I think it’s to do with the LED flicker. You can sometimes see it in your peripheral vision (ie your light/dark receptors) but your RGB cones aren’t as good at spotting it.
Insects eyes are biologically very different.
With LED lighting, if you have lots of spot lights in the ceiling and and open door, you’ll likely find that the light leaving the house is a bath of reflection from different sources inside the house and that likely cancels out the worst of the flicker.
I wonder how much of it is also the LED flicker. If I was a small bug and moving quickly with a high visual refresh rate, I would probably hate the experience of the LED flicker
The article bluntly states: "Moonlight contains ultraviolet (UV) and infrared wavelengths because it is merely reflected sunlight. Insects cue on UV, believing it to be the moon. . . . Incandescent lights transmit UV but LEDs do not. Insects are far less attracted to LED."
However, my mind developed a similar conjecture to your's: what if the common frequencies of PWM occur within a kinetic visual blindspot of insect vision, like human saccades [0] in the novel Blindsight [1], so that insects are not aware of the LED at all?
They've had many generations to evolve alongside all human false light sources. Insect generations are usually pretty short. Perhaps they just find it evolutionary useful to cluster around human sources of light. Presence of human food, liklihood of bumping into other insects of the same species, warmth, etc.
If human sources of light were interfering somehow, they've had hundreds or thousands of generations to breed out that proclivity.
The streetlights in my neighborhood still have the round photo sensors on top, that have something like a watt of standby current for the sensor itself. I don't think they're trying hard to save powwer.
The ones that have a watt of standby are the really old models (probably not sold for the last 30yrs) where you'd have an LDR controlled relay with no electronics
Anything more modern than that, even if it has a similar case, will use less power
A low-voltage photocell uses like 5mA @ 24VAC these days, it’s nowhere near a watt. You can buy a wireless battery powered photocell or occupancy sensor that will last a decade.
PWM drivers should be banned, the quality of lighting is horrendous and it murders LEDs. You have an rms currernt that is in spec but the peak is way too high.
anecdote: I work in a factory, we have thousands of light fixtures. The older constant current LED fixtures have lasted a decade, the new PWM driven lights have had a ~1% failure rate.
How do you know the difference? Constant current is almost certainly a PWM controlled buck/boost regulator. The flicker is attenuated by inductance, more or less depending on the design.
I guess the distinction is 'filtered' vs 'unfiltered' then. If you look at the lights that fail early using a high framerate camera (1k fps) they flicker between full brightness and fully off. The lights that last longer have some ripple but its 5-10% brightness.
Use a fidget spinner to see the difference. Spin up a 3 lobe fidget spinner and catch the reflection of the LED on it's surface. As the speed changes, a flickering LED will freeze the motion of the spinner. Even more fun with spinners :-).
Yes, adding an inductor will fix the problem, but that costs money. Not enough customers are complaining about the light flicker to justify the higher price.
One of my favorite things I read growing up was a passage about what it's like to be a fly watching TV.
In those days TV's were big CRT boxes, illuminated by the electron beam which would race across the screen row by row.
A housefly's "refresh rate" on its eyeballs is much higher than that of a human, so the fly wouldn't see an image as we do, but would presumably find it quite relaxing watching the dot of light slowly move across the screen.
IIR, hydrogen flames can emit enough of their energy in the UV for that to be a serious issue - both direct human exposure, and degradation of exposed surfaces and equipment.
lived with candles and kerocene lanterns, etc for years and the odd bug will go nuts and spiral in, but not very many
but all in all, there are way less bugs everywhere now
I wonder if it’s only the UV that makes a difference. I have some Yuji SunWave bulbs (and the NIR versions). Would be interesting to test those at night against normal LED bulbs and incandescent.
Yes, you need some ultraviolet to attract insects. That's why bug-zappers have near UV lamps. They're usually compact fluorescent bulbs. Some ads say 365nm is the right color.
Can confirm my spiders like cozy heat. I often get them chilling directly above my computer station, legs spread out like a pancake. Presumably there's a warm air current hitting the ceiling. It might also be the light though.
I wonder what percentage is pesticides vs development? I currently live in an area(US) where a drive to the nearest city of size absolutely coats my car in bugs. US, mostly farmland(soybeans/corn). I wasn't here 30 years ago so can't say there's as many as then, likely not. But if it were only pesticides I'd expect the rural areas to have less bugs than the more developed areas...
