Pheromone

A pheromone (from Ancient Greek φέρω (phérō) 'to bear' and hormone) is a chemical that is secreted or excreted by an organism, which triggers a social response in members of the same species. There are alarm pheromones, food trail pheromones, sex pheromones, and many others that affect behavior or physiology. Pheromones are used by many organisms, from basic unicellular prokaryotes to complex multicellular eukaryotes. Their use among insects has been particularly well documented.