Flies are a common nuisance that can quickly infest homes, businesses, farms, and other environments. While there are many ways to control fly populations, using visual deterrents is one of the simplest and most affordable options. Certain colors have been found to deter flies, creating an optical barrier that makes them less likely to enter an area. Understanding which colors flies avoid can help you use this knowledge to your advantage and design fly-free spaces.
How Do Flies See Color?
The first step in determining which colors deter flies is understanding how flies perceive color. The fly eye differs greatly from the human eye in its structure and function. Instead of having a single lens focusing light, a fly has thousands of lenses called ommatidia covering its eyes. Each lens focuses on one small part of the visual field. The lenses do not move to scan the environment, so flies rely on their fast, jerky movements to quickly capture visual information.
Flies cannot see the full range of colors detectable to the human eye. They primarily see ultraviolet, blue, and green wavelengths of light. Flies are thought to see red and orange as shades of gray. This is because flies lack red receptors in their eyes. However, they do possess receptors sensitive to ultraviolet light frequencies that humans cannot detect. Overall, fly vision is attuned to wavelengths from 300 to 600 nanometers.
Fly vision is also optimized for detecting motion and changes in light levels. Their eyes contain specialized neurons that quickly notice movement and contrasts between light and dark. Still objects with little contrast are more difficult for flies to see clearly. This is why flies may bump into objects or walls unexpectedly despite having excellent motion detection.
Knowing that flies cannot detect red well but are extremely sensitive to blue and green light provides helpful insights for choosing fly deterrent colors. Since flies rely heavily on contrasts and motion cues, maintaining visual consistency in areas where flies are unwanted can help disguise and camouflage these zones.
Which Colors Are Flies Attracted To?
Certain colors are known to attract flies based on their visual system. Here are some of the main colors that appeal to flies:
- Yellow – flies gravitate toward yellow objects. Yellow has high contrast against most backgrounds, making it eye-catching to flies.
- White – flies are drawn to white objects, particularly in low light conditions where white surfaces stand out.
- Fluorescent colors – fluorescence creates high contrast, attracting flies.
- Patterns and flowers – flies use visual landmarks for navigation, steering toward high-contrast patterns.
Yellow fly strips and traps rely on this attraction to bright yellow to lure flies in. Frequent use of yellow decor can inadvertently make an area more appealing and noticeable to flies since it activates their motion detection.
Knowing flies’ color preferences can cue you into objects, fabrics, or color schemes in your environment that may be accidentally inviting flies. Opting for less attractive colors is a simple way to make a space less desirable to flies.
Which Colors Do Flies Avoid?
Research has revealed certain colors that deter and repel flies:
| Color | Effect on Flies |
|---|---|
| Red | Appears dark or black to flies; lacks contrast to stand out |
| Purple | Appears dark or black to flies; lacks contrast |
| Blue | Visible but less attractive to flies than other colors |
| Green | Visible but less attractive to flies than yellows |
| Gray | Provides little contrast against backgrounds |
| Black | No contrast; flies cannot differentiate from surroundings |
Colors at the red end of the visible spectrum, like red and purple, are not highly discernible to flies due to their lack of red photoreceptors. Flies struggle to differentiate these low-contrast colors against backgrounds.
Meanwhile, blue and green are more easily seen by flies but still less attractive than brighter yellows and whites. Gray provides very little contrast and definition. Black objects essentially create visual blind spots for flies due to blending completely into the background.
Researchers have tested these theories by creating targets with contrasting colors and observing which colors flies are least likely to land on. In multiple studies, flies consistently avoided darker reds, purples, grays, and blacks. Bright yellow targets attracted the highest number of flies.
This color preference has a basis in fly evolution. Flies use vision primarily for finding food, plant sap, and suitable breeding sites. Colors like yellow and white signal nectar-bearing flowers and nutritious foliage to flies. Meanwhile, dark colors provide little visual stimulation, informing flies the area lacks suitable nutrition and resources.
Tips for Using Color to Deter Flies
Here are some simple ways you can apply the principles of fly vision and color preference to create low-fly zones:
- Paint walls and surfaces red, purple, gray, or black
- Use red, purple, or black fabrics for curtains, tablecloths, and upholstery
- Avoid brightly colored clothing when spending time in fly-prone areas
- Select dark-colored plates, cups, and utensils over bright white dishes
- Incorporate blue and green fabrics and decor over bright yellows and whites
- Use blacklights which emit ultraviolet wavelengths less visible to flies
- Install dark window screens to reduce outdoor fly attraction
- Swap white light bulbs for yellow bug bulbs to reduce nighttime attraction
Simple color substitutions like these can transform spaces into unattractive, low-contrast environments that flies will learn to avoid. Consistency is key – maintaining dark color themes throughout the area ensures flies perceive it as an unchanging, uniform void.
Farmers have long applied these color principles to protect livestock. Red or black structures house cattle and horses, while white structures attract more flies. Dark coats on animals have an anti-fly effect as well. Staining wood surfaces dark brown also deters barn flies.
The same approach can successfully keep flies away from homes. Opt for darker exterior paint colors and decorate with red, purple, or gray. Minimize bright whites and yellows inside and out. Keep landscaping with dense foliage away from doors and windows to reduce fly access points.
Incorporating specific colors known to deter flies creates an optical barricade against them. Leveraging knowledge of fly vision can lead to simple yet effective methods for discouraging flies without the use of chemicals or traps.
Other Fly Control Strategies
While strategic use of color can make a big impact, incorporating multiple fly deterrent strategies is key for keeping populations under control long-term. Here are some other effective options:
- Regularly remove garbage, compost and manure where flies breed
- Install fly fans over entryways to disrupt incoming flies
- Use baited traps and fly paper to catch adult flies
- Release parasitoid wasps that destroy fly larvae
- Apply granular fly bait insecticide to outdoor breeding sites
- Use natural repellents like lemongrass, mint, and clove oils
- Plug entrance points and caulk cracks to prevent fly access
- Set up fly zappers to electrocute flies
- Release sterile male flies to suppress breeding
- Install window and door screens to keep flies outside
A comprehensive fly management plan should incorporate sanitation, trapping, chemical control, exclusion, and biological methods. Since flies reproduce rapidly, diligently eliminating breeding areas is critical. Suppressing the larval and adult life stages simultaneously is most effective.
By thoughtfully incorporating fly-deterring colors into your pest management efforts, you can create an additional optical barrier against these pests. Take advantage of flies’ color limitations and biases to throw them off visually and steer them away from areas you want to keep fly-free.
Conclusion
Flies see the world much differently than humans due to the unique structure and function of their eyes. By understanding flies’ limited color perception and color preferences, we can gain insight into which colors flies find most and least attractive. Strategically using dark reds, purples, grays, and blacks makes environments less visually stimulating to flies. Meanwhile, incorporating yellows, whites, and bright patterns inadvertently welcomes flies.
Simple adjustments like swapping white dishes for darker ones and avoiding yellow decor can create optical barriers against flies. Consistency is important, as flies rely heavily on contrasts and boundaries between colors. Maintaining camouflage throughout an area ensures flies perceive it as a continuous void. Combined with vigilant sanitation and population control methods, manipulating fly vision and perception with color can be a creative addition to your pest management plan.
