Why do bedbugs crawl at night? - briefly
Bedbugs are nocturnal feeders that emerge after dark when hosts are asleep, minimizing disturbance and detection. Their activity is prompted by low light, body heat, and carbon‑dioxide levels that rise during the night.
Why do bedbugs crawl at night? - in detail
Bedbugs exhibit peak movement during darkness because their sensory systems are tuned to low‑light conditions. Their eyes contain simple ocelli that detect changes in illumination rather than detailed images, prompting activity when light levels drop. This adaptation reduces exposure to visual predators such as birds and reptiles that hunt by sight.
Thermoregulation also drives nocturnal locomotion. Human body temperature rises slightly during sleep, creating a stable heat source that bedbugs can locate through thermoreceptors. The cooler ambient temperature at night makes the temperature gradient more pronounced, facilitating host detection.
Carbon‑dioxide emission rises when a person is asleep, and bedbugs possess chemoreceptors sensitive to this gas. Nighttime ventilation often lowers indoor CO₂ concentrations, causing a relative increase near the sleeping surface and guiding insects toward the host.
Feeding cycles reinforce night‑time activity. After a blood meal, bedbugs retreat to harborages to digest and develop. The digestion period lasts several days, during which they remain hidden. Once the gut is emptied, they emerge to seek another host, typically aligning with the host’s rest period to maximize feeding success.
Circadian rhythms inherent to the species synchronize internal clocks with host behavior. Genetic studies reveal expression of clock genes that peak during the dark phase, regulating locomotor activity and feeding drive.
In summary, the combination of visual sensitivity, thermal gradients, carbon‑dioxide cues, digestive timing, and endogenous circadian mechanisms compels these insects to move primarily after dusk. This strategy enhances host contact while minimizing predation risk.