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A head louse (Pediculus humanus capitis) is a small parasitic insect which lives on the human scalp and feeds exclusively on human blood. No other animals besides humans are known to host the parasite. Though its lifespan is only approximately 1 month, a female louse lays between 5-150 eggs (nits) during that time. The young louse emerge from the egg in an initial nymphal stage. They molt three times during that phase, then develop into nymph 2 and nymph 3 stages before developing into adult male or female louse.

Adult head lice mate frequently, and females lay approximately 3-4 eggs each day. Generations last for about 1 month. Each stage of development feeds on blood, which they harvest by biting the skin 4-5 times each day. During oviposition, females excrete a glue-substance from a gland located on the posterior of their body. This substance attaches the heads to the hair of the host. While lice may colonize any part of the scalp, they favor the nape of the neck and the area behind the ears, where eggs are often laid.

A common symptom indicating infestation is the presence of pruritus on the head, which gets worse after three or four weeks. Bites are relatively mild and may not even be visible between hairs. In individuals with long hair, you can see bites when the hair is pushed aside. Sometimes, although rarely, the itching and scratching cycle can cause secondary infections such as impetigo and pyoderma. Rare symptoms include swelling of the local lymph nodes or fever. Head lice have not been found to carry any pathogenic microorganisms.

So how does one get rid of head lice? That is a tough question to answer considering there is no 100% method to get all of the eggs after one treatment. Some of the methods used include chemical treatments, hot air, combs, head shaving, etc. Using kerosene (alone or used with oil and vinegar), hair bleach and dyes, antibiotics, or ivermectin for lice treatment, or using garlic and Vitamin B to prevent lice.

No matter much you might try to comb them out, kill them with chemical solutions, or just scratch away, head lice persistently maintain a strong grip on the scalp. What's worse, they are increasingly becoming resistant to common treatment methods. Scientific estimates say that as many as 80 per cent of lice are immune to common over the counter treatments. Lice have been found to be unfazed by permathrin and phenothrin, chemicals contained in some popular remedies.

Not much can be done by us to treat head lice infection. It is well known that prevention is the best cure. By the experts opinion it is assumed that the insects have becomes resistant to the lotions due to the process of natural selection. And these findings will not just leave children, parents and teachers scratching their heads but will certainly give a direction to discover a better lotion for getting the job done.