ABSTRACT. The morphology of the reproductive systems and the coupling mechanism between the male and the female genitalia during copulation in Dioryctria rubella Hampson are described. Differing from those in other genera of Phycitinae moths, the corpus bursae possesses a well-developed signum, and the seminal duct does not exhibit a bulla seminalis, instead arising from the ventral surface of the corpus bursae. The ultrastructural observation shows that the spines on the inner surface of the ductus bursae and the cervix bursa are complementary to that of cornuti on the outer surface of vesica in position and direction, which elucidates the matching mechanism between the ductus bursae and the vesica. The male possesses well-developed scale brushes, which consist of six pairs of overlapped structures. Finally, the morphological differences of scale brushes between D. rubella and other Dioryctria species and related genera, and their function during copulation are discussed.