This article examines three locations where entomologists engage in the experimental observation of mosquitoes: the insectary, the semifield station, and the outdoors. We approach each of these settings as creating a distinct mode of interiority, a particular room‐space. This concept resets the investigative encounter in terms of an aesthetic of attention, and offers a counterpoint to the ideals of control and containment that dominate biosecurity understandings of infectious disease research. An ethnographic foray into the compositional logics of entomological experiments serves to illuminate the dialectics of caring and killing that characterize scientific inquiry into animals that pose a public health risk. [mosquitoes; vector control; entomology; multispecies ethnography; global health research]