Subscriber Discussion
Why Does IR LED Lighting Attract Insects?
I've seen claims from some LED lighting manufacturers, such as BrightGreen, that their LED lights do not attract insects. This contrasts to CFL and incandescent lights which do attract insects.
If some regular LED lights don't attract insects, why is it that cameras with integrated IR LED lighting still suffer from attracting insects? Thank you for any insight you can offer.
Luke, it's a good question. Some IR cameras do. What we have never been able to understand is why?
Specifically, why do some conditions and some cameras attract insects and others do not?
Some have speculated that it is about the camera design - bullets attract more than domes - others say it is the time of year or the humidity level.
I'd love to solve this. Anyone with theories or specific experiences to share.
John,
This is very fascinating to me as well. Maybe we can even isolate which specific kind of bugs the lights attract. Maybe the IR has a very high or low pitch sound that it gives off that attracts them? Who knows? Maybe you guys should reach out to famous insect scientists and have an article about it on IPVM?
Interesting fact: This is the only insect ever found in nature to have mechanical gears.
Here's an excerpt from a 2011 research paper by Marianne Shockley Cruz Ph.D. and Rebecca Lindner of the University of Georgia Department of Entomology reviewing insect vision literature ranging from the 1940’s to the present.
It should help shed some light (pun intended) on the matter:
"Based on our knowledge of insect vision and their subsequent sensitivity and photoreceptivity to UV light and colors across the visible spectrum, it can be assumed that if the LEDlight emission is towards the higher end of the visible spectrum (> 550 nm) this may be out of the range of vision for most insects. However if the LED light is within this range you can assume that it is visible by insects. Furthermore, there was little evidence of insect attraction to infrared radiation. Below is a figure depicting the wavelengths and their corresponding colors. Note how on the second figure (labeled figure 3) lights contain many different wavelengths."
Just based on anecdotal evidence, I heartily disagree with the findings in this white paper.
Now, it may be that only certain types of insects are attracted to IR/UV, but those insects in turn attract others. Just comparing IR cams with non-IR cams shows the problem is greater when IR LEDs are included.
I'm not a spider expert, but I know they are smart enough to build webs where they stand the best chance of collecting prey.
In my area, outdoor IR camera not only are impacted by swarms at night, but the blowing strands of burnt out spider webs during the day.
Swarms can result in big problems!
It should help shed some light (pun intended) on the matter:
With all due respect Alain, this "paper" is a non-starter and "sheds" no light on the subject since it does not support the attraction of insects to IR in the least. I mystified as to why you would reference it at all, unless your position is to deny the alleged phenomena and propose a radical means to explain the apparent deposition of insects and arachnids on illuminators.
It does not appear to have been published in any of the established peer reviewed journals, and frankly reads like an undergrad book report with its barely two pages of text, all summary I might add, with no new research. Statements like "Note how ... lights contain many different wavelengths" are representative of its true acedemic level.
Insects are an extremely diverse group and though most do not show sensitivity to IR, many do, and this is plausibly the part of the reason for the varied field response. Here is a paper regarding IR response in some insects. Its certainly not the answer but hopefully its moving in the right direction.
"actually your graph does not support such an inference. The reason is simple, if the illuminator was to emit any visible light, besides the dull glow of near infra-red, than that would be, ahem, visible."
Keep in mind that graph only shows the part of the spectrum visible to the human eye. That doesn't preclude any of those devices emitting outside that range <edit> and most seem to, judging by the wave patterns <edit>.
You also have the relative energy scale to the left. Now I'm not a physicist or a bug expert, but it's probably fair to say that at low enough energy levels, humans might not be able to "see" some of the emissions in the visible range while bugs could.
But we'll have to get that spectrometer out and consult a physicist and a bug expert to know for sure.
There appears to be little research on the subject but at least some sources agree that UV attracts many insects (that's why it is used in bug zappers). There is also some evidence that beetles, mosquitos and bedbugs are attracted to IR light, likely more due to the heat aspect than the light itself. Here are a few links:
The last article, especially, expounds an interesting theory:
"A completely different theory was first put forth in the 1970s by Philip Callahan, an entomologist then working with the U.S. Department of Agriculture. Callahan discovered that the infrared light spectrum emitted by a candle flame happens to contain a few of the exact same frequencies of light given off by female moths' pheromones, or sex hormones. Callahan had previously discovered that the pheromones are luminescent — they glow very faintly.
In short, male moths are attracted to candles under the false belief that they are females sending out sex signals. "The male moth is highly attracted to and dies attempting to mate with the candle flame," Callahan wrote in a 1977 paper in Applied Optics."
Thank you to everyone who has thought about this question and posted information. Clearly it has many of us puzzled. I have contact some manufacturers of regular LED lights who claim that their lights do not attract insects. I have asked them why that is in the hope that their answers might reveal the answer to why IR LEDs still seem to attract insects. If I learn anything useful from the manufacturers, I will post the information here.
Hi All - I'm from Raytec and 75% of what we do is IR lighting. I've been involved in IR lighting for 14 years.
So, the first truth is that spiders are absolutely attracted to IR lighting. That is the definite truth as video specialists we all have to deal with.
Next is why and actually we are not sure.
Most probably (in my opinion) is that the heat of the light source attracts them. But it could attract their pray. They do tend to make webs around other external light sources but its the ones integrated into cameras that get noticed.
So perhaps a company like bright green use lower powered LEDs which equate to less heat if they don't need the same intensity. As they made the claim it might be worth asking why they made the claim? I have never found scientific data about spiders and IR.
2 other points:
- The IR LEDs are narrow bandwidth. So let's assume 850nm +/- 30nm... max 50nm
- Spiders are arachnids not insects (which makes the post above only relevant to their pray)
Here is a good video I found on a site that uses Raytec IR. The IR is attracting a spider but because its beside the camera and not inbuilt into the camera it doesn't totally obstruct the view. Just to show that it does happen with stand alone IR too - but with less / no impact to the picture depending upon proximity
Manufacturer video claiming to rid cameras of spider problems using a 'special high frequency signal':
You may find this to be off subject, but I was at a Wildlife plantation in Florida 2 months ago. My guide told me Zebra's rarely get bit by insects and she was told by a scientist that visitied that studies are currently being done on this and how striping can be applied to things in everyday life. I guess black and white striping reflects light a certain way. I will see if I can find anything about this.
Update -
To understand why zebra stripes might have this effect, one can think of all light waves as electric fields rippling either up and down, left and right, or at any angle in between, a property known as polarization. Many insects are drawn to horizontally polarized light because it is a telltale sign of water. Light reflected off water is horizontally polarized; horseflies develop in water or mud, and so are drawn to stretches of water where they can mate and lay eggs. In contrast, the dark and light stripes of zebras each reflect different polarizations of light, and the fact they are arranged vertically might ward off horseflies looking for smooth, horizontally polarized signals, explained researcher Susanne Åkesson, an evolutionary ecologist at Lund Universityin Sweden.
Just Google and you can find what the Sweedish University found. If this is accurate research, could this be applied?
The Parson Animal folks have missed this enormous opportunity.
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