Microbes are widely known to spread disease, but could they also help prevent it? A look inside in the mosquito gut reveals a community of microbes fit for the job. Mosquitoes are well-known vectors of disease, transmitting West Nile and Zika virus and the pathogens that cause malaria and dengue fever. Unfortunately, traditional control methods have led to insecticide resistance and negative impacts on other organisms, but mosquitoes, like other animals, also host non-disease-causing microbes in their gut. These benign microorganisms can directly interact with the deadly pathogens harbored by these insects. They can also affect mosquito traits influencing pathogen transmission, such as their population density, development, biting rate, and survival. For example, certain bacterial strains can reduce female fertility and the egg-hatching rate, while others can protect mosquitoes from environmental stress. Targeting specific members of the mosquito gut microbiome may therefore help modulate mosquitoes’ capacity to spread disease, reducing the multiple threats posed to humans and the environment.