In ecological communities, several species interact with one another to regulate their abundance. For example, mutualisms benefit all species involved, commensalism benefits one species but not the other, competition (for a resource) lowers the fitness of all species involved, whereas for predation, herbivory and parasitism one species is negatively affected by the other. We present the biological interactions between the myrmecophyte Hirtella physophora (i.e. a plant sheltering ants in hollow structures) and other organisms. Two Allomerus ants build gallery-shaped traps on this plant using hairs from its stems and the mycelium of an Ascomycota fungus to capture prey. They also use their refuse to provide their host plant and the fungi with nutrients (myrmecotrophy). Social wasps build their nests under the Hirtella leaves to benefit from the protection provided by Allomerus against army ants. Several insects can rob parts of Allomerus prey (cleptobiosis), but can be captured in turn. Finally, the reduviid Zelus annulosus, which foils attacks by Allomerus due to the production of a sticky substance that covers its egg masses and coats its legs, mostly attacks prey in groups and then shares them. Their populations are regulated by parasitoid wasps. Consequently, almost all possible biological interactions were noted in this study.