Abstract: 1. Most of the poplar twig clearinwg moths Paranthrene tabanieormis Rottenburg are univoltine in Beijing area. They hibernate as larvae in the tannels of the tree trunk. No apparent diapause phenomena was found in the larvae stage. In the case of proper temperature. They could take food at any time. Through the feeding of artificial diet, the larvae has been proved to be eight instar. The sex pheromone mass trapping of adult showed that emergence time varied with atmospheric temperature in a year. emergence begins in the first ten days of May and ends in the second ten days of October. Thus, it lasts for five and a haif months. To make a check against previous report, emergence of adult occurred 20 days earlier and its duration is prolonged for two and half months. Female moths often attract male moths by the sex pheromone-(E, Z)-3, 13-Octadecadienol.2. The poplar twig clearwing moth can do harm to all kinds of cultivated poplars and sometimes to willows. The degree of harm depends on the morph adaptability and back woodify level of poplar; site class; canopy density and the number of insect's source.3. To spray a contact insecticide upon poplar repeatly during adult's emergence time was found to be effective. But this method influences the reproduction of the natural enemy and contaminates the environment. Therefore, sex pheromone was used to surround mass trapping, and spraying freaquency was decreased. In the area of a few insect's source only mass trapping of sex pheromone was used. In a good isolation area the trapping of male moths continues for years and the rate of harm was lowered greatly.