We study fungi that live in association with ants and beetles. Our interest is to describe new fungal species and their putative functions for the insects. One particular model that we study is the fungus-growing (attine) ants, that cultivate fungi for food. Colonies of these ants are threaten by the parasitic fungi in the genus Escovopsis which consumes the fungus cultivated by attine ants. We are unravelling the diversity of this parasite (and other fungi) as well as understanding its evolutionary adaptations to parasitize the ant fungus.