US Federal List: no special status
CITES: no special status
P. humanus has relatively little direct effect on its hosts. Bites itch, but do not generally cause other harm. However, lice can be vectors for important diseases. The three most important diseases they can carry are typhus, trench fever (both caused by bacteria in the genus Rickettsia), and relapsing fever (caused by another bacteria species Borrelia recurrentis). These bacterial diseases can now be treated successfully with antibiotics, but in the past, they caused the death of millions of people. Major epidemics strongly affected the political and economic history of Europe and Asia, and liice were the main agents in the spread of these diseases.
Lice cannot withstand high temperatures, so washing can eradicate the lice. Not until the practice of washing and changing our clothes on a regular basis have we been able to slow the spread of lice, and the diseases that they carry. In contrast to this, their occurrence increases greatly in time of war and hardship because people are closely packed and hygiene is not of high importance.
(Grzimek 1972; Roberts and Janovy 2000; Milne and Milne 1980)
The only way that this species could have any positive economic benefit would be to the people that are involved with selling the drugs and tools used to get rid of an infestation. Today, Lindane, permethrin, and malathion are used to kill the lice. Fine toothed combs are also used in a technique called wet combing, but this is usually accompanied with the use of one of the previously mentioned chemicals.
(Chew et. al. 2000)
Lice are obligate ectoparasites. They live off of the blood of humans. They have specially designed mouth parts for piercing the skin of humans and retrieving the blood that is present.
Animal Foods: blood
Primary Diet: carnivore (Sanguivore )
Human lice can be found anywhere on the planet that is populated by humans. They are more prevalent in areas where people change or wash their clothing infrequently and/or are unclean themselves (Milne and Milne 1980).
Biogeographic Regions: nearctic (Native ); palearctic (Native ); oriental (Native ); ethiopian (Native ); neotropical (Native ); australian (Native ); oceanic islands (Native )
Other Geographic Terms: cosmopolitan
The habitat of the human louse is solely on the human body or in the clothes. They are rarely found elsewhere because they can only survive away from the host for a few days.
(Milne and Milne 1980)
Pediculus humanus is a small insect with a large abdomen and legs equipped with sharp claws for holding onto hair and clothing fibers. The head of the louse ia slightly narrower than the body. They do not have wings like most insects, but they have piercing mouthparts for digging into the skin and draining out the blood. The head louse, Pediculus humanus capitis, is normally 1-2 mm long, while the body louse, Pediculus humanus humanus, also known as the "cootie" is usually slightly larger, 2-3.5 mm. The "nits," or eggs, of the louse are about 1 mm long and about half as wide. The young lice are often called "red backs," due to the red color they are because of the blood in them. They turn a grey color once digestion takes place, and is where they get the name "gray back".
Other Physical Features: ectothermic ; heterothermic ; bilateral symmetry
The female lice lay their eggs, which are called nits, singly on the hairs of the host (if they are head lice) or attached to clothing in the case of body lice. The nits will hatch into nymphs in about eight days. The nymphs also suck blood and mature in eight to sixteen days. Each adult female body louse produces between two and three hundred nits in her lifetime, and a single female head louse produces between eighty and one-hundred. Due to this fact and that the generations follow at about three week intervals, a single female could inundate a host in a matter of months (Burton 1968, Grzimek 1972).
Human lice (Pediculus humanus) are world-wide, obligate, wingless ectoparasites that spend their full life cycle on humans; the medical term for the condition of being infested with lice is pediculosis. This species is comprised of two morphologically identical, interbreeding (at least in laboratory conditions, although not in natural ones), but behaviorally distinguishable subspecies that occupy non-overlapping habitats: Pediculus humanus corporis (human body lice; this subspecies is also known as Pediculus humanus humanus) and Pediculus humanus capitis (human head lice). As their names suggest, body lice are found hiding in and attaching their eggs to clothing, whereas head lice infest the host's scalp, and attach their eggs to the base of hairs. These subspecies are thought to have diverged about 110,000 years ago when humans started wearing clothing. Body lice infest mostly those living with poor hygiene and who do not have access to bathing facilities and clean sheets and clothes, as infestations do not persist through bathing and laundering. Body lice can carry such diseases as louse-borne typhus (Rickettsia prowazeki), trench fever (Rochalimaea quintana), and louse-borne relapsing fever (Borrellia recurrentis). Head lice, on the other hand, are not known to be disease vectors, but are a common and persistent nuisance of millions of people in the US alone, mainly school aged children.
(Morgan 2001; Smith; Wikipedia 2011a, 2011b)
The Head Louse (Pediculus humanus capitis) is an insect in the Order Psocodea (parasitic lice, formerly Order Phthiraptera, plus bark lice, formerly Order Psocoptera). Head Lice are ectoparasites with humans as the only host. A Head Louse must feed on blood several times daily and resides close to the scalp to maintain its body temperature.
Infestation with Head Lice is common and occurs worldwide. Preschool and elementary-age children 3 to 11 years of age are infested most often. Females are infested more often than males, probably due to more frequent head to head contact. In the United States, African-Americans are rarely infested with head lice. This is believed to be due to the American louse’s preference for the shape and width of the hair shaft of other ethnic groups.
The life cycle of the Head Louse has three stages: egg, nymph, and adult.
Eggs: Nits are Head Lice eggs. They are hard to see and are often mistaken for dandruff or hair spray droplets. Nits are laid by the adult female and are cemented at the base of the hair shaft nearest the scalp. They are 0.8 mm by 0.3 mm, oval and usually yellow to white. Nits take about 1 week to hatch (range 6 to 9 days). Viable eggs are usually located within 6 mm of the scalp.
Nymphs: The egg hatches to release a nymph. The nit shell then becomes a more visible dull yellow and remains attached to the hair shaft. The nymph looks like an adult head louse, but is about the size of a pinhead. Nymphs mature after three molts and become adults about 7 days after hatching.
Adults: The adult louse is about the size of a sesame seed, has 6 legs (each with claws), and is tan to grayish-white. In persons with dark hair, the adult louse will appear darker. Females are usually larger than males and can lay up to 8 nits per day. Adult lice can live up to 30 days on a person’s head. To survive , adult lice need to feed on blood several times daily. Without blood meals, the louse will die within 1 to 2 days off the host.
From Centers for Disease Control Parasites and Health website
Check out this video of biologist Dale Clayton talking about how his research on feather lice infesting birds led to an investion to treat head lice infestations in humans.
Pediculus humanus is a species of louse that infects humans. It comprises two subspecies:[1][2]
Pediculus humanus is a species of louse that infects humans. It comprises two subspecies:
Pediculus humanus humanus Linnaeus, 1758 – body louse Pediculus humanus capitis De Geer, 1767 – head louse
