Abstract: The female gypsy moth Lymantria dispar produces a single-component sexpheromone, called (+)disparlure (2-methyl-7,8-epoxy-octadecane), for upwind attraction ofconspecific males for mating. It was recently shown that a (+)disparlure analogue, the 2-decyl-1-oxaspiro[2.2]pentane (OXP-01) is neither stimulatory nor attractive by itself, but stronglydecreases the male response to the pheromone and also inhibits its attractiveness when the twocompounds are blended at a 1:1 ratio. Aim of the present work is to study the temporal decaypatterns of the attractive effect of the 1:1 blend as compared to those of the single components,OXP-01 and (+)D. We counted the number of males trapped from field trap with (+)D and trapswith the blend and with OXP-01 within a time interval of 1-16 days. Our electrophysiologicalresults show that OXP-01 always decreases the excitatory effect of pheromone on the maleantennae. Present behavioural results suggest that the analogue may interact with the naturalgypsy moth pheromone, by modifying its attractiveness on male moths.