Liometopum occidentale velvety tree ant workers tending larvae of the copper butterfly Lycaena xanthoides. The caterpillars produce a substance attractive to the ants, and the ants provide protection from predators and parasites. Kern County, California, USA

Papyrius nitidus workers tend hemipteran nymphs on a tree in northern Australia. Iron Range National Park, Queensland, Australia

A Formica francoeuri field ant worker tending to a Lycaena xanthoides larva. The larva produces secretions attractive to ants, and in turn the ants protect the larva from predators and parasites. San Diego Co., California, USA