Head Lice – Life Cycle, Descriptions and Symptoms

Head lice (Photo credit: wordpress)
Head lice (Photo credit: wordpress)
Head lice (Photo credit: wordpress)
Head lice (Photo credit: wordpress)

What are head lice?

The head louse, or Pediculus human capitis, is a parasitic insect that can be found on the head of human beings. Head lice feed on human blood several times a day and need to live close to the scalp to maintain their body temperature.

Head Lice Life Cycle

The life cycle of the head louse has three stages: nit, nymph, and adult. The life cycle of a single louse from egg to mature adult capable of laying eggs or reproducing is about 21 days.


Head lice eggs are called nits. Nits are laid by the adult female louse and are attached to the base of the hair shaft by a strong cement like adhesive. They are located close to the scalp because they require body heat for incubation.

Size – 0.8mm by 0.3mm
Shape – Oval
Color – Yellow to white
Location – Within 6 mm of the scalp
Duration – Nits take 7 – 10 days to hatch.


When an egg hatches, it releases a nymph. The nit shell stays attached to the hair and turns a dull yellow color. The nymph looks like an adult louse but is smaller. As the nymph grows, it molts out of its exoskeleton 3 times before it becomes an adult.

Size – Variable but about the size of a pinhead
Shape – Same shape as the adult louse
Color – Yellow to rust-colored
Location – Close to the scalp, especially behind the ears and at the neckline
Duration – Nymphs become adults after about 8-12 days


The adult louse feeds about 5 times a day by piercing the skin with its claws, injecting irritating saliva, and sucking blood. Lice do not become engorged like ticks, but their color changes to a rust color after feeding. Head lice hold onto the hair with hook-like claws found at the end of each of their 6 legs. Adult lice are active and can travel quickly.

Size – The size of a pinhead. The female louse is larger than the male.
Shape – Oval with 6 legs and claws at the end of each leg
Color – Rust
Location – Close to the scalp, especially behind the ears and at the neckline
Duration – Adult lice can live up to 30 days on a person’s head
Reproduction – An adult female can lay up 6-10 eggs a day.

How They Spread

Head lice can be spread by direct contact with the head or hair of an infested person. The adult louse can survive for up to 1-2 days without feeding on the scalp; therefore lice can be found on objects that have been in contact with an infested person.

Why Other Lice Treatments and Shampoos Don’t Work

RID and other lice shampoos only kill adult lice and adolescent nymphs. These shampoos work by attacking the bug’s central nervous system. Because baby lice or “nyphms” have not yet developed a central nervous system, they cannot be killed by pesticides.

Lice Symptoms & Diagnosis

Common Symptoms of Lice

? Scalp itching
? Sensation of something moving in the hair
? Red or pustular sores on the scalp caused by scratching
? Swollen lymph nodes in the front and back of the neck

Detection and Diagnosis of Lice

Head lice and eggs are found almost exclusively on human head hair and the scalp, frequently around and behind the ears and near the neckline at the back of the head. Misdiagnosis of head lice is common.

The best way to confirm an active case of head lice is by finding a live nymph or adult louse on the scalp or hair. Adult and nymphal lice are very small, move quickly, and avoid light, so they may be difficult to find. Using a fine toothed louse comb helps in correctly diagnosing head lice.

Almost all prescription and over-the-counter medications sold today for treating head lice contain pesticides or other chemicals, many of which have the potential to cause irritating skin reactions or other harmful side effects. For anyone looking to treat head lice the safe way, the LouseBuster™ device uses only controlled, heated air, so it is very safe – even when used to treat people with asthma and those who have previously experienced side effects from other head lice treatment products. Please visit Pediatric Hair Solutions

Article Source: http://EzineArticles.com/?expert=Sheila_Fassler

Article Source: http://EzineArticles.com/7363328

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© 2012, Filipino Nurses. All rights reserved. DISCLAIMER: The accuracy of all articles contained in this website are the responsibility of their respective authors. All articles are for informational purposes only and are NOT intended to replace the advice of a doctor. The owner of this site disclaims any liability for the decisions you make based on these information. If you have any health-related questions, please consult your physician. If you feel ill, please seek medical attention immediately.

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  • Jonah Dichristopher

    Adult head lice are roughly 2-3 mm long. Head lice infest the head and neck and attach their eggs to the base of the hair shaft. Lice move by crawling; they cannot hop or fly. Head lice infestation, or pediculosis, is spread most commonly by close person-to-person contact. Dogs, cats, and other pets do not play a role in the transmission of human lice.`’..”

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