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With a habit of burrowing and creating unsightly tunnels that damage roots and weaken the surface of lawns, the eastern mole (Scalopus townsendii) has established itself as an annoyance in yards across Iowa. Fortunately, tried and true methods are available to help keep this invader at bay.

Habitat: The eastern mole is a common inhabitant of meadows, pastures, lawns, cemeteries, playgrounds, golf courses, sports fields, parks, open woods, and stream banks. Moles are especially attracted to areas with a steady supply of soft-bodied invertebrates (earthworms and grubs) to eat and soil that is moist but well-drained for ease of burrowing. Sandy or loamy soils provide ideal habitat, while heavy clay soils and excessively rocky or compacted soils are less appealing for burrowing. However, moles sometimes manage to tunnel through seemingly unsuitable soils to reach preferred areas, causing characteristic damage along the way.

Diet: The eastern mole’s habit of actively pushing or “swimming” through soil requires considerable energy. As such, a mole must consume nearly 100% of its body weight each day. Although they are often mistakenly thought of as plant eaters, moles are predators that use their exceptional sense of touch to capture invertebrates, such as centipedes, earthworms, grubs and other insects. Seed pods and other vegetable matter make up a much smaller proportion of a mole’s diet. Therefore, the damage caused by moles is primarily the result of tunneling, not the direct consumption of plants.

General biology: The eastern mole is a solitary animal except when mating, which occurs in late winter or early spring. Three to five young are born after a gestation period of six weeks. The young grow quickly and leave the underground nest chamber at about one month in age. Rainy days during late spring and summer usually trigger the greatest level of activity in moles, as they frantically gather food during this time. Prolonged periods of rain are an annual source of mole mortality. Drier conditions cause moles to burrow more deeply into the soil. Because moles do not hibernate, these deeper tunnels serve as year-round food resources, which are especially important during harsh winters. Their underground lifestyle also keeps them safer than most small animals, although raccoons, badgers, skunks, foxes, coyotes, and dogs sometimes dig moles out of their burrows and hawks and owls occasionally snatch moles from the surface.

Damage identification

Once a mole invades a yard, it can cause considerable damage almost immediately, especially when in pursuit of prey. In fact, a single mole can tunnel up to 18 feet per hour in suitable soil. A key to managing moles and curtailing their conspicuous damage is first correctly identifying their sign:

• Volcano-shaped mounds of soil with no entrance or exit holes are pushed up from deep below the soil surface.
• Raised linear ridge(s) of soil running through grass of lawns that ultimately become a complex network of multiple lines entering and exiting yard 
• Mounds and ridges are most common in the shaded portions of lawns and similar sites
• Soil around ridges and mounds feels soft and spongy.

Pocket gophers can invade some of the same areas as moles. However, pocket gophers build large, crescent-shaped dirt mounds, which often have a 1-3 inch wide plug in the middle where the gophers exit the ground to feed on the surface (which moles never do). These structures are distinct from the conical or volcano-shaped mounds and raised ridges made by moles. Meadow voles make narrow runways along the surface of grassed sites, which differ from mole runways beneath the soil surface.

Removal of Nuisance Moles

Trapping is the most effective and safe method of removing moles. Two commonly available trap types are sold at hardware and farm stores and can be targeted to capture moles in the same way. The key to successfully capturing problem moles is setting traps in the right places. Follow these suggestions for finding the right places for traps

• Place traps along long stretches of tunnels that moles most frequently use. Traps are not effective on mounds.
• Target long, straight stretches of tunnels or places where tunnels enter or exit the yard.
• Avoid tunnel sections with lots of bends ot twists.
• Stamp down the top of all the tunnels in your yard on one day and return the next to find which tunnels are frequently used. Some tunnels are runways while others are used only occasionally for feeding. You want to target traps on runways used regularly.

Setting a scissor-jaw trap

• Excavate soil at the targeted section to expose the underground tunnel.
• Replace excavated portion with loosely packed fine soil.
• Force the jaws of the trap directly into the soil until the trigger pan rests on the repacked soil surface.
• Make sure the jaws are aligned as evenly as possible on either side of tunnel, with the points of the jaws about 1 inch below the bottom of the tunnel.
• Push the jaw levers apart to lock them into place; many scissor-jaw traps have a hair-trigger mechanism to make them spring more easily.
• Fill the hole on top of the trap with loose soil and ensure that no obstructions will interfere with the closing jaws.

Setting a harpoon trap

• Press down on the ridge of tunnel to allow space for the trapping mechanism.
• Raise the spring and set the safety catch.
• Push the spikes into the ground so that the tunnel runs between them; make sure the “trigger pan” rests right on the ground above the tunnel
• Release the safety catch (this enables the impaling spike to be forced down into the ground by the spring)
• Set the trap and leave it; avoid walking on any portion of the tunnel system
• If the trap is set properly, the impaling spike will shoot down through the burrow when triggered by the mole.