As someone who has made many interstate trips through Australia's farmland, I can say that over the decades there's definitely been a drop in windshield splatter. It's unsurprising that pesticide deployed at scale reduces bug populations. Even herbicides which aren't intended as insecticides have limited product advantage to being bug-safe (apart from pollinated crops... and even then). Some aren't even human-safe. An extreme example is paraquat, that while being a herbicide, is irreversibly deadly to humans^ when consumed even in tiny amounts.
I would lean towards the urbanization of the land as well. I rarely get bugs on my car in the city, but as soon as I head out to the country at night my car is covered. I had to stop at a gas station back in May not for gas but just to squeegee the windscreen so I could see again.
wow this would be a neat twist if true - we all defaulted to the negative explanation of having killed them all where a much more positive explanation might be that we're no longer luring them to their deaths at the leading edge of automobiles?
I guess it is most likely some combination of the above, but if there's any evidence it would be a neat reframing
> The second survey, in the UK county of Kent in 2019, examined splats in a grid placed over car registration plates, known as a “splatometer”. This revealed 50% fewer impacts than in 2004. The research included vintage cars up to 70 years old to see if their less aerodynamic shape meant they killed more bugs, but it found that modern cars actually hit slightly more insects.
I think they just all collectively got tired of hearing my dad's punny about "it doesn't have the guts to do that again" any time a bug squashed on the windscreen.
> Research also found that modern cars with a more aerodynamic body shape killed more insects than boxier vintage cars.
That was a surprise to me! I checked out the Wikipedia article to see if it said "lower numbers are attributed to more aerodynamic windshields," because as a former Scion xB driver for 15+ years I saw the number of splats drop quite a lot. The area I lived in was undergoing a massive shift from farmland to housing developments too though, so I couldn't extrapolate further.
Welp, they do for mine. I've had to stop turning on outdoor LEDs because angry bees kept showing up, and there'd be 3-10 dead ones on my doorstep every morning. These are white bulbs.
Also, not sure about white bulbs, but those color-configurable spotlights definitely emit UV at least when set to anything near blue/purple. They cause certain things to glow. Probably white is doing it too but it's harder to see.
The color configurable bulbs or the high CRI bulbs typically use a 400nm led source and some do use a 380nm but those are much rarer and expensive. Also almost any amount of plastic or glass will significantly absorb that wavelength of UV.
I have a 405nm laser pointer and it makes certain things (any% titanium dioxide) absurdly bright from fluorescence. So you probably aren’t getting UV from those bulbs, but certainly some IR.
"The color configurable bulbs or the high CRI bulbs typically use a 400nm led source and some do use a 380nm but those are much rarer and expensive."
Cree, Nichia, et.al. use ~460nm LED with a cerium-doped aluminum-yttrium garnet cover to convert to white light and have done so for at least half a decade. Just a bare look at the spectral output chart from any company will tell you the wavelength of the base emitter, with a MASSIVE output peak centered around 460nm.
Nobody has used UV as a white LED base for well over a decade or more.
"those color-configurable spotlights definitely emit UV at least when set to anything near blue/purple"
Nope. Blue light just happens to do well at exciting fluorescence in some materials, especially bleached and whitened ones like paper and laundry. 420nm blue light will excite red fluorescence in a ruby. 532nm green will induce BIP in calcite. Certainly no UV present in an upconverted IR laser.
I really don’t think UV is playing much of a role here. You could also sort their chart by power usage, or IR produced. The paper conclusion paragraph even states UV and IR as candidates but the article just says UV.
Um, no. I live on a farm and often have to do chores in the dark with an LED headlight. Sometimes I have to turn it off because I'm dive bombed by so many insects.
I have LED headlights and an LED light bar on my tractor and I can say with 100% confidence that bugs swarm both. To the point I have to wear glasses to keep them out of my eyes if I’m on it for more than about 30 seconds at night.
I’m guessing he’s confusing the dramatic drop in insect life overall with a change in behavior due to different lights.
I second this. When my home was infested by flies (I stopped counting at ~1000 over a 3 week period) they would always swarm and hang out by my grow lights (full spectrum LEDs) in my kitchen window. It was a great place for fly traps on the flip side.
It is quite possible that flies prefer one part of the light spectrum more than another part, but to say in the title that they don’t swarm at LEDs is misleading at best.
