Bed bugs respond to a variety of odor cues but also respond to color. They orient to black or red objects in preference to white or other colored objects. (The bed bug visual system does not distinguish black and red.) Bed bugs prefer vertical objects to horizontal ones. This information is potentially useful to those trying to design a better bed bug trap.
*Singh N, Wang C, Cooper R. 2015. Role of Vision and Mechanoreception in Bed Bug, Cimex lectularius L. Behavior. PLoS ONE 10(3): e0118855.