The Quercus chairman, João Branco, said that there are now “many thousands” of the nests in Portugal, and the special which used to be limited to the north west of the country has now spread to other parts such as Porto, Coimbra, Aveiro, Guarda, Leiria, Santarém, Castelo Branco and there have even been reports from Alentejo.

"Perhaps it is now impossible to erradicate this pest from Portugal” he said though it would be possible to “reduce the size of the plague” using a “good plan, political will and investment”, he said.

Mr Branco added that there should be brigades all over the country to actively search out and properly destroy the wasp nests, plan that would need the population’s “strong support” and that should include environmental defence associations.