How are lice fed? - briefly
Lice obtain nutrition by piercing the host’s skin with their specialized mouthparts and sucking blood. They feed repeatedly throughout the day, each meal lasting a few minutes.
How are lice fed? - in detail
Lice obtain nourishment exclusively from the blood of their hosts. Their mouthparts are specialized for piercing the epidermis and accessing capillary blood. The process begins when a louse positions its head against the skin, aligns its maxillae and mandibles, and inserts a thin, serrated stylet into the dermal tissue. Saliva containing anticoagulant compounds is injected simultaneously, preventing clot formation and allowing a steady flow of blood.
Feeding proceeds in several distinct phases:
- Penetration: The stylet breaches the stratum corneum and reaches a capillary.
- Anticoagulation: Salivary enzymes inhibit platelet aggregation and fibrin formation.
- Ingestion: Muscular contractions of the pharynx draw blood into the foregut; ingestion rates average 0.5–1 µL per session for head lice.
- Termination: After 5–10 minutes, the louse withdraws the stylet and retreats to a sheltered site for digestion.
Lice feed repeatedly throughout their life cycle. Adult head lice typically consume a blood meal every 3–5 hours, whereas nymphs feed at slightly longer intervals due to their smaller size. Body lice, which inhabit clothing, may feed less frequently, often every 4–6 hours, while pubic lice (Pthirus pubis) feed approximately every 2–3 hours. Each feeding episode supplies sufficient nutrients for growth, egg production, and metabolic maintenance.
Digestion occurs internally; blood is broken down in the midgut where proteolytic enzymes extract hemoglobin, lipids, and carbohydrates. Excess fluid is excreted as dark fecal spots, a hallmark of infestation. The rapid turnover of blood meals supports the high reproductive rate of lice, with a female laying 3–5 eggs per day after each feeding cycle.
Environmental factors such as temperature and host activity influence feeding efficiency. Elevated temperatures increase blood flow to the skin, facilitating easier access, while vigorous host movement can disrupt the louse’s attachment and shorten feeding duration.
In summary, lice feed by piercing the host’s skin, delivering anticoagulant saliva, ingesting a small volume of blood over a brief period, and repeating this cycle multiple times daily to sustain their life processes.