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.
Nits that are attached more than ¼ inch from the base of the hair shaft are almost always non-viable (hatched or dead). Head lice and nits can be visible with the naked eye, although use of a magnifying lens may be necessary to find crawling lice or to identify a developing nymph inside a viable nit.
Dead nits are often black in colour and are found well away from the scalp. Nits are laid on the hair shaft within 1cm of the scalp and take about 7-10 days to hatch into head lice.
Once they are off, they can live for up to 48 hours without a blood meal. If they do not get the opportunity to crawl back onto a head, they will dehydrate and die.
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.
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.
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adult lice are seen, and the only nits found are more than ¼-inch from the scalp, the infestation is probably old and no longer active and does not need to be treated.
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.
Detection combs are special fine-toothed plastic combs that you can buy from your local pharmacy, supermarket or online. A comb with flat-faced teeth and a tooth spacing of 0.2 to 0.3mm is best. Detection combing can be carried out on dry or wet hair.
Fine tooth combing in dry hair is as good as wet combing to detect lice. The most reliable way to check is to wet comb because soaking wet lice stay still. In dry hair lice move quickly away from disturbance.
Nits may remain after lice have gone. They are empty eggshells and stick strongly to hair. They will eventually fall out. If you prefer, a fine-toothed 'nit comb' can remove them.
What does a dead lice egg look like? A dead lice egg will be white or grey. As they are empty, they will be flat and dry.
How do I check for head lice? To confirm a case of head lice, you need to find live lice. 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.
It's possible that the nits are leftover from a previous infestation and are no longer viable, which means they are dead and won't hatch. It's difficult to tell the difference, so you should still treat any nits you find, even if there are no lice.
Insecticide resistance is common, so you need to check that the lice you comb out are dead. If the insecticide has worked, the lice will be dead within 20 minutes. If the lice are not dead, the treatment has not worked and the lice are resistant to the product and all products containing the same active compound.
Most treated nits (lice eggs) are dead after the first treatment with Nix. The others will be killed with the 2nd treatment. Removing the dead nits is not essential or urgent. However, it prevents others from thinking your child still has untreated lice.
There are recent studies that show that treatment of lice with heat can be quite effective in killing head lice. Products such as Lousebuster are very effective but even a home hairdryer can successfully treat lice.
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.
Do wet combing on days 1, 5, 9 and 13 to catch any newly hatched head lice. Check again that everyone's hair is free of lice on day 17.
Spinosad (Natroba).
It can be applied to dry hair and rinsed with warm water after 10 minutes. It kills lice and nits and usually doesn't need repeated treatment.
Do not use a conditioner. It can keep the lice medicine from working. Rinse well with warm water and towel dry. Do not use the towel again until it has been laundered.
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.
If you do not comb out all the remaining nits, they will hatch and restart the cycle in 7-10 days from that point. That's why we recommend 3 treatments over a 12-day period of time. This stops the life cycle of lice. These are nits at different stages and a louse.
Head lice survive less than one or two days if they fall off the scalp and cannot feed. Head lice eggs (nits) cannot hatch and usually die within a week if they do not remain under ideal conditions of heat and humidity similar to those found close to the human scalp.
A nit comb (Like this one) is a fine-toothed comb that helps to pull out both head lice and their eggs. It's a good product for head lice removal, but even better if you know how to use it most effectively. A metal comb can be more effective, but a plastic comb works well too.