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Pest SolutionsPESTS + WEEDSUSING PESTICIDES OR HERBICIDES?
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Mice
Mus musculus
Updated Mar 29, 2023
Make a Positive Identification
Mice (house mouse) (Mus musculus) are small, non-native rodents found in homes and structures. They use space in walls and openings around pipes to move inside structures.
Species: Mice
Ed Freytag, City of New Orleans, Bugwood.org
Mice are small, non-native rodents found in homes and structures. Adult mice grow to about 5–7 inches long, including the tail.
Species: Mice
Liz Kasameyer, Johns Hopkins School of Public Health, Bugwood.org
Look for feces and urine on floors and under furniture and appliances. Mouse urine is smelly. Black fecal pellets have pointed ends from 1/8–1/4 of an inch long.
Species: Mice
Liz Kasameyer, Johns Hopkins School of Public Health, Bugwood.org
Mice damage buildings. Their urine and feces are health hazards.
Look-Alikes: Voles & Rats
Species: Voles
David L. Clement, University of Maryland, Bugwood.org
Voles are native species of mice. They live and prosper in grassland and similar settings, such as lawns. The burrowing shown above is a sign of vole activity in a grassy area. They generally don’t damage structures.
Different risks or methods
Mow grassy areas to limit vole habitat.
Voles will gnaw on the bark at the base of trees and shrubs. Protect new plantings of fruit trees and restoration plants with plastic guards to exclude voles.
See Meadow Voles & Pocket Gophers (OSU Extension Service) for more information.
Species: Rats
Ed Freytag, City of New Orleans, Bugwood.org
Adult rats (Rattus spp.) are much larger than mice (house mouse) and voles. Rats are non-native, invasive species. They spread diseases, damage structures, and ruin stored goods.
Different risks or methods
Take action to control rats in your home and structures. Remove food sources and habitat. Seal structures to keep them out. Control existing populations. Monitor for rat activity and take action as needed.
Mice Benefits
- House mice (Mus musculus) are non-native and invasive in North America.
- They don’t have any benefits for people and the environment.
- Deer mice (Peromyscus spp.) are native, but also pose some risks to humans.
Mice Risks
- Mice are a health threat to adults, children, and pets.
- Their gnawing, nest building, and excessive feces and urine cause property damage.
- They chew through boxes and plastic bags to get to food and nest areas. Mice ruin stored food and belongings.
- Mice populations build quickly. A single female mouse has 5–10 litters each year. Each litter has 5–6 young. Female mice reach sexual maturity in 5–7 weeks.
Human diseases such as salmonellosis and leptospirosis can be transferred to humans via contact with mouse feces. Dried urine and feces particles in the air can trigger asthma. Hanta virus, though rare in the Pacific Northwest, can be passed by inhaled deer mouse feces.
Risk Card
Does it cause harm?
Adults & Children
High
Diseases transferred via feces. Dried urine and feces particles in the air can trigger asthma.
Property
High
Damage buildings, food & belongings
Pets
High
Leptospirosis spreads from mice to pets. Pets can eat poisoned mice and become poisoned themselves.
Annoyance
High
Require control efforts
Environment
High
Invasive animal with no benefit to natural areas
Action Highly Recommended
Mice are a health hazard. Take action right away.
TAKE ACTION
Take action right away if you find mouse damage in your home or belongings. Mice are a health threat for adults, children, and pets.
Do I need to take action?
Yes. Don’t tolerate mice in your home or storage areas.
What if I do nothing?
Once mice get into your home or storage area, they will multiply quickly. They make a mess and are a human health threat.
Prevent Mice
Weston Miller, Oregon State University
Use Trashcans with Secure Lids
Make sure your trashcan excludes all rodents and clean it from time to time.
Gary Alpert, Harvard University, Bugwood.org
Don’t Leave Trash Exposed
Don’t overfill trash cans and provide a food source for rodents.
Weston Miller, Oregon State University
Store Pet Food and Bird Seed in Robust Containers
Exclude rodents from bird seed and pet food by using containers made of thick plastic or metal and a secure lid.
Weston Miller, Oregon State University
Don’t Attract Rodents with Food Scraps in Your Compost
- If you compost food scraps at home, use a rodent-proof composting system.
