Belfast Telegraph

Invasion of slugs and snails to make 2015 worst year of slime for gardeners

'Spanish slug' to escalate in numbers after winter breeding frenzy

By Linda Stewart

Gardeners across Northern Ireland are bracing themselves for an invasion of slime, as experts warn this will be the worst year on record for slugs and snails.

Millions of them, led by a voracious invasive variety from the south of France, are set to hit our gardens after an unusually mild winter.

Dr Ian Bedford, head of entomology at John Innes Centre, estimates a cubic metre of garden could be home to up to 200 slugs, each of which can spawn up to 200 offspring.

Meanwhile, a voracious intruder - dubbed the Spanish slug by media but more correctly known as the Vulgar Pest Slug - is set to escalate in numbers following a breeding frenzy over winter.

The creature reproduces at twice the rate of native slugs and has few natural predators in Northern Ireland.

Slug expert Dr Roy Anderson said the Vulgar Pest Slug (Arion vulgaris) has established populations in south Belfast and Antrim and is on the move.

It is virtually impossible to tell apart from its native counterpart, but is likely to be present "if it eats everything in your garden".

"Slug numbers are very hard to predict in my experience. It's like trying to predict the weather - it could be a winner or a no-show," he said.

"If slugs are doing a lot of damage in your garden, it's a reasonable likelihood you have what is called the Spanish slug. It is widespread in Britain, but very local in Ireland.

"It's called the Spanish slug but it's not from Spain. It's from the south of France and may have originated in the Pyrenees in the 19th century.

"It has a terrible reputation in Europe. If you're selling a house in Europe you have to certify that the garden is free of it - it's a bit like Japanese knotweed.

"I first saw it about 12 years ago south of Antrim on the banks of the Sixmilewater River. It appears to have originated in Greenmount College in the organic section. A very early conclusion might be that it is moving on organic produce.

"It arrived in Northern Ireland comparatively recently.

"It's spreading slowly but it has got as far as Dundrod from Antrim. It's spreading in south Belfast as well."

Dr Anderson says the Vulgar Pest slug will devastate vegetable crops but will target all garden plants.

"It looks so like the big brown or black slug in your garden that there is no way you will be able to tell it apart without expert help, until it eats everything in your garden," he said.

"Its skin is very thick, so I think birds have difficulty digesting it. It's not generally eaten by anything. Hedgehogs might eat it, but they are becoming quite rare. The only way of controlling it is with blue pellets or throwing them somewhere else."

Dr Anderson says the Vulgar Pest Slug is easy to misdiagnose.

But if you touch a native slug on the back it will perform a distinctive side to side rotation, while the non-native slug will stay motionless.

How to get rid of slugs

A container half buried in the ground and half filled with beer. The slug, lured by the scent, falls to its death. Keep the rim raised 2-3cm to prevent the slug-eating ground beetle from falling in too.

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