How to deal with moles

Moles are easy for homeowners to hate. When they discover mounds in their lawn or next to a beloved plant, most people want to deal with moles quickly and effectively. Unfortunately, dealing with moles is not easy, and many methods are not very effective. Here are some tips and perspectives.

1. Identify the animal

First, make sure you are dealing with moles and not voles or pocket gophers. All three are small mammals that tunnel underground.

Moles have short black, gray or dark brown hair and a prominent, hairless snout. Their eyes are very small because they live underground. They have large front claws, designed for digging, that face out to the sides. The presence of moles is often discovered because they dig tunnels that result in raised ridges of dirt running across a lawn or yard. They pile mounds of soil at their tunnel entrances. Moles eat mostly earthworms and insects along with small amounts of plants.

Voles, which look like field mice, are small rodents. They dig holes, but they are not as deep as mole tunnels. Voles eat plants, while moles eat insects. According to WSU Extension, voles eat a wide variety of mostly grasses and forbs during the summer. They eat roots, bark and bulbs during the winter. “Damage is usually identified easily by the tiny tooth-scars on woody plants.” Read about how to manage voles.

Pocket gophers have stout bodies, small ears and eyes, large clawed front paws and large front teeth. Their mounds are crescent-shaped. They may eat plant roots, bulbs, vegetables, and the leaves and stems of plants.

Moles and voles are found locally (King and Snohomish Counties), whereas pocket gophers are more commonly found in the Olympic Peninsula and southern Puget Sound (Thurston, Pierce and Mason Counties), said the Washington Department of Fish and Wildlife (WDFW). The Mazama pocket gopher is listed as threatened. Read about how to deal with pocket gophers.

2. Try living with moles

Moles play an important ecological role. “They make a significant contribution to the health of the landscape,” said WDFW. “Their extensive tunneling and mound building mixes soil nutrients and improves soil aeration and drainage. Moles also eat many lawn and garden pests, including cranefly larvae and slugs.”

Grubs and other larvae are favorite foods of moles. Larvae from chafer beetles and crane flies can damage the lawn, so getting rid of moles could increase your population of these pests.

How do you live with moles? WDFW suggests removing the visible presence of the mole:

• Molehills: Remove them as they appear with a shovel, rake or your hands. Spread grass seed over large bare areas during the rainy season.
• Surface ridges: Flatten them with your foot.
• Run depressions: Bring in sand or screens dirt to fill the depressions, then reseed.
• Passive acceptance: Let the grass grow longer to hide mole activity. Take advantage of mole digging and plant shrubs and other planting directly into mole mounds. You could eventually transform the lawn into “a wildlife-friendly landscape setting where mole activity goes unnoticed.”

3. Prevention: don’t encourage moles

Moles tend to prefer grassy areas over areas with lots of broad-leaved plants. A group of British biologists tried removing grass to see if there would be fewer mole mounds. “They found that moles built fewer mounds in plots where they had removed grass than in grassy plots. This kind of experiment has not been done with Pacific Northwest moles, but it suggests that you might want to try planting something different if you have a lawn with persistent mole problems,” said the Northwest Center for Alternatives to Pesticides.

For a list of native ground covers that can be used as replacements for grass, visit www.nwcb.wa.gov/groundcover-alternatives-for-western-wa.

4. Does food reduction work?

Since moles feed on grubs, some websites suggest eliminating grubs to get rid of moles. But grubs make up only part of the mole’s diet. When the weather is dry, moles may frequent well-irrigated lawns just for moisture. So moles may be present even if there are no grubs.

We don’t advise using insecticides to get rid of grubs and other insects. This won’t work to control moles over the long term. In the meantime, you could kill beneficial soil organisms, harm songbirds and pollute nearby water bodies or groundwater.

