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About Head Lice
Although there are many types of lice, the head louse, or Pediculus humanus capitis, is a parasitic insect that can be found on the head and, more rarely, the eyebrows and eyelashes of people. Head lice (the plural form of louse) feed on human blood several times a day and live close to the scalp to maintain their body temperature.
Head lice come in three stages: egg, nymph and adult. Eggs are often called lice nits, although many people refer to nits as the empty egg shells left behind by a hatched louse. A head louse has six claws that allow it to crawl around from hair strand to hair strand. It can move from one head to another this way, which is why head-to-head contact is the primary way head lice are spread between people.
A head-lice infestation occurs when a female adult louse makes it onto a new head and lays eggs. When those eggs hatch, the lice will most likely stay on that head throughout the entire lice life cycle. Unless the head is treated and all lice and eggs are eradicated, the lice infestation will continue for however long the lice can live.
How to Self Diagnose Head Lice
It can be hard to know if you have head lice. Since you can’t see your own scalp very easily, a head lice condition is hard to self-diagnose. The best thing to do is have someone check your head for you.
After looking at lice pictures or lice videos to know what they’re looking for, have the person carefully lift sections of your hair and look along it near the scalp. That’s where head lice are commonly found, as well as behind the ears, near the neckline and at the base of the head.
Look for anything crawling through the hair. These would most likely be adult lice. Adults are about the size of a sesame seed and will be the easiest to spot. If you see a grayish-white or tan bug crawling through the hair, look closely at it. You should be able to see human blood inside it.
Look at the hair strands within about a quarter inch (~0.5 cm) of the scalp. See if you can find lice eggs (called nits) attached to individual hairs. If you see any, try pulling them off with your fingers. Nits are extremely small and will be glued pretty securely to the hair. So if you can’t pull them off easily, they are probably eggs and not dandruff.
If you feel like something is crawling through your hair, those might be lice as well. And if your scalp gets red and itchy, you may be allergic to lice bites.
How to Self Diagnose Head Lice
It can be hard to know if you have head lice. Since you can’t see your own scalp very easily, a head lice condition is hard to self-diagnose. The best thing to do is have someone check your head for you.
After looking at lice pictures or lice videos to know what they’re looking for, have the person carefully lift sections of your hair and look along it near the scalp. That’s where head lice are commonly found, as well as behind the ears, near the neckline and at the base of the head.
Look for anything crawling through the hair. These would most likely be adult lice. Adults are about the size of a sesame seed and will be the easiest to spot. If you see a grayish-white or tan bug crawling through the hair, look closely at it. You should be able to see human blood inside it.
Look at the hair strands within about a quarter inch (~0.5 cm) of the scalp. See if you can find lice eggs (called nits) attached to individual hairs. If you see any, try pulling them off with your fingers. Nits are extremely small and will be glued pretty securely to the hair. So if you can’t pull them off easily, they are probably eggs and not dandruff.
If you feel like something is crawling through your hair, those might be lice as well. And if your scalp gets red and itchy, you may be allergic to lice bites.
Pictures of Head Lice
Click on the images to learn more.
Lice on a Dime
Here is a picture of an adult louse and a louse nymph (immature louse) on a dime. The adult is about the size of FDR’s ear, and the nymph can fit easily inside his ear. Although it is magnified a bit, it gives you a better sense of how big lice are compared to some of our other photos.
Lice on Hair
This picture shows a number of dead lice on multiple strands of hair. It uses roughly the same magnification as the dime picture.
Louse Nymph
This micrograph compares the size of a first-stage nymph with George Washington’s eye on a $1 bill.
Head Louse Grabbing Two Strands of Hair
Here is a picture of a head louse moving along two strands of hair. Notice how it wraps its claws around the hair shaft. Because lice don’t jump, they use their claws to move from the hair of one person to another during head-to-head contact, which is the primary way you can get lice.
Nymphs to Adult
Here is a picture of four head lice, ranging from three sizes of nymphs to an adult.
Hatching Nymph
This micrograph (taken by Tabitha L. Allen) shows a nymph that apparently died while emerging from the casing of its egg.
