Why are some bugs attracted to lights?

Pass by a lamppost on your way home from school or work one evening and take a closer look at how moths and other insects flutter around, over and over, until some finally zoom straight into the lightbulb and fizzle to their death.

This behavior can also be seen with ordinary lightbulbs at home (like in the porch), or around campfires outdoors, or with the electric lamps designed to lure pesky bugs.

Why are some insects attracted to light, you wonder — so irresistibly drawn to it that they head straight for it and cease to exist in the blink of an eye?

Experts from a Modesto pest control company have a few theories and observations to share:

Light scrambles an insect’s internal navigation system.

Insects like moths did not evolve to naturally live around bright lights; what light they do know about comes from faraway sources like the sun, moon and stars.

This faint light from the sky provides a sufficient and fixed light point that they can keep themselves aligned with so that they can navigate.

However, man-made light sources like lightbulbs and fires are not fixed light points from their perspective — the light changes position when they pass by the light source, and this confuses the insect, causing it to fly around in circles, attempting to stay aligned with the light they see.

A light source could be mistaken as a signal from a female insect.

Female moths (similar to the females of other species) give off pheromones to attract a mate. According to some scientists, these pheromones have frequencies that may be similar to the infrared light spectrum given off by a candle’s flame. This can lead to the unfortunate death of a male moth who must have thought that he was approaching a potential mate.

Some insects see light as beacon for safety.

If an insect sees a light source, it may interpret the light to be positioned in a place that is safer than where it is now, since the light source is elevated, so it will instinctively approach the light.

The presence of light can mean that a certain pathway is free and clear.

Finally, when light shines through and is easily visible, it would logically mean that there is no object blocking the stream of light, so an insect may follow the light source to avoid obstructions.

As it turns out, flying insects have varying biological responses to light — there’s much more to a moth being drawn to a flame than a mere death wish or a straightforward visual disability.