Why Are Bugs Attracted To Lights?

picture of lights with a black background

Have you ever noticed bugs, like moths, are attracted to street lights or even the exterior lights on your home in the evening? You’ve likely heard the phrase “drawn like a moth to a flame”, and immediately understood what the speaker meant. This phrase is obviously drawn from the habit of moths, and most other bugs, to fly towards any source of light. There are actually a number of scientific theories to explain this strange habit.


Although scientists cannot draw a conclusive reason as to why bugs are attracted to light, there’s one theory about insects being known as positively phototactic organisms. The theory is these insects have evolved to use the light reflected by the moon and stars to fly forward. Unfortunately, artificial lighting throws them into a state of confusion and draws them in causing them to flutter around the source. They fly at an angle towards the light. One problem with this theory is that there has been artificial light, in the form of fire, for thousands of years.

UV Light & Wavelength Colors

Another position among scientists is that, in seeing an unimpeded light source, the insects perceive the route to be clear, and fly directly towards it in an attempt to avoid hindrances. This may be the reason some bugs fly directly into the light bulbs. However, there is another school of thought that since artificial light emits relatively small amounts of UV rays the same way that flowers do, the bugs confuse the light with their food source. Ultraviolet light and short wavelength colors are more attractive to insects, which may have to do with their feeding patterns. Flowers naturally reflect ultraviolet light, and for many insects, flowers are a key source of food. However, this theory also has some flaws because artificial light sources have been around for a long time and you would hope that the bugs would have evolved to learn the difference. There are arguments on all sides for each theory and science has yet to reach a final answer.

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