An average of 33% more almond moths,Cadra cautella(Walker), remained unmated during a 24-h period under absolute dark conditions compared to those moths mated under a light cycle with dim night illumination. Air permeation with synthetic sex pheromone carried out at various moth densities decreased the mean level of mated female moths at 24 h by 51%. When they were combined, darkness and pheromone effects appeared to be additive, suppressing mating by 85% after 24 h and 71% after 48 h. Both dark and pheromone effects were moth density dependent. Darkness combined with pheromone would enable practical population suppression at a moth density two to three times that possible with pheromone alone.