Voles — the often unseen killer in the landscape

As we begin to refocus our activities from those outdoors in the landscape to the warmth and comfort of the indoors, it is important to remember that there are powerful forces at work in your landscape that continue right through the winter with damage often unseen until spring — when it is too late.

One of these small but mighty forces is the common vole. No, that is not a typo — V-O-L-E, not M-O-L-E.

I think we are all pretty familiar with the power and destruction of moles, but all too often, it is voles that result in substantial and sometimes permanent and costly damage to landscape plantings.

Voles, also known as field mice, are small brown rodents very common in yards and fields. Their presence is most often observed in the late winter and early spring right after the snow melts, when their grassy trails are laid bare and areas of dead grass appear.

The most serious damage from voles is the harm to small trees and shrubs when they chew on the bark, often hidden below winter snows or even mounded mulch (another good reason to limit mulch depth).

Voles spend a great deal of time eating grasses and roots and making trails. These surface runways are one of the easiest ways to identify the presence of voles. Even these runways can go unseen until early spring just after snow melts.

Voles also will make small holes about 1 inch across and underground tunnels to get to tubers and bulbs. They will even use mole tunnels, which is proof that misery loves company.

This often causes moles to be blamed for eating roots, instead of the white-grubs they actually eat.

Vole damage also may be noticed on trees and shrubs where they have chewed through the bark very near the ground. The vole’s front teeth will leave side-by-side grooves in the wood. Oftentimes, this damage goes unnoticed until the tree leafs out in the spring and then suddenly collapses, and even then it is unseen without close observation of the base of the tree.

The good news is that like most rodents, voles have a short life expectancy and are a prime food source for many predators such as snakes, hawks, owls, foxes and badgers. The bad news is that they are very productive breeders. One female vole can have five to 10 litters in a year averaging three to five young and are able to breed at 3 weeks of age.

Vole populations cycle, and about every three to five years there will be a population boom. Mild winters with good snowfall can help to increase vole populations.

Sanitation may help keep vole numbers down. Removing woodpiles and other debris from the ground and keeping grass trimmed short and bushes trimmed up from the ground may reduce hiding places for voles. Bird feeders are another attraction for voles and should either be removed or the ground kept very clean.

While lawn damage is most visible in the spring, it is rarely permanent. Simply rake up the dead grass and reseed the area. As the surrounding grass grows, it will cover up the trails.

Vole damage to tree bark, on the other hand, may be permanent and is best prevented by encircling the tree with a tree guard such as a cylinder of ¼-inch hardware cloth tall enough to reach above the snow line in the winter with the base buried in the soil. Make sure that the guard is loose enough so that it doesn’t constrict the tree.

In small areas, trapping may be an effective way of reducing vole populations. Standard mouse snap traps set along runways or near tunnels baited with peanut butter or small apple pieces will catch some animals. You may want to cover the traps so that pets and children do not accidentally find them.

Large vole populations can most effectively be reduced with toxic baits. Be sure to read the label before you buy any pesticide and again before you use the pesticide.

Vole baits should be placed inside bait stations to reduce the risk of non-target species ingesting the bait. Old asphalt shingles bent in an A-shape make a good bait station and allow voles to feel safe enough to eat the bait provided. Placing these stations a few days in advance of baiting them will allow the vole to become accustomed to them.

Baits, while effective, can be a direct hazard to non-target species either by direct consumption of the bait or by consuming dead voles.

In general, fumigants, repellents and frightening agents (aside from a good cat) are ineffective.

Voles are always there, and for a great portion of the year, they largely go unnoticed, but if one sees a lot of holes and runs in the landscape, it is probably a good idea to get ahead of the situation before the damage escalates.

Roy Ballard is an agriculture and natural resources educator with the Hancock County office of Purdue Extension. Contact him at 317-462-1113 or rballard@purdue.edu.