How do lice bite? - briefly
Lice attach to the scalp, insert their needle‑like mandibles into the epidermis, and withdraw small quantities of blood. The feeding episode typically lasts a few minutes before the insect disengages.
How do lice bite? - in detail
Lice attach to the host’s hair or clothing and insert a pair of needle‑like mouthparts called stylets through the epidermis. The stylets are housed within a flexible sheath that protects them during penetration. Once the stylets reach the dermal layer, the insect injects saliva containing anticoagulant proteins that prevent blood clotting and enzymes that reduce inflammation. Blood then flows into the feeding canal, where it is drawn upward by muscular contractions of the cibarial pump.
The feeding cycle proceeds as follows:
- Stylet insertion through the cuticle.
- Saliva release with anticoagulant and anesthetic compounds.
- Blood uptake via the cibarial pump.
- Withdrawal of stylets after approximately 5–10 minutes of activity.
Head lice (Pediculus humanus capitis) and body lice (Pediculus humanus corporis) share this mechanism, differing mainly in habitat and duration of attachment. Head lice remain on the scalp, feeding repeatedly throughout the day, while body lice inhabit clothing and feed less frequently, typically during periods of rest.
Host response includes localized erythema, itching, and possible secondary infection if the skin is broken. Repeated bites may lead to hypersensitivity, producing larger wheals and intensified pruritus. The presence of lice can be confirmed by visual inspection of nits attached near the hair shaft or by finding live insects on garments.