House Mouse. How to Identify and Get Rid of Them

A house mouse is a small rodent with big ears, small black eyes and a nearly hairless tail. Adults are about 5 to 7 inches long with a 3 to 4 inch tail and weigh about half an ounce. The coat is light brown to gray.¹ The belly is gray or buff and the tail looks scaly.²

Check the belly. Deer mice have a white underside and larger eyes.¹ White-footed mice have a white belly and white feet.⁹ If you see white, read the deer mouse and hantavirus guide. For the full picture on mice and rats, go back to mice and rats.

One pair can fill a house in a season. Pups are born 18 to 21 days after mating. A female is ready to breed at 5 to 6 weeks old, though that can be delayed to as late as 12 weeks.¹

She has 5 to 10 litters a year with about 5 or 6 pups each, and older females have larger litters.¹ Ohio sources list litters of 3 to 11 young.²

Most house mice live 9 to 12 months, and a few live up to 3 years. With plenty of steady food, they breed all year.¹ Cut off the food and the nest, or the numbers never drop.

House mice are mostly active at night, but you may see one by day when the nest is crowded.¹ Look for these signs.

• Droppings along walls, in drawers and near food.
• Fresh gnaw marks and tracks.¹
• Nests of finely shredded paper or fibrous material behind boxes, in drawers, in garages or around woodpiles.¹
• A musky smell in large or long-term infestations.¹

Droppings are the quickest check. Clean them up safely, then look for fresh ones the next morning. If new droppings show up, the mice are still active and your traps are not yet in the right place. Move traps toward the wall line where the droppings were found.

Mice are a bigger health risk than most people think. They can carry leptospirosis, salmonella and lymphocytic choriomeningitis, called LCM. UC IPM estimates about 5% of U.S. house mice carry the LCM virus.¹

Their urine is a major allergen, and exposure to urine proteins has been linked to early-onset asthma in sensitive children. Mice also gnaw electrical wires and gas lines, and many fires of unknown origin are believed to start from rodents chewing wires.¹

Mice also contaminate food. Throw out anything they touched. The hantavirus that sickens people in California is spread by deer mice, not house mice.⁸ Compare the two in the hantavirus guide.

Traps and sealing do the work. Set snap traps close to walls, behind objects and in dark corners. Mice rarely go more than 30 feet from the nest and food, so space traps no more than about 10 feet apart where they are active.¹

Use a pea-sized dab of bait on the trigger plate. Wide-trigger traps catch more. Setting traps in pairs 1 to 2 inches apart helps with mice that jump over obstacles.¹

Poison needs care. Homeowner products are ready-to-use bait stations, and the toxins are dangerous to pets and wildlife.⁴ Baits take several days to work, and mice often die inside the building, so trapping may be better when smell is a worry.¹

Call a pro for mice in walls or after two weeks of failed trapping.

A pro mouse job usually costs $150 to $550, with an average near $350. Some charge $75 to $125 per visit. Emergency or after-hours service adds $100 to $200.⁵

DIY is cheap. Snap traps run $3 to $6 each, glue traps $5 to $15, bait stations $8 to $20 and electronic traps $20 to $50.⁵

More mice, a bigger home and mice in the walls all raise the bill. Sealing entry points costs more now but may save money later.⁵ Ask what the price includes and whether a follow-up visit is covered.

Seal first. Mice live where it is easy.

• Seal gaps larger than 1/4 inch with metal or concrete. Rubber, vinyl, plastic screening, foam and wood do not work.¹
• Store food in sealed containers and clean crumbs.
• Keep woodpiles and boxes away from the house, since nests often sit there.¹
• Keep traps set after you seal, in case one mouse was left inside.¹

Cleaning alone rarely ends an infestation, but poor sanitation lets a mouse population grow. Do both. Seal the holes, then keep the kitchen, pantry and garage tidy so nothing rewards a new mouse that finds a way in.

House mice are a year-round problem. With plentiful, stable food they breed in every month, so the season grid stays flat in Ohio and California.¹

Mice are mostly nocturnal, so many people notice them only after droppings or gnaw marks appear.¹ That can happen in any month.

The one calendar rule is for sheds and cabins closed for the winter. Open the doors and windows for 30 minutes and leave before you clean, then use disinfectant and paper towels, never a broom or vacuum.³

Treat the first sign the same way in January or July. Seal, trap and check again in a week.

Ohio house mice are small, gray-brown and live close to people, usually inside buildings. They eat plants, insects and meat. Litters are 3 to 11 young.² Ohio also has white-footed mice in woody and brushy areas, which look different because of their white feet and belly.⁹

Ohio law requires pest management companies to be licensed through the Ohio Department of Agriculture. Ask for the license, proof of insurance and workers' compensation, and get at least three bids.⁶

Go back to the mice and rats hub for Ohio rat information.

In California no trapping license is needed to control house mice, and you can control them at any time by any legal method. Moving a live house mouse off the property needs a special CDFW permit.¹

Two toxins are registered for house mice, bromethalin and cholecalciferol. Zinc phosphide is restricted to licensed applicators, and residential rodenticides are sold only in ready-to-use bait stations.¹

To check a pest company, use the Structural Pest Control Board's online tool to verify a company or an individual.⁷ Deer mice, not house mice, are the California hantavirus carrier. See the deer mouse guide.