Sucking louse

Sucking lice are classified as a parvorder called Anoplura, named by Leach in 1815. Anoplura belongs to the infraorder Phthiraptera, which contains all lice, and is part of the larger order Psocodea, which also contains booklice, barklice and barkflies. A cladogram showing the position of Anoplura within Phthiraptera and Psocodea is shown below:{{Cite journal|last1=de Moya|first1=Robert S|last2=Yoshizawa|first2=Kazunori|last3=Walden|first3=Kimberly K O|last4=Sweet|first4=Andrew D|last5=Dietrich|first5=Christopher H|last6=Kevin P|first6=Johnson|date=2021-06-16|editor-last=Buckley|editor-first=Thomas|title=Phylogenomics of Parasitic and Nonparasitic Lice (Insecta: Psocodea): Combining Sequence Data and Exploring Compositional Bias Solutions in Next Generation Data Sets|url=https://academic.oup.com/sysbio/article/70/4/719/5912026|journal=Systematic Biology|language=en|volume=70|issue=4|pages=719–738|doi=10.1093/sysbio/syaa075|pmid=32979270|issn=1063-5157|doi-access=free}}

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Sucking lice are typically flattened and wingless, with sharp claws on their legs that are used to attach themselves to hair or human clothing. All sucking lice suck blood through a small proboscis that is usually kept inside of their head. Their color typically ranges between a mixture of yellow and white.{{Cite web |title=Sucking louse {{!}} Parasite, Blood-Feeding, Pest {{!}} Britannica |url=https://www.britannica.com/animal/sucking-louse |access-date=2025-05-09 |website=www.britannica.com |language=en}} There are around 540 different species of Anoplura, and unlike the closely related Mallophaga, sucking lice only parasitize mammals.

Sucking lice bodies are typically oblong, with a flattened body and a head that is rounded in the front and smaller than the thorax.{{Cite book |title=Bulletin |publisher=U.S. Government Printing Office |year=1883 |publication-date=December 12, 2011 |pages=187 |language=en |oclc=365228942 |issue=1–10}} The lice have anywhere from three to five separate thread{{ndash}}like antennae on top of the end of the head that is used to help navigate their surroundings. The head tends to slightly widen next to the antennae. The antennae are composed of three to five equal sized joints that are used to aid in sensing their surrounding.{{Cite web |date=2022-02-15 |title=Lice (Phthiraptera) - Factsheet for health professionals |url=https://www.ecdc.europa.eu/en/all-topics-z/disease-vectors/facts/factsheet-lice-phthiraptera#:~:text=Sucking%20lice%20are%20less%20biodiverse,their%20relevance%20to%20public%20health |access-date=2025-05-09 |website=www.ecdc.europa.eu |language=en}} The thorax contains two irregularly shaped triangular plates that help defend the insect's interior. Most sucking lice are no more than two millimeters in length.

All sucking lice undergo a process of slow metamorphosis, with three life stages of egg, nymph and adult.{{Cite web |title=Anoplura |url=https://entomology.k-state.edu/outreach-and-services/4-h/Guide-to-Insect-Orders/anoplura.html |access-date=2025-05-09 |website=entomology.k-state.edu}} The entire process of Anoplura's growth occurs whilst on their host; however, they are able to survive for small periods of time in outside environments.{{Cite web |title=Lice Dogs and Cats: chewing (Mallophaga), and sucking (Anoplura) - Learn About Parasites - Western College of Veterinary Medicine |url=https://wcvm.usask.ca/learnaboutparasites/parasites/lice-chewing-mallophaga,-and-sucking-anoplura.php |access-date=2025-05-09 |website=wcvm-learnaboutparasites |language=en}} Once a female louse matures, they will lay large amounts of small eggs (also known as nits) on the individual hairs of hosts. Nits are usually between 0.3 and 0.8 millimeters long, and are often pale in color or nearly transparent.{{Cite web |date=2022-05-31 |title=Life cycle of lice: Stages, how they spread, and more |url=https://www.medicalnewstoday.com/articles/life-cycle-of-lice#life-cycle-of-head-lice |access-date=2025-05-09 |website=www.medicalnewstoday.com |language=en}}

