How do bedbugs bite the skin? - briefly
Bedbugs use a needle‑like proboscis to pierce the epidermis, inject saliva that contains anticoagulants, and then withdraw, leaving a painless puncture. The saliva elicits a localized inflammatory reaction, resulting in the typical red, itchy welts.
How do bedbugs bite the skin? - in detail
Bedbugs (Cimex lectularius) possess a specialized mouthpart called a proboscis, which functions as a needle‑like stylet. The stylet comprises two elongated canals: one for injecting saliva, the other for drawing blood.
- The insect locates a host by sensing heat, carbon‑dioxide, and skin odors.
- Upon contact, the proboscis penetrates the epidermis at an angle of approximately 45°, allowing the two canals to enter separate tissue layers.
- Saliva, containing anticoagulants (e.g., apyrase) and anesthetic compounds (e.g., nitrophorin), is released into the wound. These substances prevent clot formation and mask the bite, reducing immediate detection.
- Blood is drawn through the second canal by a combination of muscular contraction and capillary action, filling the bug’s enlarged abdomen over several minutes.
- After engorgement, the proboscis withdraws, leaving a shallow puncture roughly 0.5 mm in diameter.
The injected saliva provokes a localized immune response, manifesting as a red, pruritic papule that may develop a central punctum. Histamine release contributes to itching, while the anticoagulant effect can delay clotting, extending the feeding period. Lesions typically appear within 24 hours and may persist for several days, gradually fading without scarring.
Repeated feeding on the same host can lead to cumulative skin irritation, secondary bacterial infection, and sensitization, resulting in larger, more inflamed reactions. Effective control requires eliminating the insect source, as the bite mechanism itself does not cause systemic disease.