Menthol oil test to deter Penrhyn Castle moles from destroying lawns

European Mole Moles are considered cute by some but a pest by others

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Menthol oil is being tried to deter moles from destroying lawns at a castle's walled garden.

Gardener Phil Makin came up with the idea of using the scent to dissuade moles from burrowing under the walled garden at Gwynedd's Penrhyn Castle.

String soaked with the oil is lowered into tunnels dug by moles at the National Trust property and has led to a slight decrease in new molehills.

The RSPCA says noise as well as smell could deter moles.

Phil Makin, who got the idea to try menthol oil, said it was unclear whether the oil had worked or if the moles had moved on naturally.

But he said since the oil method was introduced the number of new molehills has gone down to two a day.

Mole facts

  • One mole can dig up to 20m of tunnel per day
  • One mole can create 50 molehills in a single night
  • Moles feed mainly on earthworms, but they also eat a variety of other invertebrates, as well as snakes and lizards

Penrhyn Castle's head gardener, Mike Anderson, said he admired the animals despite their garden-wrecking habits because the castle is built on shale and rock.

"These animals are digging their tunnels on very tough terrain.

"At the moment we're making the best of the situation, by collecting the tonnes of top soil and using it for planting new vegetation," he said.

The non-lethal deterrent was thought of by gardener Phil Makin.

He said there had been a little less mole activity since the oil method was introduced.

"It's possible they are put off the area by the strong smells, or they may be moving on naturally.

Phil Makin String soaked in oil is lowered into the hole left by a molehill

"Either way, they probably have very clear sinuses now!" he added.

The RSPCA website has advice for gardeners who want to deter moles from ruining their lawns.

It says moles themselves do no direct harm, although evidence of their presence (the molehills) may be unsightly and their tunnels may affect some plants in a garden.

"As a result, many people suggest just removing the earth that makes up the hills and ignoring the animals' presence, as well as their continued disturbance.

"Mowing the lawn more frequently, or letting children play on it, may help to deter the animals. However, we can understand that removing an animal is sometimes the only answer," the society says.

Although there are many methods that allegedly deter moles, there is no scientific evidence for their effectiveness, it added.

"Some of these include putting milk bottles bases down in the soil, vibrating probes or children's seaside windmills sunk into the moles' runs, or planting 'repellent' plants such as caper (or mole) spurge or plants from the allium (garlic) family."

If the animal has to be removed, the society adds, any trapping should be done by an experienced professional.

A spokeswoman for the RSPCA said: "We welcome the efforts of the National Trust to resolve their mole problem without resorting to killing them.

"Generally, using repellents like menthol doesn't work as moles simply dig round the offending object, often causing more damage in the process, so very large amounts of repellent may have to be used.

"If a deterrent is used it is essential to ensure that there is somewhere suitable nearby for moles to move onto - soft, easily dug ground with plenty of worms but with no other moles present."

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