What Are Head Lice?
The head louse, or Pediculus humanus capitis, is a parasitic insect that can be found on the head and, more rarely, the eyebrows and eyelashes of people.
Head lice feed on human blood several times a day and live close to the scalp to maintain their body temperature. They cannot live without a host to feed on for more than 48 hours. Head lice live for about month, and their spans are categorized into three stages; nit (egg), nymph, and adult. Adult female lice attach nits to the hair follicle base via a naturally secreted adhesive. The nits are laid very close to the scalp (generally within six millimetres), as to provide heat for the incubation of the eggs. Nits are yellowish-white, oval-shaped eggs, about 0.8×0.3mm in size, and they usually hatch within a week to ten days, becoming nymphs. After the nit hatches, the shell remains attached to the hair follicle, and it’s color dampens to a darker shade of yellow. Nymphs look identical to adult lice, except they are slightly smaller and may also be slightly lighter in color. A nymph will shed it’s exoskeleton three times before reaching adulthood within a week of hatching.
Once reaching adulthood, the louse will require about 5 blood-feedings per day. The adult louse uses it’s claws to pierce the skin, after which it injects saliva and then sucks the blood through it’s mouth. The saliva that injects is primarily responsible for the irritation and itching sensation experienced. Although lice do not swell like many other ectoparasites, they do turn to a darker rust-colored shade after feeding. Despite their small size they can travel fairly quickly, and an adult female louse can lay up to eight nits per day. Since the adult lifespan of a louse is about 3 weeks, this means that a female can lay more than 150 nits in her lifespan, resulting in rapid reproduction and severe infestation if not treated.
Life Span of Head Lice
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.
Head lice and eggs are sometimes also found on the eyelashes or eyebrows, but this is uncommon. Misdiagnosis of head lice is common. Lice are very small and are very fast crawlers, therefore it’s difficult to spot them. We recommend to look for lice eggs, also called nets. Eggs that are attached within 1/4in (.635cm) of the base of hair shafts suggest the person may have an active infestation. Eggs that are found more than 1/4in (.635cm) from the base of hair shafts are almost always non-viable eggs (dead or empty egg casings).If no live nymphs or adult lice are seen, and the only eggs found are more than 1/4in (.635cm) from the scalp, the infestation is probably old and no longer active.
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The Lice Clinic offers an all natural in the home head lice treatment.
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