How do bed lice bite? - briefly
Bed lice use their mandibles to pierce the skin’s surface and feed on a minute quantity of blood, which typically results in a localized itching sensation.
How do bed lice bite? - in detail
Bed lice, scientifically known as Cimex lectularius, feed by piercing the host’s skin with a specialized mouthpart called a proboscis. The proboscis consists of two elongated, needle‑like stylets that slide between the epidermal layers, creating a narrow channel. Saliva containing anticoagulants and anesthetic compounds is injected through this channel, preventing blood clotting and reducing the host’s perception of the bite. Blood is then drawn up the stylets by capillary action.
The feeding cycle proceeds as follows:
- Attachment: The insect positions itself on exposed skin, typically during the night when the host is at rest.
- Insertion: Stylets penetrate the epidermis to reach the dermal capillaries.
- Salivation: Anticoagulant proteins (e.g., apyrase) and anesthetic peptides are released, maintaining blood flow and minimizing pain.
- Ingestion: Blood is drawn into the insect’s foregut, where it is stored temporarily before digestion.
- Detachment: After ingesting an average of 0.5 µL of blood, the louse withdraws its mouthparts and resumes a dormant state until the next feeding opportunity.
The bite itself appears as a small, red, often itchy papule. Repeated feeding can lead to a cluster of lesions, sometimes arranged linearly where the insect repeatedly probes adjacent sites. The reaction intensity varies with individual sensitivity to the salivary proteins. Understanding this mechanism clarifies why bites occur primarily at night, why they are painless during feeding, and why post‑bite inflammation emerges only after the anesthetic effect dissipates.