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How to identify it
- The back is brown or tan, with a sharply marked white belly, legs and feet, and large eyes and ears.[1][10][8]
- The tail is two-toned, dark above and white below, and furred. UC IPM calls this the easiest way to tell a deer mouse from a house mouse, whose tail is almost hairless.[1][4]
- Size figures differ: the Washington State Department of Health gives about 6 inches from nose to tail tip, while University of Arizona Extension says deer mice are usually 3 to 4 inches, with some reaching 7 inches.[8][10]
- They are quick jumpers and runners; UC IPM says that agility is where the name comes from.[1]
- Several Peromyscus mice look nearly the same. California alone has seven species, nearly all with white undersides, legs and feet, brown backs and two-toned tails, and UC IPM says they are hard to tell apart.[1]
Look-alikes
| Look-alike | How to tell them apart |
|---|---|
| House mouse | Light brown to gray all over with no clear line between back and belly, and a nearly hairless tail. House mice eat food where they find it rather than storing it near the nest, and large infestations have a musky odor. Size estimates differ: UC IPM gives 5 to 7 inches including a 3- to 4-inch tail, while University of Arizona Extension says 2 to 3 inches and never more than 5 inches including the tail.[4][10][1] |
Where it lives
Found in forests, grasslands, scrub and farmland; they enter homes mainly where fields, forests or large parks are nearby, and often move into vacant cabins and outbuildings.[1]
Biology and life cycle
Deer mice are active at night and spend the day in nests of grass stems, twigs, leaves, roots and other fibers, sometimes lined with fur, feathers or shredded cloth. Nests are in tree hollows, stumps, under rocks and logs, in old squirrel or bird nests, or inside buildings.[1]
They don't hibernate, but may become torpid in especially severe weather, and they nest in family groups through the winter.[1]
They eat mostly seeds, plus fruit, invertebrates, fungi and a little green vegetation, and they cache food near the nest, especially in autumn. That habit of storing acorns, seeds and nuts helps tell their signs from a house mouse's.[1][10]
Litters are usually 3 to 6 young, and females can breed as early as 6 weeks old. They don't usually breed in winter, but with plenty of food they may, and in warm regions they can breed all year. In the wild few live more than two years.[1]
A deer mouse's home range runs from about 1/3 acre to 4 acres or more.[1]
Damage and signs
- Indoors, deer mice shred upholstered furniture, mattresses, clothing and paper for nest material.[1]
- Outdoors they eat crop and tree seed. UC IPM says they destroy more Douglas-fir seed than any other mammal or bird, and lists damage to almonds, avocados, citrus, pomegranates, sugar beets, planted melon seed and alfalfa seed.[1]
Health risk
Infected deer mice shed the virus in urine, droppings and saliva without getting sick themselves. People are infected mainly by breathing air after fresh urine, droppings or nesting material is stirred up; the virus can also enter through cuts or the eyes, nose or mouth, and rarely through a bite. Symptoms start 1 to 8 weeks after exposure. CDC says 38 percent of people who develop respiratory symptoms may die; its surveillance table counts deaths in 35 percent of U.S. hantavirus cases, and New Mexico's health department gives a 36 percent fatality rate. Hantaviruses in the United States are not known to spread from person to person.[8][3][2][6][9]
Control
Prevention
CDC and the New Mexico Department of Health call rodent control in and around the home the main strategy for preventing HPS.[3][9]
Wash gloved hands with soap and water or disinfectant before taking the gloves off, then wash bare hands. Washington's health department notes that a dust mask doesn't protect against viruses.[7][8]
Keep them out
UC IPM says rodent-proof construction is the most effective and permanent way to keep deer mice out of houses, cabins and outbuildings.[1]
Seal openings larger than 1/4 inch (University of Arizona Extension: any gap a pencil fits through) with metal, concrete or steel wool. UC IPM warns that plastic, rubber, foam and wood can be gnawed through. Doors, screens, vents and pet doors should fit tightly.[1][8][10]
Sanitation
Clear overgrown shrubs and weeds and keep woodpiles, brush piles and fallen trees away from buildings. UC IPM says this lowers numbers but won't eliminate deer mice.[1]
Before cleaning a closed-up cabin, shed or house, open all doors and windows and leave the building for 30 minutes while it airs out.[7][8]
Don't sweep or vacuum droppings, urine or nests. Wear rubber or plastic gloves, spray the material until very wet with a household disinfectant or a bleach solution of 1 1/2 cups of bleach per gallon of water (1 part bleach to 9 parts water), let it soak, then wipe it up with paper towels and bag it. CDC says to soak 5 minutes or as the label directs; Washington's health department says 10 minutes.[7][8]
Traps and physical control
Snap traps baited with peanut butter work; UC IPM suggests setting them no more than about 10 feet apart along walls with the trigger toward the wall, and may need a dozen or more for a large population. It advises against glue boards, multiple-catch traps and live traps for deer mice because trapped mice soil them with urine and droppings.[1]
Pesticides
UC IPM says trapping or toxic bait is almost always needed once mice are established. University of Arizona Extension says toxic baits in or around homes belong only in tamper-proof bait stations.[1][10]
Deer mice around buildings: what field studies found
A 2.5-year Montana study of mice living around buildings found antibodies to Sin Nombre virus in 25 percent of deer mice tested, higher than most studies of deer mice in wild habitats; the authors suggest these settings may carry a higher risk of human infection.[11]
A follow-up radio-tracking study found that female deer mice living around buildings had smaller home ranges than those in the wild, and that the mice moved between buildings and the outdoors. The authors suggest that smaller home ranges concentrate shed virus and that protection from sunlight inside buildings may help it persist.[12]
In an experiment with small simulated buildings, deer mice entered whether or not food or bedding was inside, but were significantly more active in buildings that held food.[13]
As of the end of 2023, CDC counted 890 laboratory-confirmed U.S. hantavirus cases since surveillance began in 1993, and 94 percent occurred west of the Mississippi River. Washington's health department says infected deer mice live throughout that state.[6][8]
Deer mouse classification is changing: University of Arizona Extension now treats the western deer mouse (Peromyscus sonoriensis) separately from Peromyscus maniculatus.[10]
Common questions
- Can I vacuum up mouse droppings?