Weighing costs versus benefits: Before you set out to eliminate moles from your property, consider the following: moles play an important role in soil aeration and fertilization, along with consuming harmful insects and grubs. For instance, moles prey heavily on the “white grubs” that ruin vast sections of lawns and golf courses. As such, determine whether removing a mole and its associated damage is worth the resulting increase in lawn pests. Furthermore, when you remove a mole, another one may quickly move in, leading to an ongoing removal process.

This article is an update of "Managing Iowa Wildlife: Moles" (PM-1302b) originally authored by Kurt Johnson and James Pease.

Every winter, after the snow melts and our brown, dormant grasses see the sun for the first time, we often find evidence of the busy lives of the meadow vole. While we were snuggled warmly indoors during the long winter, these mouse-sized creatures were actively feeding on seeds and vegetation and building an intricate trial system under the blanket of snow to stay alive and warm.

The meadow vole is a small, chestnut brown rodent that is seldom seen but very common all over Iowa. The tunnels it makes beneath the snow are, in fact, lined with thatch from last year's grass, giving them added insulation and perhaps some protection from the many hawks, owls, foxes, and other predators that feed on them. Voles have longish fur that almost hides their small ears and eyes. Their tail is short, usually no more than an inch, about a third the length of their body. Their legs are also short but they move quickly. About all we ever see of them is a brown blur beneath our feet as we walk through an Iowa meadow or prairie.

Since they serve as food for so many predators, they need to be prolific and produce a lot of young. Voles are sexually mature at about 32 days of age and, with sufficient food supplies, can breed year-round. With several litters per year, populations can build quickly. Localized vole population "irruptions" are not uncommon. Just as quickly, however, local populations may practically disappear. Populations of voles are highly variable from place to place and season to season.

Voles eat a variety of plants, especially grasses and wildflowers or forbs. In late summer and fall, they gather and store seeds, tubers, and bulbs. They also eat the bark of young woody plants and, when populations are high, can eat food crops, especially small grains, and destroy alfalfa fields. Unlike other mice, they almost never enter houses. They may be mistaken, however, for another small mammal that does get into houses: the short-tailed shrew. Though they may look the same, they are not even cousins. The shrew is an insect-eating mammal, a close relative of the common mole.

The runway evidence of voles' presence is most obvious in the early spring as snow cover disappears. However, close inspection of grassy areas during the growing season may also reveal less obvious runways in the turf, sometimes including the top 2-3 inches of soil. There are often numerous entrances to this runway system and the vegetation is often closely clipped or dead in well-travelled runways. The runways are 1-2 inches in diameter and typical mouse feces may be found in them.

In addition to damage to turf, voles most often injure, weaken, and/or kill young trees and shrubs by gnawing at the bark and often girdling them completely. This most often occurs in the fall and winter but is not obvious until the spring. The plant may partially leaf out and then suddenly wilt and die. Close inspection of the base of the plant will reveal girdling of the bark at or near the soil surface. Other chew marks at various angles up to 2-3 inches above the surface also indicate vole damage.

As with most wildlife damage management, a combination of techniques leads to the most effective program:

Reduce cover by mowing. In turf areas, including lawns, golf courses, orchards, and parks, vole populations can be kept to a minimum through regular mowing. Though the grass tunnel systems are evident in the spring in many turf areas, as soon as mowing begins, the animals must retreat to areas of deeper grass in order to survive. Mowing exposes them to heavy predation. Occasional mowing in areas adjacent to turf areas will also reduce cover and expose them to predation. This is recommended, however, only in areas of high vole populations.

Exclude voles from around trees and shrubs by installing 1/4-inch mesh wire cylinders around young trees and shrubs. These should extend, where possible, into the top 1-2 inches of the soil. Pre-emergent herbicides used around the base of woody plants prevent voles from finding food and cover there. Mulches, if used around such plants for moisture retention, should consist of gravel or cinders whenever possible. If softer materials, like bark and wood chips, are used, they should be scraped back from the tree during the fall and winter months.

If you insist on reducing the vole population, trapping is the most effective method. For most lawn areas, common wooden mouse snap-traps, baited with peanut butter (or a peanut butter and rolled oats mixture) and placed along the runways at right angles to them can quickly reduce vole populations in a matter of a few days.

Additional resources

• Controlling Vole Damage from the University of Nebraska
• Managing vole damage in orchards from Penn State University

Photo credits: Meadow vole, Roger W. Barbour, Smithsonian Natural History Museum; Vole tracks, http://ICWDM.org