[Background] Animals harbor many microbial species that exert profound effects on host physiology and pathology, currently emerging as one of investigational hotspots. [Objective] To explore Staphylococcus epidermidis effects on the developmental timing of Drosophila melanogaster. [Methods] The bacteria were isolated from the fly guts by carotenoid expression medium (CEM), and the bacterial species were further determined by using 16S rRNA gene sequence. The growth and development of flies were detected. Real-time quantitative PCR was used to detect the activation of the prothoracicotropic hormone (PTTH) and insulin pathway in flies. [Results] The isolated strain was identified as S. epidermis, which was able to effectively colonize in the guts of flies. S. epidermis accelerated the development of D. melanogaster by promoting the growth rate. At the molecular level, S. epidermis activated PTTH and insulin signals to stimulate the growth of hosts. [Conclusion] S. epidermis was a commensal bacterium of flies, which stimulated the growth and development of flies by regulating PTTH and insulin signals.