Different species use a wide variety of chemical substances to send sexual signals. The first to be described chemically was bombykol, the silkworm moth's sex pheromone, which is a complex alcohol, (E,Z)-10,12-hexadecadienol, discovered in 1959. It is detected in the antennae of the male moth by a pheromone-binding protein which carries the bombykol to a receptor bound to the membrane of a nerve cell.
The chemicals used by other moths are species-specific. For example, the Eastern spruce budworm Choristoneura fumiferana female pheromones contain a 95:5 mix of E- and Z 11-tetradecenal aldehydes, while the sex pheromones of other species of spruce budworm contain acetates and alcohols.
Sexual development in the freshwater green alga Volvox is initiated by a glycoprotein pheromone. It is one of the most potent known biological effector molecules, as it can trigger sexual development at a concentration as low as 10 moles per litre. Kirk and Kirk showed that sex-inducing pheromone production can be triggered experimentally in somatic cells by heat shock.