Head lice are tiny, flat, wingless insects that measure 2 to 3 mm long, roughly the size of a sesame seed. They blend with your hair color, ranging from dirty white to greyish-black, which makes them surprisingly hard to spot with a casual glance. Recognizing lice means knowing what to look for at every life stage, where on the head to check, and how to tell lice and their eggs apart from dandruff or product buildup.
What Lice Look Like at Each Stage
Lice go through three visible stages, and each one looks different. Eggs, called nits, are the smallest and most common sign. They’re oval, about the size of a pinhead, and cemented to individual hair shafts close to the scalp, typically within a quarter inch of the skin surface. Live nits tend to be yellowish-brown or tan. Empty shells left after hatching look white or clear and are often found farther from the scalp as the hair grows out.
Newly hatched lice, called nymphs, are nearly transparent and extremely small. Over roughly nine days they pass through three growth stages, gradually turning straw-colored before reaching adulthood. Nymphs look like miniature versions of adults but are easy to miss because of their size and near-invisibility against the scalp.
Adult lice are the easiest to identify but also the rarest to catch sight of. They move quickly and avoid light. Their flat, six-legged bodies range from 2 to 3 mm and shift in color to match their host’s hair. On a person with blond hair, lice tend to be paler; on darker hair, they appear greyish-brown or nearly black. They have no wings and cannot fly or jump.
Where Lice Hide on the Head
Lice don’t distribute evenly across the scalp. They strongly prefer warm, sheltered areas. The spots to check first are behind the ears and along the nape of the neck. These zones stay warm and close to the skin, which lice need because they feed on blood and can’t survive long away from body heat. Nits are most often laid in these same areas, glued to the hair shaft right at the base near the scalp.
Symptoms That Suggest an Infestation
Many people with lice have no symptoms at all, especially during a first infestation or when only a few lice are present. When symptoms do appear, itching is by far the most common. It comes from an allergic reaction to lice saliva, and here’s what catches people off guard: it can take four to six weeks after the initial infestation for the itching to start. That delay means lice can spread for over a month before anyone notices.
Other signs include a tickling sensation or the feeling of something moving through the hair, unexplained irritability or trouble sleeping (particularly in children), and small sores on the scalp from repeated scratching. Those sores can occasionally become infected with bacteria normally found on the skin, leading to redness, crusting, or tenderness.
How to Tell Nits From Dandruff
This is the question most people actually need answered. White specks in the hair could be nits, dandruff flakes, dried hair product, or bits of lint. The simplest test: try to flick or pull the speck off the hair shaft. Dandruff slides off easily. Nits do not. They are cemented to the hair with a glue-like substance and resist removal even when you pinch and pull. You’ll often need to slide them along the full length of the strand or use a fine-toothed nit comb to detach them.
Location matters too. Live nits sit within about a quarter inch of the scalp, roughly the thickness of a pencil. Specks found much farther from the scalp are either empty shells from nits that already hatched or dead eggs, neither of which indicates an active infestation that needs treatment.
The Wet Combing Method
A visual scan alone isn’t reliable. Adult lice move fast and avoid light, and nits are small enough to go unnoticed in thick or dark hair. Wet combing is the most thorough way to check for lice at home, and it doubles as a treatment method. Here’s how to do it:
- Set up good lighting. Work under a bright lamp. Drape a white towel over the person’s shoulders so any lice that fall off are visible.
- Wet the hair thoroughly. Use a regular comb or brush first to remove tangles. Wet hair slows lice down and makes them easier to catch.
- Section the hair. Divide it into small sections about the width of your nit comb. For short hair that can’t be sectioned, comb all the hair to the right, then left, then back to front, repeating several times.
- Comb from root to tip. Place the fine-toothed nit comb as close to the scalp as possible and draw it all the way to the end of the hair. Comb each section several times before moving on.
- Rinse the comb frequently. After each pass, dip the comb in a bowl of soapy water and wipe it on a white paper towel or tissue. This lets you see what the comb is pulling out. Lice and nits will be visible against the white surface.
- Clip finished sections away. Use clips or hair ties to separate combed hair from uncombed sections. Keep a spray bottle handy to re-wet hair as you work.
After finishing, soak the comb and any clips in hot water above 130°F for five to ten minutes. Wash the towel and any clothing used during the process in hot water and dry on the hot cycle. If you find lice or nits, repeat the combing every other day for two weeks to catch newly hatched nymphs or any eggs you missed.
What Counts as an Active Infestation
Finding a live, crawling louse is the clearest confirmation. Finding nits within a quarter inch of the scalp also indicates an active or very recent infestation, because nits are laid at the base of the hair shaft and take about a week to hatch. Nits found more than a quarter inch from the scalp are most likely already hatched or dead, and on their own don’t mean treatment is necessary.
This distinction is important because old nit shells can cling to hair for months after an infestation has ended. Both the American Academy of Pediatrics and the National Association of School Nurses have recommended against “no-nit” school policies for exactly this reason: the presence of nits alone, especially farther from the scalp, doesn’t mean a child is contagious or needs to stay home.
Three Types of Human Lice
Head lice are the most common type people search for, but two other species infest humans and look quite different. Body lice resemble head lice in shape but live on clothing rather than the body. They lay their eggs in the seams of garments and only move onto the skin to feed. You’re unlikely to find them by inspecting the scalp. Body lice are associated with conditions where clothing isn’t regularly changed or laundered.
Pubic lice, often called crabs, have a distinctly different shape. Their bodies are nearly as wide as they are long, giving them a rounded, crab-like appearance. They’re smaller than head lice, measuring about 1.5 to 2 mm, and are dark grey to brown. They’re typically found in coarse body hair. All three types are wingless, cannot jump, and spread only through direct contact or shared items like clothing and bedding.