Wolbachia are widespread maternally transmitted intracellular bacteria that infect most insect species and are able to alter the reproduction of innumerous hosts. The cellular bases of these alterations remain largely unknown. Here, we report that Drosophila mauritiana infected with a native Wolbachia wMau strain produces about four times more eggs than the noninfected counterpart. Wolbachia infection leads to an increase in the mitotic activity of germline stem cells (GSCs), as well as a decrease in programmed cell death in the germarium. Our results suggest that up-regulation of GSC division is mediated by a tropism of Wolbachia for the GSC niche, the cellular microenvironment that supports GSCs.