What do lice on the head eat? - briefly
Head lice consume human blood drawn from the scalp. They use their specialized mouthparts to pierce the skin and ingest the fluid.
What do lice on the head eat? - in detail
Head lice survive by ingesting human blood. Their mouthparts are adapted into a piercing‑sucking stylet that penetrates the scalp epidermis and draws a small volume of capillary blood. An adult consumes roughly 0.5–1 µL per feeding event, which supplies the protein, iron, and lipids required for development and reproduction.
Feeding behavior:
- Frequency: every 3–5 hours while the host is awake; nightly intervals may be longer.
- Duration: each blood draw lasts 5–10 minutes, after which the louse retreats to its hair‑shaft shelter.
- Quantity: a single adult obtains about 1–2 mL of blood per week, enough to lay 3–5 eggs daily.
Nutritional composition of the ingested blood includes hemoglobin, plasma proteins, and glucose, providing the energy and building blocks for molting and egg production. Nymphs (juvenile stages) feed on the same source, but their intake is proportionally smaller, matching their growth requirements.
The louse’s digestive system stores the blood in a specialized midgut, where proteolytic enzymes break down hemoglobin and release amino acids. Excess iron is sequestered to prevent oxidative damage. Metabolic by‑products are excreted as waste, which may appear as tiny dark specks on hair shafts.
Host factors influencing feeding:
- Scalp temperature and blood flow affect the ease of blood access.
- Hair density determines the ability of lice to locate suitable feeding sites.
- Individual variations in skin chemistry can alter the attractiveness of the scalp to the parasite.
In summary, head lice rely exclusively on human blood, consuming minute, frequent meals that satisfy their physiological needs for growth, reproduction, and survival.