Appearance
1. An adult louse is 2-3 mm long (size of a sesame seed). 2. Lice are pale gray to brown in color (may vary).
3. Females live up to 3 – 4 weeks and lay approximately 10 eggs (nits) per day.
4. Nits are tiny, whitish and firmly attached to the hair shaft close to the scalp with a glue-like substance produced by the louse.
5. In general, nits found more than 1 cm from the scalp are unlikely to be viable.
6. Viable nits may be camouflaged with pigment to match the hair color of the infested person; they appear to have an “eye spot” .
7. Empty nit casings are easier to see as they appear opaque white against darker hair.
Viability
1. Nits take 10 to 14 days to hatch and grow for approximately 9 to 12 days.
2. The mature louse mates and the females lay eggs and if NOT treated may repeat every three weeks
3. Viability is on the human head only with feeding by injecting small amounts of saliva and taking tiny amounts of blood from the scalp every few hours.
4. Lice survive for up to 24 hours off the human scalp at normal temperature and eggs cannot hatch at an ambient temperature lower than that near the scalp.