(6Z, 9Z, 12Z)-6, 9, 12-Octadecatriene and (3Z, 6Z, 9Z, 12Z)-3, 6, 9, 12-icosatetraene, hydrocarbons unsaturated more highly than usual lepidopteran Type II pheromones, were identified from geometrid females of Hemithea tritonaria and Thalassodes immissaria intaminata, respectively. The triene was synthesized by a double Wittig reaction between hexanal and an ylide derived from (Z)-1, 6-diiodo-3-hexene, and the tetraene was ...