Insects rely heavily on visual cues to navigate their environment, locate resources, and govern foraging, mating, and survival. The colors of plants, light sources, and clothing can act as powerful attractants or deterrents. Their perception of the visual spectrum is fundamentally different from human vision, leading them to be drawn to certain hues rooted in their ecological needs.
How Insects Perceive Color
Insect vision is structured around the compound eye, composed of numerous individual light-sensing units called ommatidia. Unlike human vision, which uses three types of cone cells sensitive to red, green, and blue light, many insects possess a visual system sensitive to ultraviolet (UV), blue, and green light. This difference means that the insect visual world is shifted toward the shorter wavelengths of the electromagnetic spectrum.
The most significant distinction is the ability of insects to see UV light, which is invisible to the human eye. UV sensitivity allows insects to detect patterns on flowers that act as nectar guides, directing pollinators to the food source. Consequently, UV light and the colors closest to it—violet and blue—register as highly visible and attractive signals. An object that appears white or pale blue to a human may be reflecting a large amount of UV light, making it glow intensely to an insect.
The Most Attractive Colors for Pests
The most attractive colors generally mimic environmental cues associated with food or hosts; preferences are often species-specific. Yellow is a powerful, broad-spectrum attractant because it resembles the reflected light of young foliage and a wide variety of flowers, making it a universal signal for pollen and nectar. This color effectively draws many common agricultural pests, including whiteflies, aphids, and fungus gnats, which are often trapped using yellow sticky cards.
Blue and violet colors, which are close to the UV spectrum, are strong attractants for insects like thrips and some biting flies. Thrips are notoriously drawn to blue traps, likely because the color contrasts well with the green foliage they inhabit or because it signals certain host plants.
Dark colors like black, red, and deep orange are strong attractants for blood-feeding insects, such as mosquitoes, because they absorb heat, mimicking the warm body temperature of a host. Studies suggest that red and orange wavelengths, detected after the mosquito senses carbon dioxide, may stimulate the visual system in a way that resembles human skin. The combination of a dark silhouette and a heat signature makes these colors highly visible to a searching mosquito.
Colors That Deter or Go Unnoticed
Colors that deter insects are those that lack biological relevance or are poorly registered by the insect’s photoreceptors. True red, the longest wavelength in the visible spectrum, is often poorly perceived because many insects’ visual range does not extend far into that region. For most flying insects, a red object may appear as a dull gray or black, making it ineffective as a long-distance signal, though mosquitoes are a notable exception.
Green is less attractive to plant pests because it is the background color of healthy, mature leaves that are not actively flowering or signaling a fresh food source. For many insects, this color signals camouflage or simple background rather than a target.
White and very light pastel colors tend to be less attractive to many biting insects. These colors reflect most light and absorb less heat, making them poor targets for host-seeking insects like mosquitoes.
Using Color in Pest Management
The knowledge of insect color preference is directly applied in pest management through the strategic use of colored traps. Agricultural and horticultural settings commonly use bright yellow sticky traps to monitor and control general flying pests like whiteflies and aphids. For more specific problems, blue traps are deployed to target thrips, while black traps are used for pests like the tomato leaf miner, Tuta absoluta.
Color choice plays a role in outdoor lighting and clothing. To minimize attraction around homes, homeowners switch to yellow-tinted “bug lights” that filter out attractive short-wavelength blue and UV light. For outdoor activities, wearing light-colored clothing, such as white or light green, reduces the visibility and heat signature that attracts mosquitoes and other biting pests. Choosing these less-attractive colors acts as a passive barrier against insects.