Head lice are tiny parasitic insects that live on the human scalp. Their appearance can vary significantly depending on their life stage and whether they have recently fed.
Adult Lice Appearance
Adult head lice are generally small, about the size of a sesame seed, and possess six legs. Their typical coloration ranges from a grayish-white or tan to a darker reddish-brown. These insects are translucent, and their color can change based on their recent feeding activity. After feeding on human blood, the abdomen of an adult louse often appears reddish due to the ingested blood.
These adult lice are wingless and move by crawling. They can be difficult to spot on the scalp because of their small size and ability to move quickly. Their flat, oval-shaped bodies help them navigate and remain close to the scalp, where they feed.
Nymphs and Nits
The life cycle of head lice includes eggs, known as nits, and immature lice, called nymphs. Nits are tiny, oval-shaped structures. Live, unhatched nits are usually yellow, tan, or dark brown and are firmly attached to the hair shaft, very close to the scalp.
After a nit hatches, a nymph emerges, which is a smaller version of an adult louse. Nymphs are generally lighter in color, often grayish-white or pearly white, and grow through several stages before maturing into adults. The empty nit shells left behind after hatching appear white or clear and remain glued to the hair shaft. These empty shells can sometimes be mistaken for dandruff, but unlike dandruff, nits are difficult to remove by simply brushing them out.
Factors Affecting Lice Coloration
The color of head lice is primarily influenced by their feeding habits. Head lice feed on human blood from the scalp, and the presence of ingested blood within their digestive system directly impacts their appearance. Immediately after a blood meal, lice tend to appear redder or darker.
While less significant, head lice can also exhibit some degree of color adaptation to blend with the host’s hair color. This slight camouflage helps them remain undetected. However, the most noticeable and rapid changes in their coloration are a direct result of their recent feeding activity, making a well-fed louse appear considerably darker than one that has not recently fed.
Identifying Lice and Nits
Identifying head lice and nits. Begin by using a fine-toothed comb and ensure good lighting. Section the hair, starting from one side of the head, and place the comb at the top of the head with the teeth touching the scalp. Slowly pull the comb through each section of hair, maintaining contact with the scalp as much as possible.
After each stroke, wipe the comb and examine it closely for any live lice or nits. Pay particular attention to areas behind the ears and at the nape of the neck, as these are common sites for lice and nit accumulation. Live lice are typically tan or gray and can move quickly, while nits appear as tiny, oval-shaped specks firmly attached to hair shafts. Distinguish nits from common look-alikes like dandruff or hairspray droplets; nits will be securely glued to the hair and will not easily flake off, unlike dandruff. A magnifying glass can assist in differentiating nits from flat, scaly dandruff flakes.