The insecticides of microbial origin may be promising biocontrol agents to control pests. In this study, a major metabolite was extracted and purified from Serratia marcescens KH-001 and identified as prodigiosin with a molecule weight of 324.2094, and our primary aim was to evaluate the effects of prodigiosin against Diaphorina citri Kuwayama (Hemiptera: Liviidae) in the laboratory and in the field. Toxicity of purified prodigiosin to nymphs increased with increasing temperature from 25 to 35°C. The laboratory experiment results observed inhibition effects of purified prodigiosin at LC₅₀ on oviposition and egg hatch of D. citri at 30°C. Furthermore, adults that fed on citrus leaves treated with LC₂₀ and LC₅₀ solution of purified prodigiosin at 30°C excreted less honeydew (28–35%) compared with controls, suggesting moderate antifeedant activity of prodigiosin. The results of field experiment showed that 10% prodigiosin emulsifiable concentrate exhibited better control efficacy (70–100%) at three concentrations (100, 200, and 500 mg/liter) in July and August than in October. These data indicate that prodigiosin will be a highly effective compound for the control of D. citri depending on the prevailing temperature conditions and may become a commercially available product to be widely used in citrus orchards.