Moles in the Lawn and Landscape

Donald P. Reed, Koske, Thomas J.

Few people have ever seen a live mole. Many, however, are well aware of the damage they cause to lawns and flowerbeds.
Most individuals think moles feed primarily on the roots of plants and cause them to die. The truth is that a mole’s feeding on plant material is limited. It's the air pockets they create around roots and flower bulbs that cause plants to dry out and die.

The eastern mole's (Scalopus aquaticus) range of distribution reaches all of the eastern United States and most of the Midwestern states. A mole lives most of its life underground; they are highly specialized animals for their subterranean way of life. The eastern mole is a small, sturdy animal, 5  to 8 inches long, with a somewhat cylindrical body and elongated head. The eastern mole is grayish-brown on the back to pale or darker brown on the belly. The velvety fur often has a silvery sheen. Occasionally bright orange or cinnamon-yellow markings will occur. The fleshy snout serves as a highly sensitive organ of touch and smell to seek out numerous food sources. The tiny eyes are concealed in fur and covered by fused eyelids; sight is limited to distinguishing light from dark. The greatly enlarged front feet are normally held with the soles vertical and pointing outward. They have well-developed claws that have a specialized bone attached to the wrist, which aids in digging.

Moles construct networks of tunnels near the soil surface. Many of these are built after rains when the mole is in search of new sources of food. They are usually not re-used, so be sure the tunnels you watch are active. Digging surface tunnels normally proceeds at a rate of 1 foot per minute. They tend to feed and rest on two-hour cycles, 24 hours a day. Animal-material foods constitute about 85 percent of their diet. This includes earthworms (their main source of water) and grubs; however, they eat millipedes, centipedes, spiders, sow bugs, snails and slugs, too.

Now if you have grubs and they are slowly thinning your turf, you will probably want to control them anyway with soil insecticides, but moles do eat other things. Moles are insatiable eaters and can consume 70 percent to 80 percent of their body weight daily. Moles generally move up or down within the soil profile to follow food sources such as grubs and earthworms, which move with soil moisture. That is why we do not see much mole activity during a droughty summer; but with spring and fall rains, activity abounds.

Moles also create mounds of soil (called molehills) in the lawn by pushing up soil when developing deeper, permanent tunnels and nesting cavities. Mating occurs in the spring with a single annual litter of two to five. High infestations are as few as two to three moles per acre.

Management or Control

A number of home remedies are often suggested to control or repel moles. These are not effective, and some are dangerous, so simple home cures are not recommended.

Homeowners can buy products at local nurseries or garden centers to help control moles. Most work as repellents based on castor bean oil as the active ingredient. These products need to be sprayed regularly to maintain a barrier that repels these small mammals. Planting a barrier of toxic plants such as castor beans, marigold or fritillaria has no research to support the repellent claims.

Controlling earthworms is not recommended because they are considered a beneficial organism that aerates the soil and breaks down organic materials. Only thiodan and carbaryl (Sevin) are commonly available insecticides that can significantly reduce earthworm populations. The grub rate for carbaryl (4 to 8 pounds of active ingredient per acre) has been shown to reduce earthworms for a season. Benomyl fungicides and the insecticides of methomyl, bendiocarb and aldicarb damage earthworm populations. Remember, however,moles do eat other things.

If you have a mole building mounds, there really isn't much you can do unless you catch it in the act and move quickly with a spade or shovel. Your success with these tactics, however, is very limited.

At least two toxicants are registered for use in controlling moles around the home and garden. Zinc phosphide formulated at 2% active ingredient is available in a product sold under the trade name of “poison peanuts.” Poison peanuts are pelleted bait that uses grain as the carrier to entice moles in consuming the product. A major problem is that moles seldom feed naturally on any type of plant material, including cereal grains. Control by the use of this product is often accomplished by moles picking up the bait incidentally as part of their normal feeding habits. The pelleted bait is also not weather resistant; rainy or damp conditions will lead to poor bait acceptance after a short period.

A recently introduced bait on the market shows great promise for controlling moles. The commercial poison bait known as “Talpirid” is formulated to look, feel and handle like an earthworm or night crawler -- a mole’s favorite food. Tests have shown acceptance of this bait, even when live earthworms were present as an alternate food source. It can be purchased online.

Trapping is another and best recommended control measure. Two common and effective traps are the scissor and the harpoon; just be careful with your fingers! If you have the active network of shallow runways used for feeding, then you can do some effective trapping with harpoon traps. Deep runs are better hunted with scissor traps.

First, with a small stick or broom handle, poke holes in various runways over the entire network. Come back two hours later and inspect those holes. Find the tunnels with the holes plugged back up. This indicates which runways are active feeding tunnels. These are the tunnels where you want to set your traps. The key in trapping is to locate the active runways.

Second, select a straight section of tunnel to set your trap. There are several types of traps to choose from; simply follow the instructions of the manufacturer. The Nash trap (wire hoop type) and the Victor "Out O' Sight" trap (scissors type) do work, but seem to be more difficult to set. The Victor "Harpoon or Gig" type of trap has been the most successful trap. You may do well to bait the tunnel with some earthworms or grubs where the trap is to be set. To set the trap, take your foot and push down a 4-inch swath of the runway. Before setting the harpoon, push the trap into the soil with the gigs over the runway and move up and down several times to reduce the friction of the soil against the gigs. This will ensure a quick and decisive thrust of the harpoon. While the trap is in the soil, pull the harpoon up and lock it in position with the trigger pan (flat plate) slightly touching the depressed runway. Your trap is now set.

Third, poke a hole in the runway on each side of the trap a foot away, then wait several hours or until you notice the trap has been sprung. Check traps daily because something will happen soon if it's going to happen.

Fourth, look at the holes on each side of the trap. If one hole is plugged with the trap sprung, then you have more than likely caught the mole on that side. This is where you need to be prepared with a spade in hand to retrieve the trap. If both holes are plugged with the trap sprung, then the mole probably made it through the trap. Simply reset the trap on the same runway or over another active runway.

Remember, controlling and trapping moles require a little time and patience. Your success with controlling moles depends on locating active runways and the proper placement of a trap. You must find an active run on which to set the trap. Find a straight section of this run to  trap on and avoid the soil mound areas on the runs. Trip the traps to ensure they will work. Check traps daily. If you don't catch the mole in a day, move to more active run. You might try cleaning the traps or treating them with a light oil spray to hide human scent.

For more details and mole insight, go to
4/18/2005 10:49:39 PM
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