Why don’t bedbugs bite us? - briefly
Bedbugs feed only on warm‑blooded hosts, locating them by body heat and carbon‑dioxide; they bite solely when a host is within reach. In the absence of a suitable host, they remain unfed and do not bite.
Why don’t bedbugs bite us? - in detail
Bedbugs (Cimex lectularius) are obligate hematophages; they require blood to mature and reproduce. Their feeding cycle is triggered by specific sensory cues, primarily body heat, carbon‑dioxide plumes, and skin‑derived chemicals. When these signals are absent or below detection thresholds, the insects remain dormant in harborages and do not bite.
Key factors influencing the lack of feeding include:
- Host availability – In environments where humans are absent for extended periods, bedbugs enter a quiescent state lasting weeks to months. During this phase, they conserve energy and refrain from attempting a blood meal.
- Thermal and chemical thresholds – Bedbugs respond to temperature ranges of 30–34 °C and CO₂ concentrations typical of a sleeping human. Cooler surfaces or reduced exhaled CO₂ diminish attraction, preventing a bite.
- Skin microbiota and odor profile – Certain volatile compounds emitted by the skin, such as isovaleric acid, attract the insects, while others, like specific fatty acids, act as repellents. Individuals whose skin chemistry lacks attractive volatiles experience fewer encounters.
- Immune and inflammatory responses – A rapid histamine reaction can cause immediate discomfort, prompting the host to move. Movement disrupts the insect’s feeding process, leading it to abort the attempt.
- Physical barriers – Thick clothing, bedding treated with insecticidal fabrics, or impermeable mattress encasements create a mechanical obstacle that prevents the bug’s proboscis from reaching the skin.
Bedbugs do not discriminate against humans as a species; they bite when the combined sensory inputs meet the required thresholds. Absence of these stimuli, unfavorable chemical cues, or effective physical barriers explains why a person may not be bitten despite the presence of the pest.