To be effective, the list of invasive alien species that are targeted for action under the latest European Union regulation needs to focus on preventing new species from entering Europe, and to impede the spread of those that currently have a limited distribution (see also J. Pergl et al. Nature 531, 173; 2016, and F. Santarém et al. Nature 532, 177; 2016).

To be listed under the regulation, species must have been fully risk-assessed. However, existing assessments are mainly for species that are already widespread. All but 2 of the 37 invasive species on the 2015 EU list (see are present in Europe, and 14 are widely dispersed. Of the 95 species that have been identified as potentially invasive (see, only the South American raccoon (Nasua nasua) is on the present list.

In our view, post-invasion management is likely to be more successful and cost-effective if the legislation's 'black list' were to focus on potential future invaders as well as on mitigating the impacts of existing invaders.