Moths of the families Ctenuchidae and Arctiidae are attracted to dried and withered plants containing pyrrolizidine alkaloids where they spend considerable time feeding. Three sex-biased patterns of visitation are noted: strong male bias; weak male bias; and strong female bias. The biological significance of this plant-animal interaction, previously unstudied, is examined. The results of field observations and flight cage experiments discount the hypothesis that moths ingest sex pheromone precursors as in danaine and ithomiine butterflies. That pyrrolizidine alkaloids might provide a nutrient (nitrogen) source for visiting moths is discussed.