In night-flying moths, highly specific, long distance, pheromonal communication is essential for mating success and reproductive isolation of species. Emission of two or more volatile compounds by females, in precise ratios, is typically required to attract conspecific males (e.g., Cardé and Haynes 2004). Although there are thousands of moth species with unique pheromone blends (e.g., Cork and Lobos 2003; Witzgall et al. 2004; El-Sayed 2008), the evolutionary processes that resulted in this diversity of sexual communication signals and species are not understood.