Flies are insects with a pair of functional wings for flight and a pair of specialized hindwings called halteres for balance. They are classified as an order called Diptera, that name being derived from the Greek δι- di- "two", and πτερόν pteron "wings". The order Diptera is divided into two suborders (although one suborder is non-monophyletic), with about 110 families divided between them; the families contain an estimated 1,000,000 species, including the familiar housefly, horse-fly, crane fly, and hoverfly;[a] although only about 125,000 species have a species description published. The earliest fly fossils found so far are from the Triassic, about 240 million years ago; phylogenetic analysis suggests that flies originated in the Permian, about 260 million years ago.
Many insects, such as the butterfly, contain the word fly in their name, but are not Dipterans. Also, the word "fly" is sometimes used colloquially and non-scientifically as a name for any small flying insect: the term "true fly" is sometimes invoked to make clear the insect being referenced is a Dipteran.
Flies have a mobile head, with a pair of large compound eyes, and mouthparts designed for piercing and sucking (mosquitoes, black flies and robber flies), or for lapping and sucking in the other groups. The suborder Nematocera (from Greek, "thready-horns") have thin, long antennae; while the suborder Brachycera (from Greek "short-horns") have short antennae. Flies have only a single pair of wings to fly; their arrangement gives them great maneuverability in flight. The hindwings (halteres) evolved into advanced mechanosensory organs, which act as high-speed sensors of rotational movement and allow them to perform advanced aerobatics. Claws and pads on their feet enable them to cling to smooth surfaces.
The life cycle of flies consists of the eggs, larva, pupa, and the adult. Flies undergo complete metamorphosis; the eggs are laid on the larval food-source, and the larvae (which lack true limbs) develop in a protected environment, often inside their food source. The pupa in higher dipterans is a tough capsule from which the adult emerges when ready to do so. Flies have short lives: for example, the adult housefly lives about a month; the mayfly about a year. The source of nutrition for adult flies is liquified food, including nectar.
Flies are of considerable ecological and human importance. They are important pollinators, second only to the bees and their Hymenopteran relatives. They may have been responsible for the first plant pollination in the Triassic. Mosquitoes are vectors for malaria, dengue, West Nile fever, yellow fever, encephalitis, and other infectious diseases; and houseflies, commensal with humans all over the world, spread food-borne illnesses. Flies can be annoyances, especially in some parts of the world where they can occur in large numbers, buzzing and settling on the skin or eyes to bite or seek fluids. Larger flies such as tsetse flies and screwworms cause significant economic harm to cattle. Blowfly larvae, known as gentles, and other dipteran larvae, known more generally as maggots, are used as fishing bait, as food for carnivorous animals, and in medicine for debridement to clean wounds. Fruit flies are used as model organisms in research. In culture, the subject of flies appears in religion, literature, cinema, and music.
|The hoverfly Syrphus ribesii, suborder Brachycera, showing characteristic dipteran features: large eyes, small antennae, sucking mouthparts, single pair of flying wings, hindwings reduced to clublike halteres|
Dipterans are endopterygotes, insects that undergo radical metamorphosis. They belong to the Mecopterida, alongside the Mecoptera, Siphonaptera, Lepidoptera and Trichoptera. The possession of a single pair of wings distinguishes most true flies from other insects with "fly" in their names. However, some true flies such as Hippoboscidae (louse flies) have become secondarily wingless.
|part of Endopterygota||
The first true dipterans known are from the Middle Triassic around 240 million years ago, and they became widespread during the Middle and Late Triassic. Phylogenetic analysis of times of divergence suggests that dipterans originated in the Permian, some 260 million years ago. Modern flowering plants did not appear until the Cretaceous (around 140 million years ago), so the original dipterans must have had a different source of nutrition other than nectar. Based on the attraction of many modern fly groups to shiny droplets, it has been suggested that they may have fed on honeydew produced by sap-sucking bugs which were abundant at the time, and dipteran mouthparts are well-adapted to softening and lapping up the crusted residues. The basal clades in the Diptera include the Deuterophlebiidae and the enigmatic Nymphomyiidae. Three episodes of evolutionary radiation are thought to have occurred based on the fossil record. Many new species of lower Diptera developed in the Triassic, about 220 million years ago. Many lower Brachycera appeared in the Jurassic, some 180 million years ago. A third radiation took place among the Schizophora at the start of the Paleogene, 66 million years ago.
