Drones to combat toxic processionary caterpillars

The caterpillars - which are toxic to humans and animals and destroy trees, and are recognised by their “fluffy” appearance and trademark “processions” on the ground - begin their lives in cotton-wool-esque nests in pine trees.

As their numbers are expected to increase as average temperatures rise across France - and after the ban on pesticides, insect sprays and helicopter spraying - some have been investigating new methods to dispel the dangerous creatures.

Now, a new experiment from Inra (National Institute of Agricultural Research; Institut national de la recherche agronomique) will use drones.

These will pass over affected areas twice: firstly to identify the nests, and secondly to spray and destroy them, explains French news source 20 Minutes.

The experiment is set to operate across Croix-des-Gardes near Croisette and across the town of Cannes, with 20 hectares expected to be treated by Friday this week.

The spray the drones will use is an organic insecticide - the bacteria bacillus thuringiensis - which will target only the nests, and destroy the caterpillars while they are still in the larvae stage, before they begin their descent from the trees.

“This system allows us to spray in a more-targeted way than the helicopter sprays that are now not allowed,” explained Jean-Claude Martin, research engineer at Inra, speaking to 20 Minutes.

“The [spray] diffusers are positioned directly under the [drone’s] propellers,” explains Robert Bigel, director of the company that will operate the drones, Agrobio Tech. “The product is then sprayed directly onto the pine trees.”

While this is thought to be the first drone experiment of its kind in France, it is not the first time that the caterpillars have been hit with an unusual method of destruction: in 2016, a method of shooting the nests with pheromones contained within paintballs was trialled in Nice, and the Grande Corniche park, in Eze, in eastern Alpes-Maritimes.