. What is the reason behind moths being drawn to lights? After years of research, science may have finally found an explanation.
Throughout various works of literature, from the Bhagavad Gita to the Merchant of Venice, authors have cautioned against the undesirable outcome that befalls those who are irresistibly drawn to something, like a moth to a flame.
Although the strange phenomenon has a long history, the reason behind insects being attracted to lights at night remains a mystery. Some commonly accepted explanations suggest that moths use the moon as a guide and are tricked by artificial lights, or that insects instinctively fly towards light as a means of survival.
According to recent studies, there is a more convincing explanation for why moths and other flying insects are drawn to light at night – they actually become ensnared in its glow. This is an unfortunate result of an evolutionary adaptation that was once beneficial but is now ineffective in our modern environment.
Dr. Sam Fabian, an entomologist from Imperial College London, explains that moths and other nocturnal insects have adapted to tilt their backs towards the brightest light source. This has been the case for millions of years, with the sky being the brightest source rather than the ground. This behavior helps insects determine their orientation and fly in a level path.
However, with the introduction of artificial lighting, a new challenge arose for moths. They began to orient themselves towards street lamps, resulting in a perpetual cycle of flying around and getting trapped due to their ingrained behaviors.
Fabian and his team observed the flight patterns of insects near lights by utilizing precise infrared motion capture technology in a laboratory and high-speed infrared video recordings in Costa Rica. The recordings show that moths and dragonflies frequently turned away from artificial lights, disrupting their flight paths.
According to Fabian, moths may orbit a light if it is positioned above them, but if it is behind them, they may tilt backwards and potentially climb until they stall. A more concerning scenario occurs when they fly directly over a light, causing them to become inverted and potentially leading to crashes. This behavior indicates that the moth is unsure of its orientation.
According to a study published in Nature Communications, artificial lighting may not attract flying insects from the dark, but rather ensnare those that happen to pass by. Lead researcher Fabian compared it to using a net.
Scientists have cautioned for a while now that the increase in light pollution greatly contributes to the significant decrease in insect numbers. When moths and other insects get trapped near lights, they become easy targets for bats. However, the artificial lighting can also deceive them into believing it is daytime, leading to them resting and missing a night of feeding.
According to Fabian, artificial light can greatly disrupt the lives of these nocturnal insects, with their flight being just one aspect of the impact.
According to him, the research provides valuable insights. It suggests that the direction of artificial light is significant. If lights are used at night, it is important for them to be shielded and not emit excessive light to the sides or upwards into the sky. He emphasized, “Ideally, lights should be directed downwards and not contribute to light pollution.”
Professor Gareth Jones from the University of Bristol described the research as “captivating”. He noted that it is astonishing how an instinctive and adaptable behavior, used by insects to orient themselves towards light and maintain a stable flight path, can become disadvantageous in the presence of powerful light sources such as lamps. He also stated that the results indicate that the high concentration of insects at street lamps is due to their circling behavior around the lights.
Reducing the effects on insects can be achieved by minimizing their attraction to and restriction at lamps. This can be done by utilizing lights that emit fewer short wavelengths, such as blue and UV, and potentially creating metameric light that appears white to humans but is less appealing to insects.