(Z)-7-Tetradecenal appears to be the sole attractive component of the sex pheromone ofSpaelotis clandestina, from which it was identified by gas chromatography, mass spectroscopy, electrophysiological analyses, synthesis, and field trapping tests. Synthetic material was unattractive during June and July (before and during the aestivation period of the moths) but became attractive during August and September, at which time it was a potent and specific lure. None of thirty tested analogs enhanced attraction; the (Z)-9-isomer was a powerful trapping inhibitor.