The woolly whitefly, Aleurothrixus floccosus (Maskell) is a destructive invasive pest, and was found in Hainan, China, in November, 2018 on Psidium guajava. The present paper described its morphological characters of egg, larva, pupa, and adult with emphasis on field identification features, distribution and host plants, provided with color pictures. Finally, it gave out the possibility of its future dispersion, asking for close check in the Citrus growing area of the Chinese mainland.