Least-Toxic Control of Mice Choose a different pests

Factsheet: Least-toxic Control of Mice, Rodenticides 


Pest type: Animals

The house mouse's body is brown to gray, about 3 to 4 inches long, and weighs only about ½ ounce. It has a semi-naked, dark tail about the length of its head and body combined, large ears and eyes in proportion to its head, and a pointed snout. Its upper incisors are flat and notched, and its feces is rod shaped, pointed at the ends, and about ¼ inch long.

Mice breed quickly (up to ten litters/year with an average litter being 6.7 mice), and will grow as large as food, shelter, and other competing species allow.

Is it a problem?

Mice and their fleas are capable of transmitting a number of human diseases, while also contributing to asthma conditions. Some of these diseases include: hantavirus, the plague, salmonella, and typhus.

Pest prevention practices

Remove food sources
Dispose of trash
Place trash in sealed containers
Store food in air-tight, sealed containers
Remove potential habitat
Remove clutter

Stuff holes in and around the house with steel wool or copper mesh, or fill them with caulk or plaster and cover with sheet metal, paying particular attention to the foundation and holes between the house and garage. 

Seal gaps around the doors by replacing worn thresholds and weather stripping, and installing door sweeps. 

Caulk openings around water pipes, electric wires, cables, and vents. 

Use hardware cloth to screen vents, floor drains, and any other openings. 

Raise woodpiles at least 12 inches from the ground (and pet cages, if mice find them interesting), and wrap the legs in galvanized sheet metal to prevent the mice from climbing them. 

Cut tall grass, weeds, and brush from around the foundation of a house or shed and dispose of the clippings. 

Discard or recycle unused clutter around the house that may be providing a home for mice. Pick up fallen fruit and rotting vegetables from the garden, and don't place food scraps at the top of the compost pile. 

Store birdseed in a sealed container, use a birdfeeder with a catch tray, and clean up around it regularly.

Store trash, indoors and out, in a metal container with a tight cover or fastener for the lid. 

Don't leave food on counters or dirty dishes in the sink overnight.

Keep the stovetop, oven, broiler, and kitchen floor clean (especially under the stove and refrigerator). 

Store grains, cereals, nuts, and pet foods in sealed plastic, metal or glass containers, or keep them in the refrigerator. Pick up any uneaten pet food before going to bed.

In-Depth Information:
A full-grown mouse can enter your house through a hole the size of a dime. They are talented climbers and able to swim, but do not need water to survive (they get water from their food).

Monitoring and record-keeping

  • Monitoring a mouse problem may be as easy as finding one scurrying across the linoleum or finding droppings on the counter. 
  • To be certain, sprinkle the surface that you suspect that they are frequenting with a light coating of flour. If correct, you'll find footprints in the flour and tracks from the flour, hopefully, to their point of entrance.
  • Be more aware of possible mouse activity in the fall, when the cold weather hits, paying particular attention to areas where food is stored. Watch for mouse activity outdoors, in areas adjacent to houses, which may be the first sign of an impending onslaught

Non-chemical and mechanical controls

Seal cracks and crevices
Repair holes
Sticky traps
Mesh screens
Remove trash from property
Remove clutter
Mow lawn above 2 inches
Remove debris and habitat

In-Depth Information:

No method will be a permanent fix unless you seal rodents out of your house and remove their access to food.

Have-a-Heart Traps are "live" traps meant to capture the mice so that you can release them instead of killing them. They are usually metal mesh with doors at either end. You can find this type of trap at your local hardware store, or contact Beyond Pesticides for a list of resources. Be sure to release mice far enough away from your house that they won't return and block off their point of entry to prevent any further infestation.

