In order to reveal the mechanism by which an inhibitory substance acts, orientation towards an attractant and attractant-inhibitor mixed source was studied in male gypsy moths. The inhibitory (-)-disparlure had no effect on the moth's ability to locate the attractant (+)-disparlure source while walking or flying in a laminar airstream. This absence of any inhibitory effect indicates that only very specific components of the moth's orientation behavior, as discussed, are distributed by the (-)-disparlure.