Abstract: Phalanta phalantha Drury is an important defoliator of Homalium hainanense. It has 12 to 13 overlapping generations per year in Hainan Island. It is likely that the pest will come the disaster in May, if the rainfall is less than ordinary in dry season. The larvae like to dwell on the back of the leaves. The character of the imago is of flaping its wings unceasingly. The stock with 5ppm permethrin or 90% crystal Trichlorphon diluted with 2000 to 3000 times of water can be used for the chemical control. The means of forestry is to cultivate the mixed crop, and clear the FlacOurtia indica round the forestry.