Why Do Moths Fly to Light?

[Ian Woiwod]

Navigation by moon and stars is only one of several suggested reasons that
moths (and many other nocturnal animals) are attracted to artificial light. 
Another is that the insects often hide away in thick herbage and woodland at
night and often emerge at dusk when need to be attracted to the light to find
their way out. You can see this phenomenon if you observe free flying moths in
an unlit room. At dusk they will emerge and head straight for the window
despite the fact that this is light compared with the room's interior. It may
be that a bright artificial light elicits a similar response with the moth
trying to fly through the light to get to the other side.

Ian W