Of the four minor components, Z3Z6Z9-23:Hy was essential for male attraction in the Little River population. This is evident because males were caught only in traps baited with a binary blend containing Z3Z6Z9-23:Hy. Similarly, male Conogethes pluto (Butler) respond only to a multicomponent pheromone blend that contains Z3Z6Z9-23:Hy . So far, Z3Z6Z9-23:Hy has been reported in Crambid, Arctiid and Geometridae species . This result indicates that this polyunsaturated hydrocarbon plays a role in the sexual communication system of T. atristriga, and is the first report of this compound in any Noctuid species. This finding has added to the growing list of lepidopterous species that have been found to use aliphatic aldehyde, alcohol, acetate, and polyunsaturated hydrocarbon components in their pheromone blends. The variation in male response between the two locations could be due to males in the Little River population being under strong selection pressure to recognize compatible mates due to partial overlap in chemical composition with other moth species in that location, which is not the case in Lincoln's population.