Fruittree leafroller,Archips argyrospila(Walker), obliquebanded leafroller,Choristoneura rosaceana(Harris), and European leafrollerArchips rosana(Robinson), all use Z11–14:OAc and E11–14:OAc as components of their species-specific pheromone blends. Small-plot experiments (0.09 ha) were conducted in the Okanagan Valley of British Columbia to evaluate the effects of atmospheric permeation with different concentrations of Z11–14:OAc and E11–14:OAc, applied in a ratio of 93:7, on pheromone communication of these sympatric species. The relative response of male moths to synthetic and natural pheromone-baited traps in pheromone-treated and untreated plots was used to measure disruption of pheromone communication. The pheromone-disruption blend was released by polyethylene tube-type dispensers applied at various densities. Catches ofA. argyrospilain synthetic pheromone traps decreased by>92 and 97% when pheromone was applied at rates of 5–10 mg/h/ha and 20–40 mg/h/ha, respectively. Catches ofA. argyrospilain virgin female-baited traps were reduced by 99% at pheromone application rates of 20–40 mg/h/ha. Catches ofC. rosaceanaandA. rosanain synthetic pheromone-baited traps decreased by 88–96% when the pheromone disruptant was applied at rates of 20–40 mg/h/ha. In pheromone-disrupted plots, more maleA. argyrospilawere caught in traps baited with pheromone blends ofC. rosaceanaandA. rosanacontaining a higher percentage of Z11–14:OAc than the reported pheromone blend ofA. argyrospila.These results suggest an alteration of the normal pheromonal response ofA. argyrospilaon exposure to a high concentration of Z11–14:OAc for a sustained time.