Aggregations of the red and black coloured firebugs are ubiquitous under linden trees in Central Europe, where the bugs can reach astounding population densities. While these insects have no impact on humans, their African, Asian, and American relatives, the cotton stainers, are serious agricultural pests of cotton and other Malvaceous plants. Researchers at the Max Planck Institute for Chemical Ecology in Jena, Germany, recently discovered that these bugs need bacterial symbionts to survive on cotton seeds as their sole food source. By using high-throughput sequencing technologies, they found out that firebugs and cotton stainers share a characteristic bacterial community that colonises a specific region of their mid-gut.