Researchers from the University of Florida and Union College in Lincoln, Neb., wondered whether bed bugs preferred certain colors for their hiding places, so they did some testing in the lab. The tests consisted of using small tent-like harborages that were made from colored cardstock and placed in Petri dishes. A bed bug was then placed in the middle of the Petri dish and given ten minutes to choose one of the colored harborages. A few variations of the test were also conducted, such as testing bed bugs in different life stages, of different sexes, individual bugs versus groups of bugs, and fed bugs versus hungry bugs.
The results, which are published in the Journal of Medical Entomology, showed that the bed bugs strongly preferred red and black, and they seemed to avoid colors like green and yellow.
“It was speculated that a bed bug would go to any harborage in an attempt to hide,” wrote the authors. “However, these color experiments show that bed bugs do not hide in just any harborage; rather, they will select a harborage based on its color when moving in the light.”
“We originally thought the bed bugs might prefer red because blood is red and that’s what they feed on,” said Dr. Corraine McNeill, one of the co-authors. “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, as they are known to exist in aggregations.”
While this is a plausible explanation, 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 when they were in groups than when they were alone. They also chose different colors depending on whether they were hungry or fed. Furthermore, males and females seemed to prefer different colors.
The authors suggest that a possible explanation for why bed bugs avoided yellow and green colors is because those colors resemble brightly-lit areas. These findings are important because they may have implications for controlling the pests.