A gnat ( / ˈ n æ t / ) is any of many species of tiny flying insects in the dipterid suborder Nematocera , especially those in the families Mycetophilidae , Anisopodidae and Sciaridae . Most often they fly in large numbers, called clouds. "Gnat" is a loose descriptive category rather than a phylogenetic or other technical term, so there is no scientific consensus on what constitutes a gnat. Some entomologists consider only non-biting flies to be gnats. Certain universities and institutes also distinguish eye gnats : the Smithsonian Institution describes them as "non-biting flies, no bigger than a few grains of salt, ... attracted to fluids secreted by your eyes".
30-643: Genera [REDACTED] Data related to Black fly at Wikispecies A black fly or blackfly (sometimes called a buffalo gnat , turkey gnat , or white socks ) is any member of the family Simuliidae of the Culicomorpha infraorder . It is related to the Ceratopogonidae , Chironomidae , and Thaumaleidae . Over 2,200 species of black flies have been formally named, of which 15 are extinct. They are divided into two subfamilies: Parasimuliinae contains only one genus and four species; Simuliinae contains all
60-430: A basal submentum, which connects with the prementum through a narrow sclerite, the mentum. The labium forms the lower portion of the buccal cavity in insects. The prementum has a pair of labial palps laterally, and two broad soft lobes called the paraglossae medially. These paraglossae have two small slender lobes called glossae at their base. In many hexapods, the mouthparts have been modified for different functions and
90-424: A basal triangular sclerite called the cardo and a large central sclerite called the stipes from which arise three processes: the lacinia, the galea and the maxillary palp. The lacinia is often strongly sclerotized and toothed. It functions to cut and manipulate food in the mouth. The galea is a broad, scoop-like, lobe structure, which assists the maxillary palps in sampling items before ingestion. The maxillary palp
120-410: A proboscis is formed from mostly the labium specialized for lapping up liquids. The labial palps form a labella which have sclerotized bands for directing liquid to a hypopharangeal stylet, through which the fly can imbibe liquids. In lepidopterans , the fluid-sucking proboscis is formed entirely from the galea of the maxillae although labial palps are also present. In Odonata nymphs , the labium forms
150-550: 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 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 ). However, given
180-419: Is recognizably leglike in structure and consists of three segments plus an apical claw. The second maxillae also have a metameric pore, which is the opening of the maxillary gland and maxillary nephridium homologous to those of millipedes. In crustaceans , the two pairs of maxillae are called maxillulae (1st pair) and maxillae (2nd pair). They serve to transport food to the mandibles but also frequently help in
210-426: Is richly infused with chemosensory and tactile receptors along its edge. A pair of maxillary glands, also called nephridial organs, involved in osmoregulation and excreting nitrogenous waste open up to the gnathochilarium and wastes are passed entirely through the digestive tract before being evacuated. The nephridial organs are thought to be derived from similar organs in annelids , although reduced in number since
240-478: Is serially homologous to the walking leg while the cardo and stipes are regarded by most to be serially homologous to the first leg segment, the coxa. The labium is immediately posterior to the first maxillae and is formed from the fusion of the second maxillae, although in lower orders including the Archaeognatha (bristletails) and Thysanura (silverfish) the two maxillae are not completely fused. It consists of
270-642: 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 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. Work conducted at Portsmouth University in 1986–1987 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
300-579: The Hessian fly larva, form galls in flowers, leaves, stems, roots or other plant parts. Some South American pleurothallid orchids are pollinated by tiny gnats and have correspondingly small flowers . Adult non-biting gnats do not damage plants but are considered a nuisance. Usually, larvae do not cause serious plant damage, but when present in large numbers can stunt the plant growth and damage its roots. To prevent gnats from spreading, measures have to be taken to target immature stages of development of
330-408: The mandibles and obscure them from view. This pair consists of a basal plate formed from the fused coxae of each leg plus ventral sternite from this segment and is hence called a coxosternite and two pairs of conically jointed appendages called telopodites and coxal projections. The second maxillae, which partly cover the first maxillae, consist of only a telopodite and a coxosternite. The telopodite
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#1732851925369360-403: 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
390-417: The open circulatory system of arthropods lessens the demand on separate excretory organs. The reason for their anterior location is probably because these organs must be developed early on in the embryo and millipedes and other arthropods develop mainly by proliferation of cells at the posterior of the embryo. In centipedes , both pairs of maxillae are developed. The first maxillae are situated ventrally to
