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.
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.