Moles can do a number on your yard, garden

Q. I noticed mounds in my lawn where soil was dug up, which I think is the work of moles. What can I do to keep them out of my yard?

A. From what you have described, visible mounds of soil, I would agree you probably have moles residing on your premises. The raised mounds characteristic of feeding burrows, in addition to miniature volcanoes with plugged holes located close to deeper burrows, are common signs of mole infestation. If you have a garden, you may want to check for their presence there, as well.

Moles can commonly be found throughout most parts of the U.S. Because they are voracious eaters, they use their large front paws to tunnel through the ground in their search for food. These search efforts provide those visual cues that let you know they are present.

Their diet includes ants, earthworms and grubs; all of which enables them to consume more than their weight in food each day. Many homeowners find the presence of moles to be more than irritating. Molehills, when of substantial size, can damage housings and dull blades on lawn mowers.

If you have flowers and shrubs near your lawn, you may find them at risk as grubs often gather around their roots. The moles scrape the soil from the roots and deprive the plants of nourishment.

Your decision to go after these critters will depend on how much they have damaged your property and how it looks. If you want to use natural remedies, you can begin with the raised tunnels and molehills. These create primarily an aesthetic problem that can be solved by tramping down on the ridges using either a hand tramper or a good stomp of your foot.

If you want to prevent moles from tunneling under specific sections of your garden, you can vertically install metal mesh hardware cloth 2 feet below ground, and allow 5 to 6 inches to be exposed above ground. Moles tend to burrow deeper in summer than early spring, so this depth will help prevent activity during both seasons. Alternately, you could consider arranging stones to a depth of 2 feet around a garden border. Moles don't create problems in lawns in winter, because they want to get below the frost line, thus they dig deeper and don't create mounds.

Observational studies by Michigan State University showed moles often avoid fields planted with castor beans, which lead to research using castor oil. These studies showed castor-oil based spray repellent could keep moles away for periods of 30 to 60 days. However, other researchers at Ohio State University warn that use of castor oil to control moles can harm beneficial insects found in the soil, such as earthworms.

The Michigan State researchers also considered a number of other control options. Placing mothballs in mole tunnels, inserting vibration devices into the ground near their habitat, or planting mole-toxic plants such as marigolds, castor beans and fritillaria, were evaluated. However, these practices yielded ineffective or inconsistent results.

The most directly effective methods to get rid of moles involve trapping and poison baiting. If using a trap, make sure to place the trap in a frequently used tunnel. This may take some stealthy observation on your part, but remember the main function of these tunnels is to help the mole find food. The best traps for catching moles are the body gripping type and the harpoon type. You will find these at most garden supply or hardware stores.

Currently, the only general-use pesticide product available for homeowners is Talpirid/Tomcat Mole Killer. This poisonous bait is manufactured in the form of worms that are to be inserted into a mole's tunnel. Once ingested, the mole is killed within 24 hours. This product should be available at most garden supply stores or through garden catalogs.

You may find additional helpful information in the bulletin, Mole Ecology and Damage Management, available in PDF format at wildlifedamage.uwex.edu from the University of Wisconsin Extension, as well as information at www.msue.msu.edu. The latter, from Michigan State University Extension, provides more extensive information on home remedies and their limitations.

­— Mary Moisand

• Provided by Master Gardeners through the Master Gardener Answer Desk, Friendship Park Conservatory, Des Plaines, and University of Illinois Extension, North Cook Branch Office, Arlington Heights. Call (847) 298-3502 on Wednesdays or email northcookmg@gmail.com. Visit web.extension.illinois.edu/mg.