The phylogenetic position of Diptera has been controversial. The monophyly of holometabolous insects has long been accepted, with the main orders being established as Lepidoptera, Coleoptera, Hymenoptera and Diptera, and it is the relationships between these groups which has caused difficulties. Diptera is widely thought to be a member of Mecopterida, along with Lepidoptera (butterflies and moths), Trichoptera (caddisflies), Siphonaptera (fleas), Mecoptera (scorpionflies) and possibly Strepsiptera (twisted-wing flies). Diptera has been grouped with Siphonaptera and Mecoptera in the Antliophora, but this has not been confirmed by molecular studies.
Diptera were traditionally broken down into two suborders, Nematocera and Brachycera, distinguished by the differences in antennae. The Nematocera are recognized by their elongated bodies and many-segmented, often feathery antennae as represented by mosquitoes and crane flies. The Brachycera have rounder bodies and much shorter antennae. Subsequent studies have identified the Nematocera as being non-monophyletic with modern phylogenies placing the Brachycera within grades of groups formerly placed in the Nematocera. The construction of a phylogenetic tree has been the subject of ongoing research. The following cladogram is based on the FLYTREE project.
Abbreviations used in the cladogram:
Flies are often abundant and are found in almost all terrestrial habitats in the world apart from Antarctica. They include many familiar insects such as house flies, blow flies, mosquitoes, gnats, black flies, midges and fruit flies. More than 150,000 have been formally described and the actual species diversity is much greater, with the flies from many parts of the world yet to be studied intensively. The suborder Nematocera include generally small, slender insects with long antennae such as mosquitoes, gnats, midges and crane-flies, while the Brachycera includes broader, more robust flies with short antennae. Many nematoceran larvae are aquatic. There are estimated to be a total of about 19,000 species of Diptera in Europe, 22,000 in the Nearctic region, 20,000 in the Afrotropical region, 23,000 in the Oriental region and 19,000 in the Australasian region. While most species have restricted distributions, a few like the housefly (Musca domestica) are cosmopolitan. Gauromydas heros (Asiloidea), with a length of up to 7 cm (2.8 in), is generally considered to be the largest fly in the world, while the smallest is Euryplatea nanaknihali, which at 0.4 mm (0.016 in) is smaller than a grain of salt.
Brachycera are ecologically very diverse, with many being predatory at the larval stage and some being parasitic. Animals parasitised include molluscs, woodlice, millipedes, insects, mammals, and amphibians. Flies are the second largest group of pollinators after the Hymenoptera (bees, wasps and relatives). In wet and colder environments flies are significantly more important as pollinators. Compared to bees, they need less food as they do not need to provision their young. Many flowers that bear low nectar and those that have evolved trap pollination depend on flies. It is thought that some of the earliest pollinators of plants may have been flies.
The greatest diversity of gall forming insects are found among the flies, principally in the family Cecidomyiidae (gall midges). Many flies (most importantly in the family Agromyzidae) lay their eggs in the mesophyll tissue of leaves with larvae feeding between the surfaces forming blisters and mines. Some families are mycophagous or fungus feeding. These include the cave dwelling Mycetophilidae (fungus gnats) whose larvae are the only diptera with bioluminescence. The Sciaridae are also fungus feeders. Some plants are pollinated by fungus feeding flies that visit fungus infected male flowers.
The larvae of Megaselia scalaris (Phoridae) are almost omnivorous and consume such substances as paint and shoe polish. The larvae of the shore flies (Ephydridae) and some Chironomidae survive in extreme environments including glaciers (Diamesa sp., Chironomidae), hot springs, geysers, saline pools, sulphur pools, septic tanks and even crude oil (Helaeomyia petrolei). Adult hoverflies (Syrphidae) are well known for their mimicry and the larvae adopt diverse lifestyles including being inquiline scavengers inside the nests of social insects. Some brachycerans are agricultural pests, some bite animals and humans and suck their blood, and some transmit diseases.
