Pheromones are chemicals released by organisms into the enviroment making them ectohormones. They cause a change in another organisms behaviour.

Pheromones can be secreted to trigger many different behaviours

• Alarm
• Follow a trail
• Sexual arousal
• Marking territory
• Create a bond between individuals
• Tell others to back off

So when a dog urinates on a specific spot, they release pheromones in their urine which tells other dogs that this is their territory.

Pheromones are often smelt by the organism and then trigger a behavioural change. Knowing this humans have used pheromones to their advantage.

The animation above shows how farmers have used synthetic hormones to decrease moth populations on their farms.

Normally the female moth will release pheromones in the air guiding the male moth to her. The male moth will follow a zig-zag tracking method to find her.

However when the synthetic hormone is sprayed into the air, the male moth can not locate the female and becomes confused.

This is only one of the methods farmers use to stop moths from reproducing.