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Want to repel insects? Tune your LED lamp

Getting the blues: Different colour temperatures have varying attractions to insects. Blue is a popular one, although not as popular as ultraviolet.

Tunable LED lamps that allow users to dial down blue light could help keep insects away.

That’s what a group of scientists in Los Angeles have discovered, as reported by The New York Times .

The team, led by professor Travis Longcore of the University of Southern California, placed insect traps under different LED and compact fluorescent (CFL) bulbs, including experimental bulbs from Philips that allowed the researchers to modulate the colour temperature.

‘The tunable LEDs could be adjusted to attract about 20 per cent fewer [bugs] than standard LEDs did,’ the Times wrote. It said that Longcore toned down the light at the blue end of the spectrum so that the non-tunable LEDs emitted more blue light than did the tunable ones.

The CFLs ‘attracted by far the most bugs,’ because CFLs emit violet and ultraviolet light, wavelengths that are further out beyond the blue spectrum and are known to attract insects.

LEDs do not emit ultraviolet light.

The findings could help reduce human exposure to insect-borne diseases such as malaria, by deploying tunable LEDs in infested areas.

But the study essentially confirmed that, as Lux publisher Gordon Routledge wrote recently, it is a fallacy to claim that LEDs do not attract insects – a mistaken claim wrongly attributed to LEDs’ absence of utlraviolet light. LEDs simply attract fewer insects. A 2005 study in Faisalabad, Pakistan found that more insects prefer light at the blue end of the spectrum – including blue as well as ultraviolet – but that some are attracted by other frequencies, including red.

Longcore’s team published their findings in the journal Philosophical Transactions of the Royal Society B. They set out their lamps and traps in one urban location in Los Angeles and in two rural settings in the Santa Monica Mountains outside of the city.

From Faisalabad to Los Angeles, it seems, insects are getting the blues. And to some extent, the other colours too.

  • 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

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