Innate immune cells, particularly neutrophils, are known to produce DNA-based extracellular nets that can trap and kill extracellular pathogens. Now, Zhang, Zhuchenko et al. show that the social amoeba Dictyostelium discoideum can also produce nets, either following stimulation with lipopolysaccharide (LPS) or in response to Klebsiella pneumoniae. Under starvation conditions, individual amoebae form a migrating multicellular slug community that includes phagocytic sentinel cells, and only sentinel cells were capable of producing extracellular nets. Furthermore, by deleting genes that have been previously associated with the phagocytic capacity of sentinel cells, the authors could demonstrate that the production of extracellular nets requires the Toll/interleukin-1 receptor domain-containing protein TirA and the generation of reactive oxygen species. These data increase the arsenal of defence systems used by D. discoideum and suggest an ancient origin for extracellular nets.