Purity >98%. 7(Z)-Pentacosene is an unsaturated cuticular hydrocarbon that acts as a contact sex pheromone in fruit flies. In different species and genotypes of Drosophila, it can be found on both males and females. Pentacosene may stimulate copulation either by itself at high concentrations4 or when combined with other alkenes. Interestingly, the absolute level of pentacosene increases in Drosophila females immediately after copulation.