{{short description|Family of insects}} {{about|black flies in the family Simuliidae||Blackfly (disambiguation)}} {{automatic taxobox | taxon = Simuliidae | image = Blackfly.jpg | image_caption = ''Simulium trifasciatum'' | authority = Newman, 1834 | fossil_range = {{Geological range|Norian|Recent}}<ref>{{Cite journal|last1=Lukashevich |first1=E. D. |last2=Ansorge |first2=J. |title=Late Triassic immature Diptera (Insecta): aquatic and rheophilic |year=2025 |journal=PalZ |doi=10.1007/s12542-025-00732-1 |bibcode=2025PalZ..tmp...36L |doi-access=free }}</ref> | subdivision_ranks = Subfamilies | subdivision = * Parasimuliinae * Simuliinae '''Genera''' * ''Araucnephia'' * ''Araucnephioides'' * ''Archicnephia'' * ''Austrosimulium'' * ''Baisomyia'' * ''Cnephia'' * ''Cnesia'' * ''Cnesiamima'' * ''Crozetia'' * ''Ectemnia'' * ''Gigantodax'' * ''Greniera'' * ''Gydarina'' * ''Gymnopais'' * ''Kovalevimyia'' * ''Levitinia'' * ''Lutzsimulium'' * ''Mayacnephia'' * ''Metacnephia'' * ''Paracnephia'' * ''Parasimulium'' * ''Paraustrosimulium'' * ''Pedrowygomyia'' * ''Prosimulium'' * ''Simuliites'' * ''Simulimima'' * ''Simulium'' * ''Stegopterna'' * ''Sulcicnephia'' * ''Titanopteryx'' * ''Tlalocomyia'' * ''Twinnia'' {{Wikispecies-inline}} }}
'''Black flies''' or '''blackflies'''<ref>{{Cite web|url=https://www.merriam-webster.com/dictionary/blackfly |title=Definition of blackfly |website=Merriam-webster.com |access-date=18 December 2021}}</ref> (sometimes called '''buffalo gnats''', '''turkey gnats''', or '''white socks''') are flies in the family '''Simuliidae''' of the Culicomorpha infraorder. Simuliidae are related to the Ceratopogonidae, Chironomidae, and Thaumaleidae. Over 2,200 species of black flies have been formally named, of which 15 are extinct.<ref name=Adler2017_11/> They are divided into two subfamilies: Parasimuliinae contains only one genus and four species; Simuliinae contains all the rest. Over 1,800 of the species belong to the genus ''Simulium''.<ref name=Adler2017_11>{{cite book |last1=Adler |first1=Peter H. |last2=Crosskey |first2=Roger W. |date=2017 |title=World blackflies (Diptera: Simuliidae): a comprehensive revision of the taxonomic and geographical inventory [2017] |url= https://biomia.sites.clemson.edu/pdfs/blackflyinventory.pdf |page=11 }}</ref>
Black flies are usually small, black or gray, with short legs and antennae. They feed mainly on nectar for flight energy, and the females of most species also gain nourishment for egg production by feeding on the blood of birds or mammals, including humans. They are a common nuisance for humans, and many U.S. states have programs to suppress the black fly population. They spread several diseases, including river blindness in Africa (''Simulium damnosum'' and ''S. neavei'') and the Americas (''S. callidum'' and ''S. metallicum'' in Central America, ''S. ochraceum'' in Central and South America).
