George Raymond, age 14, of West Warwick, Rhode Island, for his question:
Why are insects attracted to a light?
Moths are famous for fluttering into flames. In summer, we see swarms of bugs clustering on street lamps and bashing into outdoor light bulbs. They seem helpless to resist these dazzling attractions. Researchers in biology report that actually insects are not attracted to these lights. Nor do they have suicidal tendencies. The situation occurs because their built in steering mechanisms become confused.
This highly complex problem involves eyes with special vision, angles and rays of light. The project was started some 200 million years ago quite some time before mankind invented light bulbs or even candles to illuminate the night. It eras one of nature's projects aimed to help the insect world navigate successfully.
There is a large variety of bug eyes with different types of visions. Insects see colors, but their color range is somewhat different from ours. Most of them see ultraviolet rays that are invisible to human eyes. Colors, of course, are different wave lengths of light and light is a form of electromagnetic energy. Its rays, pulsing along on different wave lengths, fan out in all directions from a source of light. They travel in straight lines at 186,000 miles per second. After crossing vast reaches of space, light rays from the sun, the moon and the stars are traveling more or less in parallel lines. But close around an electric light, the rays are fanning out at all angles. The different angles of these wave lengths of light confuse the natural steering mechanisms of the bug population.
No matter what type of eyes an insect has, or how many, he is almost sure to be sensitive to the angles from which light rays arrive. He depends upon these angles to steer him in a straight path. Through millions of years the bug world grew skillful at navigating by beams from the sun, the, moon and the stars. Insects could depend on these beams because they are more or less parallel. For example, let's assume that a moth flutters forth with the moonbeams striking her eyes at an angle of 70 degrees. If he maintains this angle, he keeps going in the same direction. Bees and other daytime bugs are keenly sensitive to ultraviolet light rays. T 'post of the sun's ultraviolet energy is filtered out by our airy atmosphere. But even on a cloudy day, the patch of sky around the sun sheds an extra quota of ultraviolet. Many daytime insects navigate by the sun's ultraviolet and usually adjust to the changing angle as it marches slowly over the sky.
All these ancient steering skills were upset when mankind invented small local lights, Since we turn them on after dark, it is the night flying bugs that get confused. For example, let's assume that a moth flies forth with the beams from a light bulb striking her eye at an angle of 70 degrees. She expects to navigate a true course by maintaining this angle. But at close quarters to the light source, the rays fan out at different angles. If she maintains her original angle, she follows a curved path that spirals inward toward the light. Billions of night flying bugs make the same steering errors and zoom into lamps and street lights.
The insect world has a multitude of talents, most of them very different from ours. One of the newest and most fascinating studies is the astonishing field of insect senses. Research biologists are just beginning to solve such mysteries as whether bugs can hear and why a moth flutters into a flame. Naturally, nobody wants to be a bug. But it's interesting to know how a bug feels in his world.