Mice

Mice are small rodents, and the one that moves into US homes is almost always the house mouse (Mus musculus): a gray-brown animal about 3 inches long with a nearly hairless tail just as long. They eat almost anything, breed every few weeks and slip through a gap the width of a pencil, so one mouse in the fall often becomes a dozen by winter.

This page covers how to recognize house mice, what they eat, how long they live, how fast they multiply and how much of a health risk they are. For the action plan, go straight to how to get rid of mice.

What house mice look like

• Size: 5-7 inches from nose to tail tip, of which 3-4 inches is tail (UC IPM); about half an ounce.
• Tail: about as long as the body, thin and scaly with almost no fur.
• Color: dusty gray to light brown on top, slightly lighter (not bright white) underneath.
• Head: pointed snout, large ears for the head, small dark eyes.

If the mouse has a sharply two-toned body, a bright white belly and white feet, it's a deer mouse or white-footed mouse, which matters because deer mice carry hantavirus. See deer mice and field mice. If it's much bigger, with a thick tail and a blunt nose, it may be a young rat; see mouse vs rat.

Types of mice you'll meet in the US

"Woolly" or "wooly mice" you may see online are usually long-haired pet mice or fluffy juvenile deer mice; they're not a separate pest. Short-tailed shrews also get called mice: they have a pointed snout, tiny eyes and velvety fur, and r/pestcontrol regulars regularly identify "voles" in trap photos as shrews.

What do mice eat?

House mice prefer seeds and grains: cereal, rice, oats, flour, pet kibble and birdseed are the usual draws. They're opportunistic, though, and will take nuts, peanut butter, chocolate, dried fruit, meat scraps, cheese (less than cartoons suggest), insects, soap, candle wax and the glue in cardboard.

What makes mice hard to starve out is how they eat. UC IPM describes them as nibblers that eat up to 20% of their body weight a day in a very large number of tiny meals each night, at many spots, and notes they don't need to drink water if their food holds enough moisture. A mouse needs only about a tenth of an ounce of food a day, so crumbs under a stove or a dog bowl left out overnight can feed a family.

What do mice like to eat most? In traps, the reliable baits are the ones close to their natural diet: a pea-sized dab of peanut butter, hazelnut spread, oats or sunflower seeds. Cheese is a weaker bait than cartoons suggest.

Behavior: nocturnal, curious, close to walls

• Mostly nocturnal. Peak activity is the first hours after dark and again before dawn, though UC IPM notes they're active whenever food is available. Regular daytime sightings mean they're well established.
• Small territory. A house mouse typically lives within 10-30 feet of its nest, so if you see droppings in one cabinet, the nest is close.
• Wall-huggers. They run along edges, leaving greasy rub marks, which is why traps go against walls.
• Curious. Unlike rats, mice explore new objects quickly, so traps can catch them the first night.
• Excellent climbers and squeezers. Mice run up any rough vertical surface, along wires and pipes, jump about 12 inches onto a flat surface, and pass under a gap 1/4 inch tall or through a 3/8-inch hole.
• Musky smell. Long-running infestations have a distinct stale, musky urine odor.

How long do mice live?

UC IPM puts the usual lifespan of a house mouse at 9 to 12 months, with a few living up to 3 years. Disease, predators, people, weather and starvation are what kill them. Pet mice in cages commonly reach 2 years or more. In practice the lifespan of one mouse matters less than how fast the colony grows.

Baby mice and how fast mice breed

House mice are sexually mature 5-6 weeks after birth (sometimes as late as 12 weeks). Young are born 18-21 days after mating, a litter is usually 5-6 pups (older females have bigger litters), and a female can mate again within a day of giving birth. That allows 5-10 litters a year. With steady food indoors they breed year-round.

Baby mice are born pink, hairless and blind, about the size of a jellybean. They get fur within a week, open their eyes at about two weeks and are weaned and on their own at three weeks. If you find a nest of pink pups, the adults are nearby and still breeding; find the nest's entry routes and trap the area.

Mice in the house: when and why

Most infestations start in fall, when outdoor temperatures drop and mice look for warm nesting sites, though in cities and apartment buildings they're a year-round problem. They come in along utility lines, under doors with worn sweeps, through foundation vents, gaps around pipes, garage doors and attached decks, and in boxes or firewood carried indoors. Nests are built in wall voids, behind appliances, in kitchen cabinet toe-kicks, under bathtubs, in attics and in stored boxes, from shredded paper, insulation and fabric.

