Queen mandibular pheromone, or QMP, is a honey bee pheromone produced by the queen and fed to her attendants who share it with the rest of the colony that gives the colony the sense of being queenright. Chemically QMP is very diverse with at least 17 major components and other minor ones. Five of these compounds are: 9-ox-2-decenoic acid (9ODA) + cis & trans 9 hydroxydec-2-enoic acid (9HDA) + methyl-p-hydroxybenzoate (HOB) and 4-hydroxy-3-methoxyphenylethanol (HVA). Newly emerged queens produce very little of this. By the sixth day they are producing enough to attract drones for mating. A laying queen makes twice that amount. QMP is responsible for inhibition of rearing replacement queens, attraction of drones for mating, stabilizing and organizing a swarm around the queen, attracting a retinue of attendants, stimulating foraging and brood rearing, and the general morale of the colony. Lack of it also seems to attract robber bees. A study of foraging worker bees has suggested that foraging bees are not attracted to QMP.
Sometimes beekeepers re-queen their hives for various reasons. Some beekeepers place these now-unneeded queens in alcohol. The alcohol preserves the deceased queen and her pheromones. This "queen juice" can then be used as a lure in swarm traps. The dead queen is either placed in a swarm trap or a q-tip or cottonball dipped in the alcohol into a swarm trap. The alcohol evaporates, leaving the queen pheromone which may enhance the chances of a swarm moving into a trap.