Sexual behaviour in most of the noctuid Lepidoptera follows a diel periodicity and is limited to a precise period of either the day or the night. The periodicity and the maturation periods are specific as well as the onset of oviposition behaviour. The knowledge of these traits of biology is an essential prerequisite for all the studies in chemical ecology. The periodicity of adult emergence, calling behaviour and oviposition of Busseola fusca (Fuller) was studied under laboratory conditions. Most males emerged before onset of the scotophase whereas most females did so one hour later. The virgin females started to exhibit calling behaviour few hours after emergence and there is no sexual maturation time. The calling behaviour starts the fourth hour after the onset of the scotophase but is lightly delayed for females having emerged the same night as compared to older females. Sexual and oviposition behaviours occur during the dark period. Oviposition started the first night after the mating night, peaked during the second night and then gradually decreased until the fifth night. The first night of oviposition, females laid eggs during the first three hours and after the 5(th) hour of the scotophase with a maximum during the 8(th) and 9(th) hour. During the second night, oviposition peaked during the second hour and tended to decrease thereafter.