- No. Sweeping or vacuuming can put virus particles in the air. Soak the droppings with disinfectant or bleach solution first, then wipe them up with paper towels.[7][8]
- How do I tell a deer mouse from a house mouse?
- Look at the belly and tail: a deer mouse has a sharply white belly and a furred tail that is dark above and white below, while a house mouse is gray-brown all over with a nearly hairless tail.[1][4][10]
- Can my dog or cat give me hantavirus?
- Washington's health department says dogs and cats can be infected without getting sick and can't spread hantavirus directly to people, but they can bring infected rodents into the house.[8]
- When would hantavirus symptoms show up?
- Usually 1 to 8 weeks after contact with an infected rodent, starting with fatigue, fever and muscle aches. If you suspect it, see a doctor right away and mention the rodent exposure.[2][8]
Sources
- University of California Statewide IPM Program, “Pest Notes: Deer Mouse, Publication 74161 (June 2012).” ipm.ucanr.edu/legacy_assets/PDF/PESTNOTES/pndeermouse.pdf (accessed 2026-11-11)
- Centers for Disease Control and Prevention, “About Hantavirus.” www.cdc.gov/hantavirus/about/index.html (accessed 2026-11-11)
- Centers for Disease Control and Prevention, “Hantavirus Prevention.” www.cdc.gov/hantavirus/prevention/index.html (accessed 2026-11-11)
- University of California Statewide IPM Program, “Pest Notes: House Mouse, Publication 7483 (revised July 2025).” ipm.ucanr.edu/legacy_assets/PDF/PESTNOTES/pnhousemouse.pdf (accessed 2026-11-11)
- iNaturalist, “Peromyscus maniculatus taxon page (order and family).” www.inaturalist.org/taxa/44396 (accessed 2026-11-11)
- Centers for Disease Control and Prevention, “Reported Cases of Hantavirus Disease.” www.cdc.gov/hantavirus/data-research/cases/index.html (accessed 2026-11-11)
- Centers for Disease Control and Prevention, “Clean Up After Rodents.” www.cdc.gov/healthy-pets/rodent-control/clean-up.html (accessed 2026-11-11)
- Washington State Department of Health, “Hantavirus.” doh.wa.gov/you-and-your-family/illness-and-disease-z/hantavirus (accessed 2026-11-11)
- New Mexico Department of Health, “Hantavirus Pulmonary Syndrome.” www.nmhealth.org/about/erd/ideb/zdp/hps/ (accessed 2026-11-11)
- University of Arizona Cooperative Extension, “Hantavirus and Disease Prevention (AZ2158).” www.extension.arizona.edu/sites/default/files/2025-09/az2158-hantavirus-disease-prevention.pdf (accessed 2026-11-11)
- American Journal of Tropical Medicine and Hygiene, via PubMed, “Kuenzi AJ, Douglass RJ, White D Jr, Bond CW, Mills JN (2001), Antibody to Sin Nombre virus in rodents associated with peridomestic habitats in west central Montana, American Journal of Tropical Medicine and Hygiene 64(3-4):137-146.” pubmed.ncbi.nlm.nih.gov/11442208/ (accessed 2026-11-11). Cited from the PubMed abstract.
- Journal of Wildlife Diseases, via PubMed, “Douglass RJ, Semmens WJ, Matlock-Cooley SJ, Kuenzi AJ (2006), Deer mouse movements in peridomestic and sylvan settings in relation to Sin Nombre virus antibody prevalence, Journal of Wildlife Diseases 42(4):813-818.” pubmed.ncbi.nlm.nih.gov/17255448/ (accessed 2026-11-11). Cited from the PubMed abstract.
- Intermountain Journal of Sciences, via PubMed, “Kuenzi AJ, Douglass R (2009), An experimental test of factors attracting deer mice into buildings, Intermountain Journal of Sciences 15(1-3):27-31.” pubmed.ncbi.nlm.nih.gov/20628475/ (accessed 2026-11-11). Cited from the PubMed abstract.