The symbiotic microbial community that many animals have floating freely in their gut is critical to their health and well-being. But some insects, like cereal weevils, take this a step further and host bacteria inside their own cells. These endosymbiotic bacteria reside in massive, specialized cells organized in an organ called the bacteriome. Previous studies have suggested that the cereal weevil bacteriome participates in immune responses. But how, or if, the bacteriome protects its resident bacteria from that immune activity remains unclear. To answer this, researchers activated the cereal weevil innate immune system with pathogen protein fragments and examined the gene expression changes in the bacteriome and its residents. Rather than differentiate between pathogens and symbionts, the cereal weevils protected their endosymbionts with physical separation. The bacteriome participated in the immune response by elevating expression of antimicrobial peptides (AMPs), but the AMPs themselves were only found outside the bacteriome. The endosymbionts didn’t show any signs of protecting themselves, as they had no changes in gene expression. While research with live pathogens is needed, this study refined our understanding of how bacteriomes protect their endosymbionts.