Surely, in the days before man invented artificial light, moths would have been attracted to the only source of night light: the moon. Wouldn’t they have kept flying until they fell from exhaustion? In fact, doesn’t this happen today in sparsely populated areas, where the moon is still the only available night light?
Navigation
Sorry to disappoint you, but there is no concrete answer, just theories. The prevailing theory at the time is that many moths do not fly directly into the light and therefore would not attempt to make a trip to the moon. No, what they do is use the moon as a navigation aid. If you wanted to keep moving in one direction and the moon was your only point of reference, you would keep it at a particular angle to your direction of travel. For example, you can keep the moon 45 degrees to your left, and since the moon is relatively static in the sky, it will most likely travel in the same direction.
“The moon just moved!”
Now, to a moth, with its poor eyesight and fairly simple outlook on life, a street lamp that is only 3 feet away can look a lot like the large moon that is thousands of miles away. I guess moths have never heard of the term “perspective”. So the moth walks past the lamp only to find that the angle of the lamp is changing rapidly. He then corrects his flight to try to keep the lamp to his left. Just when it does, the lamp has moved again … and the moth just rotates around the lamp.
Collision course
The above covers the “circulating” moths. However, there are other species of moths that fly directly into the light. I have not discovered any accepted theory on this (email me if you have any!). One possible explanation is that the moon is once again used as a navigational aid, but this time these “direct flyers” simply hold the moon in front of them to fly in a straight line. Since there is no prospect of running into the moon, this is as good a way as any to travel forward. Remember that a moth’s main purpose in life is to mate, and not mate with the moon, so they would only use this navigation aid for limited travel (until they found a mate). How are they going to know that what they thought was the moon is actually a lamppost? No wonder a collision is inevitable!
General information on moths
There are numerous species of moths and they can be a problem for stored food products, mainly because of the risk of foreign bodies. Most moths are attracted to UV light, although green light is usually an even stronger attractant.