Hornets are large social wasps that often interact with human outdoor activities, particularly during the late summer and fall. Understanding what draws these insects is practical for safety, outdoor planning, and the strategic placement of traps. Hornets share a vision system similar to other social wasps, but their perception of the world is dramatically different from ours. This means the colors used outdoors can inadvertently invite them closer.
Hornet Vision and Color Perception
A hornet perceives color through its compound eyes, which are vastly different from human eyes. These insects are trichromatic, meaning their color vision is based on three primary light receptors. These receptors are tuned to different parts of the electromagnetic spectrum than human eyes, peaking in the ultraviolet (UV), blue, and green regions.
This visual arrangement allows hornets to see UV light, which is invisible to the human eye. UV sensitivity is a significant factor in locating food sources, as many flowers have UV markings that act as nectar guides. Because their visual range is shifted toward shorter wavelengths, they are largely unable to perceive colors at the long-wavelength end of the spectrum. Consequently, the color red appears to them only as a shade of black or a very dark gray.
The Highly Attractive Color Spectrum
Colors highly visible to hornets often mimic natural food sources, triggering an investigation response. Yellow is a particularly strong attractant, as it resembles the color of many pollen-rich flowers. This color is a direct visual signal interpreted by the hornet as a potential source of nectar or a sugary meal.
Bright white is also highly attractive because it reflects a significant amount of UV light, making it stand out prominently. Similarly, bright oranges and lighter shades of blue can draw attention, as they fall within the wavelengths hornets use to locate flowers. When displayed on clothing or gear, these colors can be mistaken for a large, nutrient-rich bloom. The attraction is functional, driven by the instinct to find carbohydrates to fuel adult activities.
Minimizing Attraction Through Color Choice
Choosing colors that fall outside the hornet’s primary visual range helps reduce unwanted attention. Deep reds and colors with a strong red component are ignored, as hornets cannot distinguish the long-wavelength red pigment. This makes red a form of camouflage against their vision.
Muted, neutral tones such as khaki, tan, beige, and earth-toned grays are less likely to attract hornets. These colors do not reflect UV light strongly, nor do they mimic the vibrant hues of flowers, offering visual blending. While dark colors like black and deep navy do not attract hornets as bright yellow signals food, a large, dark, moving object can sometimes be perceived as a threat. Neutral, non-reflective colors are the most prudent choice for outdoor wear to minimize attraction or confrontation.
Non-Visual Attractants
While color plays a significant role in initial attraction, non-visual cues are often the ultimate reason hornets linger. Scent is a powerful motivator, and hornets are attracted to sweet, sugary odors. This includes spilled sugary drinks, fermented fruit, and strong floral or fruity perfumes, colognes, and lotions.
During late summer, the colony is no longer primarily focused on feeding its young protein, and adults switch their search almost entirely to carbohydrates. Hornets are also drawn to protein sources, such as pet food left outdoors or meat scraps from a barbecue. These chemical signals often override visual deterrents. Sudden or aggressive movements near a hornet can instantly change its behavior from investigative to defensive, potentially leading to a sting, even if the person’s clothing was a non-attractive color.