Abstract: Encarsia citrina (EC) and Aphytis lingnanesis (AL) are two primary paras itoids of Aonidiella aurantii in Guangdong citrus orchards. In 1988, we intr oduced Aphytis melinus (AM) from California. After a series of propagation, this exotic parasitoid was released three times in a ctrus orchard, with a total number of about 4,000 pertree (to cope with the existing population of both EC and AL). We analyzed the rate of overall parasitism as well as the parasitic rates of each species. It was found that EC was by far the most efficient parasitoi d. It worked better than AL and AM working together (parasitic rate 1.4 to 11.1% higher). The introduced species did not show too much advantage. It could overwi nter in Guangdong climate, however.