This is a Flatid planthopper (Lawana imitata), or commonly known as White moth bugs, I found in Sha Tau Kok, northern Fanling, New Territories. It can also be found in China and Vietnam.

They live in trees. Adults are active from May to October. I think they look so elegant and beautiful, but farmers just hate them because they drink plant juices from stems to leaves to fruits. This species is considered a pest of citrus, tea, mango, guava, grape, lychee, and cashew.
See more of my encounters with Hong Kong Wildlife.
白蛾蠟蟲, 紫絡蛾蠟蟬, Flatid planthopper (Lawana imitata)。
我曾經在新界粉嶺北區看過牠們, 你也可以在中國和越南發現牠們的蹤跡。
牠們住在樹上, 成蟲(成年的昆蟲)活躍於5月至10月, 我覺得牠們外型優雅美麗, 但農夫很討厭牠們, 因為牠們會吸食農作物莖部的汁液, 以至葉子及果實。牠們被認定為某些植物的農業害蟲 ,包括橙, 茶, 芒果, 石榴, 葡萄, 荔枝以及腰果。