The major component of the sex pheromone of the eastern spruce budwonn was established by Weatherston et al. (1971) to be trans-11-tetradecenal. Subsequently it was found (Sanders and Weatherston 1976) that a small proportion of cis-11-tetradecenal was essential to attraction and indeed was a component of the natural pheromone. In addition Weatherston and Maclean (1974) have shown that the female sex pheromone gland contains trans-11-tetradecenol, a presumed biosynthetic precursor to the aldehyde.