Why are moths attracted to light?

Question

Moths only come out at night right? So why in the blue hell are they attracted to candles or lights???

Answer 1

One hypothesis advanced to explain this behavior is that moths navigate by maintaining a constant angular relationship to a bright celestial light, such as the Moon. The Moon is so far away, that even after traveling great distances, the change in angle between the moth and the light source is negligible. However, when a moth encounters an artificial light and uses it for navigation, the angle changes noticeably after only a short distance. The moth instinctively attempts to correct the angle by turning toward the light, which results in a spiral flight path that gets closer and closer to the light source.

In 1972, Henry Hsiao, now professor of biomedical engineering, suggested that the reason for moths circling lights may have to do with a visual distortion called a Mach band [1]. Henry Hsiao conjectures that moths, as nocturnal creatures, fly towards the darkest part of the sky in pursuit of safety and are thus inclined to circle ambient objects in the Mach band region. This hypothesis is not scientifically accepted and has never been confirmed. It should be noted that many moths fly directly towards light source, which seems to contradict this hypothesis.

Answer 2

A moth's eyes, like a human's eyes, contain light sensors and adjust according to the amount of light the sensors detect. In high illumination, light from each of the moth's thousands of fixed-focus lens facets is channeled to its own sensor (ommatidium). In low illumination, light from multiple lenses is channeled to the same ommatidium to increase light sensitivity. You probably experience a few moments of blindness when you turn on a bright light after your eyes have adjusted to darkness, or when you are suddenly in darkness after being in bright light. A moth's dark-adapting mechanism responds much more slowly than its light-adapting mechanism. Once the moth comes close to a bright light, it might have a hard time leaving the light since going back into the dark renders it blind for so long. In the case that the moth escapes, it won't remember the problem with flying too near the light and will probably find itself in the same predicament all over again.

Answer 3

To understand this phenomenon, you need to know about phototaxis. Phototaxis is an organism's automatic movement toward or away from light. Cockroaches are an example of a negatively phototactic organism. You've probably noticed how they scurry back into dark corners and crevices when you illuminate their late-night snacking party in your kitchen. Moths are positively phototactic. They seem charmed by your porch light, your headlights or your campfire (even if it leads to their untimely demise). While there is no definitive explanation for this phenomenon, there are some interesting theories.

Some types of moths are known to migrate, and it's possible that the night sky gives them navigational clues. A moth's up-down orientation might depend in part on the brightness of the sky relative to the ground. Some lepidopterists (moth and butterfly scientists) suggest that moths use the moon as a primary reference point and have the ability to calibrate their flight paths as the Earth's rotation causes the moon to move across the sky. (There is even evidence to support the theory that migrating moths have an internal geomagnetic compass system to guide them in the right direction.) So a moth's attraction to an artificial light or to a fire could be related to orientation, and lead to disorientation -- the moth wasn't "expecting" to actually get to "the moon" (the light source) or to be able to fly above it, so confusion results.

It's also possible that moths have an escape-route mechanism related to light. Imagine disturbing a bush-full of moths at night -- they all fly up and out of the bush, toward the sky. To a moth in danger, flying toward the light (which is usually in the sky, or at least upward) tends to be a more advantageous response than flying toward darkness (which is usually downward).

Moths are more sensitive to some wavelengths of light -- ultraviolet, for example -- than they are to others. A white light will attract more moths than a yellow light. Yellow is a wavelength moths don't respond to.

Another interesting question is: Why do moths stay at lights? A moth's eyes, like a human's eyes, contain light sensors and adjust according to the amount of light the sensors detect. In high illumination, light from each of the moth's thousands of fixed-focus lens facets is channeled to its own sensor (ommatidium). In low illumination, light from multiple lenses is channeled to the same ommatidium to increase light sensitivity. You probably experience a few moments of blindness when you turn on a bright light after your eyes have adjusted to darkness, or when you are suddenly in darkness after being in bright light. A moth's dark-adapting mechanism responds much more slowly than its light-adapting mechanism. Once the moth comes close to a bright light, it might have a hard time leaving the light since going back into the dark renders it blind for so long. In the case that the moth escapes, it won't remember the problem with flying too near the light and will probably find itself in the same predicament all over again.

Another possible explanation for why moths stay at lights is that they are mostly night-flying creatures and eventually respond to the light as they would to the sun -- by settling in for their daytime "sleep."

Here are some interesting links:

How Light Works
What is in moth balls? Is it harmful to people?
Butterflies and Moths
Why are moths attracted to lights...

Answer 4

The light is like a blue movie in the moth world!

Answer 5

I think they are attracted to the heat the lights give off in the cool of the night.

Answer 6

Because female moths give of light when they want to mate and so dumb moths thinks light bulbs are a mating partner, horny little devils!

Answer 7

I think they (Moths) almost all have seen the movie "Poltergeist", (it's a Cult Classic in Moth culture, don't ya know?)....at any rate that is what they are doing, .......
"going into the light"

Answer 8

They are not attracted to the light , its the darkness behind the light that they go for..

Answer 9

Two reasons:

1) They guide themselves by the light of the moon and get confused by artificial light

2) They have a genetic appreciation for fixtures & fittings.

Answer 10

Here is the scientific explanation to why moths are attracted to light:

>http://science.howstuffworks.com/question675.htm