Why Do Moths Like Light? Amazing Moth Insects Facts

While looking at the beautiful night sky, have you noticed hundreds of moths accumulated near street lights?

You may have come across someone using the phrase 'like a moth to a flame'. What does that really mean?

Moths and many other insects and bugs are attracted to light. There are numerous theories for the reason behind a moth's inclination to bright light, whether that light is natural or artificial.

One theory for a moth's attraction to lights is that it flies towards an artificial light as this source of light confuses its internal navigation system. Moths evolved before artificial bright lights came into use, from a time when there was only natural light coming from the distant stars, moon, and sun.

These creatures navigate using natural light by flying at a fixed angle. This is called transverse orientation.

However, when flying near artificial lights, like a porch light or a campfire, they get confused, and their angle in relation to the natural light around them changes. Keep reading to learn more about the moth's attraction to lights!

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Why do moths like light if they are nocturnal?

Moths are nocturnal creatures that are not afraid to wander around in the dark. Nighttime is typically their most active time, during which time they can be seen close to artificial light sources such as street lights and porch lights.

The reason why moths are attracted to light, such as the light from a flame or a bulb, has been a mystery for quite a long time.

It is believed that they are simply disoriented by artificial lights, and aren't actually attracted to them.

Not every species of moth is attracted to lights, such as the tissue moth that flies away from lights and towards dark patches between rocks. Generally, moths prefer natural light, such as the light from the moon, which is quite distant.

The majority of moths that are active at night (nocturnal) have shown that they are attracted to lights. This phenomenon is called positive phototaxis.

There are also species that are negatively phototactic and are repelled by light, such as the old lady moth (Mormo maura).

It was largely during World War II, when ultraviolet (UV) lamps were invented, when it was discovered that UV-rich sources seemed to attract moths. Many insects and bugs, especially moths, are sensitive to the electromagnetic spectrum's UV part in artificial light sources.

There have been several theories made in an attempt to explain this further.

One such theory is that many flowers reflect UV (ultraviolet) light, and it's the nectar of these flowers that many moths feed upon. A few bulbs are also known to emit UV light, sometimes causing these small creatures to confuse a light bulb for a flower.

Another theory was put forward by Philip Callaghan in 1970 which suggested that the pheromone molecules of female moths were pumped into an excited state in the air by the presence of ultraviolet (UV) light, causing photons of infrared microwave radiation to emit.

These photons could be detected by the male's antennae's sensilla. However, this theory is not considered to be valid as moth sensilla pores can identify molecules of female pheromones directly thanks to their size.

Why do moths like light but only come out at night?

It is known that distant natural light, like the light from the moon, is the real preference of any moth. A natural light source like the moon is quite distant and the light rays from the moon are parallel to the moth's direction of flight.

Thus, it is believed that moths have evolved with regard to these rays and a fixed part of their eye expects these light rays. This phenomenon is referred to as transverse orientation.

Moths have evolved to operate under moonlight or sunlight and maintain a constant angle with their light source. It is also believed that moths use stars and the moon to orient themselves.

It is also believed that, as moths feel attracted to the light of the moon, they fly at a higher altitude on moonlit nights. A moth's natural behavior involves keeping a constant angle between these light rays and its direction of flight.

Moths can also be attracted to an artificial light source through light traps laid on the ground.

For example, street lamps have the ability to attract moths that are 30-80 ft (9.1-24.3 m) away. However, it isn't yet known exactly the distance from which an artificial source of light can attract moths.

An artificial light attracts positively phototactic moths. These moths are confused by light rays during the nighttime and often wander into the small sphere of the fixed light source.

Most moths are positively phototactic, which means that they have an attraction towards sources of light. Studies have suggested that moths from areas that are brightly lit are not as attracted to light as moths from dark, dimly lit areas are.

Moths from brightly lit areas did not exhibit an active flight-to-light behavior, suggesting that they are evolving to steer clear from artificial lighting.

