The reed leafhopper has evolved rapidly from a reed grass specialist into a dangerous pest that attacks important crops such as sugar beets, potatoes, carrots and onions, as well as reeds. It lives in close symbiosis with seven different bacteria, two of which transmit diseases leading to significant crop losses. These symbiotic bacteria likely play a pivotal role in broadening the cicada’s host range. These findings could help to develop targeted control strategies in the future, based on influencing pathogenic or beneficial bacteria.