||One of the fundamental issues regarding sexual selection is whether females select males based on signals that represent direct phenotypic or indirect genetic benefits. In Utetheisa ornatrix (Lepidoptera: Arctiidae), females choose males based on a courtship pheromone, hydroxydanaidal (HD), derived from defensive pyrrolizidine alkaloids (PAs). At mating, virgin males transfer a spermatophore whose contents are proportional to the HD titer; as a result, females receive both phenotypic benefits (more nutrients and PAs) and genotypic benefits (genes for larger size). Previous data from field-collected individuals, however, indicated that the HD signal of non-virgin males may not correlate with the spermatophore contents. Using chemical analyses, I determined that the HD signal does not change based on mating history, thus revealing that females select males based on their genetic quality. This result implies that females are choosing mates who can provide her offspring with genes that will convey better survival and reproductive advantages.