- If your compost area is not rodent-proof, avoid including meat, milk, and bread products that won’t break down quickly. Keep mixing and maintaining the pile so heat stays high and breaks materials down fast.
Weston Miller, Oregon State University
Use Door Sweeps
Install door sweeps that seal the gap between the threshold and the door base.
Gary Alpert, Harvard University, Bugwood.org
Use Good Carpentry Practices
- Seal around water, gas, water service pipes, and conduit installed in walls and floors.
- The space between the pipes allows access for mice. Use good carpentry practices and sealing techniques to close off entry points.
Gary Alpert, Harvard University, Bugwood.org
Seal Gaps in Construction
- Fill entry points as small as a dime with sealant and/or steel or copper wool.
- Larger holes similar to the hole in the building foundation shown in the photo need to be filled with concrete.
Liz Kasameyer, Johns Hopkins School of Public Health, Bugwood.org
Seal Exterior Vents
- Maintain and repair all building ventilation screens, louvers in attic spaces, and furnace closet doors and vents.
- Any gaps around the screen frames and louvers require sealing.
Weston Miller, Oregon State University
Declutter and Check for Signs of Rodents
- Declutter storage spaces to eliminate places rodents can hide. Pull boxes and items away from walls and shelves as shown in the photo.
- Monitor for rodent activity. Clean the area as needed.
Solutions for Mice
Remove Food Sources and Exclude Rodents
- Start by removing any food sources like trash access, bird seed, pet food, or compost. Sanitation must be ongoing.
- Rodent-proof your home and buildings to exclude them. Fix holes and seal gaps. Use welded wire “hardware cloth” with ¼-inch openings to exclude mice. Use copper or steel wool around pipes and cables.
- Consider hiring a pest control company or a contractor familiar with rodent-proof construction and exclusion methods. See How to Hire a Pest Control Company for details.
Clean Up Rodent Messes
- See health and safety tips to minimize risks from cleaning activities.
- Clean up rodent feces, urine, and damaged items. Use gloves. Spray with a disinfectant before handling mice damage. Wear a dust mask with a HEPA filter. Inhalation of dust from dried urine and feces is where many health problems start.
Control Mice Populations
- Get rid of mice using the trapping methods described below. Trapping is a good first choice.
- Carefully consider using toxic bait products (rodenticides). Use a bait station to reduce the risk of poisoning to children, pets, and wildlife by limiting access. Never leave loose bait unattended.
NEED HELP?
Consider a licensed pest control company. Learn How to Hire a Pest Control Company.
Your local Extension Specialist in Oregon and other states can suggest other methods.
Jump to
| Method | Does it work? | Is it safe? | Recommendation |
|---|---|---|---|
A Remove Food Sources & Repair Structures |
Very effective |
Moderate risk |
Recommended |
B Trapping |
Effective |
Moderate risk |
Recommended |
C Rodenticides (Toxic Baits) |
Effective |
High risk |
Use if Necessary |
|
D If Using Rodenticides, Protect Yourself & Minimize Risks
|
A
Remove Food Sources & Repair Structures
Non-Chemical Method
FalconScallagrim, iStock
Remove Food Sources & Repair Structures
Recommended
Before you set traps or use toxic bait, you need to remove food sources and mouse-proof your building. Otherwise, mice will return.
| Does it work? | Very effective These steps are required for successful control of mice in home and structures. |
| How much effort? | High effort Remove food sources for rodents. Use good carpentry practices and sealing techniques to close off entry points. |
| What's the risk? | Moderate risk See health and safety tips to minimize risks from sanitation and mouse-proofing activities. |
| Possible risk of exposure or harm from chemicals | NONE |
Removal of food sources and rodent-proofing your structures are key steps to get rid of mice. After you perform these steps, then use trapping and/or toxic baits to kill an existing population of rodents.
