Eighteen years after its first recorded appearance, Dolichovespula media - or Euro-wasp - has reached record numbers in Britain after many survived the mild winter, and then prospered in the humid summer that has followed.
The worst hit area is East Anglia where dozens of the wasps' nests have been found.
The experts say they are not actually more volatile, merely more likely to get into an argument than the traditional British wasp Vespula vulgaris.
George Else from the Entomology department at London's Natural History Museum defended the continental invader from any suggestion that is was deliberately trying to cause trouble.
"It is not more aggressive," he said. "It simply lives in a place where it is more likely to be disturbed.
The native wasp tucks itself away from humans in sheds and lofts, whereas Euro-wasp prefers the great outdoors, where it lives in trees and bushes in smaller, well-hidden nests.
The unsuspecting gardener or rambler is therefore more likely to make the Euro-wasp angry by dislodging its home, with the inevitable, painful result.
Mr Else says the Euro-wasp arrived at the start of the 1980s when it first colonised the Newhaven area of Sussex.
It has spread "as far as North Yorkshire and the Lake District", although it is further south that the most severe warnings are now being heard.