Why do fleas bite at night? - briefly
Fleas are nocturnal parasites that become more active in darkness, seeking the heat and carbon‑dioxide emitted by sleeping hosts. Their heightened nighttime activity raises the chance of bite incidents.
Why do fleas bite at night? - in detail
Fleas are primarily active during the dark period because their sensory systems are tuned to low‑light conditions. Their compound eyes and light‑sensitive receptors react strongly to dim environments, prompting movement and host‑seeking behavior when illumination drops.
A circadian rhythm governs flea activity. Internal clocks synchronize with the external light‑dark cycle, causing peak locomotion and feeding attempts in the hours after sunset. This rhythm persists even when artificial lighting alters natural patterns, indicating a genetically encoded schedule.
Human and animal hosts provide more accessible feeding opportunities at night. While sleeping, hosts remain relatively motionless, reducing mechanical disturbances that could alert the insect. The lack of movement also makes heat and carbon‑dioxide plumes more stable, allowing fleas to home in on the source with greater accuracy.
Environmental factors further favor nocturnal biting:
- Temperatures typically fall into the 20‑25 °C range, optimal for flea metabolism.
- Relative humidity rises, preventing desiccation of the tiny arthropod.
- Air currents diminish, preserving the gradient of host‑derived cues.
Fleas locate a target by detecting a combination of heat, carbon‑dioxide, and vibrational signals. At night, these cues are less masked by ambient activity, enhancing detection efficiency. Once positioned, the flea inserts its stylet, injects anticoagulant saliva, and draws blood, producing the characteristic bite.
Understanding these mechanisms informs control strategies. Treatments applied before the onset of darkness intercept the insects at the moment they begin feeding. Reducing indoor humidity, maintaining cooler nighttime temperatures, and employing regular vacuuming disrupt the conditions that support nocturnal activity.
In summary, the preference for feeding after dark results from an interplay of circadian regulation, host immobility, favorable microclimate, and heightened sensory cue detection.