Abstract: This paper dealt with the biological rhythm of sex pheromone of the females and the responsive-ness of the males of Illiberis pruni．The methods of electroantennogram and wind tunnel assay were used．The results showed that seX pheromone production occured in the newly emerged and 1 to 7-day-old female moths，but the maximum level occured in 3-day-old female moths，while the 3-day-old male moths had the maximum responsiveness tO seX pheromone，There were two peaks of both the sex pheromone production of the females and the responsiveness of the males in a day；the male response peaks lasted longer．This indicated the sexual sensitivity of the males and the harmonious synchronization of the sexual behaviour between the females and the males．

Key words: Illiberis pruni, Sex pheromone, Biological rhythm