It has always seemed common knowledge to me that moths and other insects are attracted by lights. As anyone who has left a window open in a lit room in summer will agree with I'm sure!

What isn't common knowledge is why they're attracted to light. At least not for me! Does anyone know why? I have a few guesses that will probably just embarrass me if I try so I won't say them

I believe it is because that's how they know which way is up! Until humans came along with various systems of lighting the dark, moths counted on either stars or the moon as their source of light.

Kingfisher

Ahh I see, makes sense! So they think the light is the sun or stars and fly towards it?

That seems to be the consensus of researchers. I'm not certain why moths and other insects don't seem to steer clear of lights combined with heat (in other words, fire), because that would be a logical correlation, but they don't seem to realise that a source of light with heat is bad for their continued success in life.

Kingfisher

I've also read that the reason they seem to stay at the light is because being nocturnal, when they see a bright light they think it is daytime and then settle there.

That could also be one reason.

Kingfisher

I do quite i bit of mothing at night, and by using a bulb which emits a certain light wave length, the amount of moths which are attracted can be quite staggering. But if there is a full moon in the sky the numbers are vastly reduced.

interesting thread Squirreler,its one of those things we all know happens but i for one have never thought why it happens,just one or those things we take for granted i suppose.
The same thing happens with daddy long legs,an open window with a light on in late summer soon brings them in.
That is fascinating Andy k about the full moon

Do you think the frequency of light emitted that attracts the most moths is the same frequency as emitted by the sun?

It could be, i have been trying to find some info on the different wave lengths, but not come up with anything yet.

I know the best bulbs to use for mothing are Mercury Vapour, we normally use a 500w. And that pulls in a lot of moths.

I don't think it could be this, as the sun emits over a very wide range of frequencies. It does have a peak emission at on frequency though.