HISTORICAL allies they may be, but in the wildlife kingdom America has declared war on England as vicious armour-plated crayfish threaten to wipe out the native variety.

The Wyre Forest area has been revealed as one of the areas in the country which is being invaded by the American Red signal crayfish.

Environment Agency spokeswoman Lyn Fraley said the area was once a major stronghold of the native white-clawed crayfish, which play an important part in river ecosystems.

However in recent times, their highly aggressive American cousins - which can grow up to 12 inches in length and live out of water for months - have been killing them off.

Areas in the north of Worcestershire - including Droitwich - have also been identified as an area where the foreign invaders have been turning up in rivers, streams and ponds.

Ms Fraley said: "Basically the American signal is so aggressive that when it takes over habitats, the native crayfish just die out."

"The Wyre Forest area has always been a stronghold of the native crayfish but the future of the species is now in doubt, with the national decline in numbers being reflected there."

The agency believes the foreign species has been illegally introduced to the wild or escaped from crayfish farms and ponds.

Not only does their vicious nature threaten native crayfish, but the American Red also carries a deadly disease known as crayfish plague, which can wipe out entire populations.

But it is not all doom-and-gloom as a community of native crayfish has recently been rediscovered by environmentalists in the Badsey Brook catchment in the county.

And now the Environment Agency is working to protect the white-clawed crayfish by enhancing their environments to encourage them to breed.

However, the agency is warning people not to catch the American varieties as it is illegal to do so without a licence.

Ms Fraley added: "Also, contrary to what people believe, it could make the problem worse as it tends to encourage them to breed and there's a risk of them spreading as they could escape."

Anyone who spots one is asked to try to take a photo of it and contact the agency on 08708 506506.

IT CLIMBS UP ALMOST ANYTHING

The American Red signal crayfish:

Can grow up to 12 inches in length, live out of water for months and climb up almost anything.

Widespread and increasing across the Midlands, they breed earlier and grow faster and bigger than the less-aggressive native crayfish.

The variety burrow into banks, making them unstable.

Their armour-plated thorax and huge claws make them impervious to attack.

Now believed to inhabit more than 80 per cent of rivers in mainland UK.

The problem of their spread is so serious, European Union scientists have been discussing how best to tackle the threat.