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What is the Reason why Insects are Attacted to Light?

Why are bugs attracted to light?

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We've all the seen the insects that buzz around our porch lights, street lamps, and headlights at night or in the evenings. Of course it may seem pointless or insanely redundant to you, and you may ask yourself "Why on earth would they do that every night?" However there are various theories on this peculiar and odd behavior (no definitive answers as to why, just theories).

You should also know that not all insects who naturally feel drawn to the light will go near it. Some insects only go in the direction of the light when they feel as if they're in a dangerous situation. The light seems to represent a way out, an exit for them. It's kind of the same way the magnet of a compass works, the light helps to give them a sense of direction. The option of moving toward a lighted area is safer than no movement, or heading toward a dark area where visibility is low.

The idea of comparing the light to a compass is only beneficial if the light source is constant and kept farther away. When an insect circles a light bulb, it's because it's naturally navigating itself by keeping the light to one side.

Another theory is Phototaxis, which Wikipedia defines as: "movement that occurs when a whole organism moves in response to the stimulus of light." When an insect has a negative phototaxis it will shy away from the light source. Earthworms and cockroaches have a negative phototaxis. Insects that can fly, such as moths, who feel inclined to be near the light source have a positive phototaxis.

A lot of insects also have numerous lenses on their eyes. Their vision would struggle to adjust from light to dark. Some ideas suggest that the extra lenses would basically make the insect blind at night. This is another reason it would be safer for the insect to stay near the light source. Without it they have no way of protecting themselves from any impending danger.
phototaxis isnt for insects only right? –  speedboat  Mar 12th, 2013 at 9:03 PM

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