An adult head louse can live about 30 days on a person's head but will die within one or two days if it falls off a person. Adult female head lice are usually larger than males and can lay about six eggs each day.
Females are usually larger than males and can lay up to 8 nits per day. Adult lice can live up to 30 days on a person's head. To live, adult lice need to feed on blood several times daily.
Only one live bug can be produced per nit or egg. After the egg is laid, it takes roughly seven to 10 days for it to hatch. Once the egg hatches, it takes another seven to 10 days to reach maturity and begin laying eggs of its own. An adult louse can lay up to six eggs per day and live for up to 30 days on a host.
After mating, the adult female louse can produce five to six eggs per day for 30 days (8), each in a shell (a nit) that is 'glued' to the hair shaft near the scalp (5,6).
These tiny insects (about 1/8” long) make their home in human hair and feed on blood. Head lice multiply rapidly, laying small greyish-colored, oval-shaped eggs (called nits) which they glue to the base of the hair, close to the scalp. Head lice are not known to spread disease.
Adults are not immune to head lice. In fact, if you have any close contact with children or even parents of children you can be at risk of catching them if they have them. Lice transfer primarily through head to head contact, so you would have to get close to the other person.
Infestation timeline
So if you look on the scalp and see no visible adult lice and several small nits, it's likely that you've caught lice in the earlier stages and had them for less than 2 weeks. Nits and nymphs: 1.5 to 2 weeks. If you see nits and small, moving lice, you've likely had lice for 1.5 to 2 weeks.
Nits are often confused with other things found in the hair such as dandruff, hair spray droplets, and dirt particles. If no live nymphs or adult lice are seen, and the only nits found are more than ¼-inch from the scalp, the infestation is probably old and no longer active and does not need to be treated.
Lice lay nits on hair shafts close to the scalp, where the temperature is perfect for keeping warm until they hatch. Nits look a bit like dandruff, but aren't removed by brushing or shaking them off. Unless a child has many head lice, it's more common to see nits in the hair than live lice crawling on the scalp.
Washing, soaking, or drying items at a temperature greater than 130°F can kill both head lice and nits.
Since eggs do not need a host to survive, they will continue to live until a nymph hatches from it. A louse will ultimately die without a human host. However, it can still live for 1-2 days on a pillow or sheet. Don't forget that a louse can also lay eggs while it's hostless.
How many head lice are usually found on an infested person? Typically, 10–15 head lice are found. The number of lice often depends on personal hygiene, for example, how often the person bathes, shampoos, or changes and washes his/her clothing.
Nymphs are smaller and become adult lice about 1 to 2 weeks after they hatch. Most lice feed on blood several times a day, but they can survive up to 2 days off the scalp. Head lice only live for about three weeks. An adult female louse will lay about six eggs (nits) each day.
Permethrin lotion, 1%;
Permethrin lotion 1% is approved by the FDA for the treatment of head lice. Permethrin is safe and effective when used as directed. Permethrin kills live lice but not unhatched eggs. Permethrin may continue to kill newly hatched lice for several days after treatment.
Suffocate the Lice
Soak your child's head in olive oil or coconut oil. Cover with a shower cap for at least 2 hours (or preferably overnight). When ready, remove the shower cap, and separate the hair into small sections, then use a metal nit comb to carefully remove the lice and eggs. Rinse the hair well with shampoo.
Repeat treatment every day or every other day for 2 weeks. Some lice eggs (nits) survive head lice treatments. The only way to be sure that lice won't come back is to pick out all nits. Nits left on the hair can hatch and cause a new case of head lice.
Lice cannot “fall” on pillows, sheets, stuffed animals, and other bedding unless the hair that they are attached to fall. But they can't live on these surfaces, or on hats, scarves, furniture, or carpet. They also can't live on pets or any other animals. Nits can't live without a human host.
The most likely explanation is that by the time H. sapiens evolved in Africa about 200,000 years ago we had our own lineage of head lice, and then picked up more from H. erectus on our travels, says Reed. The study is reported in the current issue of PLoS Biology1.
Nits that are attached more than ¼ inch from the base of the hair shaft are almost always non-viable (hatched or dead).
Children can have a few nits without actually having a case of head lice. Usually children have no more than 10 to 20 live lice. Good lighting is important when you are checking. Head lice move fast and are hard to see.
To remove lice and nits by hand, use a fine-tooth comb on wet, conditioned hair every 3–4 days for 3 weeks after the last live louse was seen. Go through small sections of hair at a time. Wetting the hair temporarily stops the lice from moving, and the conditioner makes it easier to get a comb through the hair.
New eggs are attached to the hair shaft very close to the scalp. Eggs that still contain a louse embryo are brownish in color, while the empty egg shells are white to grey.
The most common symptom of any type of lice is itching. Lice bites cause an allergic reaction that causes this itchy feeling. However, you may not feel itchy right away, especially if it's a light infestation. You may not notice any symptoms for up to six weeks the first time you get lice.
Generally, if no live crawling insects are seen three weeks after the treatment, it's safe to assume that they are gone. Nits would have hatched by that time if they were alive. Nits and their shells may remain in the hair for some time but won't be viable.
How long does head lice last? With effective treatment, head lice will completely go away after two to three weeks. The duration is dependent on how many lice made a home in your hair. Make sure you follow the instructions on your medicated shampoo, lotion or cream to get rid of lice quickly.