Identification of factors regulating diapause induction and termination was attempted with a stem borer, Busseola fusca (Lep.: Noctuidae). Diapause was induced when matured stems (15 week old) of sorghum were given to last instar larvae. It was recognized that the conditions where sorghum stems with a constant age were provided were not favorable to the larvae and as a consequence, however, no diapause incidence was induced. Water played a significant role in the termination of late diapause. During the late diapause period, larvae in the field were exposed to rainfalls in the short rainy season. This precipitation, however, terminated diapause in only a few larvae. This indicates that diapause termination of a stem borer requires sustained exposure to wet conditions, which do not usually tale place during the short rainy season. Drinking water did not stimulate a break of the larval diapause. Diapause larvae transferred to artificial wet conditions pupated without increase in fresh weight. It is thus concluded that primarily significance for diapause termination in B. fusca is association with water.