A pheromone is a chemical an animal produces which changes the behavior of another animal of the same species (animals include insects).
Some describe pheromones as behavior-altering agents. Many people do not know that pheromones trigger other behaviors in the animal of the same species, apart from sexual behavior.
Pheromones, unlike most other hormones are ectohormones – they act outside the body of the individual that is secreting them – they impact a behavior on another individual. Hormones usually only affect the individual that is secreting them.