It is a common sight: insects gathering around bright lights at night. Understanding the science behind how insects perceive their environment, especially light, clarifies this phenomenon.
How Insects Perceive Light
Insects have a unique visual system. They see through compound eyes, composed of many individual units called ommatidia. Each ommatidium contains a lens and light-sensitive cells, allowing insects to perceive a wide field of view and excel at detecting motion. This mosaic-like vision helps them quickly spot movement.
Many insects, including bees and butterflies, are sensitive to ultraviolet (UV) light, invisible to humans. While humans perceive colors from red to violet, many insects are sensitive to UV, blue, and green wavelengths. This UV sensitivity allows them to see patterns on flowers that guide them to nectar. Insects often exhibit phototaxis, a behavioral response to move toward or away from a light source; moths, for instance, are positively phototactic.
The Role of White in Insect Attraction
White’s light-reflecting properties play a significant role in insect attraction. White light, like daylight, contains all wavelengths of the visible spectrum. Many artificial white light sources also emit attractive UV light.
Bright white light sources are strong insect attractants. They often produce UV light and heat, which draw insects. Insects may mistake these bright artificial lights for natural celestial navigation cues, like the moon, becoming disoriented and circling the light source.
White surfaces, while generally less attractive than bright lights, can also draw insects. White reflects visible light and, depending on the material, can also reflect UV light. Some studies suggest that flies are attracted to white surfaces, potentially associating them with food sources or navigation. For some insects, like mosquitoes, white clothing may be less attractive than darker colors, but for others, white’s reflective properties can still attract.
Practical Implications for Avoiding Insects
Adjust lighting choices to minimize insect attraction around your home. Yellow or amber “bug lights” are effective because their longer wavelengths typically lack the UV component that attracts many insects, making them less visible. Positioning lights strategically, away from entry points, can also help direct insects elsewhere.
When it comes to clothing, lighter colors are less attractive to certain insects like mosquitoes than darker hues. However, human skin emits a red signal that mosquitoes can detect, regardless of clothing color.
Selecting paint colors less appealing to insects can reduce their presence on outdoor surfaces. Colors like blue and green may deter some insects, as they do not register vividly in the ultraviolet spectrum insects perceive.