LED lights don’t attract insects. True or false?

Gordon Routledge, lighting expert and publisher of Lux, investigates a widely held belief about insects’ lighting preferences.

Ultraviolet light has been exploited for years to lure ­flies to an early death by electrocution – as can be seen in the bug traps at any supermarket’s fresh meat counter. Over the years I have heard from numerous sources that, because LEDs don’t emit ultraviolet light, they don’t attract insects.

"Given a choice between no light and a white light, do insects give up and go home, or do they ­fly merrily around your head, laughing at your feeble LED fittings and making the occasional landing on your neck to suck your blood?"

At first glance the statement seems to pass the common sense test. I didn’t start to really question it until I left a retrofit LED bulb switched on to test in the garage for six months, during which time the diffuser accumulated a significant number of corn flies. If there’s no UV, what is it about LEDs that’s so irresistible to insects?

 

The search for truth

Spend a little time trawling the internet and you will quickly unearth a wealth of articles, reports and anecdotes on UV light, insects and LEDs, frequently contradicting each other and sometimes with a strong smell of snake oil about them.

A few calls to the Royal Entomological Society put me on a clearer track, and I was directed to some useful papers on insects and light. Perhaps the most pertinent was undertaken in 2005 at the University of Agriculture in Faisalabad, Pakistan, titled ‘Insect orientation to various colour lights in the agricultural biomes of Faisalabad’.

The research was carried out by erecting a number of illuminated one metre-square screens in two separate locations, each six metres apart, and collecting the insects that became trapped on each panel at half-hourly intervals.

The study found that 60-70 per cent of insects preferred light at the blue end of the spectrum. But that doesn’t mean the others stayed at home – insects, as it turns out, have a wide variety of preferences. Eighteen per cent headed for a white light, another eight to 10 per cent went for yellow and two per cent headed straight for the red light district.

This is all very interesting, but what if you’re the only light in town? Little research has been carried out in the area of general lighting, and more specifically LED. Given a choice between no light and a white light, do insects give up and go home, or do they ­fly merrily around your head, laughing at your feeble LED fittings and making the occasional landing on your neck to suck your blood?

 

Bugged out

After the success of the North Yorkshire garage LED trial, I took the opportunity to extend the study to my brand new LED-lit kitchen. Leaving the doors open last week, I can report that the local midges are more than happy to hang around on a wall under an LED downlight, where they are soon joined by a selection of moths and ­flies.

"It appears that insects, like humans, have quite complex and diverse tastes in lighting, and may well spend hours debating the colour rendering of a dung heap under different sources"

And with lower levels of radiated heat than traditional light sources, they are far less likely to get burned in the process. It’s only a matter of time before word gets around in the insect community about this cool new hangout.

It appears that insects, like humans, have quite complex and diverse tastes in lighting, and may well spend hours debating the colour rendering of a dung heap under different sources.

But, also like humans, they’ll make do with what light there is. I’m sure the option of hanging around in a dimly-lit Starbucks and divebombing freshly-made cappuccinos is preferable to the risk of being spattered across a truck windscreen on the M25 while trying to find a nice, white HID lamp.

So next time Snake Oil Bob drops in to hawk his wares on the basis of their anti-bug properties, send him packing with an LED torch to Faisalabad, and he can explain to the local insects himself that it doesn’t emit any UV – if they’ll stop biting him for long enough to listen.

  • You can find out more about the abilities of LED at this year's Lux Live. The exhibition will take place at ExCeL London on Wednesday 23 November and Thursday 24 November. Entrance is free if you pre-register at www.luxlive.co.uk

Comments 14

I live in Arizona and have 60W soft white LED bulbs on my porch. They attract moths like crazy! My experience in trying many different types of bulbs through the years is the only ones that don't attract moths etc. are the ones that are turned off......

My family and myself go camping a lot, I have cool white LED strips, can tell you that all types of insects absolutely love them, they come from miles away just to have a look at the light I reckon

Quick edit... When referring to prose and wonderful, I was referring to this article and its author. Sorry for the ambiguity. :) P

This was a question that I had wondered about since Mike Holmes (Canadian home-reno and contractor legend) stated in one show that LED lights didn't attract bugs. However, no other details were given, and the tiny inset step lights might have been simply too small for insects to bother seeking. Aside from the intelligent answer with correct scientific references (I checked some), it was absolutely wonderful prose and fun to read. Thanks.

Many moons ago when LED's were just something on a PCB I installed a 400w MV floodlight on the back wall of my house here in North Queensland. When I switched it on that night the wall was covered in moths. More moths than wall! I changed it to 360 HPS problem went away. So maybe the answer is put HPS throughout your house with your own Generator!

Also LED lights have less heat so don't attract the bugs or as many bugs

Yes quite right Gordon, but just think of the money you are saving whilst being bitten and as a result we can now afford to by the medication for gnat bites !

Hope you didn't spend a lot on this... lights attract insects, no lights attract insects, everything attracts insects, nothing attract insects, they're freaking insects. The rest is marketing

There's a more up to date piece of research - 'Effects of residential energy-saving lamps on the attraction of nocturnal insects' in the May 2015 edition of Lighting Research & technology. http://www.cibse.org/society-of-light-and-lighting-sll/lighting-publications/lighting,-research-and-technology-%28lr-t%29

Very interesting, I live in Far north Queensland, apart from having their own LED torches, insects up this end of Australia, have number plates and rego papers........ Like everybody else, I have my share of LED fittings. I bought the argument about UV and IR, and, sick of seeing everything tinged in yellow at night, I started replacing every fitting in the house. What seem to happen is that 99% of insects ignore the flood light in the garden (CRI 69 50W), tend to fly around a bit in the corridor (CRI 80 7W), and same thing with the lounge room downlights (CRI 85 9W), maybe a bit more than in the corridor. Does CRI, maybe, have something to do with it????

The Chinese Fisting Pussy runs on solar UV? well the one in my local bar does. It fists away under an LED light, when they turn the LED off then the fisting action stops, so LED does not only save electric it also makes it.. well it does with our LED lights anyway. Simon of www.jacksta-energy.co.uk

Insects are made to follow the sun! Sun Rays: 99% of its rays are in the form of visible light, ultraviolet rays, and infrared rays My own opinion is that any light that emits UV (as the Sun does) will attract MORE insects (cause seems like coming from the Sun) but generally a visible light with no UV radiation (Good quality of an LED light) will still attract insects if that's the only light in the area.

False by my estimation. My new LED lit porch light seems to still be pretty attractive to the wee pesky critters!

Absolutely right Gordon! The blanket claim that LED emitted light does not attract insects is false.

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