The result of an inventory on the lepidopteran fauna associated with the South American Holly (erva-mate) is described. This inventory was based on a bibliographic review, the examination of specimens deposited in scientific collections from the state of Rio Grande do Sul, the systematic collection within commercial erva-mate farms located in Anta Gorda, RS, and on the occasional collections from native trees within the Região dos Vinhedos campus of the Universidade de Caxias do Sul. Every fifteen days between 20 August 2005 and 19 August 2006, 150 trees were visually inspected and all Lepidoptera were collected. A list of 75 lepidopteran taxa belonging to 16 families is presented, including 27 new occurrences for the erva-mate crop, of which 14 species represent new records for the state.