How do bed bugs sense humans? - briefly
Bed bugs locate hosts by detecting body heat, carbon‑dioxide exhaled by humans, and skin‑derived odorants through sensory receptors on their antennae and legs. These combined cues direct the insects to a feeding site within seconds of exposure.
How do bed bugs sense humans? - in detail
Bed bugs locate a host through a combination of sensory cues that operate at different distances.
At long range, they rely primarily on carbon‑dioxide (CO₂) released by exhaled breath. Specialized receptors on the antennae detect rising CO₂ concentrations, triggering forward movement toward the source. Heat emitted by the human body forms the second long‑range cue; thermoreceptors on the antennae and the tarsi respond to temperature gradients as low as 0.1 °C, guiding the insect toward warmer areas.
When within a few centimeters, the insects shift to short‑range signals. Tactile receptors on the legs and the labial palps sense subtle air currents generated by a moving host. Chemosensory sensilla detect skin‑derived volatile organic compounds (VOCs) such as lactic acid, ammonia, and fatty acids. These chemicals bind to odorant‑binding proteins that activate olfactory neurons, refining the bug’s approach to specific body regions.
The final stage of host detection involves direct contact. Mechanoreceptors on the tarsal claws and the rostrum sense the texture and firmness of skin or fabric, confirming a suitable feeding site. Once contact is established, the bug inserts its proboscis and begins blood ingestion.
Key sensory modalities:
- CO₂ detection: antennae‑based chemoreceptors, threshold ≈ 0.04 % increase above ambient.
- Thermal sensing: cuticular thermoreceptors, responsive to 30–37 °C range.
- Volatile organic compounds: olfactory sensilla on antennae and maxillary palps, sensitive to lactic acid, ammonia, fatty acids.
- Air‑flow perception: mechanosensory hairs detect minute airflow changes.
- Tactile feedback: cuticular mechanoreceptors on legs and rostrum assess surface properties.
Integration of these signals occurs in the central nervous system, where neural pathways converge to produce a directed locomotor response. The combined effect enables bed bugs to locate, approach, and attach to a human host with high efficiency.