Bed bugs favor the colors red and black, but tend to avoid green and yellow, finds new research on the parasites.
The study is the first to show that bed bugs have color preferences. The findings could improve ways of controlling the pest, whose bites can cause itching, inflammation and allergic reactions.
For the experiments, outlined in the Journal of Medical Entomology, scientists created tent-like "harborages" for the bugs, to see which ones they gravitated to or avoided. Outside of the lab setting, bedding and luggage often function as bed bug retreats.
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"It was speculated that a bed bug would go to any harborage in an attempt to hide," the authors wrote. "However, these color experiments show that bed bugs ... will select a harborage based on its color when moving in the light."
Co-author Corraine McNeill of Union College said in a release: "We originally thought the bed bugs might prefer red because blood is red and that's what they feed on. However, after doing the study, the main reason we think they preferred red colors is because bed bugs themselves appear red, so they go to these harborages because they want to be with other bed bugs."
McNeill and her colleagues determined that many factors influenced which color the bed bugs chose. For example, the bugs' color preferences changed as they grew older, and they chose different colors in groups than when alone. Whether the bugs were satiated or hungry also affected their choices. Males and females additionally seemed to prefer different colors.
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Despite the variation, favoring red and black and avoiding yellow and green hues remained mostly consistent.
According to the "Bugs Without Borders" survey conducted last year by the University of Kentucky and the National Pest Management Association, the top three places where pest professionals report finding bed bugs are apartments/condos (95 percent), single-family homes (93 percent), and hotels/motels (75 percent). Bed bugs have also been found in nursing homes, college dorms, offices, schools and daycare centers, hospitals and public transportation.
While a CDC fact sheet maintains, "Bed bugs should not be considered as a medical or public health hazard," clearly the parasite's prevalence is a concern and bites could pose more of a threat to children, the elderly and those already weakened by illness. So creating more effective traps for the bugs is one of the researchers' goals.
"We are thinking about how you can enhance bed bug traps by using ... a specific color that is attractive to the bug," McNeill said. "However, the point isn't to use the color traps in isolation, but to use color preference as something in your toolkit to be paired with other things such as pheromones or carbon dioxide to potentially increase the number of bed bugs in a trap."
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She and her team advise not to throw out your red and black bedding and luggage just yet.
McNeill said, "I always joke with people, ‘Make sure you get yellow sheets!' But to be very honest, I think that would be stretching the results a little too much."
"I think using colors to monitor and prevent bed bugs would have to be specifically applied to some sort of trap, and it would have to be used along with another strategy for control," she said. "I don't know how far I would go to say don't get a red suitcase or red sheets, but the research hasn't been done yet, so we can't really rule that out completely."