How do lice feed? - briefly
Lice pierce the skin with specialized mouthparts and ingest blood, while their saliva contains anticoagulants that keep the flow continuous. This rapid feeding process sustains the insect for several days before it must locate another host.
How do lice feed? - in detail
Lice obtain nourishment by piercing the host’s epidermis with specialized mouthparts and drawing blood directly from capillaries. The process begins when the insect positions its head against the skin and inserts the lacinial groove—a composite of the maxillae and mandibles—into the superficial dermal layer. Saliva containing anticoagulant proteins is released simultaneously, preventing clot formation and keeping the blood flow uninterrupted.
Once the vessel is accessed, the insect contracts its cibarial pump, creating negative pressure that draws the fluid into the foregut. The ingested blood passes through a narrow esophagus into the midgut, where digestive enzymes break down hemoglobin and plasma proteins. Nutrients are absorbed across the gut epithelium, while excess water is excreted through Malpighian tubules and eliminated as a minute fecal pellet.
Feeding cycles vary among species:
- Head lice (Pediculus humanus capitis): feed every 3–5 hours, each session lasting 5–10 minutes; blood intake averages 0.5 µL per meal.
- Body lice (Pediculus humanus humanus): feed less frequently, roughly every 4–6 hours, with larger blood volumes due to a more robust abdomen.
- Pubic lice (Pthirus pubis): feed every 2–3 hours, each bout lasting 2–5 minutes; the bite is deeper, reflecting the larger size of the insect’s mandibles.
After a meal, the louse returns to a concealed site—hair shaft, clothing fibers, or pubic hair—to digest the blood and reproduce. The entire feeding sequence, from attachment to detachment, is completed within minutes, allowing the parasite to remain undetected while sustaining its metabolic needs.