Ants of the genus Camponotus visit the extrafloral nectaries of Qualea grandiflora plants in the Brazilian savanna region known as the cerrado (left). In exchange for the nectar, the ants protect the plants from predation by herbivores. However, a fly species, Rhinoleucophenga myrmecophaga, specializes in exploiting this ant-plant mutualism by laying its eggs near the nectaries. The larvae that hatch form sticky shelters atop the nectaries to trap the ants (right) and prey on them. (Images originally published in Vidal et al 2018, Annals of the Entomological Society of America)