Sucking lice live exclusively on the outside of their hosts, making them considered ectoparasites.{{Cite book |last=Lapage |first=Geoffrey |title=Parasitic Animals |publisher=Cambridge University Press |year=1951 |isbn=9781107496613 |pages=115–116 |language=en}} The louse's proboscis consists of two distinct tubes, with the upper being called a rostrum, and the lower being called a stylet. The lice will use their upper mouth piece to latch onto the skin with teeth{{ndash}}like structures, maintaining a firm hold during their feeding. The lower mouth piece consists of two stylets, also known as "stabbers". After the rostrum obtains a firm hold, the stylets will penetrate the skin with the serrated edges in a saw{{ndash}}like fashion. The louse will then regurgitate saliva through the proboscis inside of the body, before proceeding to suck the host's blood{{Cite book |last=Aspinall |first=Victoria |title=The Complete Textbook of Veterinary Nursing |publisher=Saunders/Elsevier |isbn=9780702040504 |edition=2nd |publication-date=May 25, 2006 |pages=504 |language=en}} in what has been described as a "pumping action". Different species of sucking louse have specialised anatomy to help parasitize on different mammals and to help survive various climates.

Anoplura contains three species of lice that parasitize humans.{{Cite journal |last1=Akhoundi |first1=Mohammad |last2=Heriniaina |first2=Hantatiana Juliana |last3=Brun |first3=Sophie |last4=Benamari |first4=Emma |last5=Izri |first5=Arezki |date=2024-11-03 |title=Morphological discrimination of human lice (Anoplura: Pediculidae) by eggs' cap-like operculum |journal=Scientific Reports |language=en |volume=14 |issue=1 |pages=26506 |doi=10.1038/s41598-024-78292-8 |pmid=39489815 |issn=2045-2322|pmc=11532422 |bibcode=2024NatSR..1426506A }} Anoplura body lice (Pediculus humanus humanus) typically carry the potential of causing skin irritation, and are vectors of multiple blood-born diseases.{{Cite journal |last1=Johnston |first1=J. Spencer |last2=Yoon |first2=Kyong Sup |last3=Strycharz |first3=Joseph P. |last4=Pittendrigh |first4=Barry R. |last5=Clark |first5=J. Marshall |date=2007-11-01 |title=Body Lice and Head Lice (Anoplura: Pediculidae) Have the Smallest Genomes of Any Hemimetabolous Insect Reported to Date |url=https://academic.oup.com/jme/article/44/6/1009/1088303?login=false |journal=Journal of Medical Entomology |volume=44 |issue=6 |pages=1009–1012 |doi=10.1093/jmedent/44.6.1009 |issn=0022-2585|doi-access=free |pmid=18047199 }} Common symptoms of Anoplura body lice include relapsing fever, trench fever and epidemic typhus.