Abstract: Endoclyta signifer Walker is a new wood borer on eucalyptus recorded in Guangxi Zhuang Autonomous Region and Guangdong province in recent years. In this paper, the morphology, biology and distribution of E.signifer were studied. In Guangxi Zhuang Autonomous Region, E. signifer distributes in 232 towns of 49 counties, 12 districts, and its distribution area is 2 894.42 hectares. Most of the individuals take one year to complete a generation, and over-winter with larvae in host stem from mid-December, the pupa occur in March of next year, emergence in April, the 1st instars larvae appear in May, and the larvae begin to transfer boring into host tree in June or July. Only one emergence happens in a year. It distributes mainly in the mountain area, valleys or gully, 1-2 year-old hybrid eucalyptus, Eucaluptus grandis×E. urophylla and E. urophylla×E. grandis are usually damaged seriously. The ratio of timber volume decline in 1-and 2-year-old damaged eucalyptus plantation were 16.70% and 24.78%, respectively. In valleys and gully area,1-2 year-old hybrid eucalyptus plantation are the prevention area and the control object.