"A moth (飞蛾) to a flame" is often used to indicate an inescapable attraction, yet it is a strange example of animal behavior that continues to confuse people today. Scientists have raised a number of theories over the years to explain why. One holds that insects flying at night are following their nature to fly toward the brightest spot in their field of vision, which they mistake for the sky. Another suggests that insects are trying to warm themselves with the heat produced by the light. The most popular theory, though, is that insects are confusing lights with the moon or other celestial bodies (天体) that they normally use to navigate (导航).
To find out the real reason, the team carried out a first set of experiments in an insect flight area. The researchers used eight high-speed infrared (红外线) cameras equipped with motion-capture technologies to track 30 insects from three moth and two dragonfly species. They also flew lab-raised insects from six different insect orders that were too small for motion-capture technology, including fruit flies and honeybees, to make sure different insects all showed similar responses to light. Working with co-author Pablo Allen of the Council on International Educational Exchange in Monteverde, Costa Rica, the researchers put heavy cameras, lights and tripods in two field sites to gather behavioral data from insects in the wild.
The team was able to confirm that insects were not beelining to the light but rather circling it as they tilted (倾斜) in an attempt to turn their backs toward it. This behavior, known as a "dorsal light response", normally helps insects to remain in an unchanging path of flight that is properly lined to the horizon (地平线). Artificial light that arrives from a point source causes them to fly in unpredictable patterns as they try to turn their backs to what they are mistaking for the sky.
Now research might have finally solved the mystery mentioned first: artificial light confuses insects' ability to turn themselves to the horizon, confusing their sense of what is up and down and causing them to fly in circles.
