A moth completely new to science has been found living in Britain but is thought to originate from thousands of miles away.

The exotic moth, named Prays peregrina, has mystified experts, who have been unable to find records of it anywhere else in the world.

Lepidopterists are convinced that it must have come from another continent because it is inconceivable to them that it could have been overlooked for hundreds of years in Europe.

It has been found in 17 locations in Britain – one in Kent and the rest in London – and is believed to be breeding successfully, having established itself in the past five years.

The first specimen was spotted in 2003 in Parliament Hill, North London, and two years later it was recorded at the Chelsea Physic Garden, West London. Since those two sightings there has been a rapid increase in its numbers and last year it was found in nine locations.

David Agassiz, of the Natural History Museum, described the new species of moth and named it “peregrina” from the Latin, meaning “that comes from foreign parts”.

He said that the country of origin continued to elude researchers. “It’s a complete mystery. It’s come from somewhere but it’s certainly not a European species. It couldn’t have been overlooked so it must come from somewhere exotic where the fauna is less well known.

“It’s turned up across London. There are double-figure numbers being recorded so it must have become established.”

Dr Agassiz thought it unlikely that the insect posed much of a threat to crops because that would have brought it to the attention of farmers in its home country. “It’s unlikely to be harmful. If they were economic pests they would be known,” he said.

Asia has been named as the most likely place of origin for the insect. A similar species, P. curulis, is found in Nepal and northern India.

Because of the similarity of wing shape and colours, Dr Agassiz dissected the moth, including its millimetre-long penis, and found marked differences between the species.

Analysis of moth genitalia is often the best and perhaps only way to tell moths apart. Dr Aggassiz said: “The shapes of these are consistent between species. If you can’t tell the difference from the wing pattern you can often tell from the genitalia.”

The most likely route for the creature to have reached Britain was on imported plants or crops, probably as an egg or a caterpillar. The absence of specimens elsewhere in Britain or Europe, however, has further perplexed researchers because if it was coming in on imported plants or food it would have been expected to have been seen in a range of towns and cities.

Little is known of the life cycle of the new species but it is thought to feed on vegetation including olives, ash, privets, jasmine and citrus plants.

In Britain the moth has a relative in the same genus, P. fraxinella, which has caterpillars that bore into the shoots of ash, making it droop in May.

Examples of P. peregrina have now been added to the collection of 8.7 million specimens of butterflies and moths held by the Natural History Museum in London.

Several dozen new species of butterfly and moth are identified worldwide each year. Many of them lie in museums and collections for decades before being recognised and described.

John Chainey, the moth curator for Natural History Museum, said: “When you do find something new it’s a very pleasant feeling. You do get pleasure from sorting through and finding new things.”

Foreign legion

— European yellow-tailed scorpions can be found in Sheerness, Kent, after arriving more than a century ago. Their sting is milder than a bee’s

— Little egrets are among the most recent successful arrivals. From being an occasional visitor in the 1980s, more than 160 pairs now breed in Britain with 1,600 individuals staying over winter

— Coypu, a wetland rodent almost a metre long and from South America, became established in East Anglia after escaping in the 1930s from fur farms. They were eradicated in 1989

— Chinese mitten crabs reached Britain from the Far East in ships

Source: Natural History Museum

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