Why are insects more attracted to LED light?

You’ve likely heard the phrase “drawn like a moth to a flame” and immediately understood that this depicts the habit of moths (and other bugs) flying towards a source of light.

If you’ve ever sat near a bug-zapper on a warm summer night or glanced at your outdoor light as dusk settles in, you’ve undoubtedly seen these creatures crowding around the light source.

In observing this natural attraction, Rentokil's team of scientists at the Power Centre has studied the physics of how to better attract flies to an insect light trap.

LED lights for fly control

As homeowners, we have been told that LED lights are a smarter, more energy efficient way to light our homes. It seems this light source is also attractive to insects, too.

Rentokil’s global study of insect attraction to light found LED technology, when combined with an insect light trap, was a superior attractant in killing and capturing flies than traditional light sources. We used this data to develop our proprietary LED range of insect light traps, Lumnia, which are now available to our customers in the U.S.

But what is it about LED light that makes it so attractive to flies?

LED lights produce intense beams of UV-A light that penetrate further into the surrounding environment and appear more attractive to certain insects than the light traditional lamps produce.

Greater reach of UV Light

The house fly is attracted to UV-A as their eyes are sensitive to light at that wavelength. The absolute intensity of light is secondary as it’s the relative intensity above ambient light levels which come into play. For this reason, wavelengths of light outside the visible light range are more attractive to house flies than those that fall within it.

The graph below shows the wavelengths of light that a house fly’s eyes can detect.

This shows that the fly’s photoreceptors are tuned to wavelengths around 0.00035 mm. This is close to the UV output of the Lumnia LEDs (0.000365 mm). The horizontal reach of UV light from a Lumnia unit is 40% greater than traditional fluorescent tubes. This gives Lumnia a greater range over which it is attractive to flies while using less power.

Half-life measure

To prove the efficacy of LED insect light traps in attracting flies, Rentokil's research team compared the Lumnia range with 5 of the leading competitive units using a standard performance test called the half-life measure. This measure represents the time taken to eliminate 50% of flies released in a test chamber. The lower the half-life measure, the more effective the insect light trap.

The test is based on releasing 100 house flies in a standard test room in which the product/unit installed. The number of flies captured was counted at regular intervals over a seven-hour period. This process was repeated at least six times to ensure a fair reflection of performance over time.

Graph 1 indicates half-life catch rates, with the Lumnia unit (red) catching flies in the fastest time.

Graph 2 indicates how the half-life value (red) is a measure of flies caught in the fastest time.

Lumnia is now available to all Rentokil customers in the U.S. The unit comes in four sizes: Slim, Compact, Standard, and Ultimate. If you'd like to see a Lumnia unit, contact your Rentokil representative or call 800-868-0089.

Rentokil’s fly control solutions are used as part of its Exclusion, Restriction, Destruction and Monitoring approach to ensure businesses have effective, long-term protection from flies.

Contact Rentokil to book your free inspection today.