Moths are attracted to lights primarily because they use natural light sources like the moon to navigate at night, a behavior known as positive phototaxis. They maintain a constant angle to the light to fly straight; however, artificial lights confuse this system because the light rays radiate in all directions, making moths spiral inward and circle around the light. This disorientation causes them to stay near lights rather than flying away. Additionally, moths have slower dark-adapting mechanisms, making it harder for them to leave brightly lit areas once they get close. The attraction is particularly strong to ultraviolet light, which acts as a super-stimulant to moths. The emergence of widespread artificial lighting has created an environment full of "artificial moons," disrupting their natural navigation and often leading to fatal consequences for the moths.
Moreover, studies show that street lamps attract moths within a radius of about 23 meters, affecting their movement and potentially acting as barriers to their normal migration and behavior. This has significant ecological implications, as artificial lighting can disrupt moth populations and entire food webs.
In summary, moths are not attracted to lights out of curiosity but due to an evolved navigational system based on natural celestial light sources, which artificial lights disrupt and exploit.