Moles and voles

Should I be concerned?

The mole can be considered beneficial in some ways since it eats insects, including grubs, other insect larvae, and slugs. Moles also feed on earthworms, and some will even eat small snakes and mice.

But the mole and its tunnels can damage lawns, gardens, parks, golf courses, and cemeteries. They can kill plants when tunnelling by removing soil around roots (the unprotected roots then dry out and die). Plant diseases may also be spread by the mole's movements. Pests like voles, field mice, and other rodents use these tunnels to feed on exposed roots.

Moles do not hibernate. They remain active day or night all year long. During the winter, the mole looks for food deep below the frost line. Most surface activity happens in the spring and fall. Moles are solitary animals, and it is likely that only one or two moles are responsible for the damage to your lawn or garden.

How do I know if I have a problem?

Moles create an extensive network of tunnels, many of which are used only once. Temporary surface tunnels are where the sod is raised and looks like ridges. These feeding tunnels are used a few times, then abandoned. Deeper tunnels from which the mole must dig dirt, forming molehills, are used mainly as the living quarters.

You probably have a vole infestation if you find:

• bark that has been removed completely around the base of a tree (girdling)
• 2.5 to 5 cm (1- to 2-inch) wide dead strips (surface runways) through matted grass leading to shallow underground burrows
• small piles of brownish droppings (feces) and short pieces of grass along the runways

How can I get rid of moles?

Physical control

Licensed pest control operators may offer a trapping service, or traps can be rented from them or a farming co-op. Be sure to ask for instructions on the proper use of mole traps if you decide to set one.

• To ensure success, trapping efforts should be concentrated on the main runways in the spring and fall.
• Look for tunnels that appear to directly connect two or more mounds that run parallel to permanent structures (like fences or concrete paths), or that follow a tree line bordering a grassy area.
• Another way to find an actively used run would be to lightly step on a small section of several tunnels so that they are disturbed, but not completely collapsed. Make sure that these disturbed sections are clearly marked. After a few days, the raised sections can be identified as active runs, and therefore good locations for traps.

To a certain extent, a healthy lawn where the risk of grub infestations is minimized will be less attractive to moles. Cats or dogs can also discourage a mole from entering a yard.

Products

• Baits are rarely taken by moles because they prefer to feed on soil insects. Some baits containing zinc phosphide are available only to licensed pest control operators. No registered baits are available to the general public.

How can I get rid of voles?

Physical control

• Cleaning up all possible food sources like vegetables left in the garden at season's end will help keep voles and other rodents away from your yard. Removing mulch from the base of fruit trees in winter will also help avoid an increase in vole numbers. If you intend to put mulch down on strawberries or other perennials, do so only after the soil freezes. If you do so before the soil freezes, you will be providing an ideal location for rodents to gain access to roots in unfrozen soil.
• Use metal or glass rodent-proof containers to store seeds and bird feed. Composters should also be inaccessible to rodents.
• Gravel or cinder barriers around garden plots are an effective and easy means of protection. The barrier should be 20 cm (6 to 8 inches) deep and a foot or more wide. The sharpness of cinder particles deters voles from pushing their noses into the soil.
• Commercial plastic tree guards, a piece of chicken wire or small mesh wrapped around the base of trees and extending below the soil will help prevent tree girdling. Talk to your local tree specialist for how to use these materials properly.
• Traditional snap mouse traps can be used. Place them in areas where voles are known to be. Barricades may be used that allow only voles to enter a trap. Buy a large number of snap-traps and set them all out at once for a one- or two-night period. A good technique is to bait the traps with a tiny dab of peanut butter or bacon for two or three nights without setting the traps. When the traps are finally set, voles are less likely to shy away from them. Always exercise extreme caution when handling a trap and keep them out of the reach of children and pets.

Predators

Natural predators including cats, owls, and snakes can help keep the vole population down.

Products

• Treated baits may be needed if populations have built up. Baits are available in home garden centres and are registered for the control of voles. Licensed pest control operators can use commercial baits containing different active ingredients.
• Registered animal repellents can be sprayed on plant surfaces to deter voles from chewing. Animal repellents have an extremely bitter and unpleasant taste. They should not be used on food, edible plants, or directly on the fruits or nuts of trees. Do not use them on sugar maple trees if the sap is being used to make syrup, since the taste of the maple syrup may be affected.