A pheromone (from Greek φέρω phero "to bear" + Hormone from Greek ὁρμή - "impetus")'s a chemical signal that triggers a natural response in another member of the same species. There're alarm pheromones, food trail pheromones, sex pheromones, and many others that affect behavior or physiology. Their use among insects has been particularly well documented. In addition, some vertebrates and plants communicate by using pheromones. Background The term "phero… (More on Pheromone)