In a semi-enclosed courtyard, two Pherocon 1C traps baited with the synthetic sex pheromone ofArgyrotaenia citrana(Fernald) caught 16, 32, and 49% fewer marked maleA. citranawhen in the presence of 5, 10, and 20 virgin femaleA. citranacaged in cardboard cylinders and housed in Pherocon 1C traps, respectively, than did controls with synthetic pheromone-baited traps only. Capture efficiencies of released marked males ranged from 27–53%. Competition coefficients of virgin females calculated at three female moth densities suggested that pheromone catch per trap per night may be reduced by 2.56–3.27% per competing female. These results indicate that calling virgin femaleA. citranacan significantly affect captures of male moths in synthetic pheromone-baited traps and, therefore, may influence moth phenology and density interpretations made from these types of monitoring data in the field.