Tree-eating bugs invade south-west France forests hit by wildfires

30,000 hectares of forest in south-west France burned in ferocious wildfires in 2022. Now they face a “double punishment”: tree-eating bugs are boring into the fire-damaged trees, leaving authorities with no choice but to kill 1,000s of trees.

“The year 2023 is as cruel and dramatic as the fire,” says Matthieu Cabaussel, one of the general trustees managing the forest of La Teste-de-Buch. “It is a double punishment.”

Stenographer bark beetles, a small flying insect measuring just half a centimeter, primarily attack pine trees that have been damaged by fire or storm. 

When mating, the brown beetle infiltrates between the bark and wood, laying 30 to 50 larvae that will dig tunnels and destroy the sap channels, until the tree dies.

Some say authorities didn’t move quickly enough

When bark beetles strike there is only one way forward: cutting down the trees.

They have previously infested a storm-affected forest in Northern Italy.

“Exploiting the attacked woods is the only control tool,” Francis Maugard, Natural Hazards Officer for the National Forestry Office (NFB), told news agency AFP.

The culling has removed some 80,000 m3 of wood, the equivalent of twenty years of harvest.

But in La Teste-de-Buch, where almost all of the 3,800 hectares were burned, the reaction was delayed. Its managers were only able to start cutting in January, after some dithering.

“Calamitous management” says Hervé Jactel, research director of INRAE’s BioGeCo laboratory (Biodiversity Genes and Communities), which also criticises the storage of infested wood piles in the forest.

“It was the ideal breeding ground,” he points out, describing the succession of several generations of bark beetles in 2023 against a backdrop of persistent heat. 

“A real time bomb: if we do nothing, spring 2024 will be several thousand times more dangerous.”

“We had difficulties in the user forest,” admits Matthieu Cabaussel. For him, bad luck was mixed with hot weather, as well as a “little buoyant” market that “slows down the exit of the wood”.

“Utmost vigilance” is needed

The bark beetle has already spread to the urban areas of La Teste, forcing locals to cut down pine trees in their gardens.

“There is a risk of population explosion,” confirms François Hervieu of the Regional Directorate of Food, Agriculture and Forestry (DRAAF), but he says things could be worse: “We are not in an epidemic situation: we are in a situation that requires the utmost vigilance to evacuate the trees in due time.”

“The cataclysm we have suffered is hard because in our lifetime we will not see an old forest again. But forest ecosystems will recover very well,’ Matthieu Cabaussel believes.