But the tropical plants have been all but wiped out in parts of southern France by two beautiful but voracious insects: a South American moth and the Asian red palm weevil.

The larvae of these two deadly "palmivores" ruthlessly eat their way through palm tree hearts often fatally wounding the plant.

The paysandisia archon moth, with olive-green forewings and bright red, black and white hind-wings, is believed to have landed in France in 1997 in a consignment of palms from Argentina, its country of origin.

It has since been so effective in chomping its way through paradise palms that experts say the insect has wiped out 80 per cent of the plants in the Languedoc Roussillon region.

The beautiful moth, with a wingspan of up to 4 ins (11cm), lays its eggs on the trees from May to October. Once hatched, the fat white grub munches through young fronds then bores galleries into the palm tree heart. A year later, the larva turns into a moth, leaves the palm and the female lays another batch of up to 150 eggs.

Further east, meanwhile, the Côte d'Azur's palms have been colonised by an army of rust-coloured weevils. They were accidentally introduced to the Riviera three years ago in a consignment of palms from southeast Asia and have wreaked destruction among larger palm species such as the Phoenix variety lining the Cannes croisette.

"The moths have been more deadly to the Languedoc region as they have killed off the thinner palm varieties," Perez Laurene, technical expert at Fredon, the regional harmful pest federation, told The Daily Telegraph.

"The weevils, however like to stick together in large numbers and have been more damaging to the bigger palms of the Côte d'Azur which can withstand solitary moth grubs," she said.

However, the two-pronged foreign insect invaders may have finally met their match. After a variety of increasingly desperate ad unsuccessful pest control attempts, experts believe the palm's saviour could be a microscopic ringworm that latches on to the moth and weevil larvae.

The worm is a type of nematode, some of whose relations can be terrible plant pests – killing off grape vines and pine trees, while others can be lethal to humans.

This type is harmless to man and plants but kills any insect larva it meets.

"It finishes them off by septicaemia," said Caroline Gutleben, researcher at Plante et Cité, which has been testing the worm's effects.

Controlled tests have proven 100 per cent effective, she said, while recent field tests in eight sites in the Hérault and Côte d'Azur regions have shown a "stabilisation or improvement of treated palms", bringing near-condemned plants back to life. The worms are sprayed on to the palms in a water-based solution.

However, experts warned that the nematodes were no "miracle" cure.

"Some alarmists are predicting that southern France will be bereft of palms within a few years. I'm optimistic and think that we now have the means to protect them," said Miss Laurene.