How to confirm you have them: signs of mice.

Are mice dangerous?

House mice don't attack people and bite only when handled. The risks are indirect:

• Food contamination. Mice urinate and drop feces as they move, and can spread salmonella and other bacteria onto counters and food.
• Allergens. Mouse urine proteins are a major allergen; UC IPM cites links to early-onset asthma in sensitive children.
• Diseases from urine and droppings. Leptospirosis and lymphocytic choriomeningitis virus (LCMV) come from house mice (UC IPM estimates about 5% of US house mice carry LCMV); hantavirus comes mainly from deer mice and related wild rodents, and you can catch it by breathing dust from droppings and nests.
• Fires and damage. Mice gnaw wiring, insulation, stored papers and car wiring harnesses.

Do mice carry rabies? Practically no. CDC notes rodents aren't a rabies reservoir, no rodent-to-human rabies transmission has been documented, and bites from small rodents rarely require rabies shots. (Hantavirus is a different story: about 890 US cases were reported from 1993 through 2023, mostly in the West, and CDC says 38% of people who develop the lung phase may die.) A mouse bite still deserves washing with soap and water and a call to a doctor if it gets red, swollen or you're unsure about tetanus.

Clean up droppings safely

Never sweep or vacuum dry droppings; that puts particles into the air. Air out the space for 30 minutes, put on rubber or nitrile gloves, spray droppings and nests with a disinfectant or a 1:10 bleach solution, wait 5 minutes, wipe up with paper towels, bag them, then mop and wash your hands. See a doctor if you develop fever, muscle aches and shortness of breath within a few weeks of cleaning up after rodents, and mention the exposure.

What people who dealt with mice say

Threads in r/pestcontrol and r/homeowners repeat the same story, and the pros who answer them agree on most of it:

• The first traps "don't work" because of the bait. The most common complaint is mice licking the peanut butter off without setting off the trap. The fix is a pea-sized smear pushed into the trigger, not a gob on top.
• Placement beats trap type. Pros tell people to set traps with the bait end against the wall, right where droppings are, not in the open. One tip that comes up often: leave traps unset for two or three nights so mice feed freely, then set them all at once.
• Trapping without sealing just recycles the problem. The answer to "I've caught 10 and they keep coming" is almost always an unsealed entry: AC line and cable penetrations, gaps behind the stove and dishwasher, the space above cabinet kick plates, baseboard heating pipes, garage doors and rim joists. Foam alone gets chewed through; pros pack steel wool or copper mesh first and lock it in with foam or sealant. Several commenters put it bluntly: a company that traps but doesn't seal holes isn't finishing the job.
• Released mice come back. People who catch and release a few hundred yards away report the same mice returning.
• Glue boards get pushback. Pros generally prefer snap traps: glue boards are meant for monitoring, catch fewer mice and leave a live animal to deal with.
• Hantavirus fear spikes after news stories. After the widely reported 2025 hantavirus death in New Mexico, threads filled with people who had vacuumed droppings. The pros' answer: the risk is low, symptoms would have shown within 1-8 weeks, and next time wet everything with disinfectant before cleaning.

What actually works against mice

The short version, which is covered in detail on the get rid of mice page:

1. Put food away in glass, metal or thick plastic, and don't leave pet food out overnight.
2. Trap heavily: snap traps baited with peanut butter, set perpendicular to the wall, many at once (a dozen for a typical kitchen is not too many). See mouse traps.
3. Seal entry points with steel wool or copper mesh plus sealant, hardware cloth over vents, and door sweeps. See how to keep mice out.
4. Use poison only in tamper-resistant bait stations, following the label, and preferably outdoors. Baits take several days to work, and a mouse that dies in a wall void will smell.

Ultrasonic plug-ins and peppermint sachets, including products like Vamoose sold for mice, are at best a weak, short-lived deterrent; UC IPM states plainly that high-frequency electronic devices aren't effective.

When to call a pro

Call a pest control company if you're still catching mice after 2-3 weeks of trapping, you hear activity in several walls or floors, you live in a multi-unit building (the problem is shared), mice are in the attic insulation, or you suspect deer mice in a cabin and don't want to handle cleanup yourself. Expect roughly $200-$600 for an inspection, trapping and exclusion package (approximate; more for extensive sealing). See rodent control.