We also don’t recommend letting your lawn dry out in an attempt to deter moles. Proper irrigation is important to keep your lawn healthy. If your lawn is too dry, it will get weak and thin, making it vulnerable to invasion by moss, weeds and insect pests. Read more about lawn watering. If your lawn is wet because of poor drainage, improving the drainage will improve its health.

5. Do scare tactics work?

One suggested strategy to deal with moles is to scare them way. You can find lots of devices online and in hardware stores to frighten moles. This might include vibrating stakes, ultrasonic devices, pinwheels, etc.

Be skeptical of these products. Moles don’t frighten easily. “This is probably because of their repeated exposure to noise and vibrations from sprinklers, people moving about, and lawnmowers and other power equipment. Consequently, frightening devices have not proven to be effective in Washington,” said WDFW.

6. Do repellents work?

People have tried many repellents to deal with moles, “most of them intermittently successful or completely unsuccessful,” according to Seattle Public Utilities. People have tried stuffing tunnels with sharp thorny branches, human hair, ground glass, razor blades and bleach. Moles won’t eat chewing gum or laxatives. Auto exhaust, mothballs and drain cleaner have been tried, but they are toxic or dangerous to people and pets and may not remove the mole.

Castor oil repellents are commercially available. According to the U.S. Environmental Protection Agency, they do not pose known health or environmental hazards. There has been some research on the effectiveness of castor oil on eastern moles, but there has been no research on moles in the western United States.

Research by Michigan State University scientists found that a commercial product containing 65% castor oil kept eastern moles away for 30 to 60 days. “However, researchers from Ohio State University and the University of Arkansas disagree with the MSU findings, citing the short duration and effect of weather on the tests,” said Consumer Reports. “Marne Titchenell, a professor of wildlife ecology at OSU, also warns that castor oil can harm insects, earthworms and other creatures that populate the soil.”

The University of Nebraska Extension said castor oil has only shown “minor effectiveness” in repelling the eastern mole. To be effective, UN Extension said you must thoroughly water the lawn: one-half inch of water before applying the repellent solution and one inch or more of water after applying it.

“Keep in mind that you’ll be driving the moles into the adjoining property, which might not endear you to your neighbor,” said Consumer Reports.

7. Flooding may work for small areas

Can you deal with moles by flooding them out? Moles will easily withstand normal lawn and garden irrigation. Flooding can sometimes to be used to force moles out of their burrows where you can quickly kill them with a shovel, according to WDFW.

You will need to flood the entire tunnel system quickly and completely, WDFW added. Five-gallon buckets of water poured in the hole will flood the area more quickly than a running hose. “Flooding has the greatest chance of succeeding if moles are invading the property for the first time. Where they are already well established, their systems are too extensive.”

According to Seattle Public Utilities, if you flood the tunnels in spring, you can reduce mole populations by killing the young moles which cannot escape their nests. This may work best if the tunnels and runs are confined to a small area. Flooding is no use in a widespread set of runs which cannot be filled with water. “To attempt this, open a molehill, poke the hose in, and flood for at least 15 minutes. Adults will be able to leave and move on even with the flooding.”

8. Barriers work but are tough to build

You could build an underground barrier to keep moles from tunneling into an area, but this can be labor-intensive and costly. Because of that, WDFW only recommends it for exceptional situations. See “Preventing Conflicts” section in Pocket Gophers for information and designs.

“Hardware cloth (1/4 inch wire mesh) buried in an “L” shape, 8 inches deep, will keep tunneling moles out of flower beds. This barrier is best incorporated into new beds,” said Seattle Public Utilities.

9. Trapping is effective, but lethal traps are illegal 

“Trapping is the most effective choice for mole control when it becomes necessary,” according to Seattle Public Utilities. However, trapping is a temporary solution. “If nothing is done to change the habitat conditions, other moles will return.”

In Washington, “body-gripping traps” such as scissor-jaw traps are unlawful for trapping wild animals, including moles. This resulted from passage of Washington Initiative 713 in 2000. You could use a live trap and remove the mole to another location.