Abstract: Thysanogyna limbata is an important pest of the phoenix tree, an excellent shade one. Its adults and nymphs infest the trees by sucking. The nymphs affect the photosynthesis and respiration of the trees and pollute environments seriof usly in May and June by secreting waxy filaments, which induce sooty mould, thus causing double infestation. A systematic study of the psyllid was made from 1982 to 1985. In Hefei, this psyllid has 3 generations in a year and its eggs overwinter on twigs and trunks. The first generation causes the most serious damage. Some research has been made on its biological characters, rela tionships between its occurence and environments, and control methods. According to the tests of insecticides and various powders, 80% emulsion of DDVP and 40% emulsion of dimethoate showed much promise.