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.

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 www.slugwatch.co.uk for people to report sightings and get help.

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 www.slugwatch.co.uk.

Have you found some? Email catherine.morris-gretton@archant.co.uk