The lepidopteran Amydria anceps Walsingham (Acrolophidae) is reported for the first time as a myrmecophile. Its gregarious larvae feed on the exhausted fungal substrate accumulations outside mature colonies of the Mexican leaf-cutting ant, Atta mexicana (Smith), a fungus-growing ant in Mexico. This constitutes the second report of an acrolophid myrmecophile. Morphology of the principal life stages of A. anceps are described, as well as its general natural history. No interactions were observed between Amydria larvae and A. mexicana, although the larvae of A. anceps are attacked by ichneumonid and tachinid parasitoids. Chalcids (primary or secondary parasitoids) also are associated with A. anceps larvae. Thus, there are potentially five trophic levels in this system: fresh plant material[long dash]Atta fungal symbiont[long dash]Amydria anceps[long dash]ichneumonid and tachinid parasitoids[long dash]chalcid hyperparasitoids. Systematics; Nomenclature; Life cycle and development; Associations; Parasites diseases and disorders; Parasites; Insect parasites; Hosts; Insect hosts; Land and freshwater zones; Nearctic region; North America Tachinidae; Ichneumonidae; Chalcidae (Chalcididae ); Lepidopteran hosts; Amydria anceps; Recorded from host larvae associated with Hymenoptera; Mexico; Recorded from lepidopteran host larvae associated with Hymenoptera Amydria anceps (Tineidae); Life cycle; Associations; Atta mexicana (Hymenoptera); Larval feeding on exhausted fungal substrate accumulations, new record; Dipteran parasites; Tachinidae; Hymenopteran parasites; Ichneumonidae & Chalcidae; Mexico; Association with Hymenoptera, life cycle & biology relationships Atta mexicana (Formicidae); Associations; Amydria anceps (Lepidoptera); Associate larval feeding on exhausted fungal substrate accumulations, new record; Mexico; New lepidopteran associate record Amydria anceps Walsingham 1914 (Tineidae); Description; P. 188 none no species