Emerald ash borer (Agrilusplanipennis Fairmaire)(Coleoptera: Buprestidae) is a major stem borer of ash (Fraxinus spp.). It is univoltine in Tianjin, while it is semivoltine in Heilongjiang Province, and both univoltine and semivoltine in Changchun, Jilin Province,where the majority is univoltine. The longevity of emerald ash borer adults is 17.2 ± 4.6 days (n = 45), eggs 9.0 ± 1.1 days (n = 103), univoltine larvae 308 days, semivoltine larvae 673 days, and pupae 61.2± 1.6 days (n = 45). It takes about 100 days from the time larvae bore into the phloem to when they complete the pupal cell. In a 10-year-old velvet ash (Fraxinus velutina Torr.) plantation in Tianjin, emerald ash borer preferred to oviposit on the regions of boles from 50-150 cm above ground, accounting for 76.7% of the total girdling.Girdling on the south side of the tree boles accounted for 43.40% of the total girdling. The emerald ash borer population density is higher at the edge of the plantation compared with the center.