Question: What is a pheromone ?

Jennifer Bates answered on 16 Nov 2016:

A pheromone is a chemical or mixture of chemicals that when released by one member of a species affects the physiology or behaviour of another member of the same species. Insects and animals often produce these for a lot of reasons, like attracting a mate, laying down a trail (ants do this for example) or mark territory, but plants can produce them too. When grazed some plants produce a pheromone that tells their neighbours to make tannins that are bitter to try to persuade the animal grazing on them not to eat them!