It is quite a claim to fame to be the least wanted species in Europe but the red swamp crayfish, Procambarus clarkii, seems to have that distinction. It was picked out as a major threat to other wildlife, riverbanks and ponds in 14 countries to illustrate the efforts of a new Europe-wide organisation trying to eliminate alien species.
So far this native of North America has only been found at 16 locations in England, including the ponds on Hampstead Heath in London, and more ominously in the Grand Union canal, which could give the crayfish access to a large part of the country.
