[Objectives]  To determine the activity of adult Cosmopolites sordidus (Germar) in banana plantations and provide a scientific basis for the control of this species. [Methods]  The activity of adult C. sordidus in banana plantations in Chengmai in Hainan province was studied using traps. [Results]  The results showed that C. sordidus adults hovered mainly near the sheath and petioles of bananas. Insect traps were hung at three different heights (160, 250 and 0 cm) above ground. The number of insects trapped at 160 cm was significantly higher than at 250 cm (14.3 insects per trap) and 0 cm (14.2 insects per trap). There was no significant difference in the number of adults trapped in the east, west, south and north of the plantation (P>0.05), which indicates that C. sordidus adults do not tend to fly in any particular direction in banana fields. With respect to circadian rhythms, C. sordidus adults were mainly active from evening to early morning; 100% of females and 92% of males were trapped between 16:00 and 4:00 am. [Conclusion]  C. sordidus adults have well defined patterns of circadian activity and flight height. This information provides a scientific basis for developing and implementing control measures, including attractants and sex pheromone that may ultimately help to control C. sordidus in banana plantations.