Our mild fall postponed the inevitable invasion of mice into our homes, but now you notice you’ve got quite an infestation. What can you do?
Mice and rats are commonly referred to as “commensal” rodents. Commensal means they share our table. Like us, mice need food, water and shelter. The best way to prevent an infestation in the future and to reduce your present infestation is to eliminate one or all three of these requirements from your home.
Food sources are an important factor attracting mice into our homes. Unsealed food in the pantry, garden seeds, bird seed, pet food and other spilled or unprotected edibles can become a buffet for invading mice. Keep all of these materials in mice-proof containers and clean up all spills promptly.
Leaking water or standing water can be an invitation to all sorts of home pests. Clean up spilled water and repair all leaks promptly to prevent pests and subsequent water damage.
Perhaps the most troubling aspect is removing shelter sites. Mice can shelter in wood piles, hay or straw, piles of fabric, and boxes of books or papers. They will even shelter in a food source, such as a bag of bird seed. Eliminating these nesting sites can prove difficult, but must be done to control an existing infestation and prevent further infestations in the future.
Excluding mice from your home is a very important facet of a management plan. Mice can squeeze through any opening their head can fit through. For young mice, this means a ¼-inch opening, an opening the size of a pencil, can provide access into your house! Block off entry to smaller openings with steel wool. For larger openings, such as those around pipes or vents, use hardware cloth with mesh openings less than ¼-inch.
What can you do about your existing infestation? Snap traps are a good option. Peanut butter or gum drops as bait on the trap is very effective. Mice do not like moving out in the open. They prefer creeping near cover or next to a wall, so place the traps in these areas. Dispose of trapped mice promptly, and reset traps. Generally, mice will leave droppings along their travel paths. If you are not sure how they are moving through your home, a fine dusting of flour or baby powder may aid in discovering their travel paths.
What about rodenticides, chemical controls for mice? There are products that work quite well. The problem is limiting the baits to mice. Do you have children or pets that might get into the poison baits? Can you place the baits so that they are not accessible to your kids and pets? What about pets or wildlife that may consume the poisoned mice, resulting in secondary injury or death? If you decide on a chemical control, read, understand and follow all label directions. Be thoughtful about the placement of these materials and prevent access by children, pets and other wildlife.
Whether you decide to trap or bait the mice infesting your home, remember that you must also eliminate access. If you don’t, new mice will just move into the vacated space in your home.
Melody Hefner is the Urban IPM and Pesticide Safety Education Program Assistant for the University of Nevada Cooperative Extension. Have a gardening question? Ask a Master Gardener at firstname.lastname@example.org.