Cicada larvae live in the soil and have a pair of powerful digging front legs. Sucking the sap from the roots of plants with mouthparts weakens the tree, makes the branches die and affects the growth of trees. Usually I will stay in the soil for several years or even more than ten years, such as three years, five years, and 17 years. These numbers have one thing in common, they are all prime numbers. This is because there are few prime factors, which can prevent them from drilling out with other cicadas when they drill out of the soil, competing for territory and food. When it is about to emerge, drill out of the ground at dusk and night, climb to the tree, and then grab the bark to shed its skin and emerge. When a black crack appears on the back of the cicada pupa, the molting process begins. The head came out first, and then the green body and wrinkled wings were revealed. Stop for a minute with hardened wings and deepened colors, and start to take off. The whole process takes about an hour. At the end of June, the larvae began to emerge as adults, and the newly emerged cicadas were green, and their longest life span was about 60 ~ 70 days. Female adults began to lay eggs in late July, and the peak of laying eggs was in early and middle August. Most of the eggs were laid on branches 4 ~ 5 mm thick. In summer, they crowed loudly on trees. It was harmful to trees to suck tree juice with acupuncture mouthparts. Larvae lived in the soil and sucked tree root juice.