Tuesday, April 16, 2019

Paul Hetzler: Mountains of Molehills

mole hills in a pasture Just as we began to doubt the existence of soil, snow began to give way in early April to reveal, well in many cases, a brown mess. As backyard glaciers recede, some homeowners may find an outbreak of mole-volcanoes in the lawn as if an army of subterranean rodents spent the winter detonating explosives.

The star-nosed mole and the hairy-tail mole are the two species that live in our area, and as their soil mounds indicate, they’re active all winter. If they’ve turned your once-flat lawn into a relief map of the Badlands, don’t panic – it’s not as bad as it seems.

It may not change your opinion of them, but moles consume lawn-damaging grubs. In addition to the Japanese beetle, we have four other nasty beetle species out there. The Asiatic garden beetle, European chafer, rose chafer, and Oriental beetle are all pests of ornamentals, and their larval, or grub, stages all feed on your grass roots. Besides creating dead patches in the lawn, grubs weaken turf grasses, making them more susceptible to disease, and weed competition (this is mostly a problem in lawns that get mowed too short).

So the moles, while messy in spring and fall, have been “grubbing” these larvae out of the lawn for you. A five-ounce mole can eat about 50 pounds of grubs and worms a year. In addition, moles contribute to healthier soils. Their activities help blend materials throughout the soil profile, which improves aeration and drainage.

If mole damage becomes severe you may have to implement control measures. Fortunately, as rodents go, moles have a low reproductive rate. While the extent of damage may suggest your yard is teeming with them, it’s likely there are just two or three. This means is you only have to eliminate a few animals to vastly reduce or stop their effects.

Moles have two kinds of tunnels, permanent ones 6-18 inches deep, and temporary feeding tunnels just below the surface. They’re able to dig these shallow tunnels at nearly 20 feet per hour, and can scuttle through their deep runways at about 80 feet a minute. In spring and fall they feed closer to the surface, and this is the best time to control them.

Mole repellants may have some effect, but only in the short term. Cat feces, coyote or fox urine, and castor oil mixed with dish soap might help drive them off your property for a little while. Studies have shown that ultrasonic and vibratory devices intended to repel moles (or mice, rats, etc.) simply do not work. Remedies such as placing broken glass or mothballs in mole tunnels are also useless, and potentially dangerous, as moth balls can contaminate groundwater, and thus your well.

Poison baits work for mice and rats, but have limited, if any, value for mole control. Zinc phosphide is registered for use in NYS against moles, but you’d have to put it on a live worm to get the critters to go for it. Moles are strict carnivores which, like Tolkein’s character Gollum, prefer to eat their slimy prey live and wriggling. The only effective way to remove them (moles, not deranged Hobbit-like things) from your yard is by trapping. It’s simple, although it does take time.

Scissor or harpoon-type traps work, but must be set in active surface tunnels. To find which ones are active, walk along their surface runs every few yards. If the flattened sections are “re-inflated” the following day, the tunnel is active and you can set a trap there. Mole traps can be found at most hardware stores, or purchased online. Actually, moles are surprisingly fragile. Evidently their skulls are very thin compared to other rodents, and a blow from a shovel onto a surface run where they are feeding can kill them, even several inches down.

Regardless of how you deal with moles, it’s easy to get rid of their soil piles. Once the ground dries out enough, rake the molehills into the surrounding grass. After a few warm days and a spring shower or two, the lawn will take off and you’d never know the place had suffered a rash of tiny volcanoes.

A strategy of tolerance will leave you with more money and free time. I suggest trying to live with a little seasonal mess, for just this year, and see how it goes. After all, we’re talking about molehills here, not mountains.

Photo of mole hills in a pasture by wikimedia user Rasbak.

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Paul Hetzler has been an ISA Certified Arborist since 1996. His work has appeared in the medical journal The Lancet, as well as Highlights for Children Magazine.You can read more of his work at PaulHetzlerNature.org or by picking up a copy of his book Shady Characters: Plant Vampires, Caterpillar Soup, Leprechaun Trees and Other Hilarities of the Natural World

6 Responses

  1. Amy Godine says:

    This is terrific. Can I assume the situation you describe applies as well to our devastated side lawn in a family home in central Vermont? And what if we have skunks as well? How about them onions?

    • Pamela Harder says:

      Yes! The skunks really gobble Japanese beetle larvae as well. Once the beetle population is down, the moles and skunks leave.

      What about onions???? You have something that eats your onions?

  2. Richard L Daly says:

    Paul: Living on a slab on Cumberland Head (Clinton County/Town of Pbgh). What are the chances of a MOLE -vs- mouse entering house (and leaving promptly!) during high-water-table in Spring? It never happened to my knowledge in the 53 years family has been here. It happened this week … and as I pondered, I said to meself: rat? Nah. But it was brown -vs- grey and too big for a mouse of any class/order. Thanks and Joyous Easter to you and yours!

  3. Harv Sibley says:

    Great article. Our local hardware store used to stock a rubber coupler device for mole issues. Believe it or not, you put the rubber coupler on your auto exhaust pipe ( assuming you do not drive a Tesla) and hook up a garden hose to the other end of the coupler, which had a fitting for it. Then run the hose to your first mole hole, turn on the ignition, and wait….
    I never used this “product” but the store stocked it for years. I may just head to the store today to see if they have it…just for kicks.
    This is a true story…

  4. Pamela Harder says:

    Just tolerate them while they do their good work! They are a real blessing. Later in the spring rake the dirt humps and sprinkle some grass seed or let the grass fill in naturally. The whole “lawn” ethic is pretty bogus any way!

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