Abstract: The host selection process of parasitoid, eventually leading to successful parasitism. The influence of host plant odour was studied using the different type of olfactometers like eight arm olfactometer, six arm olfactometer and Y- tube olfactometer. The olfactometer studies revealed that there were more number of parsitoid attraction events towards the infested hosts than healthy host plants over time. While observing on eight arm olfactometer with mealybugs as standard check, mealybugs attracted more number of parasitoids in the healthy leaves, but at the same time, papaya and cotton leaves infested with mealybug attracted more number of parasitoids than mealybug standard. The parasitoid orientation in Y - tube olfactometer of the present study revealed that, infested leaves attracted more number of parasitoids, when they are tested with healthy leaves. Infested leaves with mealy covering attracted even a more numbers than in infested leaves alone.