Rove beetles are among the chemists of the insect world, concocting noxious compounds within their bodies that are weaponized to ward off predators, enabling the beetles to survive in leaf litter and soil in ecosystems across the planet. Investigators studying a species of rove beetle report how two distinct cell types have come together to form a specialized gland for making and secreting these defensive cocktails. The work has implications for mapping out the evolution of more sophisticated organs found across the animal kingdom, including in humans.