Flies are adapted for aerial movement and typically have short and streamlined bodies. The first tagma of the fly, the head, bears the eyes, the antennae, and the mouthparts (the labrum, labium, mandible, and maxilla make up the mouthparts). The second tagma, the thorax, bears the wings and contains the flight muscles on the second segment, which is greatly enlarged; the first and third segments have been reduced to collar-like structures, and the third segment bears the halteres, which help to balance the insect during flight. The third tagma is the abdomen consisting of 11 segments, some of which may be fused, and with the 3 hindermost segments modified for reproduction.
Flies have a mobile head with a pair of large compound eyes on the sides of the head, and in most species, three small ocelli on the top. The compound eyes may be close together or widely separated, and in some instances are divided into a dorsal region and a ventral region, perhaps to assist in swarming behaviour. The antennae are well-developed but variable, being thread-like, feathery or comb-like in the different families. The mouthparts are adapted for piercing and sucking, as in the black flies, mosquitoes and robber flies, and for lapping and sucking as in many other groups. Female horse-flies use knife-like mandibles and maxillae to make a cross-shaped incision in the host's skin and then lap up the blood that flows. The gut includes large diverticulae, allowing the insect to store small quantities of liquid after a meal.
For visual course control, flies' optic flow field is analyzed by a set of motion-sensitive neurons. A subset of these neurons is thought to be involved in using the optic flow to estimate the parameters of self-motion, such as yaw, roll, and sideward translation. Other neurons are thought to be involved in analyzing the content of the visual scene itself, such as separating figures from the ground using motion parallax. The H1 neuron is responsible for detecting horizontal motion across the entire visual field of the fly, allowing the fly to generate and guide stabilizing motor corrections midflight with respect to yaw. The ocelli are concerned in the detection of changes in light intensity, enabling the fly to react swiftly to the approach of an object.
Like other insects, flies have chemoreceptors that detect smell and taste, and mechanoreceptors that respond to touch. The third segments of the antennae and the maxillary palps bear the main olfactory receptors, while the gustatory receptors are in the labium, pharynx, feet, wing margins and female genitalia, enabling flies to taste their food by walking on it. The taste receptors in females at the tip of the abdomen receive information on the suitability of a site for ovipositing. Flies that feed on blood have special sensory structures that can detect infrared emissions, and use them to home in on their hosts, and many blood-sucking flies can detect the raised concentration of carbon dioxide that occurs near large animals. Some tachinid flies (Ormiinae) which are parasitoids of bush crickets, have sound receptors to help them locate their singing hosts.
Diptera have one pair of fore wings on the mesothorax and a pair of halteres, or reduced hind wings, on the metathorax. A further adaptation for flight is the reduction in number of the neural ganglia, and concentration of nerve tissue in the thorax, a feature that is most extreme in the highly derived Muscomorpha infraorder. Some species of flies are exceptional in that they are secondarily flightless. The only other order of insects bearing a single pair of true, functional wings, in addition to any form of halteres, are the Strepsiptera. In contrast to the flies, the Strepsiptera bear their halteres on the mesothorax and their flight wings on the metathorax. Each of the fly's six legs has a typical insect structure of coxa, trochanter, femur, tibia and tarsus, with the tarsus in most instances being subdivided into five tarsomeres. At the tip of the limb is a pair of claws, and between these are cushion-like structures known as pulvilli which provide adhesion.
The abdomen shows considerable variability among members of the order. It consists of eleven segments in primitive groups and ten segments in more derived groups, the tenth and eleventh segments having fused. The last two or three segments are adapted for reproduction. Each segment is made up of a dorsal and a ventral sclerite, connected by an elastic membrane. In some females, the sclerites are rolled into a flexible, telescopic ovipositor.
Flies are capable of great manoeuvrability during flight due to the presence of the halteres. These act as gyroscopic organs and are rapidly oscillated in time with the wings; they act as a balance and guidance system by providing rapid feedback to the wing-steering muscles, and flies deprived of their halteres are unable to fly. The wings and halteres move in synchrony but the amplitude of each wing beat is independent, allowing the fly to turn sideways. The wings of the fly are attached to two kinds of muscles, those used to power it and another set used for fine control.
Flies tend to fly in a straight line, then make a rapid change in direction before continuing on a different straight path. The directional changes are called saccades and typically involve an angle of 90°, achieved in 50 milliseconds. They are initiated by visual stimuli as the fly observes an object; nerves then activate steering muscles in the thorax that cause a small change in wing stroke, which generate sufficient torque to turn. Detecting this within four or five wingbeats, the halteres trigger a counter-turn and the fly heads off in a new direction.