== Ecology == Eggs are laid in running water, and the larvae attach themselves to submerged rocks. Breeding success is highly sensitive to water pollution.<ref>{{cite news |first=Beth |last=Daley |title=Black flies surge in Maine's clean rivers |url=http://archive.boston.com/news/science/articles/2008/06/23/black_flies_surge_in_maines_clean_rivers/ |work=Boston Globe |date=2008-06-23 |access-date=2008-06-23}}</ref> The larvae use tiny hooks at the ends of their abdomens to hold on to the substrate, using silk holdfasts and threads to move or hold their place. They have foldable fans surrounding their mouths, also termed "mouth brushes".<ref name="PRS">{{cite journal |last1=Brackenbury |first1=John |title=Locomotion through use of the mouth brushes in the larva of Culex pipiens (Diptera: Culicidae) |journal=Proceedings of the Royal Society of London. Series B: Biological Sciences |date=7 January 2001 |volume=268 |issue=1462 |pages=101–106 |doi=10.1098/rspb.2000.1336|pmid=12123291 |pmc=1087607 }}</ref> The fans expand when feeding, catching passing debris (small organic particles, algae, and bacteria). The larva scrapes the fan's catch into its mouth every few seconds. Black flies depend on lotic (flowing water) habitats to bring food to them. They will pupate under water and then emerge in a bubble of air as flying adults. They are often preyed upon by trout during emergence. The larva of some South African species are known to be phoretic on mayfly nymphs.{{Citation needed|date=September 2025}}
thumb|left|A female black fly
Adult males and females feed on water and a source of carbohydrate, such as nectar or honeydew, for energy for flight.<ref name=EncEnt>{{cite encyclopedia |first=Peter H. |last=Adler |date=2008 |title=Black Flies (Diptera: Simuliidae) |pages=525–528 |encyclopedia=Encyclopedia of Entomology |publisher=Springer}}</ref> Females of most species also exhibit anautogeny and bite birds or mammals to feed on blood for nutrients to produce eggs;<ref name=CanEncy /> the mouths of males are not able to bite through skin.<ref name=EncEnt /> Different species prefer different hosts for their blood meals, which is sometimes reflected in the common name for the species. They feed in the daytime, preferably when wind speeds are low. Some species in Africa can range as far as {{convert|40|mi|km|abbr=on}} from aquatic breeding sites in search of their blood meals, while other species have more limited ranges.{{Citation needed|date=September 2025}} In the small percentage of species that do not bite, the females produce eggs using nutrients they have retained from the larval stage.<ref name=EncEnt /> Male black flies are rarely seen.<ref name=CanEncy />
Black flies may be either univoltine or multivoltine, depending on the species. The number of generations a particular pest species has each year tends to correlate with the intensity of human efforts to control those pests.{{Citation needed|date=September 2025}}
Work conducted at Portsmouth University in 1986–1987{{Citation needed|date=April 2010}} indicates ''Simulium'' spp. create highly acidic conditions within their midguts. This acidic environment provides conditions ideally suited to bacteria that metabolise cellulose. Insects cannot metabolise cellulose independently, but the presence of these bacteria allows cellulose to be metabolised into basic sugars. This provides nutrition to the black fly larvae, as well as the bacteria. This symbiotic relationship indicates a specific adaptation, as fresh-flowing streams could not provide sufficient nutrition to the growing larva in any other way.{{Citation needed|date=April 2010}}
== Regional effects of black fly populations == [[File:Black Fly Attack on theDubawnt River Nunavut.jpg|thumb|300px|left|Black flies attack a canoe expedition in Dubawnt River, Nunavut.]] * In the wetter parts of the northern latitudes of North America, including parts of Canada, New England, Upstate New York, Minnesota, and the Upper Peninsula of Michigan, black fly populations swell from late April to July, becoming a nuisance to humans engaging in outdoor activities, such as gardening, boating, camping, backpacking, and just walking. They can also be a significant nuisance in mountainous areas. * Black flies are a scourge to livestock in Canada, where they can cause weight loss in cattle, and the saliva of one species can cause anaphylactic shock and death.<ref name=CanEncy>{{cite encyclopedia |date=7 February 2020 |title=Black fly |url= https://www.thecanadianencyclopedia.ca/en/article/black-fly |encyclopedia=The Canadian Encyclopedia |access-date=23 September 2025}}</ref> * Pennsylvania operates the largest single black fly control program in North America.{{citation needed|date=September 2025}} The program benefits both the quality of life of residents and the state's tourism industry.<ref>{{cite web |title=Black Fly |url= https://www.pa.gov/agencies/dep/programs-and-services/integration/vector-management/black-fly |publisher=Commonwealth of Pennsylvania |access-date=23 September 2025}}</ref> * The Blandford fly (''Simulium posticatum'') in England was once a public health problem in the area around Blandford Forum, Dorset, due to its large numbers and the painful lesions caused by its bite. It was eventually controlled by carefully targeted applications of ''Bacillus thuringiensis israelensis''.<ref>{{cite journal|title=Blandford's Most pernicious beast|journal=Dorset Life|date=28 May 2015 |url=http://www.dorsetlife.co.uk/2015/05/blandfords-most-pernicious-beast/|access-date=6 September 2016}}</ref> In 2010, a summer surge of insect bites blamed on the Blandford fly required many who had been bitten to be treated in a hospital.<ref>{{cite news| url=https://www.telegraph.co.uk/health/healthnews/7915695/Blandford-fly-surge-in-infected-insect-bites-blamed-on-new-superfly.html | archive-url=https://web.archive.org/web/20100801002728/http://www.telegraph.co.uk/health/healthnews/7915695/Blandford-fly-surge-in-infected-insect-bites-blamed-on-new-superfly.html | url-status=dead | archive-date=2010-08-01 | location=London | work=The Daily Telegraph | first=Andrew | last=Hough | title=Blandford fly: surge in 'infected' insect bites blamed on new superfly | date=2010-07-29}}</ref> * The New Zealand biting "sandflies" are actually black flies of the species ''Austrosimulium australense'' and ''A. ungulatum''.<ref>{{cite encyclopedia |first=Carl |last=Walrond |date=1 March 2009 |title=Sandflies and mosquitoes – Sandflies: New Zealand's blackflies |url= https://teara.govt.nz/en/sandflies-and-mosquitoes/page-1 |encyclopedia=Te Ara – the Encyclopedia of New Zealand |access-date=24 September 2025}}</ref> * In parts of Scotland, various species of black flies are a nuisance and bite humans, mainly between May and September. They are found mainly in mixed birch and juniper woodlands, and at lower levels in pine forests, moorlands, and pastures. Bites are most often found on the head, neck, and back. They also frequently land on legs and arms.
