What do human lice feed on? - briefly
Human lice survive by sucking blood from the host’s skin, mainly from the scalp or body hair. They ingest tiny amounts several times daily to meet their nutritional needs.
What do human lice feed on? - in detail
Human lice are obligate ectoparasites that survive exclusively on the blood of their human hosts. All three species that infest people—head lice (Pediculus humanus capitis), body lice (Pediculus humanus humanus), and pubic lice (Pthirus pubis)—derive nourishment by piercing the skin and extracting capillary blood.
Feeding occurs through a specialized mouthpart called a stylet, which penetrates the epidermis to reach a superficial blood vessel. Saliva injected during each bite contains anticoagulants and anesthetic compounds that facilitate blood flow and reduce host detection. The ingested fluid consists primarily of plasma, erythrocytes, and dissolved proteins, providing the nutrients required for growth, reproduction, and metabolic maintenance.
Key aspects of the feeding behavior include:
- Frequency: Adult lice feed several times per day, typically every 2–4 hours, depending on temperature, host activity, and the insect’s reproductive stage.
- Volume: An individual consumes approximately 0.5–1 µL of blood per feeding event, amounting to 5–10 µL over a 24‑hour period.
- Digestive processing: Blood is stored in a midgut reservoir where proteolytic enzymes break down hemoglobin and other proteins; waste is excreted as dark fecal spots on the host’s hair or clothing.
- Developmental dependence: Nymphs require blood meals after each molt to progress through the five instar stages before reaching adulthood.
Body lice differ slightly in habitat but share the same dietary requirements, often feeding from contaminated clothing that contacts the skin. Pubic lice attach to coarse hair in the genital region and similarly obtain sustenance from the host’s blood, though their feeding intervals may be longer due to the lower density of hair follicles.
Overall, the exclusive reliance on human blood defines the ecological niche of these parasites and governs their life cycle, population dynamics, and the clinical manifestations associated with infestation.