Animals depend on their sense of smell to locate food, identify mates and evade danger. In mammals, olfactory perception typically relies on G protein–coupled receptor (GPCR) pathways. Insects, by contrast, use a distinct receptor system made up of odorant receptors (OrX) paired with a co-receptor known as Orco. For years, a key question has lingered: Do these insect receptors signal through GPCR-like routes or an entirely different mechanism?