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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.

Insects are attracted to low wavelength light, which includes both UV and blue light. Cool color LEDs are usually blue LEDs, and are often used for headlights/etc because they get higher lumen ratings for the power used. Headlights/lightbars are also really bright compared to porch lights.

If you compare an incandescent soft white porch light to a similar brightness soft white led light, you will probably see dramatically more insects at the incandescent bulb. .

Yep, my Fenix headlamp and flashlights attract flying insects like crazy.

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.

You don't need UV to stimulate florescence. 395nm blue light will cause yellow highlighters to light up quite brightly: https://par.nsf.gov/servlets/purl/10326338

Yeah, we have solar powered LED lights in the walking path where I live and the lights are covered with them. They look nasty.

This. It likely depends on the driving technology. Some repell me too :P

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

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.

Don't forget about flicker free dimmable LEDs. I install them in my house.

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 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?

0. https://www.ncbi.nlm.nih.gov/books/NBK10991/

1. https://www.rifters.com/real/Blindsight.htm#:~:text=%22There...

Bugs don’t just materialize out of the ether to swarm lights. Not to feed swallows. They are there and you will encounter them if the density is much more than zero.

There are bugs. You photographed bugs. Maybe more than you would have without lights at all, maybe about the same.

Also better lights don’t necessarily mean perfect lights. We do lots of things to reduce harm. Unfortunately sometimes we do them too much and conserve a significant fraction of the original harm by increasing demand.

Can we see that? Bet it looks cool.

> 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?

a conclusion can be right even if an argument for it is wrong.

Ever used a blacklight outdoors? They are not bright, but will be covered in bugs.

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.

Do they cluster around the bulbs? If not, they might not be attracted to the lights.

Install a single incandescent somewhere and be less mystified by the claim.

They didn't say no bug ever goes to any led light.

I get quite a few insects that fly around a camera, and that is near-ir. So many that a spider finds it worth it's while to build a web in front.

There is no such thing as refresh rate for any kind of eye.

The best light.

The gold standard for mothing is a mercury vapor bulb. They are pricey and power-hungry, but they'll have your sheet covered in bugs in no time!

There's a Wikipedia entry for that: https://en.wikipedia.org/wiki/Windshield_phenomenon

The answer to that is pesticides. There's still plenty of insects ready to smash into your windshield in many parts of the world.

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

My hypothesis is better wind tunnel testing for modern cars so that the bugs go over instead of splatting.

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.

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.

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.

Yes, but how much UV depends on what's burnin / how hot its burning. Otherwise they mostly put out IR.

We use UV/IR combo Flame detectors at work for this purpose.

a little but not much, from my quick look online.

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

No but they emit smoke

They can. It's either ignorance or malice. It's not economics.