Head lice are tiny 2-4 mm wingless insects. They cannot fly or jump, but they can crawl. 24 hours after mating, female head lice lays her eggs (nits) on the hair shaft about 1/4-inch away from the scalp, although they can be found anywhere on the scalp. Lice can live up to a month and can lay up to 10 eggs a day. An egg takes 7-10 days to hatch. A nymph is a baby louse. A nymph takes 7-10 days to mature into an adult louse. Only adults can lay eggs. The dark brown eggs are the newly laid eggs. Nymphs are transparent, except for a dark center. They are extremely difficult to spot and are flush on the scalp. Tweezers or nails are needed to remove them. Baby lice (nymphs) are almost transparent. In a week they will mature and become grayish white to reddish brown. Once mature, they will mate and start laying eggs again.

Cut the hair and look at the nit closely. It would be difficult to remove, tear drop shaped, and yellowish white or tan. Most scalp particles will flake off - eggs do not move and will need to be scraped off the hair.

Lice preparations kill only 50-70 % of nits. If all the nits are not removed they will hatch into crawling lice, generating a cycle of self re-infestation. Most people mistakenly believe one application of an over the counter shampoo will be enough to control the infestation. Unfortunately, that is not the case.

These shampoos do not kill eggs under the age of four days, so manual removal is still the most important step in eradicating all lice.

According to Harold George Scott, Ph.D., Board Certified Entomologist, "Resistance is a reflection of populations undergoing selection to produce survival of the fittest. Resistance does not occur all at once. It develops over time in louse populations, so, in any particular location, both resistant and nonresistant populations may exist. This can cause much confusion, because pediculicides that work one day fail to work the next." Therefore, relying on pediculicides alone may fail to eliminate head lice.

More and more lice are growing resistant to Nix, Rid, and typical permethrine-based treatments. Manual removal of viable nits is the only way to prevent re-infestation.

Basically, the more they have, the longer they have it, but it's very hard to tell. If you just have live lice, than you just got it.

Nits are poppy seed sized eggs attached at an angle to the hair shaft. They can be yellowish or grayish white ovals, most often found near the ears and at the nape of the neck.

Over the counter pesticide shampoos will kill lice, but children under the age of 2, people with asthma, allergies, seizures, pregnant and breastfeeding women should consult their doctors before applying these shampoos. These shampoos do not kill the eggs under the age of 4 days, so manual removal is still the most important step in eradicating all lice. Click here to read more about over the counter shampoos.
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The National Pediculosis Association believes that mechanical removal with a comb is the safest and most effective way to remove nits and lice. Combing removes both nits and lice when done correctly, but hair must be dampened with conditioner to immobilize the live lice. Even when using other lice treatments, a thorough combing is required to remove lice and nits killed by the treatment.

Lice only live 30 days. They are not as hardy as nits, which stick to the hair. Also, it is possible to miss live lice even with combing, but if you have eggs, you had to have bugs at some point.

It has to be a buzz cut so the head is no longer a warm and hospitable place.

Not everyone itches.

No, they feed on blood, not human hair.

No.

Because that is where the hair is thickest and therefore warmest.