Major sex pheromone component of female herald moth Scoliopteryx libatrix is the novel branched alkene (6Z, 13)-methylheneicosene

The major component of the female-produced sex pheromone of Scoliopteryx li batrix has been characterized by chemical analysis, synthesis, electrophysi ological studies and field tests as (6Z,13)-methylheneicosene, probably the 13S-isomer. This is the first example of a branched chain alkene as a sex pheromone in the Noctuidae and is markedly different from the pheromones of other members of the family. The systematic position of S. libatrix, belon ging to a monotypic genus of a one-member subfamily within the Noctuidae, m ay reflect the unusual structure of the sex pheromone.