Origin, dispersion, host plants, control : principal findings of research carried out within the framework of a European Controcam project Horse-chestnut leaf-miner Cameraria ohridella, the origins of which are somewhat unclear, is an invasive species in Europe. It is capable of extremely rapid dispersion and five years after first being reported on the French mainland it had already spread to most parts of the country by Autumn 2003. The pest presents an extremely large development potential, and just two or three years after establishing on its preferred host, Aesculus hippocastanum, can cause the latter to lose its leaves. The article presents the main findings of research into the pest carried out under the terms of a European Controcam contract.