Why do bedbugs fly toward light? - briefly
Bedbugs exhibit positive phototaxis, moving toward illuminated areas because light often indicates warm, humid environments where hosts are likely to be found. This behavior helps them locate suitable feeding sites and shelter.
Why do bedbugs fly toward light? - in detail
Bedbugs (Cimex lectularius) often move toward artificial illumination, a behavior known as positive phototaxis. This response is most evident when insects are disturbed, when they are searching for a host, or when they are transitioning between hiding places.
The attraction is mediated by the insects’ compound eyes, which contain ommatidia tuned to short‑wavelength light. Photoreceptor cells generate neural signals that direct locomotion toward brighter areas. In addition, the dorsal ocelli—simple light‑sensing organs—provide a coarse assessment of ambient brightness, reinforcing the movement toward sources of illumination.
Ecologically, light cues can indicate the presence of a warm, blood‑feeding opportunity. Human activity typically creates lighted environments, and bedbugs exploit these cues to locate potential hosts. Moreover, exposure to light often coincides with temperature gradients; warmer surfaces near lamps may signal a suitable feeding site. When darkness prevails, the insects tend to remain concealed in cracks and crevices, reducing the risk of desiccation and predation.
Laboratory studies have quantified the response. In controlled arenas, bedbugs exposed to a 500‑lux LED source moved an average of 4 cm toward the light within 30 seconds, whereas individuals in completely dark conditions showed random movement. Spectral analysis revealed strongest attraction to wavelengths between 400 nm and 500 nm, corresponding to blue‑green light, while red wavelengths elicited minimal response.
Understanding this behavior informs pest‑management strategies. Light traps equipped with UV‑emitting bulbs can attract and capture insects, but their effectiveness diminishes if traps are placed near host habitats where bedbugs prefer darkness. Combining illumination with adhesive surfaces or chemical lures increases capture rates. Conversely, minimizing unnecessary lighting in sleeping areas reduces the cues that draw bedbugs out of hiding, limiting their exposure to humans.