{{Cite journal |last1=Bonilla |first1=Denise L. |last2=Durden |first2=Lance A. |last3=Eremeeva |first3=Marina E. |last4=Dasch |first4=Gregory A. |date=2013 |title=The biology and taxonomy of head and body lice--implications for louse-borne disease prevention |journal=PLOS Pathogens |volume=9 |issue=11 |pages=e1003724 |doi=10.1371/journal.ppat.1003724 |issn=1553-7374 |pmc=3828170 |pmid=24244157 |doi-access=free}} Due to increased societal standards for hygiene, body lice in general is significantly less prevalent in developed regions. During the American Civil War, body lice were colloquially known as "seam squirrels" due to their tendency to lay eggs within the seams of soldier's clothes.{{Cite web |last=Parsons |first=Susan |title=The Civil War and Body Lice |url=https://www.cayugacounty.us/DocumentCenter/View/1775/Civil-War-and-Body-Lice-PDF#:~:text=Body%20lice%2C%20Pediculus%20Vestimenti%2C%20had,bit%20larger%20than%20head%20lice |access-date=May 11, 2025 |website=cayugacounty.us |format=PDF}}{{Cite book |title=The Oxford Dictionary of Modern Slang |date=2013 |publisher=Oxford University Press |isbn=9780191727719 |editor-last=Ayto |editor-first=John |edition=2nd |chapter=seam-squirrel |doi=10.1093/acref/9780199543700.001.0001 |orig-date=2010 |editor-last2=Simpson |editor-first2=John}} Anoplura head lice (Pediculus humanus capitis) is significantly more common than pubic or body lice, with studies reporting an infestation rate between 3.6% and 61.4% from countries in North and South America.{{Cite journal |last1=Falagas |first1=Matthew E. |last2=Matthaiou |first2=Dimitrios K. |last3=Rafailidis |first3=Petros I. |last4=Panos |first4=George |last5=Pappas |first5=Georgios |date=2008 |title=Worldwide prevalence of head lice |journal=Emerging Infectious Diseases |volume=14 |issue=9 |pages=1493–1494 |doi=10.3201/eid1409.080368 |issn=1080-6059 |pmc=2603110 |pmid=18760032}} Cases of head lice are most common in children between the ages of 3 and 11.{{Cite web |date=2022-02-15 |title=Lice (Phthiraptera) - Factsheet for health professionals |url=https://www.ecdc.europa.eu/en/all-topics-z/disease-vectors/facts/factsheet-lice-phthiraptera#:~:text=Due%20to%20their%20blood%20feeding,mechanical%20transmission%20of%20opportunistic%20bacteria. |access-date=2025-05-10 |website=www.ecdc.europa.eu |language=en}} Pthirus pubis (also known as pubic lice or crabs) is a species of sucking lice that affects the genitals of humans, and is the cause of Pediculosis pubis. Public lice are often mistaken as sexually transmitted infections due to frequently being contracted through sexual contact; however, they are only considered parasites as they can be spread through non-sexual methods such as sharing blankets or towels.{{Cite web |title=Pubic Lice (Crabs) |url=https://my.clevelandclinic.org/health/diseases/4522-pubic-lice-crabs |access-date=May 10, 2025 |website=clevelandclinic.org}}