Also the light bulbs have excellent performance at "catching" bugs because they land on hot stuff and die. I had some GU-12 ceiling halogen lights in my previous apartment and the rims were always covered by bugs that decided to land there and as they were hot from halogens, boom, bug destruction machine
Same. I use my headlamp red beam when they start to swarm, they immediately fly somewhere else. If I camp somewhere with high bug pressure to the point that they try follow me into my tent, I'd actually use the white light to lure them away by attaching it to the apex of my tent while I settle inside before grabbing it quickly.
I bought LED "bug lights" — those yellow bulbs that are supposed to be invisible to bugs.
Every bulb in the pack electrically failed within 10 minutes.
I gave up and went back to an incandescent. Still works perfectly.
So sick of the zero-quality LED bulbs that have entirely flooded the market. Of course they had their hand forced by government mandates, they didn't have this problem when LED bulbs were $20 each (and weighed about as much, due to the heat sink).
A cheaply made bulb doesn't really support your theory though. Before LEDs, the anti-bug yellow incandescent bulb was available. It puts of a horrendous light and most people didn't like them. It's in the top 3 of lights that I do not like: 1) anything CFL, 2) any cool white (>3600K) light at night, 3) ugly yellow anti-bug light, 4) whatever the ugly greenish light 7-11 uses at some gas stations, 5) 4300K fluoro tubes.
It was always a scam because LED bulbs need power supply and that creates heat, switching hundreds of volts ac to low volt dc. They don't last any longer than incandescent in fact they have much shorter lifetimes.
> Sky is always brighter than the land, moon is not required.
Speaking of things being wrong...how can you come to this conclusion? There are many beaches where turtle hatchlings get confused by all of the lights on land where they crawl away from the ocean instead of towards it. Land is so bright, that the vast majority of humans can no longer see the night sky. So again I ask, how do you come to the conclusion that land is darker than the sky?
I made a huge LED display using lifx tiles (which are no longer sold). 5x5 tiles in a square, so I could hack video rendering and images to the lights. Each tile had 64 LED bulbs which could be independently controlled, both in brightness and colour.
When I did this I was in the countryside and I can state without hesitation that the insects loved it and flocked to it and while I found it cute, it was annoying because they would occasionally get trapped in the small gaps between the tiles and get stuck.
I'm therefore 100% convinced that insects just love fancy lighting setups.
I love to shoot long exposure timelapse of the night sky. I set up a couple of LEDs dimmed as low as possible to light a bit of the foreground (over the course of the long exposure the low light adds up so it looks normal for those not familiar). Out of sheer laziness, I just placed them on either side of my tripod. The next day after processing the shot, it was pretty much ruined because of all of the bugs showing up as tracers in each frame.
116 comments
[ 4.9 ms ] story [ 71.0 ms ] threadInsects eyes are biologically very different.
With LED lighting, if you have lots of spot lights in the ceiling and and open door, you’ll likely find that the light leaving the house is a bath of reflection from different sources inside the house and that likely cancels out the worst of the flicker.
The thing that insects can see and we don't is the rapid flashing of a PWM power controller.
I wonder if these streetlights have power saving fade-ins as the nightfall approaches instead of clicking on at sunset.
Like - https://doi.org/10.1109/CSNT51715.2021.9509652
However, my mind developed a similar conjecture to your's: what if the common frequencies of PWM occur within a kinetic visual blindspot of insect vision, like human saccades [0] in the novel Blindsight [1], so that insects are not aware of the LED at all?
0. https://www.ncbi.nlm.nih.gov/books/NBK10991/
1. https://www.rifters.com/real/Blindsight.htm#:~:text=%22There...
They've had many generations to evolve alongside all human false light sources. Insect generations are usually pretty short. Perhaps they just find it evolutionary useful to cluster around human sources of light. Presence of human food, liklihood of bumping into other insects of the same species, warmth, etc.
If human sources of light were interfering somehow, they've had hundreds or thousands of generations to breed out that proclivity.
Anything more modern than that, even if it has a similar case, will use less power
This Acuity occ sensor/photocell combo draws 4mA @ 24VDC: https://pdmassets.azureedge.net/library/SS/documents/specshe...
Note you can make LEDs dim without PWM via constant current drivers, just less efficient as the duty cycle is 100%, they look much nicer though
anecdote: I work in a factory, we have thousands of light fixtures. The older constant current LED fixtures have lasted a decade, the new PWM driven lights have had a ~1% failure rate.
