(By Megan Dunn, Healthy People and Communities Program Director)

The poem “A Visit from St. Nicholas” by Clement Clarke Moore may have you thinking about ways to prevent creatures from stirring! And for good reason. Mice are thought to be responsible for 20-25% of house fires. They can damage wires and dwellings and spread disease, so it's important in every season to control rodents in your house, apartment or condo. 

Using alternatives to pesticides is essential for dealing with rodents because rodenticides are the most toxic pesticide to humans and are also responsible for poisoning non-target animals (children, pets, birds of prey). Anticoagulants, a common type of rodenticide, prevent blood from clotting and cause direct harm to humans if consumed (humans and mice are both mammals). Rodent baits and pellets can resemble candy. Poison control centers list pesticides as one of the top 10 most common substances involved in human poison exposure. [1]

If you’d like to sleep with visions of sugarplums in your head and not worry about pests, not even a mouse, follow the five steps below to prohibit and control rodents.

5 Steps to Keep Creatures from Stirring:

1. 1. Identification: life cycle, habits, food sources
   2. Prevention
   3. Thresholds
   4. Treatment: cultural, mechanical/physical, biological, chemical
   5. Monitoring

Step One: Identification: life cycle, habits, food sources

Mice and rats are part of the larger order of rodents, which also includes squirrels and porcupines. There are two types of rats (which are larger than mice) in the Pacific Northwest. Norway rats burrow in soil or sewers; you would find this type on the ground floor or in the basement. Also common are roof rats (or black rats), which you might find climbing trees to get to attics and ceiling spaces. Roof rats have larger ears and their prehensile tail is slender and longer than their body. Smaller than their larger rat cousins, mice prefer cluttered spaces. The house mouse has a light brown belly while the deer mouse has a white belly.

To identify if you have mice, roof rats or Norway rats, you need to first understand the behavior of each pest and expect to hear these animals or see their droppings. Both mice and rats are nocturnal. Rats have poor eyesight, excellent smell, taste, touch and they avoid new objects (like traps). Norway rats can also swim. Mice typically travel along walls. They are known to hide or take cover, and the average mouse travels 12 feet from its home (so don’t store your trash cans within 12 feet of an external door).

Step 2: Prevention/Exclusion

Prevent rodents from stirring by sealing all cracks and holes from the outside. Try to eliminate all gaps larger than ¼ inch. Mice can fit through a hole the size of a dime; rats can fit through a hole the size of a quarter! Seal holes in the foundation with metal or concrete. Repair windows, doors and screens. Fill openings from pipes, vents, utility cables and don’t use chewable materials; use steel wool or copper mesh. Install door sweeps or weather stripping to exclude entry (if you can see light coming in from the outside, you could be inviting in the creatures). Mice can jump 12 inches and cross wires and climb vegetation, so remove tree branches, blackberries and ivy that contact your building.

If you have a property manager, ask them to perform maintenance to prevent rodents. Some managers may be required by law to make these improvements.

Step 3: What’s your threshold?

Establish your threshold level for tolerating pests. How many mice in your tool shed can you tolerate (a few) vs. your kitchen (none)? If your threshold is exceeded, begin treatment.

Step 4: Treatment/Action

If you have unwanted visitors, you can take action with cultural, mechanical/physical, biological and (only as a last resort) chemical methods. To control mice with cultural methods and prevention, make your home unattractive by sealing all food and garbage in air tight containers (even art supplies), remove water sources by fixing leaks and removing standing water, and remove shelter by reducing clutter both inside and outside.

Physical controls involve trapping. Watch our videos on how to trap, where to set up traps and how to find a mouse pathway. Put traps 5 to 10 feet apart and move them every night. Placement and size to match the pest are key. Sticky traps are inhumane, and snap traps can be dangerous to children and pets. Humane (catch and release) traps are available, but they need to be checked frequently, so the animals don't suffer needlessly or die from stress and/or dehydration. Don't set traps if they can't be checked regularly. Remember that the critters need to be released far from home (yours and others' homes). The most effective baits are peanut butter, bacon, nuts, and dried fruit.

Cats are an example of a biological control, and they may control or deter rodents. Installing owl houses in your yard can also help!

For an infestation or if you feel you need to use chemicals, use the least toxic option first and call a professional. Humane, patented birth control is effective for reducing mice and rat populations (professional application is required). Contact your professional pest control company about availability. For more information on treatment, check out our fact sheets on mice and rats.

Some treatments are not recommended for control based on a lack of peer-reviewed evidence: electric traps, repellents and sound emitting devices.

Step 5: Monitoring

Monitor for pests all year long to see if they are naughty or nice and be prepared to repeat these steps to prevent an infestation. These are some signs of rodents in the home: torn, open packages, droppings, holes, noises at night not on Dec 25th, nests or borrows, smudge marks (from oils in their fur), chew marks on wood/soap and urine stains.

Rodents can be controlled without harmful pesticides. Check out our three part video series for more information.

Trapping:

Exclusion:

Sanitation:

Wishing you a healthy, pest-free home and a "Happy Christmas to all, and to all a good-night."

[1]  2015 Annual Report of the American Association of Poison Control Centers’ National Poison Data System (NPDS): 32nd Annual Report. Clin Toxicol (Phila). 2016