Anonychomyrma species are common in moist to semi-arid forested areas (and are less common in rain forests). They nest either in soil with or without coverings, or arboreally in living or dead wood. Workers forage in conspicuous trails on the ground and on tree trunks. Although not studied in detail, they seem to be general predators and also collect plant juices. Some species are associated with the caterpillars of selected butterflies. Nest sizes are moderate to large, ranging from 500 to tens of thousands of workers. When disturbed, most species elevate their gasters and release strong, acrid smelling chemicals as a defensive measure. While similar to Iridomyrmex in general habitat preferences and ecology, most Anonychomyrma prefer moister sites and are predominately arboreal. Iridomyrmex species occur in drier sites and are predominantly terrestrial.