One way of catching the pest Cydia molesta, the peach tree moth, is to use its pheromone chemical Acenol to attract the male to traps. Dienol traps the codling moth, whilst plum fruit moths can be attracted by Fenemol.
These moths have vast arrays of antennae, very similar to the banks of listening radars we have for alien messages.
The pheromone Bombykol which works for the bombyx mori moth, can be smelled by this insect at a distance of two miles.
Scaling that up for humans, that is like your being able to smell your beloved in Boston whilst you are in New York!