Abstract:Elm wood moth，Holcocerus vicarius Walker，bores through and harms the root and trunk of the broadleaf tree．It harms mainly Elm，Locust，Oak and Willow etc．In Shandong．In the field，the adult has one generation two years．If it is acquried by making use of half artificial compound fodder in the room，it has mainly one generation two years and one generation four years and one generation per or three years too．The adult appears in middle May．Under the lamp,there are two heights in June and August．The adult moves at night and its moving heights is at half past twenty-two to twenty-four hours．It has phototaxis and．Can be induced by moth-killing lamp of black light or illumination．The time of adult mating is very short．It needs usually sevetal minutes to ten or more．The larval period includes ten to twenty-three instars，majority more than fifteen．Before five instars，it harms trunk then diver to the neck of root．The middle-aged larva has very hunger-resistant and lifetime without taking food comes up to 113-447 days．