The article presents a study of the various meanings given by different actors to the biological invasion of Cameraria ohridella in Paris's green spaces. This insect of unknown origin has spread throughout Europe, mining the leaves of horse chestnut (Aesculus hippocastanum), a tree species widely distributed in European capital cities. The elaboration of a map of actors allowed the identification of the stages in the bioinvasion management. The research shows that: i) despite the existence of specialized regional and international species monitoring organizations, the key alert networks were of an informal nature; ii) Paris's Green Areas Directorate assessed and treated the invasive species with a rationale that did not include other sectors of society; iii) the effectiveness of the adopted measures was undermined by the fact that the Green Areas Directorate does not control all the parks or gardens within the city. Owners/managers acted independently, so allowing the development of new sources of infestation. The article concludes that the invasiveness of an ecosystem is not only shaped by its ecological traits but also by social organizations and policies.