Abstract: Citrus is one of the most important export products and citrus production is one of the most developing agricultural sectors in Turkey. Citrus mealybug is one of the main pests of citrus. Biological control is often preferred against citrus mealybug because mealybug control with chemicals is quite difficult due to the wax that covers the insect and its habit of feeding in dark and inner places. The parasitoid Leptomastix dactylopii Howard (Hymenoptera: Encyrtidae) can suppress the mealybug population. As it is thought that the activity of natural enemies is intensive in citrus orchards, it is important to know the impact of white oils on natural enemies. For this reason, the effects of the white oils used widely in citrus orchards on some biological aspects of parasitoid L. dactylopii were determinated in laboratory condition. The experiments were conducted on 28 ± 1 °C temperature, 65 ± 10% relative humidity and 16:8 h light: dark photoperiod conditions. The effects of the white oil applied at 0, 2, 4, 6 and 8 days after parasitization of citrus mealybug on different ages were examined. The period of maturity of the parasitoid grown in young female mealybugs increased compared to control, while the time to full grown in third instar mealybugs decreased. Ratio of being mummy and emergence increased with the application time in both host ages. Longevity of female and male parasitoids emerged from third instar mealybugs increased with the exposure time. No differences were observed in male parasitoid when longevity of female parasitoid emerged from young female mealybugs decreased. These results could help to further improve the safe use of white oil in IPM.