The seven components of the Heliothis spp. female sex pheromones, formulated individually in polymeric flake dispensers and applied at 25 g al/ha in 0.202 ha plots of cotton, were evaluated in replicated tests as mating disruptants or confusants of wild male bollworm and tobacco budworm moths. Four of the components [(Z)-7-hexadecenal, (Z)-g-hexadecenal, hexadecanal, and tetradecanall did not disrupt or confuse pheromone communication or mating of the bollworm or tobacco budworm. Permeation of the atmosphere with (Z)-11-hexadecenal caused almost total disruption of pheromone communication of both the bollworm and tobacco budworm and resulted in significant reductions in both trap catch and mating of both species. Permeation of the atmosphere with (Z)- 9-tetradecenal or (Z)-11-hexadecenal-ol caused significant numbers of male bollworm moths to be attracted to and mate with tethered female tobacco budworm moths. Due to morphological incompatibility of their genitalia such matings proved lethal to both individuals.