What does the head louse feed on while parasitizing a human? - briefly
Head lice obtain nutrition by piercing the scalp skin and sucking the host’s blood. Frequent blood meals are essential for their survival and reproduction.
What does the head louse feed on while parasitizing a human? - in detail
The human head louse subsists exclusively on the host’s blood. Using specialized mandibular stylets, the insect penetrates the epidermis of the scalp and accesses superficial capillaries. During each feeding episode it draws a minute volume of plasma, which contains hemoglobin, albumin, glucose, lipids, and electrolytes. The ingested blood supplies the amino acids, fatty acids, and carbohydrates required for growth, egg production, and metabolic maintenance.
Feeding occurs several times daily. An adult louse typically takes 4–5 meals per 24 hours, each lasting 5–10 minutes. The total daily intake ranges from 0.5 to 1 µL of blood. Salivary secretions contain anticoagulant proteins that prevent clotting and facilitate continuous flow. After ingestion, blood is stored in a distensible midgut where proteolytic enzymes break down hemoglobin and other proteins into absorbable peptides. Lipid droplets are assimilated for membrane synthesis, while glucose is utilized immediately for energy.
Nymphs, which undergo three molts before reaching maturity, follow the same feeding pattern but ingest smaller volumes proportional to their size. Egg development within the female’s oviduct depends on a steady supply of blood-derived nutrients; each egg receives a yolk rich in protein and lipids derived from the mother’s recent meals.
The louse cannot survive more than 24–48 hours without a blood source. Deprivation leads to rapid loss of vigor, cessation of egg laying, and eventual death. Consequently, the parasite’s entire life cycle—egg, nymph, adult—is tightly linked to continuous access to human scalp blood.