Dogs can be affected by three individual species of Anoplura lice: Linognathus setosus, Heterodoxus spiniger and Trichodectes canis.{{Cite web |title=Lice of Dogs - Dog Owners |url=https://www.merckvetmanual.com/dog-owners/skin-disorders-of-dogs/lice-of-dogs |access-date=2025-05-10 |website=Merck Veterinary Manual |language=en-US}} Dogs infested by lice show symptoms of discomfort such as rubbing, scratching and biting areas affected. Coats of affected animals are often rough to the tough, and can become matted over time if left untreated.{{Cite web |title=Overview of Lice in Animals - Integumentary System |url=https://www.merckvetmanual.com/integumentary-system/lice/overview-of-lice-in-animals |access-date=2025-05-10 |website=Merck Veterinary Manual |language=en-US}} Severe infestations of sucking lice can lead to anemia from the loss of blood as well. Lice in dogs can only be contracted through either direct or indirect contact with another infested dog, and cannot be transferred across different species.{{Cite web |title=Lice |url=https://capcvet.org/guidelines/lice/#:~:text=Lice%20of%20dogs%20and%20cats,combs,%20or%20similar%20grooming%20equipment. |access-date=2025-05-10 |website=Companion Animal Parasite Council |language=en}}

Cats are not affected by Anoplura lice, rather they can only contract the species Felicola subrostrata, a type of chewing lice.{{Cite web |title=Lice of Cats - Cat Owners |url=https://www.merckvetmanual.com/cat-owners/skin-disorders-of-cats/lice-of-cats |access-date=2025-05-10 |website=Merck Veterinary Manual |language=en-US}}{{Cite journal |last1=Paul Pion |first1=D. V. M. |last2=Spadafori |first2=Gina |date=2017-08-08 |title=Veterinary Partner |url=https://veterinarypartner.vin.com/default.aspx?pid=19239&id=4952773#:~:text=There%20is%20one%20kind%20of,chewing%20louse)%20that%20affects%20cats.&text=What%20you%20will%20notice%20with,areas%20will%20be%20most%20affected. |website=VIN.com}}

Most cattle species can be affected by sucking lice, with certain lice species being specially adapted to their preferred cattle and unable to be transferred across any other species.{{Cite web |last= |first= |last2= |last3= |first3= |date=2021-02-03 |title=Lice: A Wintertime Threat - Oklahoma State University |url=https://news.okstate.edu/articles/veterinary-medicine/2021/lice_a_wintertime_threat.html#:~:text=Lice%20that%20affect%20cattle%20cannot,or%20chewing)%20and%20sucking%20lice. |access-date=2025-05-10 |website=news.okstate.edu |language=en}} Anoplura lice can only live off of the animal for a few days.{{Cite web |last=Schlesser |first=Heather |title=Lice Management For Cattle |url=https://livestock.extension.wisc.edu/articles/lice-management-for-cattle/#:~:text=It%20takes%20the%20nymphs%20about,weight%20gain,%20and%20general%20thriftiness. |access-date=2025-05-10 |website=Livestock |language=en-US}} Female lice specialized to cattle tend to lay a single egg every day for around 2 to 3 weeks. Similar to sucking lice in dogs, severe infestations can cause cattle to experience anemia, with newborn calves being particularly vulnerable.

These 15 families are generally recognized in the Anoplura:{{Cite journal |last1=Light |first1=Jessica E. |last2=Smith |first2=Vincent S. |last3=Allen |first3=Julie M. |last4=Durden |first4=Lance A. |last5=Reed |first5=David L. |date=2010-09-22 |title=Evolutionary history of mammalian sucking lice (Phthiraptera: Anoplura) |journal=BMC Evolutionary Biology |volume=10 |issue=1 |pages=292 |doi=10.1186/1471-2148-10-292 |issn=1471-2148 |pmc=2949877 |pmid=20860811 |doi-access=free|bibcode=2010BMCEE..10..292L }}

• Echinophthiriidae Enderlein, 1904 – (seal lice)
• Enderleinellidae Ewing, 1929
• Haematopinidae Enderlein, 1904 – (ungulate lice)
• Hamophthiriidae Johnson, 1969
• Hoplopleuridae Ewing, 1929 – (armoured lice)
• Hybophthiridae Ewing, 1929
• Linognathidae Webb, 1946 – (pale lice)
• Microthoraciidae Kim & Lugwig, 1978
• Neolinognathidae Fahrenholz, 1936
• Pecaroecidae von Kéler, 1963
• Pedicinidae Enderlein, 1904 – (Old World monkey lice)
• Pediculidae Leach, 1817 – (body lice)
• Polyplacidae Fahrenholz, 1912 – (spiny rat lice)
• Pthiridae Ewing, 1929 – (pubic lice)
• Ratemiidae Kim & Lugwig, 1978

• Mallophaga

{{Reflist}}

{{commons category|Anoplura}}

{{Wikispecies|Anoplura}}

• [http://entomology.ifas.ufl.edu/creatures/livestock/little_blue_cattle_louse.htm Solenopotes capillatus, little blue cattle louse] on the UF / IFAS Featured Creatures Web site
• [https://web.archive.org/web/20100821222458/http://phumanus.vectorbase.org/ VectorBase homepage for Pediculus humanus] (genome browser, downloads and more)

{{Human lice}}

{{Pediculosis, acariasis and other infestations}}

{{Psocodea|2}}

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{{Authority control}}

Category:Lice