Many insects and other organisms communicate with each other through ectohormones or pheromones. The specific molecular structure of these chemicals helps individuals recognize members of their own species and has far-reaching effects on their ecology. The hypothesis has been proposed that air pollutants are able to destroy pheromones. This assertion was demonstrated as a first step in experiments which examined the effects of ozone on aggregation pheromones of Drosphila melanogaster. The results showed that both total pheromone containing extracts as well as commercially available pheromones lost their biological activity after short-term ozone fumigation at environmentally realistic concentrations. Gas chromatographic analysis revealed the degradation of the chemical. Some consequences of the findings are discussed.