Climate change and risks Reading time 3 min
Heightened monitoring after the confirmed arrival of the cotton leafhopper in French vineyards
Originating in North Africa, the long-overlooked cotton leafhopper is appearing in several winegrowing regions in France. The spectacular damage it causes surprised professionals before researchers confirmed its identity. This discovery was driven by OVNI, a participatory monitoring network which collects and analyses insect traps installed around the country. Thanks to this collective monitoring, winegrowers are beginning to grasp the magnitude of the threat – and anticipate its spread.
Published on 20 November 2025
The detection of cotton leafhoppers in France is no accident: it is the result of careful monitoring carried out by OVNI, a participatory observatory for endemic or invasive vineyard pests that operates with some sixty partners nationwide. “It starts with the traps,” explain Lionel Delbac and Adrien Rusch, researchers at INRAE’s Vineyard Health and Agroecology (SAVE) joint research unit. The system consists of simple yellow sticky insect traps, which are coated in glue and installed by partners according to a defined protocol. Once collected and sent to a laboratory, every insect is examined, sorted and studied under a stereo microscope. It was through detailed examination of traps sent from the island of Corsica in 2023 that scientists noticed “a few too many leafhoppers...which were a little too different,” according to Lionel Delbac. Molecular analysis carried out by INRAE entomologist Jean‑Claude Streito confirmed the species: Jacobiasca lybica, the cotton leafhopper, was indeed present.
Warning signs appeared as early as 2019. On the Aléria plain in Corsica, local partners reported unusual roasting on vine leaves — more severe than damage typically caused by the native vine leafhopper, Hebata vitis. Entire leaves were drying out, as though burnt. At the time, nobody suspected a North African species. It was only when these symptoms intensified, and an alert was issued in early summer 2024, that monitoring was stepped up. When traps laid in the Pyrénées-Orientales and Var regions also revealed the presence of the insect in 2024, cooperation was reinforced between partners and researchers to lay more traps, verify and confirm the presence of leafhoppers.
Jacobiasca lybica is a small insect, 3–4 millimetres in length, that closely resembles the vine leafhopper already found in Europe. But unlike the native species, which causes moderate leaf hopperburn, J. lybica punctures sap-carrying tissues and causes discolouration followed by the sometimes complete scorching of leaves. The worst infestations make entire vineyards appear burnt. Photosynthesis collapses, grape ripening fails, and vines struggle to rebuild reserves. In Corsica and along the Côte Vermeille, certain grape varieties are proving to be particularly vulnerable.
Methods available to control this emerging pest remain limited. Traditional insecticides are only partially effective and kaolin, a natural mineral treatment, provides some protection but is not convincing. Biological options, such as the use of fairy wasps (Anagrus atomus), require further study. For the time being, researchers are relying on what enabled the detection in the first place: an extensive network, committed partners, and vigilant monitoring. The OVNI network will soon be enhanced with improved documentation, imagery, and innovative molecular identification tools. Anticipating the spread of the cotton leafhopper has become a major challenge for winegrowers.