Flies have rapid reflexes that aid their escape from predators but their sustained flight speeds are low. Dolichopodid flies in the genus Condylostylus respond in less than 5 milliseconds to camera flashes by taking flight. In the past, the deer bot fly, Cephenemyia, was claimed to be one of the fastest insects on the basis of an estimate made visually by Charles Townsend in 1927. This claim, of speeds of 600 to 800 miles per hour, was regularly repeated until Irving Langmuir showed it to be physically impossible as well as incorrect. Langmuir suggested an estimated speed of 25 miles per hour.
Although most flies live and fly close to the ground, a few are known to fly at heights and a few like Oscinella (Chloropidae) are known to be dispersed by winds at altitudes of up to 2000 ft and over long distances. Some hover flies like Metasyrphus corollae have been known to undertake long flights in response to aphid population spurts.
Males of fly species such as Cuterebra, many hover flies, bee flies (Bombyliidae) and fruit flies (Tephritidae) maintain territories within which they engage in aerial pursuit to drive away intruding males and other species. While these territories may be held by individual males, some species form leks with many males aggregating in displays. Some flies maintain an airspace and still others form dense swarms that maintain a stationary location with respect to landmarks. Many flies mate in flight while swarming.
Diptera go through a complete metamorphosis with four distinct life stages – egg, larva, pupa and adult.
In many flies, the larval stage is long and adults may have a short life. Most dipteran larvae develop in protected environments; many are aquatic and others are found in moist places such as carrion, fruit, vegetable matter, fungi and, in the case of parasitic species, inside their hosts. They tend to have thin cuticles and become desiccated if exposed to the air. Apart from the Brachycera, most dipteran larvae have sclerotinised head capsules, which may be reduced to remnant mouth hooks; the Brachycera, however, have soft, gelatinized head capsules from which the sclerites are reduced or missing. Many of these larvae retract their heads into their thorax.
Some other anatomical distinction exists between the larvae of the Nematocera and the Brachycera. Especially in the Brachycera, little demarcation is seen between the thorax and abdomen, though the demarcation may be visible in many Nematocera, such as mosquitoes; in the Brachycera, the head of the larva is not clearly distinguishable from the rest of the body, and few, if any, sclerites are present. Informally, such brachyceran larvae are called maggots, but the term is not technical and often applied indifferently to fly larvae or insect larvae in general. The eyes and antennae of brachyceran larvae are reduced or absent, and the abdomen also lacks appendages such as cerci. This lack of features is an adaptation to food such as carrion, decaying detritus, or host tissues surrounding endoparasites. Nematoceran larvae generally have well-developed eyes and antennae, while those of Brachyceran larvae are reduced or modified.
Dipteran larvae have no jointed, "true legs", but some dipteran larvae, such as species of Simuliidae, Tabanidae and Vermileonidae, have prolegs adapted to hold onto a substrate in flowing water, host tissues or prey. The majority of dipterans are oviparous and lay batches of eggs, but some species are ovoviviparous, where the larvae starting development inside the eggs before they hatch or viviparous, the larvae hatching and maturing in the body of the mother before being externally deposited. These are found especially in groups that have larvae dependent on food sources that are short-lived or are accessible for brief periods. This is widespread in some families such as the Sarcophagidae. In Hylemya strigosa (Anthomyiidae) the larva moults to the second instar before hatching, and in Termitoxenia (Phoridae) females have incubation pouches, and a full developed third instar larva is deposited by the adult and it almost immediately pupates with no freely feeding larval stage. The tsetse fly (as well as other Glossinidae, Hippoboscidae, Nycteribidae and Streblidae) exhibits adenotrophic viviparity; a single fertilised egg is retained in the oviduct and the developing larva feeds on glandular secretions. When fully grown, the female finds a spot with soft soil and the larva works its way out of the oviduct, buries itself and pupates. Some flies like Lundstroemia parthenogenetica (Chironomidae) reproduce by thelytokous parthenogenesis, and some gall midges have larvae that can produce eggs (paedogenesis).
