Hercon dispensers, adsorbed with (Z,E)-9, 11-tetradecadienyl acetate (1.5 g/ha) and located 65 m apart (one dispenser per 0.4 ha), effectively disrupted communication inSpodoptera littoralisfor about 4 weeks. This was inferred from the reduction in trap captures and in number of virgin female traps that captured at least one male in the pheromone-treated vs. control plots. The release rate of the pheromone from the Hercon dispenser was of the first order: an average of 1.4 mg/cm2per day was released during the first days, and ca. 0.6 mg/cm2per day during days 9 to 24. Most of the pheromone (ca. 87%) was emitted within the first 24 days. The laminated structure protected the pheromone effectively, and oxidation or isomerization was prevented without any addition of stabilizer or antioxidant. The method of emitting pheromone from widely separated Hercon dispensers seems promising for applied control ofS. littoralis.