If you use snap traps, purchase traps that have expanded triggers that snap when a mouse runs over them, even when unbaited, and a clothespin-like closing mechanism, which is thin enough to allow the bait pan to be bent by hand, allowing for the regulation of trigger sensitivity. Your chances of catching your mouse are greater with a more sensitive trigger. Set baited traps out for a few days without setting the triggers, as mice are wary of new objects in their environment. You will also have a chance to see if your bait is disappearing, indicating that you have chosen a good location for your traps and bait that your mice enjoy. If there is no sign that your bait has been eaten, move your traps to a new location. If that doesn’t work, then change your bait. Mice tend to scurry along the walls, often referred to as runways. Traps should be positioned at a right angle to the wall, with the bait end towards the wall. Place five to ten traps near mouse holes, one to two feet apart. If you are the lucky host to a multitude of mice, it is more likely that they will approach from more than two directions. Try setting the traps in pairs parallel to the wall, with bait pans facing outwards. Traps should always be handled with gloves, as mice are sensitive to the odor of humans. Coating the trap with bacon grease will also help to mask your scent. Bait should be sticky so that the mouse will disturb the trigger mechanism even if it only touches the bait lightly. Good choices include peanut butter mixed with rolled oats, raisins, gum drops, or even a small piece of cotton that your little friends will attempt to acquire for nesting material. Various baked breads have also had great success rates, with trap shyness minimized by alternating the type of bread used.

Many people object to glue traps because they don’t kill the mouse immediately and may trap non-target species. The Center for Disease Control cautions against the use because urine that may be excreted from a frightened mouse can spread germs. A mouse that does die in the trap can contain pathogens that are also a health hazard. Another problem with the glue traps is what to do with the living mouse once it has been caught. Traps need to be checked at least once daily and, once trapped, must be killed quickly and humanely. The American Veterinary Medical Association (AVMA) has a guide on acceptable euthanasia and has denounced glue or sticky traps, unless it is required for pest control. Though it is sometimes suggested by trap manufacturers, drowning is explicitly illegal in many jurisdictions. For these reasons, many animal welfare groups and individuals have identified this as an unacceptable measure for mice control.

Repellent sound devices disrupt the sound communication between mice and repel rodents by generating a sound that annoys them, but at a frequency that is not heard by humans. There is little scientific proof that this is an effective method of control, though there have been reports of success using these devices. One example is a solid-state electronic unit that uses a patented method of directing variable pulsating frequencies onto a carrier, usually either the electrical wiring of a building or home, the metal gridwork within a building or the earth around the building, depending on where the unit is used. In your home, it would plug into a three-pronged electrical outlet and use the building's existing wiring to carry a variable, pulsating frequency that would distress your mouse visitors, causing them to leave. This system is designed to affect mice no matter where they are, between walls, in ceilings, and below floors. It is best used with another method of control for the first few months during the "flushing out" period, and when accompanied by habitat modification.

Biological controls

  • Cats may be effective in knocking off the occasional mouse, but it is unlikely that they will be capable of suppressing an established mouse problem. If you decide to get a cat, females are more predacious than males, especially if they have a new litter or have been trained by a good mouser. Only count on your cat to prevent initial mouse entry or to detect and remove new mouse colonizers, and remember that, in the small amount of time it lives in your house, a mouse may have time to contaminate food, destroy furnishings, or spread pathogens over clean dishes.
  • Outside, the mouse has many natural enemies, including native hawks, owls, snakes, mites, ticks, fleas, flies, nematodes, bacteria, and viruses. Maintaining parks with wild areas within urban settings can encourage these beneficial organisms. Owl boxes can help control rodents and be a fun project for the family - contact your local agricultural extension or visit non-profit sites like the hungry owl project to learn more.

Peppermint Oil

Chemicals to Avoid

Look at your product labels and try to avoid products containing those chemicals listed below:

(A = acute health effects, C = chronic health effects, SW = surface water contaminant, GW = ground water contaminant, W = wildlife poison, B = bee poison, LT = long-range transport)

Bromadiolone (A, C, W)

Methyl bromide (A, C, W)

Warfarin (A, W)

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