Resident microbes and the microbiome (collective microbial genomes associated with individuals) can provide novel functional benefits to their hosts. In insects, microbial associations mediate host adaptation to abiotic and biotic stresses and are important contributors to the insects’ remarkable ecological success. This talk will highlight the microbiome’s role in insect dietary specialization and in their utilization of challenging breeding resources. I will present my research on microbiome-mediated usage of unconventional and potentially noxious diets such as carrion and dung that are ephemeral and select for rapid development. Despite being susceptible to microbial spoilage, carrion beetles and dung beetles prolong the palatability of these diets to support larval development and are immune to any ill effects of feeding on decomposing matter. I will discuss the importance of the microbiome in the nutritional ecology of these insects, its implications on host diversification, behavior, and regulation of ecological processes.