LED and Flying Insects
Last year I had asked the lighting community if there was any topics of interest that I might write about. I was happy to receive a question from Mr. Steve Schafer of Milow Electric in Long Lake Minnesota. Steve asked me to investigate the effects of LED light and flying insects.
We have all enjoyed a family meal out on the patio. During the summer months the flying insects can make these times unbearable. Halogen, incandescent and fluorescent light sources all have the potential to attract flying insects, due to the light wavelength and the heat generated by the lamps. With the rise in West Nile virus cases, people are more carefully selecting their light sources. For several years there has been discussion on which new LED light sources will reduce the attraction of insects. In studies relating to this subject, it has been determined that the lighting wavelength and proper thermal management of LED light sources can successfully reduce the attraction of insects. Insects process light differently than humans. But like us they seem to have a particular “taste” in the lights that attract them. Insects use ultraviolet light to guide themselves at night, thus making the BUG ZAPPER light on the back porch a great success for us humans.
In Pakistan, the scientists at the Department of Entomology have discovered that insects are more attracted to one particular color spectrum than others. The purpose of this study was to engineer light driven insect traps as an alternative to pesticides for the agricultural industry. The results found that 22% percent of the insects were attracted to a blue spectrum of light.
So, how these findings help us design a bug free lighting system? We now know that the warmer the wavelength the fewer insects are attracted. When designing a lighting system were people may congregate it will be necessary to select light sources more toward the red spectrum. Using a kelvin temperature such as 2200k in these areas can create a warm relaxing atmosphere with a reduced number of insects. Bistro strings equipped with 2200k can provide this effect as well as a broader span of lighting. In some commercial applications I have seen red and 2200k mixed in these strings. Designing with this color tones can also help us relax our eyes from the blue spectrum of light we view all day on the computer. In other areas of the property, away from people, other color temperatures can be used. This means you can still light up the big trees out in the yard and create the depth with back lighting. Task lighting in 5700k or brighter should always be put on some type of switch if located close to patios or gathering areas. For outdoor rooms it may be required to use two different kelvin temperatures, warmer for dining and cooler for clean-up. Both should be on separate switches. Some manufacturers have made this switching easier through smart systems and color changing products. When selecting light sources for your outdoor environments, be sure to read the specifications carefully. Select sources with no UV. This will help not only reduce the insects but also help to avoid color shift in the phosphors applied to the diode. Often customers who purchase the light sources from an unknown supplier on line can find themselves with a bug attractor.
In my research I have not found any true bug free light sources. It is up to us, as contractors and designers, to do the best job possible to reduce insect attraction in our designs.
I wish to thank Steve Schafer for asking me to research this subject. If you have a lighting topic you would like me to investigate, please email me. In the meantime, keep your customer buzzing about your great design … not the bugs!