Understanding the New Theory of What Attracts Insects to Lights

Scientists recently conducted field experiments in Costa Rica to investigate how various insects react to artificial lights at night. This study has shed light on a long-standing mystery regarding what lures insects to artificial light. Researchers observed peculiar flight patterns in insects flying towards artificial lights at night, implying that the bugs utilize light as a guide to maintain a straight flight path. Entomologist Mary Esther Murtfeldt first noticed this phenomenon in 1884, when she captured daytime butterflies attracted to her lamps at night. The age-old question of what draws insects to various types of light, from flames to porch lamps, has puzzled scientists for centuries. Sam Fabian, a postdoctoral research associate at Imperial College London, embarked on a mission to unravel this mystery. The research aimed at understanding the reasons driving insects toward artificial light.
The researchers observed unique flight patterns in insects attracted to lights at night. Fabian, Yash Sondhi, and other biologists employed high-speed video cameras in both field and laboratory settings to monitor the movements of flying insects such as butterflies, moths, and dragonflies at night. In the lab, they utilized motion capture technology to track the insects’ movements by outfitting them with miniaturized markers. Through the video footage, the researchers noticed a consistent trend across several species, characterized by unusual flight paths. The insects would orient themselves with their backs to the light, and if the light was positioned below or horizontally to their flight trajectory, it often led them to fly in circles or crash. It appeared as though they were utilizing the light source as a reference to ascertain the sky’s orientation. The study also concluded that when insects come in close proximity to artificial light, they can become disoriented and virtually trapped by it.
To gain insight into the flight behavior of insects near lights, the researchers attached markers to the backs of moths and dragonflies. Despite fish displaying similar behavior, as cited by Fabian, this study represents the first documentation of this phenomenon occurring in nocturnal insects around artificial light. The study results were published in the peer-reviewed journal Nature Communications. It emerged that insects, like many other animals, rely on gravity and visual cues to maintain their orientation. One way in which some insects achieve this is through dorsal light response, which allows them to ascertain the direction of “up” by sensing the light source, typically emanating from the sky. However, when confronted with a different light source, such as a fire from below or a headlight from the side, the insects attempt to orient their dorsal side toward the source, leading to confusion and potential crashes. The study primarily focused on the behavior of insects when the light was in close proximity, less than 7 feet away, leaving the question unresolved about what initially attracts them to the light.
Several theories have been proposed to explain why insects are drawn to lights, with one common belief being lunar or celestial navigation, where insects use the position of the moon as a directional cue. However, the study’s findings indicated otherwise, as some insects altered their direction in response to a new light source. This contradicts the hypothesis that insects mistake artificial lights for the moon and use it as a guide for a straight flight path. The study suggested that the insects’ response to light was influenced by the direction of the light, with upward-facing or horizontally placed lights having the most disruptive effect.
The implications of understanding why insects are attracted to artificial light are both practical and theoretical. One practical application is the potential to reduce inadvertent insect fatalities, such as those caused by bug zappers, by identifying the specific light that attracts mosquitoes. Moreover, there are concerns about the impact of light pollution on insects’ navigation and behavior, potentially affecting their ability to locate mates and food resources. This, in turn, could disrupt their natural ecosystems. From a theoretical standpoint, gaining insights into insect flight behavior could also contribute to future advancements in engineering, such as the development of flying cars. An immediate measure to mitigate the attraction of insects to lights would be to consider the orientation of outdoor bulbs, ensuring they are directed downwards to reduce insect attraction.

Author: OpenAI