Nits are tiny oval eggs, roughly the size of a pinhead, glued firmly to individual hair shafts close to the scalp. They range in color from yellow to white when alive and shift to brown or black when dead. Spotting them is the most reliable way to confirm a lice infestation, but they’re easy to confuse with dandruff or other debris if you don’t know exactly what to look for.
Size, Shape, and Color
Each nit is a small oval capsule attached at an angle to a single strand of hair. They’re too small to see clearly with the naked eye in dim light, but under bright light or with a magnifying glass they become visible as slightly raised bumps along the hair shaft. Living nits that haven’t hatched yet can appear white, yellow, beige, or pale brown depending on how far along the embryo is. The darker a live nit looks, the closer it is to hatching.
Dead nits that never hatched tend to turn brown or black. Once a nit has hatched and the louse has emerged, the leftover casing turns white, gray, or translucent. These empty shells stay glued to the hair and grow out with it, so you can find them inches from the scalp long after the infestation is over.
Where Nits Are Found on the Head
Female lice lay their eggs close to the scalp, where body heat keeps them warm enough to develop. The most common spots are behind the ears and along the nape of the neck. These are the best places to start looking. You’ll also find them along the crown of the head, though they can technically appear anywhere there’s hair.
According to the CDC, viable nits are usually found within about 6 millimeters (roughly a quarter inch) of the scalp surface. Finding multiple nits that close to the scalp strongly suggests an active infestation. Nits found more than a quarter inch from the scalp are most likely old, either already hatched or no longer viable, since they’ve been carried away from the warmth zone as the hair grew out.
How Nits Attach to Hair
Nits don’t just sit on hair. They’re cemented in place. When a female louse lays an egg, she secretes a glue substance from a specialized gland. This glue hardens into a protective sheath around the egg and the hair shaft, locking the nit in position. The bond is remarkably strong, which is why nits don’t fall off when you wash or brush your hair. You generally need a fine-toothed nit comb and deliberate effort to slide them off.
This firm attachment is actually one of the best ways to confirm you’re looking at a real nit. If a white speck flicks off easily when you touch it, it’s probably not a nit.
Nits vs. Dandruff and Other Look-Alikes
Misidentification is extremely common. The CDC notes that misdiagnosis of nits is very common during checks conducted by nonmedical professionals. Here’s how to tell the difference:
- Dandruff flakes are flat, irregularly shaped, and slide easily along the hair or fall off when you run your fingers through it. Nits are oval, three-dimensional, and firmly stuck in place.
- Hair casts (sometimes called pseudo-nits) are small tubes of skin cells that wrap around the hair shaft. Under magnification they look like irregular, amorphous white clumps rather than the neat oval shape of a nit. They also slide more freely along the hair.
- Hair spray residue or dirt tends to coat multiple strands at once and doesn’t have the distinct teardrop-on-a-shaft appearance of a nit.
The simplest test: pinch the speck between your fingers and try to slide it along the hair. If it moves easily or falls off, it’s not a nit. If it resists and you have to use your fingernails or a comb to drag it off, it likely is one.
How to Check Effectively
Natural sunlight or a bright lamp makes the biggest difference. Nits are small enough that overhead indoor lighting can make them nearly invisible, especially in light-colored hair. A magnifying glass or magnifying visor helps significantly. Wet the hair first if possible, which makes lice move more slowly and makes nits slightly easier to see against the hair strand.
Part the hair in small sections using a fine-toothed comb, starting behind the ears and at the nape of the neck. Work your way across the entire scalp. Look for the characteristic tiny ovals glued close to the base of the hair. If you find nits within a quarter inch of the scalp, the infestation is likely active and worth treating. If all the nits you find are far from the scalp and appear white or translucent, you’re probably seeing remnants of an old infestation that has already resolved.
What Active vs. Old Nits Tell You
Color and location together give you the clearest picture. A yellow or tan nit sitting right against the scalp is almost certainly alive and developing. A translucent or white shell found half an inch or more from the scalp is an empty casing left behind after hatching. A dark brown or black nit is one that died before hatching.
Finding a few empty casings far from the scalp with no live nits near the scalp and no crawling lice generally means the infestation is over. Finding even a small number of nits close to the scalp, especially if they’re tan or brown in color, means treatment is warranted. The CDC recommends treating anyone with live crawling lice or nits found within a quarter inch of the scalp.