The World Mosquito Program (WMP) is a global health intervention releasing bacteria-infected Aedes aegypti mosquitoes as a biotechnology against viruses like Zika, dengue, and chikungunya in countries across the world. These mosquitos are infected with Wolbachia bacteria, which significantly reduces their ability to transmit diseases. Moreover, the bacteria are passed on to the mosquitos’ offspring when they reproduce with their ‘wild’ counterparts. In this way, the WMP seeks to replace the pathogenic mosquito population with its bacteria-infected version, asking humans to coexist with an insect usually framed as an enemy. Based on over 12 months of ethnographic fieldwork, this thesis analyses how the WMP is intervening in Medellín, Colombia, in order to tease out the biopolitical narratives surrounding the mosquito and the implementation of this global health intervention at the local level. This research finds that the WMP is premised on the cultivation of coexistence between humans and a bacteria-infected mosquito and thus on a reconfiguration of multispecies relations. The dissertation unpacks the project of coexistence and considers the social, entomological, epidemiological, and political labour involved in its cultivation, as well as the material and affective engagements that characterise this work. It analyses how this coexistence is experimental and Medellín is rendered into an urban laboratory; how coexistence is embodied and ambivalent as it is always mediated by human blood; how it involves cultivation, in the sense that coexistence requires active engagement with the mosquito; and finally how coexistence burdens society in unequal ways, and thus is always political.