Biology of the sapwood borer,Nyphasia apicalis Gahan is discussed with special reference to some aspects of adult behaviour, Development and survival of eggs and pupae are dependent on high humidity. Life-cycle is annual but may be prolonged to the next year. Adult emergence mainly occurs in June and July and is synchronized with the onset of rains. Beetles are diurnal, being most active in bright sunlight and are flower visitors feeding on different floral components. They are sexually mature on emergence and mate soon afterwards usually on the material from which they have emerged. Females prefer logs after a month of felling for oviposition. Logs lying in shady areas are avoided by the ovipositing females.