Why do moths go to light?

Search: why do moths go to flames

Why: The other night, one bounced around the TV for a while before it flew into Chandler's beer and he ate it.

Answer: Who knows! Bug researcher Henry Hsiao said they do 2 things:

1. When far away from a light source (up to 200 ft.), they fly straight toward it. Maybe they think light = people = stuff to eat, or maybe light = other moths.
2. When they get close to the light, they try to avoid it. Now, daylight and bright light = danger.

But it doesn't fly directly away from the light because, like all sighted animals, it perceives the region immediately surrounding the light as darker than any part of the sky. This is called the Mach band. The moth, being kind of dumb, thinks this dark space is the safest part of the sky, and so it circles it until it finds something better to do, like flit around another light.

Here's a thing of a time exposure at a floodlight showing the flight paths of some moths:

Source: The Straight Dope

The More You Know: I would like to see this movie. No sir, that's no bug co-moon: