Why are Insects Attracted to Light?

If you’ve spent time outside in the backyard or on the porch during a summer evening, you have probably seen insects flying around porch lights, street lights, or even a campfire flame. Some insects like moths just seem to be naturally drawn to and mesmerized by these sources of light, occasionally even colliding with light bulbs head on. So, why do these bugs like light?

Side photo of a moth perched on the wall

Although flying insects such as flies and moths are known for this behavior, scientists have not been able to figure out exactly why bugs are attracted to light. However, they’ve come up with a few theories as to why bugs behave this way.

Bugs Use Light to Navigate

One of the most popular theories is that bugs rely on light sources to guide their travels and movement. Many believe that insects use natural light sources like the moon or sun to help them navigate, similar to how sailors used to rely on the stars to guide their ships.

So, when a insect sees your porch light, it flies towards the source. However, if a moth or fly mistakes your porch light for the sun or moon, they can become easily confused and start to circle around the source.

Bugs are Looking for Food

Many moths feed on the nectar from flowers, which are known to reflect ultraviolet (UV) light. Some light bulbs give off a small amount of ultraviolet light, potentially causing hungry bugs to mistake a bulb for a flower.

bee collects nectar from sunflower.

Bugs are Trying to Escape from Predators

Another theory for why insects are attracted to light is that, in the wild, light signals an escape from potential danger for insects. When an insect sees light, it can tell them that a path is not blocked by a predator or obstacles. This might explain why pests fly right into light sources, seeming to unknowingly crash into bulbs and lanterns.

Searching for a Meal

Finally, others believe that insects are attracted to porch lights and campfires because they know other insects are too. These critters may be predators looking for a meal or suitors searching for a mate.


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