Yes, adding an inductor will fix the problem, but that costs money. Not enough customers are complaining about the light flicker to justify the higher price.
In those days TV's were big CRT boxes, illuminated by the electron beam which would race across the screen row by row.
A housefly's "refresh rate" on its eyeballs is much higher than that of a human, so the fly wouldn't see an image as we do, but would presumably find it quite relaxing watching the dot of light slowly move across the screen.
We use UV/IR combo Flame detectors at work for this purpose.
^ Obligatory Chubbyemu: https://www.youtube.com/watch?v=0VtUGoGZtI8
I guess it is most likely some combination of the above, but if there's any evidence it would be a neat reframing
Germany: "More than 75 percent decline over 27 years in total flying insect biomass in protected areas" https://journals.plos.org/plosone/article?id=10.1371/journal...
Puerto Rico: "dry weight biomass of arthropods captured in sweep samples had declined 4 to 8 times, and 30 to 60 times in sticky traps." https://www.pnas.org/doi/10.1073/pnas.1722477115
https://www.theguardian.com/environment/2020/feb/12/car-spla...
That was a surprise to me! I checked out the Wikipedia article to see if it said "lower numbers are attributed to more aerodynamic windshields," because as a former Scion xB driver for 15+ years I saw the number of splats drop quite a lot. The area I lived in was undergoing a massive shift from farmland to housing developments too though, so I couldn't extrapolate further.
Also, not sure about white bulbs, but those color-configurable spotlights definitely emit UV at least when set to anything near blue/purple. They cause certain things to glow. Probably white is doing it too but it's harder to see.
I have a 405nm laser pointer and it makes certain things (any% titanium dioxide) absurdly bright from fluorescence. So you probably aren’t getting UV from those bulbs, but certainly some IR.
Cree, Nichia, et.al. use ~460nm LED with a cerium-doped aluminum-yttrium garnet cover to convert to white light and have done so for at least half a decade. Just a bare look at the spectral output chart from any company will tell you the wavelength of the base emitter, with a MASSIVE output peak centered around 460nm.
Nobody has used UV as a white LED base for well over a decade or more.
Nope. Blue light just happens to do well at exciting fluorescence in some materials, especially bleached and whitened ones like paper and laundry. 420nm blue light will excite red fluorescence in a ruby. 532nm green will induce BIP in calcite. Certainly no UV present in an upconverted IR laser.
It's not UV.
I’m guessing he’s confusing the dramatic drop in insect life overall with a change in behavior due to different lights.
It is quite possible that flies prefer one part of the light spectrum more than another part, but to say in the title that they don’t swarm at LEDs is misleading at best.
Also the light bulbs have excellent performance at "catching" bugs because they land on hot stuff and die. I had some GU-12 ceiling halogen lights in my previous apartment and the rims were always covered by bugs that decided to land there and as they were hot from halogens, boom, bug destruction machine
There probably are insects that don't perceive the "thinner" spectrum, but generally it (sadly) isn't true.
I bought LED "bug lights" — those yellow bulbs that are supposed to be invisible to bugs.
Every bulb in the pack electrically failed within 10 minutes.
I gave up and went back to an incandescent. Still works perfectly.
So sick of the zero-quality LED bulbs that have entirely flooded the market. Of course they had their hand forced by government mandates, they didn't have this problem when LED bulbs were $20 each (and weighed about as much, due to the heat sink).
The leds do, but the "low-quality" electronic drivers do not and die first. Often well before the advertised lifespan.
Sky is always brighter than the land, moon is not required.
Lamp movement is the confusion of where is “up”
https://www.nature.com/articles/s41467-024-44785-3
Speaking of things being wrong...how can you come to this conclusion? There are many beaches where turtle hatchlings get confused by all of the lights on land where they crawl away from the ocean instead of towards it. Land is so bright, that the vast majority of humans can no longer see the night sky. So again I ask, how do you come to the conclusion that land is darker than the sky?
When I did this I was in the countryside and I can state without hesitation that the insects loved it and flocked to it and while I found it cute, it was annoying because they would occasionally get trapped in the small gaps between the tiles and get stuck.
I'm therefore 100% convinced that insects just love fancy lighting setups.
So, no, not my experience at all.