About Head Lice
Excerpts from Steve Tvedten's book "The Best Control"
(Used here with permission.)

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Head Lice
Pedicululus humanus var capitis

Adult - Head lice spread easily and infestations often occur at all social and economic levels, especially  among school children who are in close daily contact. At least 10 million children are infected each year.  Infestations are called pediculosis, which is a communicable disease. They vary in color from dirty white to reddish-brown to rust to grayish black in color. If the nymphal stages are passed on a person of blonde or light coloration, the adult louse is light in color, but if they are passed on a person of dark hair coloring, then the resulting wingless adult is more pronounced in coloration. They are small - about the size of a sesame seed.  They need a warm, moist habitat. They spread by crawling we have had some reports of a strain  that appears to "jump".  They live by biting and sucking blood from the scalp and can not normally survive for more than 2 days unless they are on the human head. Head lice aren't nice.

Egg - Eggs or nits (that look like tiny white or tan dots) are usually laid by the female close to the base of the hair near the scalp and they are firmly cemented to the hair. The eggs (and the empty shell) are known as nits and are always oval- or tear-shaped, and are glued at an angle to the side of the hair shaft. They are usually tan when alive and pearly or grayish white in color after dying. The nits usually occur near the scalp (clustered in groups), but can often be found nestled behind the ears and at the nape of the neck. The hatched egg is easily identified by its opalescent and translucent appearance. Just before hatching the eyes and other structures of the embryo can be made out through the translucent shell. On hatching, the top of the egg opens like a lid. Live nits may be occasionally found anywhere on the hair shaft, but normally they are found near the scalp and they are "super-glued" on and do not flake off like dandruff. They are so hard to remove we invented the term "nitpicking" to describe the difficulty. One louse can lay 150 nits a month (normal lifetime). They hatch in about 10 days, depending on the climate. Nits need at least 82o F.; and 70% humidity to incubate. During the incubation time the respiratory passages of the louse shut whenever the nits are immersed in water and they can survive under water for over 24 hours.  Nuthall(1917) found 80% laid on hair and 20% laid on flannel.

Nymphal stages - There are three nymphal stages, all of which resemble the adult except in size and possession of sexual organs, but they do have some change in color. During the first stage the nymph is a pale straw color and has no central nervous system (CNS) and, therefore, can not be killed using volatile, synthetic pesticide neurotoxins or by poisons that attack the CNS. The poisons and the "inerts" in these volatile pesticides can and do, however, attack your CNS! The gut of the nymph is clearly visible through the almost translucent cuticle, and when the first-stage nymphs have taken a meal of blood they are shining red in color, like rubies.  Afterwards the blood darkens and thereafter the gut appears purplish-black. The young nymph is able to feed  almost immediately after emergence and after this feeds regularly, at least twice daily. The nymphs and adults feed by pressing the front of their heads against the skin of their hosts; a series of curved teeth around their mouths then fasten on to the skin and the piercing stylets are released from a pouch where they are normally invisible, to pierce the skin. Saliva from the salivary glands lubricates the stylets and they begin to feed on you.  Kleen Kill® enzymes create an extra "molt" they weren't anticipating and will quickly destroy live lice and help remove nits/glue. Lice can not become resistant (immune) to Pestisafes®, e.g., Kleen Kill® enzymes and/or soaps or Not Nice to Lice® shampoos or borax or heat.

Length of life cycle - The egg hatches within 8 - 9 days and the nymphal stages take approximately the same length of time. The life cycle takes place, therefore, every 18 days. The length of the adult stage in the male is about 10 days and in the female can vary from 9 - 22 days. A maximum of about 6 to 10 nits/eggs are laid each day by each female and the maximum hatch rate has been found to be 88%. All lice feed on blood every 3 - 6 hours and can only survive about 20 - 48 hours without a blood meal. Nits are the size of the period at the end of this sentence.  At cooler temperatures (50 - 68oF) eggs may hatch up to 30 days later.

