British gardens face 15cm Spanish 'superslug' invasion

Gardeners in Britain face a battle against 15cm Spanish "superslugs" following the warmer than average winter, according to experts.

Dr Ian Bedford, head of entomology at John Innes Centre in Norwich, discovered the new species in the UK in 2012 and is predicting an explosion in their population this year.

The Spanish slug, or Arion vulgaris, eats not only plants but dog excrement, dead animals and its own kind, and its "aggressive breeding cycle" means numbers can multiply quickly, says the BBC.

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According to the Slugwatch website, set up by Bedford, Spanish slugs can self-fertilise and lay around 400 eggs a year. They also produce "huge amounts of mucus" that repels predators.

They vary in colour from bright orange to reddish brown and can grow to between 8cm and 15cm when they have reached maturity.

"It's been estimated that a cubic metre of a garden in the UK could accommodate up to 200 slugs, each of which can have up to 200 offspring," says Bedford.

"They usually survive the winter in our gardens as eggs. Without a cold snap, it's fair to say that slug numbers, especially the invading Spanish slug, which can lay up to 400 eggs, will escalate this year."

It is thought that the species came to the UK on imported produce such as fruit and vegetables, bare root trees or potted plants.

The Arion vulgaris is different to another kind of Spanish slug called the Arion Flagellus, which was first identified in the UK 60 years ago. Known as the Spanish stealth slug, the Arion Flagellus grows to 10cm and has a reproductive capacity of around 350 eggs a year.

The Daily Telegraph has produced a 30-day "plan of attack" for gardeners, which includes rotovating soil to expose slugs and eggs to hedgehogs and birds, heading out at night with a torch to collect and remove slugs and greasing the rim of plant pots with Vaseline and salt.