Controlling Moles In Your LawnMaster Gardener Scoop – June 29, 2016

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Controlling Moles In Your Lawn

Lawn moles are a common nuisance to many homeowners in Southern Illinois. Homeowners frequently complain of raised turf and soil mounds caused by these tunneling creatures. However, it is a misconception to think these animals are wholly detrimental. Before considering a treatment, consider understanding the biology of this unique animal.

The common eastern mole (Scalopus aquaticus) eats lawn insects and whatever worms, grubs, slugs, centipedes and spiders it finds under your turf. The star-nosed mole (Condylura cristata) is considered rare in our area. In their tunneling, moles aerate, fertilize and add humus as they remove the larvae of several garden pests such as cutworms and Japanese beetles. Before considering controlling moles as pests, there are many interesting things to learn about their biology.

Moles are highly territorial. In good habitat, moles seldom reach a density of more than three to five moles per acre. They will not tolerate another mole in their territories. Moles are solitary, and females drive off the young as soon as they are weened. If another mole wanders into another mole’s territory, they will fight to the death.

Females bear one litter a year of three or four offspring each spring. The young moles are fully grown and venture out on their own when about three months of age.

Moles lift the turf to create feeding tracks. The tracks meander and once used are seldom revisited. To the contrary, straight tunnels are used by moles to access deep dens and other feeding tubes. Moles frequent straight tunnels as runways. Moles also excavate a third tunnel, usually straight down, reaching to a depth of three to five feet for the purpose of escape, nesting, birthing and rearing their young. These include larger rooms lined with leaves and grass and may crate multi-chambered galleries.

The tunnels represent food traps for moles. Moles are voracious eaters, consuming up to their full weight each day. Worms and grubs, mole’s chief food-source, accumulate in the cool, moist tunnel environment where the mole makes frequent forays to gather them as food.

Controlling moles combines skill and luck. Applying a pesticide that kills earthworms and grubs eliminates the mole’s food source but may also remove beneficial organisms as well. A better approach would be to apply a yearly application of insecticidal nematodes, or to inoculate the soil with a bacterium under the trade-name of “Milky Spore,” which will only kill the larvae of beetles such as Japanese beetles and June beetles. Expect both of these methods to take a few seasons to remove moles.

Trapping is more difficult but considered most effective of any control. Traps spear, strangle, or crush moles in their central runways. Traps require trial and error learning but yields a recognizable victim. One disadvantage to traps is that moles may return in areas or years of adjacent high mole populations.

Many home remedies and folklore exist for removing moles from our lawns. Sound-producing devices range from a child’s pinwheel stuck in the ground to solar-powered noise makers, and they may temporarily reduce moles within a 50-foot radius. However, moles acclimate to these non-lethal techniques and soon disregard them. Ionic pulse sounding devices are not proven effective and should be avoided. Fumigants such as gas cartridges can be dangerous. Mouse and rat baits and poison grains are not usually effective since moles are nearly entirely carnivorous. Fruity chewing gum has been an unproven folk-cure for many years.

If you live next to forests, pastures or other unmown fields, expect moles to never entirely leave your lawn. The benefit that moles leave behind must be weighed against any apparent damage. In most cases, damage is temporary and wholly cosmetic. The aforementioned benefits contribute to a better lawn. Once the food source becomes scarce, the moles move on to “greener-pastures” elsewhere.

For more information on controlling moles or other garden pests, please consult your local Master Gardener, the University of Illinois Extension office, or your local public library.