Abstract: Leptocimbex gracilenta(Mocsary) is an injuriuos pest destructive to Acer palmatum Thunb．And other trees．In Lushart it has one generation a year and overwinter as prepupa in cocoons in debris and soil．Pupation takes place in the last decade of May the following year．Emergence begins in the last decade of June．Oviposition occurs early in July，and damage beginsin the first decade of the month．In the last decade of August the mature larvae creep down the trunks to make cocoons．The occurrence of the pest iS related to the tree Species and the precipitation of May．As a means of control phoxim may be used during the peak of larvae occurrence，and the effect may reach a mortality of over 95％．More over，the removal of debris and weeds，together with the proper selectin of tree species，may also bring about good control．