420-437: The pedipalps in spiders are also called "maxillae", although they are not homologous with mandibulate maxillae. In millipedes , the second maxillae have been lost, reducing the mouthparts to only the first maxillae which have fused together to form a gnathochilarium , acting as a lower lip to the buccal cavity and the mandibles which have been enlarged and specialized greatly, used for chewing food. The gnathochilarium
450-454: The species . Physical tactics include eliminating favorable living conditions: reduction of excess moisture, drainage of pools with standing water, and removal of decaying organic matter. Commercially available control agents and insecticides can be used as a control measure, but are not recommended for use in a household. To control adult gnats in smaller areas, pressurized aerosol sprays with pyrethrins can be used. Other control measures in
480-425: 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
510-755: The Americas ( S. callidum and S. metallicum in Central America, S. ochraceum in Central and South America). Eggs are laid in running water, and the larvae attach 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
540-736: The fan's catch into its mouth every few seconds. Black flies depend on lotic 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. Adult males feed on nectar, while females exhibit anautogeny and 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
570-439: The filtration process and additionally they may sometimes play a role in cleaning and grooming. These structures show an incredible diversity throughout crustaceans but generally are very much flattened and leaf-like. The two pairs are normally positioned very close together and their apical parts generally are in direct contact with the mandible. The generalized condition in hexapods is for the first pair of maxillae to consist of
600-546: The gnat category, are small, sometimes barely visible, blood-sucking flies commonly known in many areas as biting gnats, sand flies, punkies or " no-see-ums ", among other names. In general, gnats go through the four life stages of egg, larva, pupa and adult, similar to other flies. The fungus gnats lay their eggs in moist organic debris or soil, which hatch into larvae. The larvae feed on organic matter such as leaf mold, mulch, compost, grass clippings, root hairs and fungi. They eventually become pupae and then adults emerge from
630-402: The head and the maxillary palps; segmented appendages extending from the base of the maxilla represent the former leg of those respective segments. In most cases, two pairs of maxillae are present and in different arthropod groups the two pairs of maxillae have been variously modified. In crustaceans , the first pair are called maxillulae (singular maxillula ). Modified coxae at the base of
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#1732851925369660-410: The household can include turning off unnecessary lights at dusk and sealing vents and other openings. Maxilla (arthropod mouthpart) In arthropods , the maxillae (singular maxilla ) are paired structures present on the head as mouthparts in members of the clade Mandibulata , used for tasting and manipulating food. Embryologically , the maxillae are derived from the 4th and 5th segment of
690-464: 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. Black flies are central to
720-425: The maxillae and labium can change in structure greatly. In bees , the maxillae and labium have been modified and fused to form a nectar-sucking proboscis. In the order Hemiptera , the true bugs, plant hoppers, etc., the mouthparts have been modified to form a beak for piercing. The labium forms a sheath around a set of stylets that consist of an outer pair of mandibles and an inner pair of maxillae. In lapping flies ,
750-399: 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
780-554: 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. 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 ,
810-824: The pupae. At a temperature of 75 °F (23.9 °C), the cycle takes approximately 17 days: 3 days as eggs, 10 days as larvae and 4 days as pupae. Warmer temperatures allow more rapid development. Some species of fungus gnats (e.g. those in genus Bradysia ) are pests of mushrooms and roots of plants in greenhouses . Other gnats begin their lives as eggs laid in masses in water, or laid on aquatic plants. The aquatic larvae dwell in ponds, pools, water-filled containers, clogged rain gutters or wet soil, which generally feed on plant matter (living or dead). The larvae develop into pupae and then into adults. Adults live only long enough to reproduce and they may form large mating swarms , often around dusk. The life cycle generally takes 4-5 weeks. The larvae of most gall gnats ( Cecidomyiidae ), such as
840-501: The rest. Over 1,800 of the species belong to the genus Simulium . Most black flies gain nourishment by feeding on the blood of mammals, including humans, although the males feed mainly on nectar . They are usually small, black or gray, with short legs and antennae . 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
870-730: 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. Gnat As nematoceran flies, adult gnats have antennae with at least six segments that are often long and slender. They are generally slender-bodied with long and narrow wings. Black fly (Simuliidae) and biting midges (Ceratopogonidae), also belonging to
900-417: 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
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