Invasive species threaten flora and fauna and can destroy ecological balance. However, combating these dangerous invaders is costly and requires unusual measures. The EU list of invasive species includes 42 animal and 46 plant species. The Intergovernmental Panel on Climate Change has identified these unwanted intruders as one of six "climate killers," because they can throw entire ecosystems out of balance. According to research reports, invasive species cause around €400 billion worth of damage worldwide every year - from crop losses and the decline of native species to expensive control measures.