Zelus annulosus is an assassin bug found in South America. It frequently associates with Hirtella physophora (Chrysobalanaceae), a plant that houses colonies of plant-ants Allomerus decemarticulatus and provides the ants with nectar. Some species of Zelus gather sticky substances from certain plants to coat their legs; Z. annulosus does not engage in this behavior, instead secreting the substance.