Animals

Why are insects attracted to light?

Its the winter time so this question doesn’t really apply now but what the hell. Plus I just watched the movie ‘A Bug’s Life’ and you guys know the scene where…….? Actually, I’ll just get to the blog.

So for some insects, a bright light source is seen as a emergency beacon. When in doubt, they will instinctively head for the light, which is generally higher than their current danger-filled position. Moving towards the dark would be seen as a move downward, which can be even worse than not moving at all. Light for some insects could be viewed in the same way as air bubbles pointing the way up to the surface for other creatures.

Another popular theory is that insects attracted to light use it as a navigational aid. An insect flying north, for example, could judge its direction by keeping a natural source of light such as the sun or moon on its right side. This method works well as long as the source of light remains constant and at a distance. If an insect encounters a round incandescent porch light, however, it becomes confused by the light source. A moth will continue to circle a light because it instinctively wants to keep the light on a certain side of its body while navigating. Now, not all insects are attracted to light.The difference between insects attracted to light and insects not attracted to light is a phenomenon known as phototaxis. Certain insects such as cockroaches or earthworms have negative phototaxis, meaning they are repelled by exposure to light. Moths, flies and many other flying insects have positive phototaxis, meaning they are naturally attracted to light.

In fact, artificial lights interfere with an insect’s ability to detect the moonlight. They appear brighter, and radiate their light in multiple directions. Once an insect flies close enough to a light bulb, it attempts to navigate by way of the artificial light, rather than the moon. Since the light bulb radiates light on all sides, the insect simply cannot keep the light source at a constant angle, as it does with the moon. It attempts to navigate a straight path, but ends up caught in an endless spiral dance around the bulb.Some scientists believe light pollution is leading to a decline in certain insects. Fireflies, for example, have difficulty identifying the flashes of other fireflies where artificial lights are present.

Your Thoughts?

Oh yea, here’s the scene I was referring to earlier, from ‘A Bug’s Life’.

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