Abstract: Litchi is an important tropical cash crop in China, and Conpomorpha sinensis is the primary pest affecting the yield and quality of fruit. In order to explore the feasibility and optimal application period of the juvenile hormone analogue-pyriproxyfen for controlling C. sinensis, the toxicity of pyriproxyfen to adult, egg, larva and pupa of C. sinensis was measured indoors by residual film method, egg dipping method, fruit dipping method and pupa dipping method, respectively. Additionally, changes in pupation and emergence of C. sinensis after pyriproxyfen treatment with fallen fruits were studied. The experimental results showed that pyriproxyfen had low toxicity to adult and egg of C. sinensis with LC₅₀ values of 458.353 and IC₅₀ values of 47.748 mg/L, which were equivalent to those of diflubenzuron for adults or significantly lower for eggs. However, the activity of pyriproxyfen to larva and pupa of C. sinensis was significantly higher than that of diflubenzuron, with LC₅₀ values of 18.643 and IC₅₀ values of 28.170 mg/L. In addition, pyriproxyfen treatment with fallen fruits significantly decreased the pupation and emergence of C. sinensis. The pupation inhibition rates of 50 and 100 mg/L treatment reached 82.64% and 97.22%, respectively, while the adult emergence inhibition rates were 100%. The study demonstrated that besides high toxicity to larva and pupa, pyriproxyfen effectively inhibits pupation and emergence of C. sinensis. The research results provide a theoretical basis and empirical support for the scientific application of pyriproxyfen in the chemical control of C. sinensis.