In an immune mechanism known as “hygienic behavior,” adult honey bees (Apis mellifera) can detect and remove brood afflicted with parasites or pathogens. A new study shows that part of this process relies on chemical signals emitted by unhealthy brood, and brood coming from colonies bred to be more hygienic are more effective in signaling for their own removal. In this image, brood can be seen in some uncapped cells. (Photo credit: Kaira Wagoner, Ph.D.)