== Public health == Only four genera in the family Simuliidae, ''Simulium'', ''Prosimulium'', ''Austrosimulium'', and ''Cnephia'', contain species that feed on people, though other species prefer to feed on other mammals or on birds. ''Simulium'', the type genus, is the most widespread and is a vector for several diseases, including river blindness.
Mature adults can disperse tens or hundreds of miles from their breeding grounds in fresh flowing water, under their own power and assisted by prevailing winds, complicating control efforts. Swarming behavior can make outdoor activities unpleasant or intolerable, and can affect livestock production. During the 18th century, the "Golubatz fly" (''Simulium colombaschense'') was a notorious pest in central Europe.<ref name="Thompson2001">{{cite journal | title = The Name of the Type Species of Simulium (Diptera: Simuliidae): an historical footnote | journal = Entomological News | date = March 2001 | first = F. Christian | last = Thompson | volume = 112 | issue = 2 | page = 125| url = https://www.biodiversitylibrary.org/item/93089#page/137/mode/1up | access-date = 2011-04-08}}</ref> Even non-biting clouds of black flies, whether composed of males or of species that do not feed on humans or do not require a blood meal before egg laying, can form a nuisance by swarming into orifices.
Bites are shallow and accomplished by first stretching the skin using teeth on the labrum and then abrading it with the maxillae and mandibles, cutting the skin and rupturing its fine capillaries. Feeding is facilitated by a powerful anticoagulant in the flies' saliva, which also partially numbs the site of the bite, reducing the host's awareness of being bitten and thereby extending the flies' feeding time. Biting flies feed during daylight hours only and tend to zero in on areas of thinner skin, such as the nape of the neck or ears and ankles.
Itching and localized swelling and inflammation sometimes result from a bite. Swelling can be quite pronounced depending on the species and the individual's immune response, and irritation may persist for weeks. Intense feeding can cause "black fly fever", with headache, nausea, fever, swollen lymph nodes, and aching joints; these symptoms are probably a reaction to a compound from the flies' salivary glands. Less common severe allergic reactions may require hospitalization.<ref name="Mullen2009">{{cite book | last1 = Mullen | first1 = Gary | last2 = Durden | first2 = Lance | title = Medical and Veterinary Entomology | publisher = Academic Press | year = 2009 | isbn = 978-0-12-372500-4}}</ref><ref name="Service2008">{{cite book | last1 = Service | first1 = MW | title = Medical Entomology for Students | publisher = Cambridge University Press | year = 2008 | pages = 81–92 | isbn = 978-0-521-70928-6}}</ref>
Repellents provide some protection against biting flies. Products containing the active ingredient ethyl butylacetylaminopropionate (IR3535), DEET (''N'',''N''-diethyl-''meta''-toluamide), or picaridin are most effective. Some beauty products have been found effective, and their use as insect repellents have been approved by EPA (e.g., Skin So Soft).<ref>{{cite web|url= https://www3.epa.gov/pesticides/chem_search/ppls/000806-00027-20060306.pdf|title=Avon Skin-So-Soft SSS Bug Guard Plus|website=3.epa.gov|access-date=18 December 2021}}</ref> However, given the limited effectiveness of repellents, protecting oneself against biting flies requires taking additional measures, such as avoiding areas inhabited by the flies, avoiding peak biting times, and wearing heavy-duty, light-colored clothing, including long-sleeve shirts, long pants and hats. When black flies are numerous and unavoidable, netting that covers the head, like the “bee bonnets” used by beekeepers, can provide protection.<ref>{{cite web|url=http://www.idph.state.il.us/envhealth/pcbitingflies.htm|title=Biting Flies|website=Idph.state.il.us}}</ref>
