Controlling moles in your lawn

By Jim Crawford

Sunshine warming the soils have started the return of moles to mess up our otherwise “perfect” lawns. Moles are small mammals that spend most of their lives in underground burrows, seldom seen by humans. Mole activity usually shows up as ridges of upheaved soil. The ridges are created where the runways are constructed as the animals move about foraging for food. Burrowing occurs year-round, but peaks during warm, wet months. Some of these tunnels are used as travel lanes and may be abandoned immediately after being dug. Mounds of soil called molehills may be brought to the surface of the ground as moles dig deep, permanent tunnels and nest cavities.

Moles prefer moist, sandy loam soils in lawns, gardens, pastures and woodlands. They generally avoid heavy, dry clay soils. They construct extensive underground passageways - shallow surface tunnels for spring, summer and fall; deep, permanent tunnels for winter use. Nests are located deep underground.

Moles often are more of a nuisance than a financial liability. The ridges of their tunnels make lawn mowing difficult. Since the roots are disturbed, grass may turn brown. Moles rarely eat flower bulbs, ornamentals or other vegetative material while tunneling, but plants may be physically disturbed as moles tunnel in search of animal organisms in the soil. Mole activity may indirectly damage vegetation, but their feeding on insects and other soil organisms is beneficial.

Because moles have high energy requirements, they have large appetites. They can eat 70 to 80 percent of their weight daily. They actively feed day and night at all times of the year. Moles feed on mature insects, snail larvae, spiders, small vertebrates, earthworms, and occasionally small amounts of vegetation. Earthworms are their preferred foods.

If you are like most homeowners, you are probably confused by all of the conflicting advice on mole control. Numerous home remedies have been used, but results are inconsistent and generally ineffective. Remedies such as pickle juice, broken glass, red pepper, razor blades, bleach, moth balls, rose branches, human hair balls, ground vibrators, ultrasonic devices, castor bean derivatives (Castor Oil), and explosives may relieve frustrations, but they have little value in controlling moles and may harm you or the environment. Furthermore, certain chemicals or explosives are illegal to use.

On large properties, mole activity may move from one part of the lawn to another. This movement is affected by climate and ground moisture. Moles will respond to changes in food supply as it becomes available in different places and at different times throughout the year. If disturbed, moles may temporarily leave an area but will usually return. Even without disturbance, mole activity may last only a week or two in a particular area. This here-today, gone-tomorrow behavior is probably the root of most of the misconceptions that make some home remedies appear credible.

In practice, packing the soil with a roller or reducing soil moisture may make an area less habitable for moles. Because moles feed largely on grubs and worms, the use of insecticides to control these organisms may reduce their food supply, causing them to leave the area. However, before leaving, the moles may increase their digging in search of food, thereby possibly increasing damage to turf or garden areas.

The repellent Thiram is federally registered for protecting bulbs from mole damage. Mole repellents with castor oil as the active ingredient are now on the market and may potentially prevent eastern mole damage under certain circumstances. In using any repellent, follow directions and application rates provided on the package label. Also be aware that using any repellent for controlling moles has limitations and may not eliminate damage or effectively control the problem.

There are a number of difficulties in poisoning moles. Since moles normally do not consume grain, seeds or nuts, poison baits are seldom effective. However, in the past few years, several, similar products have come on the market that do an excellent job of controlling moles. These are sold under the names Talpirid, MOTOMCO, Tomcat mole killer and others. These products look like, feel like and presumably taste like earthworms, a moles primary diet. Talpirid is the only mole bait that has submitted efficacy studies to the EPA. Make sure to follow all label instructions.

Fumigants are also federally registered for use against moles. They are aluminum phosphide, calcium cyanide and gas cartridges. Most of these are restricted-use pesticides. These fumigants are much more effective if the material is placed in the deep mole burrows, not the surface runways. Care should be taken when using chemicals and the label instructions should be read, understood and followed.

Trapping is one of the most effective and practical method of mole control. In general, trapping success is greatest in the spring and fall, especially after rain. In the summer and winter, moles are active in deep soil and more difficult to locate. Three types of mole traps are especially effective: harpoon, scissor-jaw, and choker loop. To ensure safe and humane deployment, be sure to follow printed instructions that come with the trap.

Proper placement of a poison, fumigant or trap is critical. Moles will feed on earthworms and grubs every two hours, 24 hours a day. Once a mole has eaten the food supply throughout a run, the mole will stop using that run and start a new one. Mole traps and baits must be placed in the active runs to be most effective. That makes good scouting essential. To find active mole runs, poke a hole through the top of the run. Mark the location with a flag or stick a few inches to the side of the run. In about 2 hours, check the run and if the hole is repaired or plugged back up, the run is active and will be a good location for baits and traps.

For more information, stop by your county University of Missouri Extension Center for a copy of MU Guide G9440, Controlling Nuisance Moles or access it from the Internet at https://extension2.missouri.edu/g9440.

Jim Crawford is a Field Specialist in Agricultural Engineering with the University of Missouri Extension.