Rhinoleucophenga myrmecophaga sp. nov., a Drosophilidae species associated with extrafloral nectaries of Qualea grandiflora Mart. (Vochysiaceae) and whose larvae are mostly predaceous on ants, is described from specimens collected in the Cerrado biome of Itirapina, state of São Paulo, Brazil. Illustrations of imagos, male terminalia, and immatures are also included. This is the first evidence of dipteran larvae that are closely associated with extrafloral nectaries and that feed on visiting ants.