Pubic lice, commonly called “crabs,” are tiny parasitic insects that look like miniature crabs when seen up close. Adults measure just 1.5 to 2.0 mm long, roughly the size of a pinhead, and have a broad, flat body with six legs. The front pair of legs are smaller, while the second and third pairs end in large, curved claws that grip onto hair shafts. This wide, claw-heavy shape is what gives them their nickname.
What Adult Crabs Look Like
Adult pubic lice are tan to grayish-white and flat from top to bottom. Their bodies are noticeably wider and rounder than head lice or body lice, which are longer and more narrow. For comparison, head lice are about 3 to 4 mm long with an elongated shape, while pubic lice are roughly half that length and almost as wide as they are long. That squat, rounded outline with oversized front claws is the easiest way to tell them apart.
Because they’re so small, you can spot them with the naked eye, but they’re easy to miss. A magnifying glass helps considerably. They tend to stay still when attached to a hair shaft, gripping the base near the skin. After feeding, they may appear slightly darker or rust-colored from the blood they’ve consumed.
What the Eggs (Nits) Look Like
Nits are even harder to see than adult lice. They are tiny oval-shaped eggs that cling firmly to the base of a hair shaft, close to the skin where the warmth helps them develop. They’re usually yellowish-white and can be mistaken for flakes of skin or dandruff. The key difference is that nits don’t brush away easily. They’re cemented to the hair and require deliberate removal with your fingernails or a fine-toothed comb.
After the lice hatch, the empty egg casings remain on the hair and may appear more white or translucent. Seeing nits alone is enough to confirm an infestation, even if you haven’t spotted a live louse.
Signs on Your Skin
Beyond seeing the lice themselves, your skin will usually tell you something is wrong. The most common symptom is persistent itching in the pubic area, which typically starts a few days to weeks after the lice arrive. The itching comes from an allergic reaction to their bites.
If you look closely at the skin, you may notice small red bite marks or tiny spots of blood on your underwear. Some people develop bluish-gray spots at the sites of louse bites. These flat discolorations, sometimes called “sky-blue spots,” are a distinctive sign of a lice infestation and are caused by a reaction to the lice’s saliva. They’re painless but can help confirm what you’re dealing with.
Where Crabs Show Up on the Body
Pubic hair is the most common location, but crabs can live in any coarse body hair. That includes armpit hair, chest hair, beards, and in some cases, eyebrows and eyelashes. They don’t typically infest the finer hair on your head because they’re adapted to grip thicker hair shafts. If you’re checking yourself, look at all areas with coarse hair, not just the genital region.
How to Check Yourself
Pubic lice infestations are diagnosed by finding either a live louse or nits attached to hair. Start by examining your pubic area in good lighting. A magnifying glass makes identification much easier. Look for small, flat insects clinging to the base of hairs, or tiny oval eggs stuck to the shafts. Lice tend to stay close to the skin rather than at the tips of the hair.
You may also notice fine dark specks on your skin or underwear. These are lice droppings, another visual clue. If you see nits but no crawling lice, you likely still have an active infestation, since nits are laid by live adults that may simply be out of view.
How Crabs Spread
Pubic lice spread primarily through close body-to-body contact, which is why they’re classified as sexually transmitted. They can also spread through shared towels, bedding, or clothing in rare cases, since lice can survive briefly off the body. They do not spread from toilet seats. The lice need warmth and a host to survive, so casual contact in public spaces is not a realistic risk.
Treatment Options
Over-the-counter lice-killing lotions and mousses are the standard first treatment. Products containing 1% permethrin or pyrethrins with piperonyl butoxide are available at most pharmacies without a prescription. You wash the affected area, apply the product to all infested hair, leave it on for the recommended time, then rinse. Afterward, you’ll need to manually remove remaining nits with your fingernails or a fine-toothed comb, since the medication kills live lice but doesn’t always detach the eggs.
If live lice are still present after the first treatment, repeat the application in 9 to 10 days. This second round catches any lice that may have hatched from surviving eggs in the interim.
Crabs on the eyelashes or eyebrows require special care. Regular lice shampoos should not be used near the eyes. A prescription ophthalmic-grade petrolatum ointment can be applied to the eyelid margins several times a day for about 10 days. Standard petroleum jelly is not a safe substitute, as it can irritate the eyes. If only a few lice or nits are present on the lashes, careful manual removal with fingernails may be sufficient.
During treatment, wash all clothing, towels, and bedding in hot water and dry on the highest heat setting. Items that can’t be washed should be sealed in a plastic bag for two weeks to ensure any lice or eggs die off.