This evolution will increase the reproductive success of moths from these areas significantly. It is also known that some moths turn inwards constantly on the wings so that a constant angle is maintained between themselves and the artificial light source.

This eventually leads the moth to unintentionally move in a spiral path that ultimately results in the moth crashing with the artificial light. Most moths, however, do not exhibit this pattern often.

Do moths use light to orient themselves?

It is theorized that moths often use stars or moonlight to orient themselves and that their flying track is adjusted according to the natural light present, so that they maintain a constant angle between the light and their eye.

Celestial rays, such as those of the sun, moon, or stars, are parallel, however, those of a bulb aren't parallel and instead radiate around the moth.

However, this theory has its own flaws. Bulbs with bright lights are relatively new, but what about campfires?

They have been in use for approximately 400,000 years.

It is frequently questioned if moths that existed 400,000 years ago died due to their instinct to fly straight towards a bright source of light. Therefore, it is believed by some that moths are not attracted to bright light or a flame and that, instead, their flying track becomes disoriented by them.

Also, it is believed by some that moths might not even utilize transverse navigation.

It is assumed by a few researchers that only moth species that migrate use the moon to orient themselves. Another theory states that light sources emit infrared radiation that looks like the chemicals released by moths to attract partners.

It could be possible that many males, if not all, are attracted to lights, assuming that a female is waiting there for them.

It has also been observed that moths are attracted more to artificial lights during the new moon week than during the full moon week. This observation has led to another theory suggesting that moths are attracted to the new moon.

One study has proved that moths are not attracted to bright moonlight as this moonlight does not drop much, and that they are not energetic during the full moon night.

It is also proven that darkness and nightfall trigger moths to become more active and energetic. Finally, it has also been observed that moths are affected by the dorsal light reaction, during which they keep the lighter sky above them by flying close to an artificial light (lamp), which they mistake as the sky.

What other insects are attracted to light like moths?

Many insects and bugs are attracted to light. All of these insects possess a positive phototaxis. Those that have a negative phototaxis are repelled by any exposure to light. Insects such as earthworms and cockroaches have negative phototaxis, whereas insects like flies and moths possess a positive phototaxis and are naturally drawn to light.

Insects can be differentiated from each other on the basis of a phenomenon known as phototaxis. Phototaxis determines whether an insect is attracted to light or if it is repelled by it.

Insects like beetles, mayflies, crane flies, flies, and moths are naturally attracted to artificial lights. Even insect predators, as well as frogs, can often be found during nighttime near a porch light, where they feed upon these insects that have a positive phototaxis.

Moths are even known to be likely to die when they are close to these lights as they are a feeding ground for insect predators. They can also die as they fly towards a lamp and ultimately crash straight into it.

They also may overheat when close to lamps for long periods of time. Flying termites also have positive phototaxis and are extremely attracted to light.

Swarms of flying termites under a streetlight are a common sight in some areas at night. Praying mantis bugs are another example of insects that are also naturally drawn to light and possess positive phototaxis.

Did You Know...

A male moth sometimes becomes highly attracted to the bright light of a flame as he mistakes it to be a female, and these male moths can be known to die when they attempt to mate with the flame!

Many moths are attracted to different factors such as heat, odor, color, and sweat, and they may even fly straight towards a human!

Many moths are harmless to humans but if a moth that possesses spiny hairs touches a human, red patches of bumps may appear that can sting as well as burn.

There is an ancient saying 'like a moth to a flame' that is used to refer to someone who is feeling a self-destructive attraction to something or someone, that has gone beyond their control.

Various species of insects find UV (ultraviolet) light much more attractive than infrared light.

A moth adapts to darkness much slower than it adapts to light.

Here at Kidadl, we have carefully created lots of interesting family-friendly facts for everyone to enjoy! If you liked our suggestions for why do moths like light? Amazing moth insects facts then why not take a look at why do cats bring you dead animals, or why do dogs cough? Know curious facts about dog breeds.