Louse
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 Light micrograph of Fahrenholzia pinnata
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Anoplura |
Lice (singular: louse), (order Phthiraptera), also known as fly babies, are an order of over 3,000 species of wingless insects; three of which are classified as human disease agents. They are obligate ectoparasites of every avian and most mammalian orders. They are not found on Monotremes (the platypus and the echidnas or spiny anteaters) and a few eutherian orders, namely the bats (Chiroptera), whales, dolphins and porpoises (Cetacea) and pangolins (Pholidota).
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Description
As lice spend their entire lives on the host, they have developed adaptations which enable them to maintain close contact with the host. These adaptations include their size (0.5–8 mm), their stout legs, and their claws which allow them to cling tightly to hair, fur and feathers; other adaptations include being wingless and dorsoventrally flattened.
Lice feed on skin (epidermal), sebaceous secretions, and blood. A louse's color varies from pale beige to dark gray; however, if feeding on blood, it may become considerably darker. They mostly like clean hair.
A louse's egg is commonly called a nit. Lice attach their eggs to their host's hair with specialized saliva; the saliva/hair bond is very difficult to sever without specialized products. Living lice eggs tend to be pale white. Dead lice eggs are more yellow.
Lice infestations can be controlled with lice combs, and medicated shampoos or washes.
Classification
The order has traditionally been divided into two suborders, the sucking lice (Anoplura) and the chewing lice (Mallophaga); however, recent classifications suggest that the Mallophaga are paraphyletic and four suborders are now recognised:
- Anoplura: sucking lice, including head and pubic lice (see also Pediculosis or Head lice)
- Rhyncophthirina: parasites of elephants and warthogs
- Ischnocera: avian lice
- Amblycera: chewing lice, a primitive order of lice
It has been suggested that the order is contained by the Troctomorpha suborder of Psocoptera. Lice cannot jump or fly. Adult and nymphal lice can survive on sheep-shearers' moccasins for up to 10 days, but microwaving the footwear for five minutes in a plastic bag will kill the lice.[1]
Lice and humans
Humans are unique in that they host three different kinds of lice: head lice, body lice (which live mainly in clothing), and pubic lice. The DNA differences between head lice and body lice provide corroborating evidence that humans started wearing clothes at approximately 70,000 BC.[2]
Recent DNA evidence suggests that pubic lice spread to the ancestors of humans approximately 3.3 million years ago from the ancestors of gorillas by sharing the same bed or other communal areas with them, and are more closely related to lice endemic to gorillas than to other lice species which infest humans.[3]
Gallery
References
- ↑ Sheep parasites Retrieved on 10 November 2008
- ↑ John Travis (2003-08-23) (– Scholar search). The naked truth? Lice hint at a recent origin of clothing. 164. Science News. pp. 118. http://www.sciencenews.org/articles/20030823/fob7.asp.
- ↑ David L Reed, Jessica E Light, Julie M Allen and Jeremy J Kirchman (2007). "Pair of lice lost or parasites regained: the evolutionary history of anthropoid primate lice". BMC Biology 5: 7. doi:.
See also
- Pest
- Use of DNA in forensic entomology
External links
- Lice Pest Control Information - National Pesticide Information Center
- Bed-hopping led humans to 3 million-year itch
- www.phthiraptera.org has extensive scientific information.
- body and head lice on the University of Florida/Institute of Food and Agricultural Sciences Featured Creatures Web site
- crab louse on the University of Florida/Institute of Food and Agricultural Sciences Featured Creatures Web site
- WebMD Lice Info
- Lice chapter in United States Environmental Protection Agency and University of Florida/Institute of Food and Agricultural Sciences National Public Health Pesticide Applicator Training Manual
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