Phytoncides are volatile substances diffused largely from trees to protect themselves against harmful factors. Many people are attracted to forest bathing and the effects of forest bathing involve the effect of protecting human dermal cell against reactive oxygen species (ROS), the activation of immune function and the reduction of stress hormones. Since phytoncides are released to prevent plants from rotting or being eaten by animals, we expect that phytoncides have negative effects on insects. However, there is almost no study to show the effects of phytoncides of Chamaecyparis obtusa on insects so far. Therefore, we examined the effects of phytoncides on insects using fruit fly, Drosophila melanogaster. Our results showed that the exposure to phytoncides scents reduced the lifespan of Drosophila in a dose-dependent manner. Moreover, development rate, locomotion and fecundity of fruit flies were also decreased with phytoncides exposure. In food preference test, fruit flies and house flies showed strong avoidance behavior to the food containing phytoncides in a dose dependent manner. Overall, these results suggest the possibility of phytoncides as human-friendly insect repellent.