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Perhaps no landscape event arouses as much anger as the eruption of excavated mole hills in the middle of an otherwise smooth, green lawn. Gardeners exhaust themselves with futile gestures and colorful language, neither of which will get rid of moles. It's probably no comfort to realize that these interesting mammals were part of the Northwest long before modern home building began. We are, in effect, building lawns and gardens in their natural territory. Homes near wooded areas provide ideal mole habitat. Moles, like us, are here to stay.
In war, there's a saying that one should "know the enemy." So let's start with a look at the creature itself. Three different species of moles live in the Pacific Northwest, the most common being Townsend's mole (Scapanus townsendi). This mole, the largest in the continental US, can grow to 8 or 9 inches long, covered with velvety black or gray fur. The short forearms end in great digging tools, outwardly-turned flattened feet and claws. (Anyone looking at a mole hill and a series of tunnel runs knows that these mammals are perfectly equipped with powerful earth-movers.) Mole hills result when the animal makes a lateral chimney to the surface and expels the excess soil from runs, sometimes tossing out as much as two gallons at a time in a volcano shape.
Moles live in moist, fertile soils. They like precisely the conditions provided by a well-kept lawn with plenty of worms in it. They create their runs for feeding, resting, and nesting, and may spend as much as half their time looking for food. They eat a variety of soil-dwelling insects such as beetles, earthworms, and insect larvae. They have narrow, slim jaws and needle-like teeth. Despite the anger of gardeners who see lily bulbs toppling and turf disturbed, moles don't usually eat plants. Their tunnels and runs can offer passage to other animals like voles, mice, and pocket gophers that do eat roots and vegetation.
Moles produce one litter a year, averaging three young. The young moles stay for about one month in the nest and are nearly full-grown when they leave it, usually by late May or mid-June. This time of year, moles are active and their garden damage is obvious.
Wishful thinking about what might eliminate moles has produced dozens of imaginative solutions that don't work. Don't try to eliminate them by feeding them something exotic. Various substances like chewing gum, chocolate-covered laxatives, and assorted concoctions can't help. The mole, with its narrow jaw, eats things that are worm-shaped or grub-shaped, not pieces of gum. Human hair doesn't repel them, either. People also try electronic devices and vibrating windmills, but sonic devices and vibration haven't proved effective for long-term control. .
Some often-suggested solutions are frankly dangerous. Running car exhaust hoses or other poison fumes down the runs, or pouring in gasoline, or tossing in mothballs or drain-cleaner are unsafe and environmentally unsound. Lethal fumigants don't stay in one place, but move throughout loose soil. Flooding the runways with water with just cause the moles to move along and find another place to dig.
People sometimes ask how to kill earthworms to remove the mole food source. This isn't a wise idea either, because earthworms help the health of gardens by aerating the soil and by producing "castings" that help with soil fertility. They are part of a balanced, ecologically sensible garden environment.
If your household includes a motivated dog or cat, these good hunting predators can keep the mole population down. A digging dog can, of course, increase the havoc on the lawn while attempting to extract the mole. Constant animal harassment may also induce the mole to move on to a quieter run in a less inhabited area.
You still want to get rid of the mole? The only proven method, if you have decided that you can't coexist with moles, is proper trapping. (NOTE: All lethal mole traps were outlawed for use in Washington State in the Nov. 2000 elections) A scissors trap, such as "Out O' Sight" is strong and effective. Trap where there is new, fresh activity, with two or more fresh hills. Practice probing the run to place the trap in a straight section of a main run (not a feeder run, just under the soil surface.) Disturbing the run as little as possible, set the trap following instructions. Practice and patience is required.
WSU Extension has a bulletin with clear drawings of mole trap setting. To receive a copy, call your local county WSU Extension Office and ask for "Community Horticulture Factsheet #50 Moles." Individual county offices will inform you of costs for handling and mailing. In Pierce County, call 253-798-7170. In King County, 206-296-3900, and in Snohomish County, 425-338-2400.
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