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How bright (and what colour) does a light have to be before it will distract / confuse / attract moths at night? Answered

How bright does a light have to be before it will distract / confuse / attract moths at night? What is the best colour of light? Would "white" LEDs do the job, or would UV LEDs work better? How many?



8 years ago

This is quite simple. Moths are not attracted to light, they are more "forced" towards it. A simple reflex action in all moths cause them to fly with the moon on one side constantly, so they fly straight. However, this reflex can interpret lighting as the moon, so the moth flies with the light to one side. This is what causes them to circle the light. So if your light is the same or greater brightness than the moon, and the moon is out of sight, then a passing moth will faithfully circle it.


8 years ago

Bright lights does not attract moths. The moths don't like light. They go to the back of the light which is the darkest ( near the socket ).

 I will completely agree with Jex52 in the fact that they are not attracted to light and are just trying to get away from it but since there stupid they just fly around it  if its a free-standing light instead of flying off.
*Purple Guy*

Better tell that to the moth expert who brought his trap to our Cub hut.

The bait was a large, bright light.

i would suggest using neon colours

I know they're attracted to my white lcd monitor - which should be putting off very little in the uv spectrum, but lots in the violet/visible spectrum...not sure if that helps any.

Blatantly ripped from howstuffworks:

To understand this phenomenon, you need to know about phototaxis. Phototaxis is an organism's automatic movement toward or away from light. Cockroaches are an example of a negatively phototactic organism. You've probably noticed how they scurry back into dark corners and crevices when you illuminate their late-night snacking party in your kitchen. Moths are positively phototactic. They seem charmed by your porch light, your headlights or your campfire (even if it leads to their untimely demise). While there is no definitive explanation for this phenomenon, there are some interesting theories.


One of the theories - moths use overhead light 'that they cannot fly over' as a 'thats the sky, thats the ground' orientation. When they get close to the light, they get very disoriented, and dont know how to fly away from the light. Plus they sensitize to light MUCH faster than they sensitize to dark, so once they're there - they stay near the light for being blind quite some time away from the light.

Ripped from an article:
Nocturnal moths and geckos can discriminate colours at extremely dim light intensities when humans are colour-blind, by sacrificing spatial and temporal rather than spectral resolution. The advantages of colour vision are just as obvious at night as they are during the day. Colour vision is much more reliable than achromatic contrast, not only under changing light intensities, but also under the colour changes occurring during dusk and dawn.

I think white will do just fine!

Thanks, frollard. Have you any idea how bright your screen is?

Backlights use CCFL Tubes, Which Emmit UV Light, Try Ripping a CCFL out of some broken LCD and light it up at night outside, see how the moths are attracted or not to it... You will need an inverter, and that means HV, I think that the moths and such are attracted to UV light...not sure though Just make sure it is visible and it is UV...


well, its cold cathode I assume, which is comparable to fluorescent...

and if I recall its about 50-70 watts. I dont remember kill-a-watting it recently.

website for samsung says Brightness : 300 cd/㎡
and its 24" diagonal 16:10 ratio...wow trig...
1848cm squared...
1m sq = 10000 cm sq
1848/10000*300candelas = 55 candelas brightness.

they are attractd to the moon so i would suggest yellow, white, or blue light. light them at about the usual, not too bright, not too dim.

Moth on the Moon - Small flight for moth, big flyswatter for man. - Atom

Hi Kiteman. Whatare you up to??

The professionals use mercury vapour lights as these are very rich in UV and violet which the moths are after, and I'm pretty sure white LEDs don't give any appreciable amount of that. UV LEDs are much less efficient that the other colours (around 1/10th the output at max current) so I think the answer to your question is "many" when you consider a typical UV led puts out 300 milli-candelas and a MV lamp outputs about 30 candelas/ watt (over a 45 degree angle).

It may be possible to run a reptile UV tube via a small 240V inverter (e.g. caravan light) driven from a 12V NiCad pack, but It's an expensive experiment if it doesn't work.

There's a moth / light attraction simulator HERE which you may find useful (or otherwise). If all else fails, you could cover yourself in female moth hormone and stand in your garden in your underpants ;¬)

I think I'll try a mixture of superbrights and UV...

As they come out at night why are they attracted to UV? L

I've wondered that too.
My first thought is that their breeding pattern may be influenced by the moon so they get extremely excited by a close 'super-moon', but I doubt that any appreciable amount of UV is reflected from the Sun by the Moon. I may be wrong.

I don't get it either. I might experiment a bit with the UV LEDs I've got. L

I am pretty sure I read somewhere that they ARE attracted by UV wavelengths....um, the longwave kind I think...but check me on that one...

It's one of those "experiment and see" things I think. I look forward to "How to attract moths" L