Head lice are tiny parasitic insects that live on the human scalp, and identifying their eggs, known as nits, can be a source of concern for caregivers. An infestation can lead to discomfort, and determining if it has been fully resolved often depends on distinguishing between viable and non-viable nits. The presence of nits can be confusing, as they may remain in the hair even after treatment, leading to uncertainty about whether an infestation is gone. This article clarifies how to identify whether lice eggs are alive, dead, or merely empty casings.
Understanding Live Lice Eggs
Live lice eggs, or nits, are small, about the size of a sesame seed and oval or tear-drop shaped. They are white, yellow, beige, or pale brown, their color darkening as they near hatching. A female louse lays these eggs close to the scalp, within 1/4 inch, because they require the warmth of the head to incubate and hatch. Each live nit is firmly cemented to a hair shaft with a strong, glue-like substance, making them difficult to slide off. This firm attachment distinguishes them from common hair debris like dandruff.
Live nits can appear somewhat translucent and may reflect light, sometimes giving them a pearl-like sheen. They are typically plump and shiny when they contain a developing embryo. As they near hatching, their color may become dark brown or black.
Identifying Dead or Empty Lice Eggs
Dead nits that did not hatch typically appear darker than live eggs, often brown or black. Unlike empty casings, dead nits still contain a nonviable louse embryo inside. They can remain stuck to the hair shaft for an extended period. They may appear duller or shriveled compared to viable eggs.
Empty nit casings are the shells left behind after a louse has hatched. These casings are translucent, white, or light-colored. As hair grows, these empty shells are carried further down the hair shaft, found more than 1/4 inch from the scalp. Both dead and empty nits are easier to slide off the hair or may be found detached.
Key Differences: Live vs. Dead vs. Empty Nits
Distinguishing between live, dead, and empty nits requires careful observation of their appearance, location on the hair shaft, and ease of removal. Live nits are found close to the scalp, within 1/4 inch, and are light-colored (white, yellow, tan, or light brown), becoming darker as they mature. They are firmly glued to the hair and are difficult to dislodge. In contrast, dead nits are darker, brown or black, and can be found anywhere along the hair shaft as the hair grows.
Empty nit casings are translucent or white and are also found further from the scalp. Both dead and empty nits are easier to slide off the hair. To accurately identify them, use good lighting, a magnifying glass, and a fine-toothed nit comb. Common mistakes include confusing nits with dandruff, which flakes off easily, or hairspray droplets, which are not firmly attached.
Post-Identification Steps
If live nits are present, re-treatment of the infestation is usually necessary to prevent further hatching and spread. Many over-the-counter treatments target live lice, and some also kill eggs, though re-treatment after a week may be recommended to address newly hatched nymphs. Regular combing with a fine-toothed nit comb every few days is important to remove any remaining nits or newly hatched lice.
If only dead or empty nits are found, further chemical treatment may not be required, as these do not pose a risk of re-infestation. These non-viable nits remain attached until physically removed or the hair grows out. Manual removal with a nit comb is effective for clearing both dead and empty casings from the hair. Ongoing monitoring of the scalp is wise to detect any new infestations early.