Head lice are tiny, flat, wingless insects about 2 to 3 mm long, roughly the size of a sesame seed. Nits, their eggs, are even smaller, around 0.8 mm, oval-shaped, and glued firmly to individual hair strands near the scalp. Spotting either one takes patience and good lighting, because both are designed to blend in.
What Adult Lice Look Like
A fully grown head louse has six legs, a flat oval body, and no wings. Its color ranges from tan to grayish-white when it hasn’t fed recently, shifting to a darker reddish-brown after a blood meal. Against dark hair, an unfed louse can look almost translucent; against light hair, it appears as a small dark speck. On the scalp itself, lice tend to look like dark dots about the size of a poppy seed or sesame seed, depending on whether they’ve recently eaten.
Lice move quickly and avoid light, which is why parting the hair under a bright lamp sometimes sends them scurrying deeper toward the scalp. They crawl but cannot jump or fly. You’re most likely to spot one behind the ears or at the nape of the neck, where the scalp is warmest. A fine-toothed lice comb dragged slowly from root to tip is more reliable than just scanning visually, because the insects are fast enough to dodge a casual look.
What Nymphs Look Like
When a louse first hatches, it’s called a nymph. At this stage it’s about the size of a pinhead and nearly transparent, making it extremely difficult to see with the naked eye. A nymph looks like a miniature version of an adult louse, same body shape and six legs, just much smaller and lighter in color.
Nymphs go through three molts over about seven days before reaching adult size. With each molt they grow slightly larger and darker. During this week-long window, they’re already feeding on the scalp but are easy to miss if you’re only looking for full-size adults.
What Nits Look Like on Hair
Nits are teardrop-shaped to slightly oval eggs attached to individual hair strands, usually within a quarter inch of the scalp. They measure about 0.8 mm, smaller than a sesame seed but visible if you know what to look for. Each one is cemented in place with a glue-like substance the female louse secretes when she lays it, so nits don’t slide or flick off easily.
A viable, living nit can appear white, yellow, beige, or pale brown depending on how far along the embryo is. At the top of each egg sits a tiny cap called an operculum, a lid-like structure dotted with microscopic breathing pores that keep the developing louse alive. When the nymph hatches, it pushes this cap open and crawls out, leaving behind an empty shell. These empty casings look collapsed, matte, and whitish, and they’re no longer translucent. Because the glue stays intact, empty shells can ride the hair shaft for weeks or months as the hair grows out, long after the infestation is over.
The most common spots to find nits are behind the ears and along the nape of the neck, the same warm zones adult lice prefer.
How to Tell Living Nits From Dead Ones
Color is the most useful clue. Living nits incubating inside their shells tend to be lighter: white, yellowish, or pale brown. A nit that has died before hatching darkens to brown or black. Empty shells that already hatched look dull white or yellowish but appear flat or deflated, with the cap visibly open or missing.
Location on the hair strand also helps. Because nits are laid close to the scalp and hair grows about a centimeter per month, a nit found more than half an inch from the scalp is likely either already hatched or dead. Finding nits right at the base of the hair, especially if they’re plump and pale, suggests an active infestation.
Lice and Nits vs. Dandruff and Debris
Dandruff flakes, dried hair product, and sand grains can all look like nits at first glance. The key difference is how they behave when you try to move them. Dandruff flakes slide off the hair easily or fall when you shake your head. Nits don’t. They’re cemented on and require real effort, pinching the hair between two fingernails and sliding firmly, to pull them off the strand.
Dandruff also sits on the scalp, while nits attach to the hair itself. If you see white specks scattered loosely across the scalp surface, that’s more consistent with dandruff or dry skin. Nits line up along individual strands, often on one side of the shaft, like tiny beads strung close to the root. If you also notice dark brown or black dots on the scalp or moving through the hair, those are likely lice, not flakes.
Tips for Spotting Lice and Nits
Good lighting makes a significant difference. Natural daylight or a bright desk lamp angled at the scalp will catch the slight sheen of a viable nit and the movement of a crawling louse. Wetting the hair or applying conditioner before combing slows lice down and makes them easier to catch on a fine-toothed comb. A small magnifying glass at 2x to 6x magnification can help confirm what you’re seeing, especially with nymphs and freshly laid nits that are nearly transparent.
Start your search behind the ears and at the nape of the neck. Part the hair in small sections and look at the first quarter inch of each strand near the scalp. If you find even one live louse or a few nits close to the root, that’s enough to confirm an active case. Finding only empty shells far from the scalp, with no live bugs, typically means the infestation has already resolved or been treated.