Head lice are tiny, wingless insects that live on human scalps, feeding on small amounts of blood. These common parasites do not spread disease and are not a sign of poor hygiene. Understanding what head lice look like at each stage of their life cycle is important for early and accurate identification and effective treatment.
Identifying Adult Lice
Full-grown head lice are small, measuring about 2 to 3 millimeters, comparable to a sesame seed. Their bodies are oval-shaped with six legs, each equipped with hook-like claws for gripping hair shafts. Adult lice appear tan to grayish-white, though their color can darken to reddish-brown after consuming blood.
These insects crawl quickly through hair, making them challenging to spot. They avoid light, staying close to the scalp, particularly behind the ears and near the nape of the neck, where warmth and blood supply are available. Though visible to the naked eye, their size and rapid movement make detection difficult without close inspection or a magnifying glass.
Spotting Nits (Lice Eggs)
Nits are lice eggs, often the most common indicator of an infestation. These tiny, oval eggs firmly attach to individual hair strands with a strong, waterproof, glue-like substance. They are yellowish-white or tan in color, though they can appear bright, transparent, or even similar to the host’s hair color.
Nits are found very close to the scalp (generally within 1/4 inch or 6 millimeters), as they require the warmth of the scalp to hatch. A key difference between nits and common hair debris like dandruff or dry skin flakes is their adherence: nits are firmly glued to the hair and cannot be easily brushed, flicked, or shaken off. Dandruff, in contrast, is loose and flakes away.
Once a nit hatches, within 6 to 9 days, the empty shell remains attached to the hair shaft. These empty casings appear white, translucent, or dull yellow and can be found further down the hair strand as the hair grows. Finding these empty casings indicates a past or present infestation, even without visible live lice.
Recognizing Nymphs
Nymphs are immature head lice that hatch from nits. They resemble adult lice but are significantly smaller. Upon hatching, nymphs are tiny, often described as pinhead-sized, and grow larger as they develop. Initially, they may be translucent or lighter in color than adult lice, gradually darkening as they mature and begin to feed on blood from the scalp.
Nymphs undergo several molts, shedding their skin as they grow, before reaching adulthood, a process that takes about 7 to 12 days. Because of their small size and tendency to move quickly and avoid light, nymphs are less commonly seen than nits or adult lice. Their elusive nature makes them challenging to detect during a visual inspection of the scalp and hair.