To gain insight into the genetic basis of the divergence of sex pheromone signals in the genus Ostrinia, we conducted crossing experiments between three congeners: Ostrinia zealis (Guenée), Ostrinia zaguliaevi Mutuura & Munroe, and Ostrinia sp. near zaguliaevi. Female sex pheromones of the three species are comprised of three common components—(Z)-9-tetradecenyl acetate, (E)-11-tetradecenyl acetate, and (Z)-11-tetradecenyl acetate—blended at species-specific ratios: 70:24:6 in O. zealis, 45:5:50 in O. zaguliaevi, and 19:6:75 in O. sp. near zaguliaevi. The differences between O. zealis and O. zaguliaevi blends, and O. zealis and O. sp. near zaguliaevi blends, could be explained by a single autosomal locus with three alleles. However, sex chromosomal as well as autosomal genes should be taken into consideration to explain the difference between O. zaguliaevi and O. sp. near zaguliaevi blends. From analyses of the fatty acyl precursors of pheromone components, it seems that these genetic factors are involved in the last steps of pheromone biosynthesis including reduction. The process of divergence of pheromone components in the genus Ostrinia is discussed with reference to the findings of previous studies.