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Return of the giant “killer” slugs - gardeners and farmers warned pests could return in their millions

PUBLISHED: 08:47 17 July 2014 | UPDATED: 09:44 17 July 2014

Spanish slugs are invading Norwich. Photo: Supplied

Spanish slugs are invading Norwich. Photo: Supplied


Giant “killer” slugs, that hit headlines across the country in 2012 after being discovered by scientists in Norwich, are set for a comeback – in their millions.

About the Spanish slug

The Spanish slug varies in colour from bright orange to reddish brown and can grow to a size between 8cm and 15cm. They are known to:

• Produce twice as many eggs as slugs native to the UK;

• Tolerate hotter and dryer environments;

• Have an extensive omnivorous diet which includes excrement, dead animals and crops that are not normally susceptible to slug feeding;

• Push out other species to dominate an area.

Gardeners and farmers are being warned about the return of the Spanish slug (Arion vulgaris), which can grow up to 15cm long and lay between 200 and 400 eggs.

They feast on dead animals – as well as meat, plants and dog excrement – and can eat up to 20 slug pellets before they start to die.

Ian Bedford, head of entomology at the John Innes Centre, in Norwich, first found the slugs here in East Anglia in 2012 and sent them to a colleague in Aberdeen to be identified.

He and others were finding thousands of the species in their gardens, prompting the creation of for people to report sightings and get help.

What to with the slugs

If you come across one, Dr Bedford and the team do not advise cutting the slugs in half, as is commonly done.

“If there are pets or children around they could ingest bacteria from inside the slugs if you cut them in half,” he said.

“The best way to get rid of them is to collect them, using gloves or a piece of wood, and put them in a bucket of water. Add a bit of detergent and that will be enough to make them sink to the bottom. Then dispose of them by digging a hole in the garden, but make sure you disinfect the bucket afterwards.”

Anyone with a large number of slugs in their garden should visit or call the John Innes Centre on 01603 450000.

The slugs started to re-emerge in April last year, but a cold snap killed them off, stopping them from any further breeding.

However, this year’s weather has been much better for them, with Dr Bedford warning they could return in numbers similar to 2012.

“With the mild winter climate and the conditions we have seen in the spring, we are expecting them to make a comeback this year,”he said.

“I am starting to find a few dozen in the garden already.”

Dr Bedford and other scientists at the John Innes Centre are waiting to hear if they have secured grants to carry out research into the species.

They are asking people to report any findings of large numbers of slugs at

Have you found some? Email

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