What do human lice eat? - briefly
Human lice subsist exclusively on the blood of their human host, piercing the skin to ingest plasma and red blood cells. Their diet is limited to this fluid, with no other food sources required.
What do human lice eat? - in detail
Human lice are obligate ectoparasites that survive exclusively on the blood of their human hosts. Their mouthparts are adapted for piercing the epidermis and extracting plasma, providing all necessary nutrients for growth, reproduction, and metabolism.
The primary components of their diet include:
- Plasma, which supplies carbohydrates, amino acids, and electrolytes;
- Red blood cells, a source of iron and heme, essential for enzyme function;
- White blood cells, occasionally ingested during feeding, contributing minor protein content.
Feeding behavior varies among the three species that infest humans:
- Head lice (Pediculus humanus capitis) attach to hair shafts near the scalp, feeding several times a day for short intervals of 5–10 minutes each.
- Body lice (Pediculus humanus humanus) reside in clothing seams, accessing the host’s skin to feed for longer periods, up to 30 minutes per session.
- Pubic lice (Pthirus pubis) occupy coarse body hair, performing brief, frequent meals similar to head lice.
Nutrient acquisition is efficient: each blood meal delivers approximately 0.5–1 µl of plasma, sufficient to sustain an adult for 24–48 hours. Eggs (nits) receive no direct nourishment; embryonic development relies on yolk reserves deposited by the female during oviposition.
Metabolic adaptations enable survival between meals. Lice possess a reduced digestive system, lacking a true gut, and rely on intracellular digestion within midgut epithelial cells. Enzymatic pathways metabolize glucose and amino acids rapidly, supporting high reproductive rates—females lay up to 8 eggs per day.
In summary, human lice subsist solely on host blood, extracting plasma and cellular components to meet all physiological demands, with feeding patterns and durations tailored to the ecological niche of each species.