How and where do lice live? - briefly
Lice are obligate ectoparasites that reside permanently on the bodies of warm‑blooded hosts, clinging to hair or feathers and feeding on blood. They complete their entire life cycle—egg, nymph, adult—within this confined microhabitat, never leaving the host except for brief transfers during direct contact.
How and where do lice live? - in detail
Lice are obligate ectoparasites that complete their entire life cycle on a host’s body or immediate surroundings. Adult females lay 6–10 eggs (nits) every 24–48 hours; the eggs adhere firmly to hair shafts, feathers, or fibers using a cement secreted by the female. Incubation lasts 7–10 days, after which nymphs emerge and undergo three molts over 9–12 days before reaching reproductive maturity.
The three principal groups differ in host preference and microhabitat:
- Head lice (Pediculus humanus capitis) – occupy the scalp, attaching to hair shafts near the skin. They thrive in warm, humid conditions (30–35 °C, >70 % relative humidity) and avoid frequent washing or harsh chemical treatments.
- Body lice (Pediculus humanus corporis) – live in the seams of clothing, especially undergarments, and move to the skin only to feed. They require infrequent laundering and crowded, unhygienic conditions to persist.
- Pubic lice (Pthirus pubis) – inhabit coarse body hair, such as the pubic region, chest, or facial hair. They prefer temperatures around 32 °C and are transmitted primarily through close physical contact.
In addition to human‑associated species, numerous lice infest birds, mammals, and reptiles. Avian lice (e.g., Menacanthus spp.) reside among feathers, feeding on skin debris and blood; they are transmitted through direct contact or shared nesting material. Mammalian lice (e.g., Linognathus spp.) colonize fur, often confined to specific host species.
Environmental resilience varies among groups. Eggs can survive up to 10 days away from a host if temperature and humidity remain within optimal ranges. Adult lice cannot endure temperatures below 15 °C for more than a few hours and die within minutes at temperatures exceeding 45 °C.
Transmission pathways include:
- Direct head‑to‑head contact for scalp lice.
- Sharing of clothing, bedding, or towels for body lice.
- Sexual or intimate contact for pubic lice.
- Contact with infested nests, perches, or grooming tools for animal lice.
Control measures target both the parasite and its habitat: regular combing and removal of nits, laundering clothing and bedding at ≥60 °C, and maintaining low humidity in living spaces. Effective management requires simultaneous treatment of the host and elimination of the microenvironment that supports egg attachment and nymph development.