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Why flying insects gather at artificial light

nature.com

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Re: Why flying insects gather at artificial light

#51

Post by kevin_thibedeau »

scotty79 wrote: post #9

I had a really weird observation. Do you know how in the summer flies tend to enter rooms and circle the middle of it (where usually the turned off light fixture is)? And they seemingly can't or don't want to find open window to leave the room? At one point for unrelated reasons I replaced light fixture in my room with more than 200W worth of strongest E27 Philips LED lightbulbs I could find (20*1521lumen). Few flies…

I notice that clouds of gnats will gather at the boundaries between light and shade. Other insects may adopt similar behaviors.

Re: Why flying insects gather at artificial light

#52

Post by codetrotter »

mapreduce wrote: post #48
jgilias wrote: post #37

Earlier quoted context omitted.

That’s my understanding too. The way I thought about this before was that normally an insect would ‘keep the moon’ on one side to navigate straight, but artificial light messes that up and they end up spiraling around those light sources. Which seems exactly the behavior that they have demonstrated in the research.

> they end up spiraling around those light sources What I'm struggling to understand is how the insects then reach so close to the artificial light. Why don't they spiral the artificial light from a great distance like 1 metre or 2 metres away? I see the insects hovering like millimetres or centimetres away from artificial light.

See this comment by another user ITT:

> Wait, so it could be a parallax thing?

> The moon is in practical terms infinitely far away, and no matter how far the insect flies it won't budge and stay as a stationary feature to localize by.

> But do the same with a lamp that's only 3 m away, and keeping it in the same spot can only mean flying around it in circles, towards, or away from it, otherwise it'll move around a lot relative to the insect observer.

https://news.ycombinator.com/item?id=39195508

Seems a reasonable explanation to me :)

Re: Why flying insects gather at artificial light

#53

Post by micromacrofoot »

Simon_ORourke wrote: post #25
micromacrofoot wrote: post #22

Earlier quoted context omitted.

In my experience... kind of. Light isn't the only thing they're attracted to so you'd have to optimize distance and cover different variables for different bugs. One fun thing you can do is relocate small swarms of bugs with a torch to another light source. So if you're being pestered, turn on a torch... and slowly walk the bugs to a different light source (a distant lamp for example). Then turn off the torch and wal…

Would or could that be automated? We are hounded from late spring to the fall by all kinds of flying nasties at our front porch. Some led string that moved them all away would be awesome!

would be interesting to try, it's easy to walk over because you can watch the swarm but if you've got a slow moving light on a string I could imagine it working

a bug zapper is a lot easier

Re: Why flying insects gather at artificial light

#54

Post by throw_pm23 »

sschueller wrote: post #12

So one could optimize an outdoor light location design to reduce insects? Like for example an outdoor dining terrace?

What do you want to reduce further, a large fraction of insect-species are already getting extinct across most of the developed world.

Re: Why flying insects gather at artificial light

#55

Post by rdtsc »

mapreduce wrote: post #29
codetrotter wrote: post #27

So am I understanding correctly that this confirms the common perception they cited: > Insects use the moon as a celestial compass cue to navigate, and mistakenly use artificial light sources instead

I don't think it confirms that. It seems to be one of the popular theories they investigated. Later they say - "In both field and lab conditions, insects rarely head directly towards, but consistently fly orthogonal to the light source. This refutes the fundamental premise of an escape response." "An insect should keep a light source at a fixed visual location for maintaining its heading. Switching light position (Su…

> Imagine you were an insect and you would use the moon for navigation. Would you really be flying directly towards moon? No, right? Then how could someone think that insects flying directly towards artificial light source is the basis for the theory that insects use moon as navigational aid?

If you're flying parallel to the ground (horizontally), you'd want the moon to be where your back is and you'd have a good change of flying straight. It's like when the kids say that the moon seems to "follow" them.

"Dorsal" means where the top part is, the insect's back, as it were.

Re: Why flying insects gather at artificial light

#58

Post by LudwigNagasena »

topherclay wrote: post #20
dmd wrote: post #15

Earlier quoted context omitted.

This explanation is in a Cricket Magazine I have from the mid-80s, so perhaps there's something new here also?

The novelty is that they tested this one theory instead of just proposing it as an explanation. The introduction of this paper lists some other explanations that you may or may not have seen in the past and it says some have been disproven and some have not yet been tested.

The paper lists some other explanations and references the papers that analyzed them. Maybe the paper presents a novel convincing technique, but it is not like they are the first to study the behavior.

Re: Why flying insects gather at artificial light

#60

Post by zuzun »

scotty79 wrote: post #9

I had a really weird observation. Do you know how in the summer flies tend to enter rooms and circle the middle of it (where usually the turned off light fixture is)? And they seemingly can't or don't want to find open window to leave the room? At one point for unrelated reasons I replaced light fixture in my room with more than 200W worth of strongest E27 Philips LED lightbulbs I could find (20*1521lumen). Few flies…

Flies easily fly through the window if it's substantially brighter than the room.
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