Abstract: Lymantria xylina Swinhoe is a major pest of casuarina in Fujian Coastal Protection Forest.It has also become the main pest of Dimocarpus longan Lour.in Xiamen since 2003.The life history,developmental periods and biological characteristics of Lymantria xylina Swinhoe are presented in this paper.The results of our study showed that the pest bred one generation per year in Xiamen,and winterized itself as diapause larvae.Generally,it has seven instars with a larval stage lasting 36 to 51 days.