House Mouse Identification and Behaviors

Seeing a mouse scurry across your kitchen floor is a surefire way to ruin your morning coffee. Whether you’ve spotted a brown mouse behind the fridge or a black mouse darting into the garage, you’re likely dealing with the same culprit: the common house mouse (Mus musculus).

Don’t let their size fool you. These pint-sized intruders are master survivalists that can squeeze through gaps the size of a dime. Here is everything you need to know to identify, prevent, and get rid of house mice.

What Orkin Does to Get Rid of House Mice

Almost all mice problems require the use of an Integrated Pest Management Program (IPM) approach. Therefore, the first thing your Orkin Pro will do is correctly identify the mouse species and develop a targeted, efficient rodent treatment plan.

Depending on your specific situation, the Orkin Pro may employ both non-chemical and chemical methods. Some effective non-chemical control procedures your exterminator will recommend include:

• Exclusion – sealing off sites that allow mice to enter a structure.

• Sanitation & debris – Your Pro will recommend using both inside and outside sanitation measures to help minimize available food and water that attracts and supports a mouse population.

• Traps – Many times your treatment plan will include using traps and other mechanical devices to kill or remove mice.

• Baits – Your Orkin Pro may also elect to use chemical products, such as rodent baits, that are formulated to kill mice.

One final thing you should keep in mind – don’t procrastinate when you see signs of a mouse problem. If you wait too long to start control measures, a few of them can quickly become a large infestation.

What does a house mouse look like?

• Color: First, let’s clear up a common misconception. You might think you’re dealing with a different species if you see a black mouse or a brown mouse, but usually, they are just color variations of house mice. While the standard house mouse is typically dusty grey with a cream-colored belly, their coats can range from light brown to dark black.

• Body: Their ears and tail also bear hair, although much less than their bodies.

• Size: Adult mice weigh approximately 12 to 30 grams and can grow up to 20 cm from the nose to the tip of the tail.

• Feces: Droppings are rod-shaped and pointed on both ends.

Brown Mice

Brown house mice are one of the most common color variations found indoors. They typically have light to medium brown fur with a slightly lighter belly. These mice are highly adaptable and often seek shelter in homes for warmth and food. Key characteristics of brown mice include:

• Color: Light to medium brown with a pale underside

• Size: About 2.5–4 inches long, excluding the tail

• Behavior: Active at night, excellent climbers and burrowers

• Habitat: Frequently found in kitchens, basements, and storage areas

• Risks: Can contaminate food, spread bacteria, and damage insulation

Black Mice

Black house mice are less common but still pose serious risks. They have dark gray to nearly black fur and share similar habits with brown mice, making them equally destructive indoors. Key characteristics of black mice:

• Color: Dark gray to black with a slightly lighter belly

• Size: Similar to brown mice, averaging 2.5–4 inches

• Behavior: Nocturnal, skilled at squeezing through tiny openings

• Habitat: Often nests in attics, wall voids, and cluttered spaces

• Risks: Known for chewing electrical wiring, increasing fire hazards

House Mouse Habitat and Origins

The house mouse is a small mammal named for its propensity to live within human habitats. Next to humans, the common house mouse is one of the most prevalent mammalian species in the world. Native to Asia, these brown and black mice have spread throughout the world. They are most commonly seen living within or near human habitations. They may also be used as laboratory subjects and contribute greatly to scientific studies.

Normally, the house mouse makes its home in farm fields, grassy and wooded areas, building nests in areas that are dark and protected from the elements and close to a readily available food source. When they move indoors, house mice often nest in quiet, undisturbed areas of homes such as wall voids, attics, basements, crawl spaces, cabinets, and behind appliances, where warmth, protection, and food are easily accessible.

What Do House Mice Eat?

When available, the house mouse prefers seeds and nuts in its diet, but this opportunistic feeder will eat almost anything available.

House Mouse Activity

Very inquisitive in nature, the house mouse will spend the day roaming its territory, exploring anything new or out of the ordinary.

When the temperatures outside begin to drop, house mice, since they don’t hibernate, begin searching for a warmer place to live. Often attracted by the smell of food and the warmth of a structure, the house mouse can use any opening, such as utility lines, pipe openings, and gaps beneath doors, to gain entry into a home.

House Mouse Behavior

House mice walk, run and stand on all fours. They can stand on the hind legs, as well, and are supported by the tail, which also provides balance while in motion.

Do house mice make noise?

The house mouse has a sharp sense of hearing and communicates with other house mice through squeaks. Some of these squeaks are audible to humans, while others extend into the ultrasonic range.

House Mouse Risks

Black and brown house mice pose significant health and safety hazards in homes and businesses. These rodents can contaminate food supplies, spread harmful bacteria, and even trigger allergic reactions. Beyond health concerns, mice are notorious for chewing through electrical wiring, which increases the risk of fires and costly repairs. Common risks include:

• Food contamination from droppings and urine

• Disease transmission through bacteria and pathogens

• Damage to insulation and electrical wiring caused by gnawing

• Unpleasant odors from nesting areas and decaying matter

House Mouse Prevention

To prevent black and brown mice from entering the home, all cracks, crevices, holes and gaps larger than a pen cap should be sealed with cement or a mixing compound. It is not advised that wood be used to seal these holes, as mice are capable of chewing through those surfaces.

Cleanliness may also have an effect on pest infestations. Be sure to wash dishes immediately following use. Food should be stored in glass or metal containers with tight lids. Mice acquire most of their water from scavenged food particles and no crumbs or morsels should be left on tabletops or floors.

When a home is already infested, prevention methods prove inefficient. The most effective mouse control methods are those administered by trained professionals.

More House Mice Resources

One-page Fact Sheet about Rodents

A quick-reference overview of common rodent species, their behaviors, risks, and prevention tips to help homeowners identify and address rodent issues efficiently.

House Mouse Enemies

Learn about the natural predators and environmental threats that help control brown and black mouse populations and why they’re not enough to prevent infestations indoors.

How to Find a Dead Mouse in the House

Step-by-step guidance on locating a dead mouse in your home, recognizing odor clues, and knowing when to call a professional for safe removal.

House Mouse Life Cycle

An overview of the house mouse life cycle, from birth to adulthood, and how rapid reproduction contributes to fast-growing infestations.

Signs of a House Mouse Infestation

Discover the most common warning signs of a house mouse infestation, including droppings, noises, and damage, so you can act before the problem worsens.

Where Do House Mice Hide?

Learn where black or brown mice commonly hide inside homes and buildings, and why these hidden nesting spots make infestations difficult to detect early.