Black fly: Difference between revisions

Work conducted at Portsmouth University by Bob Harris in 1986-1987^[citation needed] indicates that Simulium sp. create conditions within their mid guts that are highly acidic. This acidic environment provides conditions that are ideally suited to bacteria that metabolise cellulose, insects cannot metabolise cellulose so the presence of these bacteria allow cellulose to be metabolised into basic sugars , this provides nutrition to the black fly larva as well as the bacteria. A symbiotic relationship that indicates a specific relationship as fresh flowing streams could not provide sufficient nutrition to the growing larva in any other way.^{[citation needed]}

Regional effects of black fly populations

• In the wetter parts of the northern latitudes of
  backpacking
  . 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, in some cases, death.^[3]
• Pennsylvania, in the United States, operates 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.^[4]
• 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.^[5] In 2010 there was a summer surge of insect bites blamed on the the Blandford fly that required many who had been bitten to be treated in hospital.^[6]
• The New Zealand "sandfly" is actually a type of black fly.^[7]

Public health

Only four genera in the Simuliidae family, 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 species, is the most widespread and is a vector for several diseases, including river blindness. Preferred timing and location of bites varies by species, though feeding always occurs during the day and is usually sited on areas of thinner skin, such as the nape of the neck or ears. Mature adults can disperse tens or hundreds of kilometers 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 eighteenth century, the "Golubatz fly" (Simulium colombaschense) was a notorious pest in central Europe.^[8] 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. Itching and localized swelling and inflammation sometimes occurs at the site of a bite; swelling can be quite pronounced depending on the species and the individual's immune response, and irritation may persist for several days to 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 in the flies' salivary glands. Less commonly, severe allergic reactions may require hospitalization.^[9][10]

River blindness

The black fly is central to the transmission of the

• Gnat
• "
  The Black Fly Song", a song by Wade Hemsworth
  inspired by his experiences with them
• Use of DNA in forensic entomology

Common names in other languages

• German: Kriebelmücke
• Norwegian: knott
• Polish: meszkowate
• Finnish: mäkärä
• French: simulie
• Swedish: knott
• Central America: bocone
• South America, Brazil: pium; Chile: jerjel; Argentina, Venezuela: jején
• Comprehensive list of local names for Simuliidae

Notes