Flies interact with the world through senses different from human perception, especially regarding how they see and react to colors. Understanding these visual cues provides insight into their behavior and can inform strategies for managing their presence.
Colors That Attract Flies
Flies are strongly drawn to certain colors. Blue consistently emerges as a top visual attractant in controlled tests, outperforming others. This attraction is partly because blue light is highly visible and stimulating to a fly’s compound eyes. Biting flies, for instance, are particularly attracted to blue objects, often mistaking them for animals they seek to feed on. This understanding has led to the development of fly traps that utilize blue light or blue-colored designs to effectively lure and capture flies.
Dark colors, including black, also attract flies. Dark surfaces absorb heat and create visual contrast, mimicking cues that flies use to locate shelter, food sources, or mates. Traps sometimes incorporate black stripes to mimic the dark crevices flies prefer for hiding.
Yellow is another color frequently used in fly traps, as it can mimic flowers or fruits that flies feed on. For instance, fruit flies are specifically drawn to yellow, likely associating it with ripe produce like bananas. However, studies on house flies indicate that while yellow is used in traps, blue is considerably more attractive, and yellow can even have a repellent effect on these specific flies.
The Science Behind Fly Vision
The unique visual system of flies underpins their color preferences. Flies possess compound eyes, visual organs composed of ommatidia. Each ommatidium contains photoreceptor cells capable of distinguishing brightness and color. While this mosaic vision provides a wide field of view and is exceptional at detecting rapid movement, it generally offers lower image resolution compared to human eyes.
Flies perceive light through several types of photoreceptors, each sensitive to different wavelengths. Flies are sensitive to ultraviolet (UV) light, a spectrum invisible to humans. UV light is a potent attractant for flies, and their photoreceptors are tuned to detect UV, green, and blue light. The ability to distinguish colors relies on the comparison of signals received by photoreceptors that respond to these distinct light wavelengths.
Colors That Deter Flies
Certain colors are less attractive to flies, and some can even deter them. White and other light colors are generally less appealing to flies. These lighter hues reflect more light and do not provide the visual cues that typically attract flies. Similarly, light green colors can help repel flies, as they tend to blend with natural vegetation, making them less noticeable to insects.
Red is another color that flies often cannot detect. Utilizing red light or red-colored objects can therefore make an area less appealing to flies without disturbing them. Some research suggests that warmer tones, such as certain shades of yellow, may also act as repellents for house flies, contrasting with the strong attraction to blue. Practical applications of this knowledge include choosing lighter-colored clothing for outdoor activities to minimize fly presence or using light paint colors on outdoor structures to make them less inviting to flies.