Black flies are central to the transmission of the parasitic nematode ''Onchocerca volvulus'' which causes onchocerciasis, or "river blindness", which is endemic in parts of South America, Africa, and the Arabian Peninsula. It serves as the larval host for the nematode and acts as the vector by which the disease is spread. The parasite lives on human skin and is transmitted to the black fly during feeding.<ref name="Service2008" /> <!-- uncited over a year, can't find what it is ''Simulium pruinosum'' bite is thought to be involved in the pathogenesis of Fogo Selvagem, the endemic form of pemphigus foliaceus, a bullous dermatosis.{{Citation needed|date=April 2011}} -->
== See also == * "The Blackfly Song", a song by Wade Hemsworth inspired by his experiences with them in Northern Ontario * Gnat * Midge * Use of DNA in forensic entomology
== Citations == {{Reflist}}
== Further reading == * Crosskey R. W.; ''The natural history of blackflies''. Willey, New York, 1990. {{ISBN|0-471-92755-4}} * Honomichl K.; Bellmann, H.; ''Biologie und Ökologie der Insekten''. CD-Rom. Gustav Fischer, Stuttgart, 1994. {{ISBN|0271004177}} * Jedlicka, L.; Stloukalova, V.; ''Family Simuliidae''. pp. 331–347 in: Papp, L. and Darvas, B. (eds.): ''Contributions to a Manual of Palaearctic Diptera'', Volume 2. Science Herald, Budapest, 1997. * Jensen, F.; Diptera Simuliidae, Blackflies. pp. 209–241 in: Nilsson, A.N. (ed.): ''Aquatic Insects of North Europe. A Taxonomic Handbook''. Apollo Books, Stenstrup, 1997. * Kim, K. C.; Merritt, R. W. (Eds.); ''Black flies, ecology, population management, and annotat. world list''. University Park, London, 1987. {{ISBN|0-271-00417-7}} * Kurtak, D. C. 1973. ''Observations on filter feeding by the larvae of black flies''. PhD thesis. Cornell Univ., Ithaca. 157 pp. * Kurtak, D. C. 1978. "Efficiency of filter feeding of black fly larvae". ''Can. J. ZooL'' 56:1608–23 110. * Laird, M. (Ed.); ''Blackflies''. Academic Press, London, 1981. {{ISBN|0124340601}} * Lechthaler, W.; Car, M.; ''Simuliidae – Key to Larvae and Pupae from Central- and Western Europe''. Vienna 2005, {{ISBN|3-9501839-3-0}} * Seitz, G.; ''Verbreitung und Ökologie der Kriebelmücken (Diptera: Simuliidae) in Niederbayern''. in: ''Lauterbornia''. Mauch, Dinkelscherben 11.1992, pp. 1–230. * Timm, T.; ''Dormanzformen bei Kriebelmücken unter besonderer Berücksichtigung des Ei-Stadiums (Diptera: Simuliidae)''. in: ''Entomologia generalis''. Schweizerbart, Stuttgart 12.1987, 133–142. {{ISSN|0340-2266}} * Timm, T.; ''Unterschiede in Habitatselektion und Eibiologie bei sympatrischen Kriebelmückenarten (Diptera, Simuliidae)''. in: ''Mitteilungen der Deutschen Gesellschaft für Allgemeine und Angewandte Entomologie''. Bremen 6.1988, 156–158. {{ISSN|0344-9084}} * Timm, T.; Rühm, W. (Hrsg.); ''Beiträge zur Taxonomie, Faunistik und Ökologie der Kriebelmücken in Mitteleuropa''. Essener Ökologische Schriften. Bd.2. Westarp Wissenschaften, Magdeburg 1993. {{ISBN|3-89432-078-8}} * Wichard, W.; Arens, W.; Eisenbeis, G.; ''Atlas zur Biologie der Wasserinsekten''. Stuttgart, 1994. {{ISBN|3-437-30743-6}} * Wirtz, H. P.; ''Analyse der Histaminanteile im Speichel verschiedener Kriebelmückenarten (Diptera: Simuliidae)''. in: ''Mitteilungen der Deutschen Gesellschaft für Allgemeine und Angewandte Entomologie''. Bremen 6.1988, 441–442. {{ISSN|0344-9084}}
== External links == * [https://www.diptera.info/photogallery.php?album_id=101 Diptera.info Gallery] Images
{{Diptera|1}} {{Taxonbar|from=Q720467}} {{Authority control}}
Category:Simuliidae Category:Insect vectors of human pathogens Category:Upper Peninsula of Michigan Category:Taxa named by Edward Newman <!-- Category:Insect families moved to Simuliidae redirect -->