangular nose. A Norway rat, the most common rat in homes, runs seven to nine inches long with a blunter nose and a thick, hairless tail.
The behavioral gap is more important than the size difference. Mice are curious and will investigate new objects, including traps, almost immediately. Rats are the opposite. They live cautiously and avoid anything unfamiliar, which means trapping them takes longer and requires a different approach (more on that below). Mice are agile climbers that readily nest in attics and upper walls. Most rats prefer ground-level or basement nesting, though roof rats are the exception.
How to Tell What You Have
Droppings are the most reliable clue. Mouse droppings are about 1/4 inch long, smaller than an uncooked grain of rice, with pointed ends. A single mouse produces 40 to 100 pellets per day, usually concentrated in the areas where it feeds or nests. Rat droppings are significantly larger: 1/2 inch for roof rats and up to 3/4 inch for Norway rats. Norway rat droppings are rectangular with blunt ends and tend to appear in small clusters. Roof rat droppings are curved with pointed ends and scattered more randomly. Rats produce 40 to 50 pellets daily.
Beyond droppings, check food packaging and pet food bags for gnaw marks. Mice leave small tooth marks and fine wood chips around baseboards, door frames, and cupboards. Rat gnaw marks are larger and more obvious. Greasy rub marks along walls, especially at floor level, indicate a well-established travel route.
Seal Entry Points First
Exclusion is the single most important step. A mouse can squeeze through a hole the width of a pencil, just 1/4 inch in diameter. Rats need slightly larger openings, but not by much. If you trap every rodent inside your home without sealing entry points, the population will rebound within weeks.
The CDC recommends filling small holes with steel wool held in place by caulk or spray foam. For larger gaps, use hardware cloth, metal sheeting, lath screen, or cement. Pay special attention to where pipes and utility lines enter your home, gaps in siding at the foundation line, and spaces around doors and windows. If your home has a crawl space or trailer skirting, check for gaps there too and use metal flashing around the base. Block any opening larger than 1/4 inch. Rodents can chew through expanding foam alone, so always back it with steel wool or metal.
Trapping: The Safest First Option
Snap traps are the most effective and safest method for most home infestations. They kill quickly, let you confirm catches, and don’t carry the poisoning risks that rodenticides do.
Placement matters more than bait choice. Set traps along walls, fence lines, or any linear surface where you’ve seen droppings or rub marks. Position the trigger facing the wall, or place two traps side by side with triggers facing outward in opposite directions. Setting multiple traps increases your odds significantly, especially with rats. Three traps in a row with alternating trigger directions is a proven configuration.
For bait, use a pea-sized amount of something the rodents are already eating. Peanut butter works well for both species. With mice, you can also try small bits of cotton or dental floss, since mice actively collect nesting material and will trip the trap trying to pull it free.
The Key Difference for Rats
Because rats avoid new objects, you need to prebait your traps. Place baited but unset traps along their travel routes for a couple of days. Once the bait has been taken multiple times and the rats are comfortable approaching, set the traps. Skipping this step is one of the main reasons people think “the traps aren’t working” for rats.
Rodenticides: Effective but Risky
Poison baits fall into several categories, and the risks vary dramatically depending on the active ingredient. The most common type, anticoagulants, work by blocking the liver enzyme that recycles vitamin K. Without vitamin K, the blood can’t clot, and the rodent eventually dies from internal bleeding.
Anticoagulants come in two strengths. First-generation versions require the rodent to feed over multiple days to accumulate a lethal dose. Second-generation anticoagulants can deliver a fatal dose in a single feeding. That potency comes with a serious downside: secondary poisoning. When a cat, dog, hawk, or owl eats a rodent that consumed a second-generation anticoagulant, it ingests the toxin too. The National Pesticide Information Center rates brodifacoum and difethialone as high risk for secondary poisoning in both birds and mammals. Bromadiolone carries high risk for mammals and moderate risk for birds.
Non-anticoagulant options exist but have their own concerns. One type uses a high dose of vitamin D3 to flood the body with calcium, damaging organs. Another attacks the nervous system by causing brain swelling. Zinc phosphide converts to a toxic gas in the stomach and works fast, but it’s also acutely dangerous to any animal that eats it directly. Of these alternatives, zinc phosphide and vitamin D3 have relatively low secondary poisoning risk based on current evidence, making them somewhat safer choices in areas with pets or wildlife.
If you use any rodenticide, place it in tamper-resistant bait stations that children and pets can’t access. Check stations regularly and dispose of dead rodents promptly to reduce the secondary poisoning chain.
Health Risks and Safe Cleanup
Rodent infestations aren’t just a nuisance. Mice and rats carry pathogens that cause serious illness. Hantavirus, spread through contact with infected rodent urine, droppings, or saliva, can cause hantavirus cardiopulmonary syndrome in the Americas, a severe respiratory illness with a case fatality rate up to 50%. In Europe and Asia, related strains cause hemorrhagic fever with kidney damage. Activities that disturb rodent waste in enclosed or poorly ventilated spaces, like cleaning out a garage, shed, or attic, are among the highest-risk exposures.
The critical rule for cleanup: never sweep or vacuum rodent droppings. Sweeping and vacuuming launch tiny virus-carrying particles into the air where you can inhale them. Instead, follow this process:
- Ventilate first. Open all doors and windows for 30 minutes and leave the area.
- Wear rubber or plastic gloves throughout the entire cleanup.
- Spray droppings and urine with a disinfectant or a bleach solution (1.5 cups bleach per gallon of water). Let it soak for at least 5 minutes.
- Wipe up with paper towels and dispose of them in a covered garbage can.
- Mop or sponge all hard surfaces, including floors, countertops, and the insides of cabinets.
- Wash gloved hands with soap and water before removing gloves, then wash bare hands again.
For dead rodents or nests, spray everything with disinfectant first, then double-bag in sealed plastic bags before disposal. Fleas are common on rodents, so applying DEET or another EPA-registered repellent to your clothing and hands during cleanup reduces the risk of flea-borne disease.
When to Hire a Professional
DIY methods work well for small infestations caught early, typically a few mice or a single rat. Signs that you need professional help include droppings in multiple rooms or on multiple floors, sounds of activity in walls during the day (not just at night, which suggests overcrowding), a persistent smell of urine, or failed trapping attempts over two or more weeks.
Professional rodent control costs vary widely based on the size of your home, severity of the infestation, and how many entry points need sealing. Expect to pay roughly $500 to $1,600 for a standard job that includes trapping, extraction visits, sanitization, and sealing entry points, often with a one-year warranty. Two-story homes with extensive roof-line gaps or dozens of entry points can run significantly higher. Many companies also offer ongoing monitoring plans in the $35 to $150 per year range after the initial service.
The value of professional exclusion work is hard to overstate. A thorough seal-up is what prevents the problem from recurring, and professionals with experience can spot entry points that most homeowners miss, particularly along rooflines, where plumbing penetrates exterior walls, and around HVAC conduits.