Head lice are tiny parasitic insects that live on the human scalp, feeding on small amounts of blood. While the adult lice are small, their eggs, known as nits, are often the first sign of an infestation. Accurately identifying nits is important for effective treatment and preventing further spread.
What to Look For
Head lice nits are minuscule, oval-shaped eggs, typically resembling a tiny knot in a thread or about half the size of a pinhead, measuring approximately 0.8 to 1.2 millimeters in length. Their color can vary, appearing translucent, whitish, yellowish, tan, or even dark brown, depending on their development stage and the hair color they are attached to.
Nits are found cemented firmly to individual hair shafts, usually very close to the scalp, within a quarter-inch (about 6 millimeters) from the base. Common areas to check include behind the ears and at the nape of the neck, where nits are frequently concentrated.
The attachment of nits is a key identifying feature; they are “glued” to the hair with a strong, waterproof substance secreted by the female louse. This strong bond makes them difficult to remove by simply brushing, shaking, or washing the hair. When viewed under good lighting, live nits can have a shiny or pearly appearance.
Common Look-Alikes
Many common scalp conditions and hair debris can be mistaken for head lice nits, leading to misdiagnosis. Dandruff, for instance, consists of loose, irregular skin flakes that can be easily brushed off the hair or scalp. Unlike nits, dandruff does not adhere firmly to the hair shaft.
Hair casts are another common look-alike, appearing as thin, cylindrical pieces of keratin or product residue that encircle the hair shaft. These are distinct from nits because they can slide easily along the hair shaft, while nits remain stuck. Similarly, hair spray droplets or other product residues can resemble nits but can often be flaked or washed off the hair.
Dirt or lint particles may also be found in the hair, but they are irregular in shape and do not uniformly attach to the hair shaft like nits. The distinguishing factor for all these look-alikes is their ease of removal. If a particle can be easily flicked, brushed, or washed away, it is unlikely to be a head lice nit.