FalconScallagrim, iStock
Liz Kasameyer, Johns Hopkins School of Public Health, Bugwood.org
B
Trapping
Non-Chemical Method
Weston Miller, Oregon State University
Trapping
Recommended
Trapping is an effective way to reduce the population of mice. It is a good first choice. Follow the directions below for best results.
| Does it work? | Effective Trapping effectively gets rid of mice when used with preventive measures. You must also remove food sources and exclude rodents from the structure to get rid of them successfully. |
| How much effort? | High effort You must set multiple traps and reset them daily until you no longer see fresh signs of rodent activity. |
| What's the risk? | Moderate risk
|
| Possible risk of exposure or harm from chemicals | NONE |
Set multiple traps and use the prebaiting method. Be persistent in your mice-trapping efforts.
Weston Miller, Oregon State University
Weston Miller, Oregon State University
Mouse-Trapping TIps
- Mice rarely figure out traps and avoid them. In fact, they tend to prefer traps that have captured other mice.
- Check traps daily or more often when you are dealing with a large population. Rats do figure out traps.
How to Set Mouse Traps
- Plastic snap traps are easy to set and disinfect.
- Nuts, peanut butter, cheese, dried fruit, and pet food are good baits.
- Fasten solid bait securely to the trap trigger with a fine wire.
- Set traps so the trigger will spring easily.
- Place traps where mice travel so they will pass directly over the trigger of the trap; for example, along walls, behind boxes, and under equipment and furniture. Look for mice droppings and gnaw damage, and install traps there.
- Check traps every 24 hours.
- Remove and dispose of captured mice and reset the traps. Wear disposable gloves or rubber gloves that can be disinfected.
Prebait, Move Traps & Reset Method
- Prebait the traps by baiting and placing them without setting them to snap. After 2–3 days, rebait the traps and then set them.
- This process encourages the mice to ignore the traps. It makes your trapping more effective once you do set the triggers.
- If you don’t trap mice after 2–3 days, remove the traps and stop using them for several days.
- Move the traps to a new spot 5–10 feet away. Prebait and then set the traps.
- Repeat the sequence until you get rid of all the mice.
Other Trap Options Have Disadvantages
Battery Traps
- Battery-operated electrocution traps have been shown to provide good control of mice.
- They are considerably more expensive than snap traps.
Live Traps
- Live catch traps are boxes that have an entrance but no exit, and do not injure mice. However, trapped mice may be noisy as they try to escape. When you use these traps, mice have to be removed and humanely euthanized with a strong blow to the head. Drowning is considered inhumane. Releasing live mice caught in the traps won’t solve your rodent problem.
- Glue boards are pieces of flat cardboard with a thick layer of glue on one side, similar to fly paper. Mice don’t die quickly and struggle to get free. If you find a live mouse in a glue board, it needs to be immediately and humanely euthanized with a strong blow to the head.
iStock
C
Rodenticides (Toxic Baits)
Chemical Method: Use with caution
Weston Miller, Oregon State University
Rodenticides (Toxic Baits)
Use if Necessary
- Rodenticides effectively control mice populations when used according to label directions.
- Use rodent bait stations to minimize access of the toxic bait for people, pets, and wildlife.
| Does it work? | Effective
|
| How much effort? | Moderate effort Many rodenticide product labels recommend maintaining fresh bait in bait stations until there are no longer signs of new rodent activity. |
| What's the risk? | High risk
|
| Possible risk of exposure or harm from chemicals | El uso de rodenticidas conlleva cierto grado de riesgo. El riesgo más bajo se presenta con el uso de métodos alternativos. You may be exposed to a rodenticide if you:
Follow directions closely to reduce risk. |
It is critically important that you follow rodenticide product directions to properly and legally place stations inside buildings or near the building perimeter.
Liz Kasameyer, Johns Hopkins School of Public Health, Bugwood.org
Rodenticide Active Ingredients
Warfarin, chlorophacinone, diphacinone and cholecalciferol are common active ingredients in rodenticide products for use in homes and structures.
Application Tips
- Place bait in tamper-proof bait stations that limit access to the toxic bait.
- Poisoned rodents sometimes die in hard-to-reach places, decay in place, and then smell bad and create a new health hazard.
- Collect and dispose of any dead rodents. See health & safety tips.
- Bait products require several days to kill rodents.
- Ensure the stations are continuously supplied with bait. Replace moldy or damaged bait.
Remove Food Sources and Repair Structures BEFORE Using Toxic Baits
- If you don’t remove food sources and secure your buildings, toxic baits won’t get rid of rodents.
