A "myrmecophile" is an organism that lives in association with ants

Myrmecophiles may have various roles in their host ant colony. Many consume waste materials in the nests, such as dead ants, dead larvae, or fungi growing in the nest. Some myrmecophiles, however, feed on the stored food supplies of ants, and a few are predatory on ant eggs, larvae, or pupae. Others benefit the ants by providing a food source for them. Most associations are facultative, benefiting one or both participants, but not being necessary to their survival, although many myrmecophilous relationships are obligate, meaning one or the other participant requires the relationship for survival.

Myrmecophilous associations are best known in butterflies of the family Lycaenidae. Many lycaenid caterpillars produce nectar by specialized organs, and communicate with the ants through sound and vibrations. The association with ants is believed to reduce the parasitisation of the butterfly caterpillars.

Some myrmecophilous beetles are in the families Coccinellidae (e.g. the ladybird Thalassa saginata), Aphodiidae, Scarabaeidae, Lucanidae, Cholevidae, Pselaphidae, Staphylinidae, Histeridae, and Ptiliidae (some treated here as subfamilies). In ant-beetle associations, the myrmecophilous staphylinids are the most diverse of the beetle families. Myrmecophilous associations are also seen in various other insects, such as aphids and treehoppers, as well as the hoverfly genus Microdon and several other groups of flies.