Insect behavior can be influenced by color. Trap manufacturers make extensive use of color research to design more efficient ways of attracting, capturing and killing insects. If color can attract insects, then it is possible that color could be used to repel insects, but there is little evidence to support this hypothesis. For most insects, if an object is not attractive, it is simply ignored. Specific color avoidance behavior is rarely reported.
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Blue, Blue, My Porch is Blue
Some home owners believe that painting their porch ceiling blue will discourage wasps from building nests in the entryway. While it is unlikely that blue paint actively repels wasps, the color may not be particularly attractive to them.
Research in China on Ichneumonidae wasps lends limited support to this theory, insofar as research on one species of wasps can also apply to totally different wasp species in another country. The study results showed that the most effective wasp traps were yellow or green. Blue lures were one of the least effective. However, researchers also found that the same species of wasps showed changes in color preference that were dependent on the location of the trap. Black lures were the least successful at trapping wasps in two locations but were the most successful lures at a third location.
Moths to a Light Bulb
Some homeowners purchase yellow light bulbs with the expectation that the bulb will drive away moths and mosquitoes. Unfortunately, yellow light bulbs do not actively repel insects, the bulbs simply attract fewer insects. Most insects are unable to see light with a wavelength longer than 650 nanometers; red light is invisible to a moth, and yellow light, at about 580 nanometers, is difficult for most insects to see. A red bulb would attract even fewer insects, but red light also appears dim to the human eye, making it an unpopular choice for outdoor lighting.
To Bee Or Not to Bee
According to the U.S. Department of Agriculture, honey bees will attack objects that resemble nest-raiding predators such as skunks and bears. Any object that is dark, furry or leathery, including a human wearing dark clothes, may be seen as a threat to bees protecting a nest. The bees may respond to the threat with aggression. Bees perceive the color red as black, so red is included on the list of colors to avoid when approaching a bee. Light-colored clothing won't repel a honey bee, but it may be less likely to attract its attention.
Shoo Fly, Don't Bother Me
Flies may be one of the few insect families that are actively repelled by a color, at least enough to avoid a fly trap. Research published in the Proceedings of the Royal Society reports that near-ultraviolet light and blue light attract tsetse flies, whereas UV-reflecting surfaces, or objects with green-yellow reflectivity, repel them. While exploring the effectiveness of house fly traps, a team of researchers at the University of Florida noticed a similar reaction to color in house flies. Blue attracted house flies, whereas yellow actively repelled them.
Unfortunately, the results of these tests may have no practical use beyond designing more effective fly traps. A yellow tablecloth on a picnic table might repel house flies but could attract more wasps.
- United States Department of Agriculture: Bee Safety
- 1000 Bulbs: Do Yellow Bug Light Bulbs Work?
- Proceedings of the Royal Society: On the role of blue shadows in the visual behaviour of tsetse flies
- University of Florida: Insect Attractants and Traps
- Revista Colombiana de Entomología: Effect of the trap color on the capture of ichneumonids wasps
- Journal of Medical Entomology: Behavioral and Physiological Response of Musca domestica to Colored Visual Targets
- Sherwin-Williams: The Whys Behind the Blue Porch Ceiling
- Live Science: Why Are Moths Drawn to Artificial Lights?
- University of Florida: Color is key in controlling flies