Symptoms: Adults and nymphs gather on the back of the leaves to suck juice, and a black sticky substance appears on the back of the injured leaves, which looks like it has been splashed. This feature is easily distinguished from other sucking pests. The whole damaged leaf is rusty yellow on the back and many light spots are formed on the front. When severely damaged, the spots turn into patches, making the whole leaf green. From a distance, it looks pale, leaves are early and no flower buds are formed.
Prevention and control methods: thoroughly eradicate flowers, fallen leaves and weeds around the bonsai garden in winter. For plants with thicker stems, apply white paint. When overwintering adults come out of their spines, they move to the next generation.