Pediculus humanus capitus (DeGeer) - Adult head lice are gray and about 1/8 inch long about the size of a sesame seed. They often have a tiny dot on their backs. They thrive only on human hair and scalps. Hatching occurs about one week after attachment. Since lice go through a gradual/simple metamorphosis, the tiny nymphs resemble adults. They grow to maturity in about 10 days. Adult lice mate and the female can lay about 50-150 eggs, but often falls short of that in her life of only several weeks. Wetting the hair and rubbing the scalp with a towel irritates the adult lice and makes them move about, aiding in their detection. You may wish to simply shave off the hair and thus remove the infestation, or you may soak the hair with baby oil until you feel the nits "move" or loosen and then use a lice comb and then shampoo, or sauna and/or wash your hair with Not Nice to Lice® , Kleen Kill ® enzyme cleaners, Kleen Kill® peppermint or neem soap and/or borax laundry powder before trying anything more toxic. Wash your hair with Not Nice to Lice® shampoo; leave on for 10 - 15 minutes or until you feel the nits move, then rinse (comb with a metal lice or flea comb if you wish) then use a good hair conditioner. Then go to your public health practitioners for an examination. In the United States, lice live in the head hair of preschoolers and of children of elementary school age (only rarely on adolescents or adults). This could simply be because little children hate having their hair shampooed with soap. Lice scuttle about on the scalp between hairs with much more speed than expected of a small, soft, wingless insect with slender hair grasping claws on the end of blunt legs. They are very sensitive to dry heat, so we advise saunas and/or hair dryers rather than poison head/hair treatments. They are sensitive to oil, so we also advise adding a conditioner and/or soaking the hair with olive, coconut or baby oil to kill the lice and help remove the nits.  Pestisafes® such as Kleen Kill® peppermint soap is simply pure Castile soap with peppermint oil; Castile soap is basically water, potassium soaps of olive, coconut and tall oils, etc. - all things to which they are sensitive.

Close adaptation locks head lice into the human scalp in several ways. First, louse claws grasp human hair so firmly that they do not fall or wander out of it and yet they can crawl fast. Second, head lice suck blood by grasping the scalp with tiny hooks that surround their mouth, and painlessly pierce the skin with slender stylets.  (Head lice feed several times a day but do not engorge themselves.) Most importantly, head lice neatly glue their eggs (called nits) to the hair shaft, usually within 1/4 inch of the scalp. The tiny, pearl-like eggs (they look like miniature wax tear drops) stick alongside the hair so tightly that they can be dislodged only by being torn from their neat sleeve of biological glue by fingernails or a metal lice comb or enzyme cleaners. Usually nits found further away from the scalp than 1 /2 inch will have already hatched; what is found is the empty shell which remains attached. The easiest way to remove cemented eggs is to cut them out or try to soak the hair in vinegar or baby oil or in Kleen Kill® enzymes for 10 - 60 minutes; them comb out with a metal nit or flea comb.

How head lice are spread from child to child other than crawling is not well known, but they do not jump off or freely wander onto coat collars or hats, since they are restricted to humans with a scalp surface temperature of around 80o F. or a little more, but head-to-head contact and sharing of clothing, hair ornaments and grooming materials are thought to be the normal routes of invasion. Temperature preference and perhaps humidity is so critical that lice easily die at elevated temperatures and from excess perspiration - so sauna! Conversely, at lower surface temperatures (about 50o F.) lice become torpid and do not move or feed. A reasonable speculation is that head louse nymphs hatch from nits on hair shafts snatched by brushes and deposited on knit hats. The tiny nymphs then move toward the warmth of the next head covered by the cap or brushed by the brush. This normally limits transmission to siblings that have their hair brushed with a "family brush" or children who share knit hats or hair brushes of friends. Get your own brush and cap and become "selfish".

Louse infestations are often discovered by school teachers who are watching for the signs of itching heads and/or frequent scratching, but classroom neighbors are not as likely to be infested as are brothers and sisters or close friends that sleep over with head-to-head contact or share combs and hair brushes and/or head gear.  (American) head lice have been shown by surveys in several large eastern cities to infest the heads of Caucasian and oriental children but they very seldom infest those of African Americans (whose hair may be more oily and flattened). If you are using Kleen Kill® enzymes - wash your hair again in 5 - 10 days with the same protocol, if necessary. Be sure not to confuse nits with hair debris such as irregularly-shaped clumps of dandruff stuck to the hair shaft or elongated segments of dandruff encircling the hair shaft - that are easily dislodged. You have to get rid of all the nits on the hair shafts to prevent a reinfestation; use a bright light, a magnifying glass and metal (nit/flea) comb.

(Web Mistress Note:  A little license was taken with title and some emphasis.  However, the content is correct as it appears in "The Best Control)