Bugs like moths, mosquitoes, and other flying insects are often attracted to bright lights at night. This phenomenon is called phototaxis and occurs because the insects use light from the moon and stars for navigation. When they encounter an artificial bright light, like a porch light or streetlamp, it can confuse them and draw them in. However, not all bright lights attract bugs equally. The color and type of light makes a big difference in how attractive it is to insects.
Ultraviolet Light
Many bugs are able to see ultraviolet (UV) light, which has shorter wavelengths than visible light. UV light is abundant in sunlight, so bugs have evolved to use it for navigation. At night, artificial lights that emit UV wavelengths are far more attractive to insects than regular incandescent or LED bulbs that do not. Bug zappers are designed to exploit this effect by using UV light to lure insects to their electrocution grids.
Color Temperature
The color temperature of a light source also impacts how many bugs it draws in. Light color is measured in kelvins (K) to indicate its warmth or coolness. Lights with a higher color temperature produce cooler, bluer light. Research has found that warm yellow and orange light around 2000K to 3000K does not attract nearly as many insects as cooler light above 4000K. This is because the cooler blue and purple light is closer to UV wavelengths that bugs seek out.
Types of Lights that Don’t Attract Bugs
Here are some types of lights that produce little UV light and are less attractive to insects:
- Incandescent bulbs – These traditional bulbs emit light by heating a tungsten filament. The light is very warm, around 2700K.
- Warm white LEDs – LEDs can be manufactured to produce warmer color light, often 2700K – 3000K.
- Sodium vapor lamps – Often used on highways, these lights are yellow and have very little UV.
- Enclosed lights – Covering or shielding lights limits their ability to attract bugs from a distance.
Why Bugs Are Attracted to Light
Here are some of the main reasons insects are drawn to bright lights:
- Navigation – Many flying insects use light from the moon and stars to orient themselves while flying at night. Bright lights can confuse this ability.
- Attraction to UV light – Insects are able to see UV wavelengths invisible to humans. They have evolved to be attracted to UV when searching for food, mates, and habitats.
- Misconception it is daylight or moonlight – Bright lights can trick insects into thinking it is daylight or that they have found the moon, disrupting their natural rhythms.
- Attraction of prey to light – Some predatory insects are drawn to lights because other insects they feed on congregate there.
Wavelengths that Attract Bugs
Here are the wavelengths of light that tend to attract the most insects:
- 300-400 nm – Near ultraviolet light. Many insects see UV light that is invisible to humans.
- 400-500 nm – Violet and blue light. Cooler light near the UV range.
- 500-600 nm – Green light. At the middle of the visible light spectrum.
In contrast, these warmer wavelengths attract fewer bugs:
- 600-700 nm – Yellow and orange light
- 700-800 nm – Red light
Tips for Limiting Bugs Around Lights
Here are some tips to prevent lights from attracting as many unwanted insects:
- Use yellow bulbs like sodium vapor lights
- Use bulbs rated 2700K or below
- Block UV with plastic covers
- Illuminate only where needed
- Turn off lights when not in use
- Use fans near lights to disrupt insect flight
Conclusion
While many bright lights attract bugs, not all do. The best way to limit insects swarming around lights is to use enclosed warm yellow or orange bulbs below 3000K. Avoid exposing UV light unnecessarily outdoors during summer nights when flies and moths are most active. With some adjustments, you can illuminate spaces without drawing in as many annoying insect visitors.
