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Voles, or meadow mice as they are often called, belong in the rodent group. They are heavyset, greyish-brown rodents with tiny ears, small, dark eyes, and a relatively short tail. Adult voles reach 4-7 inches including their tail. Populations may periodically explode (usually about once every 4 years) and reach several hundred mice per acre in good, grassy habitats. This is a much higher density than thirteen-lined ground squirrels which typically infest an area at levels of 2-8 per acre and the relatively solitary moles and gophers.
Unlike the other small mammal pests, voles do not burrow extensively underground.
Much of the damage caused by voles results from their girdling the bark from trees and shrubs. Damage is most severe in winter when food supplies dwindle and the voles are protected from predators while burrowing beneath the snow. Thin-barked trees are the preferred food of voles. Voles can also cause damage to turf by clipping the grass close to the roots when they construct surface runways beneath the snow. Turf damage usually isn't as bad as it appears. Rake away the dead grass in spring and surrounding grass will quickly fill in the area.
Monitoring should begin in early fall when the voles are constructing nests. Runways in the grass, fresh grass clippings, feces and sightings of the animals as you walk in the grass are indicators of a population.
Frequent mowing and maintaining a grass-free area around young trees will reduce damage and destroy hiding places. Severe weather and food shortages will reduce mouse populations.
Placing 1/4 inch mesh hardware cloth around the base of young trees will physically exclude voles from feeding on the plants. Be sure to submerge the hardware cloth at least 2-3 inches beneath the ground to prevent voles from burrowing under. It should extend at least 18 inches above ground as well to prevent damage higher up the trunk during the winter when snow cover can afford the voles access higher up on the trunk of the tree. Wire mouse guards may remain in place for up to five years but they should be checked annually and removed or replaced to prevent the tree from growing into, and incorporating, the hardware cloth.
Trapping is an effective way to eliminate voles in small areas. Mouse-size snap traps baited with peanut butter, oatmeal, or apple slices placed perpendicular to the runways will reduce vole populations in small areas. Another option is to place two traps, back to back in the runway so the vole will be trapped regardless of the direction from which it comes in the runway. The best time to set such traps is in mid-October through mid-November before snow covers the ground. This may be impractical in some situations because of the presence of children in such areas at that time and the chance of a child becoming injured as a result of tampering with a trap. However, traps may be placed along building foundations behind boards or boxes leaning against the building to minimize problems with children and other animals.
Hawks, owls, foxes, skunks, weasels and snakes are predators of voles. Encouraging predators may be a viable control option. Owls in urban areas often don't use owl boxes so using these will likely not attract owls as a predator.
Chemical repellents are available to control voles but should only be relied upon as a temporary means of control. Most commercial repellents contain the fungicide thiram but some are available that contain capsaicin, the chemical found in hot peppers. Repellents should be applied in late fall and reapplied in winter when weather permits.
Rodenticides are available but may not be practical for use on school grounds. The most widely used rodenticide contains zinc phosphide in pelleted form. Non-target animals and children can become sick or die from eating the bait which is why they are not recommended for use on school grounds. Keep in mind, however that rodenticides such as the anticoagulant Volid are the only practical way to control high vole populations. In these situations, lockable bait stations can be used to reduce the risk to children and other non-target species.
UWEX publication A2148 "Meadow Mouse Control" by Scott R. Craven. 3pp.
