Host organisms contain complex microbial populations that serve critical functions. A type VI secretion system (T6SS) is a contact-dependent killing apparatus that bacterial cells can employ against each other. In host organisms, the amount and efficacy of T6SS-mediated killing can affect the host’s microbial composition. Little is known, however, about the extent to which environmental factors such as temperature may impact killing, and therefore how they ultimately impact the structure of microbial communities within hosts.