Pheromones

A chemical secreted by an animal, especially an insect, that influences the behavior or development of others of the same species, often functioning as an attractant of the opposite sex.

Pheromones are used to bring creatures together (e.g., in termite, bee, and ant colonies), lead them to food (e.g., in scent trails laid by ants), signal danger (e.g., when released by wounded fish to alert others), attract a mate and elicit sexual behaviour (numerous examples, possibly including humans), and influence sexual development (in many mammals and certain insects)