.Sitting at my study table, focusing on comprehensive reading;
Surrounded by utter silence, only noise was the keys stroking;
Something caught my attention, so unexpected and surprising;
Sensing a touch on my neck, the reflex was a bit alarming.
It happened so fast, I jolted forward and fingertips observing;
I jumped out of the chair, little moth went for the light hanging;
It crashes on the bulb and falls, not conscious to avoid hurting;
Doing that for a lifetime, lights off, I showed it out for light-hunting.
One any given night, you would see many flies and other insects continuously crashing in or making endless circles around lights in your living room or even on the streets. The little disturbance caused by a moth tonight, I wanted to find out why they fly towards or around bright lights and surprisingly found many theories. However, none of them seems to be based on concrete scientific evidence.

Insects that attract to light, and that doesn’t are described by a phenomenon called ‘phototaxis’. Earthworms and cockroaches are repelled by exposure to too much light and are known to have negative ‘phototaxis’ while insects like flies and moths are naturally attracted to light and have positive ‘phototaxis’. One theory states that certain insects use light from the moon as a navigational beacon and flies, keeping the moon on its right side. This would work well because the moon is very much distant from the insect. But, if the insect takes artificial light as a beacon, such as a bulb which is much closer than moon, it would be flying around the bulb in an endless circle trying to keep the light on its side.
Another theory about the same so-called light-compass states that, as the light coming from distant is a straight line, the insect flies towards the moon, and speed of its wings is based on the strength of light on each eye. But, when it flies towards an artificial light, the strength of light on one eye differs from the other causing one wing to beat stronger. As a result, the moth flight becomes unbalanced causing it to crash into the light.

The other theory is the idea that flies are attracted to darkness and are nocturnal. Lights at short distance, they see the immediate area around it as the darkest space. They fly in to this ‘darkness’, and as the light is so close they get confused and end up flying around the light. There is debate going on about why insects are attracted to artificial light while natural light is still there. Some believe that it is, because of this dark space they see around artificial lights.

Unfortunately, there is no right answer to this question leaving us to make personal preferences on the most debated theories.

Which theory do you believe in?


Image taken from here