Some responses of cryptic mealybug, Pseudococcus cryptus, for a sex pheromone, [(1R,3R)-3-isopropenyl-2,2-dimethylcyclobutyl]methyl 3-methyl-3-butenoate, were studied to develop the applying strategy of sex pheromone trap for efficient monitoring and control-time decision in citrus orchards grown in greenhouse for 2 years (2007-2008). The optimal concentration of a sex pheromone was 1.0㎎ per hexane 100㎕ in a using pheromone lure. There was no significant effect of the attraction of male adults among different colours (white, blue and yellow) of plate-type trap baited with sex pheromone. The more male adults were attracted, as the distance of a pheromone trap form a citrus tree infested with cryptic mealybug was closer. The male adults were caught to sex pheromone trap from middle April to late November, and its peak period was the middle of July. The thermal constant for the next attraction was about 640 degree-days (lower threshold temperature=12℃) after confirmed the first attraction of male adults. The optimum control time for cryptic mealybug after the first attraction of male adults were confirmed was estimated as 450 to 500 degree-days.