As the weather cools and bears are headed to hibernation, mice may be seeking the warmth of your home and voles may be setting up their homes in your landscaping. How do you keep these unwanted visitors out of your house and protect your landscape plants?
Start inside the house by storing food in rodent proof containers. Store cereal, rice, flour, noodles, chips and other foods in either metal or heavy plastic containers with tight lids. Immediately clean up any food spills. Keep the area where you feed your pets clean and don’t leave their food out after they have finished eating. Make sure that you do the same in your garage if you store pet, bird or poultry feed there. Metal trash cans with tight fittings lids work well to keep rodents out of livestock feed.
Exclusion is essential to keep mice out of the house. Check around your house for openings where mice can enter. Mice can squeeze their bodies through a ¼” diameter hole, basically the size of a pencil eraser. One of the most likely places for them to enter is an opening around the pipes in your house. Start by finding where pipes come through the foundation or walls and under sinks. The opening in the foundation, wall or cabinet base is normally larger than the pipe diameter and the pipe is a great pathway into or around the home. The easiest way to close these openings is to stuff steel wool into the opening. You can use a spray foam insulation to secure the steel wool in place. Don’t use the foam by itself as mice like to chew on it. You need the combination to keep them out.
Look around your foundation for cracks or other openings that are ¼” diameter or larger. You can repair those cracks or openings using steel wool and caulking or foam. For any vents (i.e. dryer vent or other air vent) that are near to the ground, cover them with heavy duty screen material (also known as hardware cloth) with openings of ¼” or less.
Another rodent that you may have problems with over the winter is the vole. While they most likely will not enter your home, they can damage or kill landscape plants. Vole damage tends to be cyclical with more damage occurring during those years when we have snow cover lingering for longer periods. The voles make tunnels under the snow and avoid being caught by their predators. For the plants that you can protect such as shrubs and young trees, enclose the trunk with heavy duty screen with less than ¼” size openings. If you can, bury the screen a couple of inches deep into the soil. Mature trees do not need to be protected as their bark is thick enough to keep voles from chewing on them. During the winter when we have snow cover, voles create tunnels under the snow and chew on the lower bark and roots of young trees and shrubs. If you have shrubs like junipers with branches laying on the ground, remove the lower branches so that a predator such as a fox or your pet can get to the voles. Doing one last fall mowing of your lawn also helps to keep voles from doing as much damage.
If you live near an open field or open space, you can expect to have more problems with both rodents. There’s a limit to what you can do if you live in this situation with exclusion being your best tool. Pets, cats and dogs, can help by hazing the rodents and providing a “predator” odor around your property.
By Sharon Bokan, Colorado State University Extension Boulder County. Sharon is the Small Acreage Coordinator at Colorado State University Extension Boulder County. For more information call 303.678.6176, e-mail firstname.lastname@example.org or visit ext.colostate.edu/boulder.