Giant Spanish slugs have been mating with their British counterparts to create a mutant strain of "superslugs".
The Spanish molluscs are thought to have arrived in the UK in salads during the summer months, and have already spread all the way across the country to Wales.
The Mirror reports that they can grow up to 15cm in length, and produce hundreds more eggs than the typical British slug, which could spell trouble for the indigenous slug population.
Slug expert Les Noble of Aberdeen University said: "These slugs are like conquistadors were to the Aztecs. Native slugs can't keep pace and may become extinct.
"They are simply being overrun and when you consider the Spanish slug will happily make a meal out of a dead rabbit as much as out of dog muck you can see why they are so successful.
"We have already seen when these slugs move into an area, the native slugs vanish almost immediately. They can wipe out whole crops and prevent them growing there again."
A 72-year-old from Wales has claimed to have seen the giant slugs in her garden "eating snails", and added: "Our dog caught one, it was so big I thought it was a mouse."