Volatile scents are employed in patterning signals. Some moths advertise sex-attractant pheromones in single-second pulses. But most moth pheromones strike a compromise between ease of dispersal and persistence. A male moth may catch the scent of a female 4–5 kilometers downwind. It is a short-lived pheromone with excellent dispersal.
Other chemical missives are meant to last. Moth territory markers tend to be persistent and carry a fairly high molecular weight, but not so high as to not stay airborne.
Hefty molecules are more difficult to synthesize, secret and spread. For moths, territory goes to those with stamina.