Black fly

This article is about black flies in the family Simuliidae. For other uses, seeBlackfly (disambiguation).

Ablack flyorblackfly(sometimes called abuffalognat,turkey gnat,orwhite socks) is any member of the familySimuliidaeof theCulicomorphainfraorder.It is related to theCeratopogonidae,Chironomidae,andThaumaleidae.Over 2,200 species of black flies have been formally named, of which 15 are extinct.They are divided into two subfamilies:Parasimuliinaecontains only one genus and four species;Simuliinaecontains all the rest. Over 1,800 of the species belong to the genusSimulium.

Black fly Temporal range:
Simulium trifasciatum
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Insecta
Order:	Diptera
Superfamily:	Chironomoidea
Family:	Simuliidae Newman,1834
Subfamilies
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 Data related toBlack flyat Wikispecies

Most black flies gain nourishment byfeeding on the bloodof mammals, including humans, although the males feed mainly onnectar.They are usually small, black or gray, with shortlegsandantennae.They are a common nuisance for humans, and many U.S. states have programs to suppress the black fly population. They spread several diseases, includingriver blindnessin Africa (Simulium damnosumandS. neavei) and the Americas (S. callidumandS. metallicumin Central America,S. ochraceumin Central and South America).

Ecology

Eggsare laid in running water, and thelarvaeattach themselves to rocks. Breeding success is highly sensitive to water pollution.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".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 onlotichabitats 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 bephoreticon mayfly nymphs.

A female black fly

Adult males feed on nectar, while females exhibitanautogenyand feed on blood before laying eggs. Some species in Africa can range as far as 40 mi (64 km) from aquatic breeding sites in search of their blood meals, while other species have more limited ranges.

Different species prefer different host sources 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.

Black flies may be eitherunivoltineormultivoltine,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.

Work conducted atPortsmouth Universityin 1986–1987indicatesSimuliumspp. 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.

Regional effects of black fly populations

Black flies attack a canoe expedition inDubawnt River,Nunavut.

• In the wetter parts of the northern latitudes ofNorth America,including parts ofCanada,New England,Upstate New York,Minnesota,and theUpper Peninsula of Michigan,black fly populations swell from late April to July, becoming a nuisance to humans engaging in common outdoor activities, such asgardening,boating,camping,andbackpacking.They can also be a significant nuisance in mountainous areas.
• Black flies are a scourge to livestock in Canada, causing weight loss in cattle and sometimes death.
• Pennsylvaniaoperates the largest single black fly control program in North America. The program is seen as beneficial to both the quality of life for residents and to the state's tourism industry.
• TheBlandford fly(Simulium posticatum) in England was once a public health problem in the area aroundBlandford Forum,Dorset, due to its large numbers and the painful lesions caused by its bite. It was eventually controlled by carefully targeted applications ofBacillus thuringiensis israelensis.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.
• The New Zealand "sandflies" are actually black flies of the speciesAustrosimulium australenseandA. ungulatum.
• 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.
• InPeninsular Malaysia35 species of preimaginal black flies were discovered in a study in 2016, includingSimulium digrammicum,which had been considered locally extinct.

Public health

Only four genera in the family Simuliidae,Simulium,Prosimulium,Austrosimulium,andCnephia,contain species that feed on people, though other species prefer to feed on othermammalsor onbirds.Simulium,the type genus, is the most widespread and is a vector for several diseases, includingriver 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.Swarmingbehavior 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.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 themaxillaeandmandibles,cutting the skin and rupturing its fine capillaries. Feeding is facilitated by a powerfulanticoagulantin 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.

Itchingand 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.

Repellents provide some protection against biting flies. Products containing the active ingredientethyl butylacetylaminopropionate(IR3535),DEET(N,N-diethyl-meta-toluamide), orpicaridinare 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).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.

River blindness

Black flies are central to the transmission of theparasiticnematodeOnchocerca volvuluswhich causesonchocerciasis,or "river blindness", which is endemic in parts ofSouth America,Africa,and theArabian Peninsula.It serves as thelarvalhost for the nematode and acts as thevectorby which the disease is spread. The parasite lives on human skin and is transmitted to the black fly during feeding.

See also

• "The Black Fly Song",a song byWade Hemsworthinspired by his experiences with them inNorthern Ontarioand popularized in the United States byBill Staines.
• Gnat
• Midge
• Use of DNA in forensic entomology

General references

• Black Flies Fact SheetfromOhio State University
• Extensive Simuliidae (black fly) Web pages at blackfly.org.uk
• Black fly species inventory

Further reading

• Crosskey R. W.;The natural history of blackflies.Willey, New York, 1990.ISBN0-471-92755-4
• Honomichl K.; Bellmann, H.;Biologie und Ökologie der Insekten.CD-Rom. Gustav Fischer, Stuttgart, 1994.ISBN0271004177
• 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.ISBN0-271-00417-7
• Kurtak, D. C. 1973.Observations onfilter feedingby 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. ZooL56:1608–23 110.
• Laird, M. (Ed.);Blackflies.Academic Press, London, 1981.ISBN0124340601
• Lechthaler, W.; Car, M.;Simuliidae – Key to Larvae and Pupae from Central- and Western Europe.Vienna 2005,ISBN3-9501839-3-0
• 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.ISSN0340-2266
• 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.ISSN0344-9084
• Timm, T.; Rühm, W. (Hrsg.);Beiträge zur Taxonomie, Faunistik und Ökologie der Kriebelmücken in Mitteleuropa.Essener Ökologische Schriften. Bd.2. Westarp Wissenschaften, Magdeburg 1993.ISBN3-89432-078-8
• Wichard, W.; Arens, W.; Eisenbeis, G.;Atlas zur Biologie der Wasserinsekten.Stuttgart, 1994.ISBN3-437-30743-6
• 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.ISSN0344-9084

External links

• Taxonomy and systematics of Simuliidae
• Diptera.info GalleryImages