AM1-type molecular orbital calculations were performed on the geometry-optimized struc-tures of various 4-(1', 5' - dimethly -4' - heptenylidene) -1- methylcyclohexene isomers. It was found that the major component (4Z, 4'E isomer) of the sex pheromone of Eurygoaster integriceps is very dissimilar in chemical composition to the other isomers, although the stabilities and heats of the for-mation characteristics are comparable. However, some small molecules resembling only a part of the pheromone might exhibit some partial activity.

AM1-type molecular orbital calculations were performed on the geometry-optimized struc-tures of various 4-(1', 5' - dimethly -4' - heptenylidene) -1- methylcyclohexene isomers. It was found that the major component (4Z, 4'E isomer) of the sex pheromone of Eurygoaster integriceps is very dissimilar in chemical composition to the other isomers, although the stabilities and heats of the for-mation characteristics are comparable. However, some small molecules resembling only a part of the pheromone might exhibit some partial activity.