- You’ll need to keep using poison bait repeatedly.
- If you can’t block access or remove rodent nesting areas, ongoing baiting might be necessary.
If Using Rodenticides, Protect Yourself & Minimize Risks
Chemical Method: Use with Caution
chendongshan, iStock
Rodenticides are extremely toxic to humans, pets, and wildlife. Baits are made to attract animals with tasty smells and flavors. Pets and wildlife can be poisoned if they eat rodents that consume rodenticides.
Why Is It Important to Read Rodenticide Labels?
- They have detailed information on how to use the product correctly and legally.
- They contain information about specific rodent species, their habits, and control methods.
- They provide information on potential hazards of the product. They have instructions you should follow for poisonings and spills.
The Label is the Law
ALWAYS read the label before using rodenticide products. The label is a legal document that provides information on how to safely use the rodenticide. This helps avoid harm to human health and the environment. Using a rondenticide in off-label ways is illegal. It can result in legal enforcement actions.
READ THE LABEL & Follow Instructions
It has instructions to protect you and the environment.
- Labels are different for every product and they often change over time.
- Use a magnifying glass for small print.
- Pay attention to CAUTION, WARNING, and DANGER statements.
- Pay attention to the PRECAUTIONARY STATEMENTS.
- The law states you must read and follow rodenticide instructions.
Protect Children, Pets, Domestic Animals & Wildlife
Children, pets, and wildlife are at risk if they touch or consume poison toxic bait for rodents.
- Keep rodenticides out of reach from children and pets at all times.
- Dogs, cats, and wildlife are also attracted to and harmed by rodenticides.
- Use bait stations to protect children, pets, and wildlife.
- Rodenticides may be gathered by mice or rats and cached for later use. The cache location may not be safe for pets or children.
- Dogs, cats, and wildlife can be poisoned if they feed upon rats that have eaten rodenticide.
Protect Yourself
Eye, skin & lung irritants
- Wear gloves and safety glasses when handling rodenticides.
- Avoid contact with eyes, skin, or clothing.
Storage & Disposal
- Store out of the reach of children and pets.
- Follow the label instructions for disposal of rodenticide products.
Call 1-800-CLEANUP (1-800-253-2687) to find out where to dispose of pesticides.
For the Portland metro region in Oregon, contact Metro’s Recycling Information. Call 503-234-3000, email or visit Metro’s website
More about:
About Using Pesticides on School Grounds in Oregon
If using pesticides on school grounds, there are special rules in Oregon. See School Integrated Pest Management (Oregon Department of Agriculture).
NEED HELP?
The National Pesticide Information Center (NPIC) can answer questions about pest control chemicals.
1-800-858-7378 or npic@ace.orst.edu
Consider using a licensed pest or weed control company. Learn How to Hire a Pest Control Company.
Your local Extension Specialist in Oregon and other states can suggest other methods.
HEALTH & SAFETY TIPS
Use disposable or rubber gloves to clean up dead rodents and their feces, urine, and nests.
Wear a dust mask with a HEPA filter when cleaning an area with excessive rodent droppings and damage.
Don’t use a broom or vacuum. These actions may cause the viruses and bacteria living on the rodent droppings to become airborne. Inhaling those could make you sick.
HOW TO CLEAN UP RODENT DAMAGE, FECES & URINE
- Wet the stained or damaged area with a disinfectant. Disinfectants such as 10 percent bleach/water solution will kill disease-causing bacteria and virus.
- Apply a disinfectant and wait ten minutes. Use a moist cloth or paper towel to wipe up the droppings and mouse damage.
- Put all of the waste, including your disposable gloves, in a trash bag. Dispose of it right away.
- If you use a washable cloth and reusable gloves, clean those items in soapy water and disinfectant.
Liz Kasameyer, Johns Hopkins School of Public Health, Bugwood.org
Content provided by editor Weston Miller and writer J. Jeremiah Mann. Vertebrate information edited by Dana Sanchez. Pesticide safety information edited by Kaci Buhl.
Peer reviewed by OSU Department of Horticulture.
MICE CONTROL REFERENCES
Get Rid of Mice with Kids in the House
National Pesticide Information Center
Evict and Exile Mice from Your Home
Cornell University