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
> Insects use the moon as a celestial compass cue to navigate, and mistakenly use artificial light sources instead
The paper states that it is the general brightness of the sky, even at night, compared to the ground that is the point of reference. So insect point top side at diffuse bright area and bottom side will be parallel to ground.
Might also explain why they don’t go directly to the light but eventually end up there circling it erratically, increased odds of bumping into a mate.
"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 (Supplementary Fig. 5) shows that insects readily hold the light source on either side of the body."
It makes sense to me. 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?
This definitely refutes the theory that insects are trying to escape towards the light, because, as the article shows, insects don't head directly for the light, but instead move orthogonal to it.
But this doesn't mean they can't use moonlight to help with flying. The theory, as I understand it, is that they use a distant light source -- e.g. the daytime sky -- to maintain altitude. There's no reason they couldn't use the moon to do this too.
Again, they would not be flying towards the moon, they'd be keeping the brightest light to their dorsal side. Since the moon is distant, unlike a lamp, this would result in steady flight.
I'm not sure that it confirms whether they use the moon or not, but it seems like a possibility.
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.
When the moon's directly overhead, this makes lots of sense. Fly goes around wherever. But if the moon's low on the eastern horizon, would we expect flies to mostly be facing upwards, and mostly flying west?
Depending on your precise navigation logic, you'll either end up with an increasing or decreasing orbit radius. If it decreases, you'll eventually crash into the light source.
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.
The article talks about the ‘dorsal flight response’ being more about the overall alignment to the sky hemisphere, not the moon specifically.
“the brightest part of the visual field has been the sky, and thus it is a robust indicator of which way is up. This is true even at night, especially at short wavelengths (<450 nm)”
Since we're to imagine the grandparent flying around like an insect. I imagined them as person flying but with insect wings. Since we're mammals with eyes pointing straight ahead, as opposed with them being on the side of our heads, we'd need some light sensor on our back to ensure we're flying straight at night and keeping the moon above, as opposed to having to look behind every so often to ensure the moon is still there :-)
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.
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.
> 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 :)
The insects you see are the ones that happen to get too close and thus their nav gets 'jammed'.
It's similar to planes navigating by compass. Works great, until you go up to the arctic circle, then you better have another nav source or you too will be flying in circles.
Haven't seen flying insects since last summer but if I think they kind of lose altitude the closer they get to the light source, which would be when their torso is less horizontally oriented.
Also this is just a guess but I imagine the closer they're to the light source and the larger the contrast between bright and dark is, the stronger is their tendency to get locked into the orbiting path as opposed to flying randomly.
I think that was one of the theories being investigated by this research. The paper demonstrates that it is the actual light (of the moon or stars or sun or artificial source) they use to orientate themselves in the horizontal plain BUT that is not navigation. With a "tilt" in their orientation they will fly in circles around the light but this tilt also causes inefficiencies in their actual flight mechanism so will cause erratic directional stability as their flight path rapidly changes their spacial relationship to the light source. Whatever their navigation imperative (heat, cold pheromones,smell, sight, sound) will be affected by this spacial relationship instability.