The pupae take various forms. In some groups, particularly the Nematocera, the pupa is intermediate between the larval and adult form; these pupae are described as "obtect", having the future appendages visible as structures that adhere to the pupal body. The outer surface of the pupa may be leathery and bear spines, respiratory features or locomotory paddles. In other groups, described as "coarctate", the appendages are not visible. In these, the outer surface is a puparium, formed from the last larval skin, and the actual pupa is concealed within. When the adult insect is ready to emerge from this tough, desiccation-resistant capsule, it inflates a balloon-like structure on its head, and forces its way out.
The adult stage is usually short, its function only to mate and lay eggs. The genitalia of male flies are rotated to a varying degree from the position found in other insects. In some flies, this is a temporary rotation during mating, but in others, it is a permanent torsion of the organs that occurs during the pupal stage. This torsion may lead to the anus being below the genitals, or, in the case of 360° torsion, to the sperm duct being wrapped around the gut and the external organs being in their usual position. When flies mate, the male initially flies on top of the female, facing in the same direction, but then turns around to face in the opposite direction. This forces the male to lie on his back for his genitalia to remain engaged with those of the female, or the torsion of the male genitals allows the male to mate while remaining upright. This leads to flies having more reproduction abilities than most insects, and much quicker. Flies occur in large populations due to their ability to mate effectively and quickly during the mating season.
As ubiquitous insects, dipterans play an important role at various trophic levels both as consumers and as prey. In some groups the larvae complete their development without feeding, and in others the adults do not feed. The larvae can be herbivores, scavengers, decomposers, predators or parasites, with the consumption of decaying organic matter being one of the most prevalent feeding behaviours. The fruit or detritus is consumed along with the associated micro-organisms, a sieve-like filter in the pharynx being used to concentrate the particles, while flesh-eating larvae have mouth-hooks to help shred their food. The larvae of some groups feed on or in the living tissues of plants and fungi, and some of these are serious pests of agricultural crops. Some aquatic larvae consume the films of algae that form underwater on rocks and plants. Many of the parasitoid larvae grow inside and eventually kill other arthropods, while parasitic larvae may attack vertebrate hosts.
Whereas many dipteran larvae are aquatic or live in enclosed terrestrial locations, the majority of adults live above ground and are capable of flight. Predominantly they feed on nectar or plant or animal exudates, such as honeydew, for which their lapping mouthparts are adapted. The flies that feed on vertebrate blood have sharp stylets that pierce the skin, the insects inserting anticoagulant saliva and absorbing the blood that flows; in this process, certain diseases can be transmitted. The bot flies (Oestridae) have evolved to parasitize mammals. Many species complete their life cycle inside the bodies of their hosts.
In many dipteran groups, swarming is a feature of adult life, with clouds of insects gathering in certain locations. These swarming insects are mostly males, and the swarm may serve the purpose of making their location more visible to females.
Flies are eaten by other animals at all stages of their development. The eggs and larvae are parasitised by other insects and are eaten by many creatures, some of which specialise in feeding on flies but most of which consume them as part of a mixed diet. Birds, bats, frogs, lizards, dragonflies and spiders are among the predators of flies. Many flies have evolved mimetic resemblances that aid their protection. Batesian mimicry is widespread with many hoverflies resembling bees and wasps, ants and some species of tephritid fruit fly resembling spiders. Some species of hoverfly are myrmecophilous, their young live and grow within the nests of ants. They are protected from the ants by imitating chemical odours given by ant colony members. Bombyliid bee flies such as Bombylius major are short-bodied, round, furry, and distinctly bee-like as they visit flowers for nectar, and are likely also Batesian mimics of bees.
Flies play a variety of symbolic roles in different cultures. These include both positive and negative roles in religion. In the traditional Navajo religion, Big Fly is an important spirit being. In Christian demonology, Beelzebub is a demonic fly, the "Lord of the Flies", and a god of the Philistines.
Flies have appeared in literature since ancient Sumer. In a Sumerian poem, a fly helps the goddess Inanna when her husband Dumuzid is being chased by galla demons. In the Mesopotamian versions of the flood myth, the dead corpses floating on the waters are compared to flies. Later, the gods are said to swarm "like flies" around the hero Utnapishtim's offering. Flies appear on Old Babylonian seals as symbols of Nergal, the god of death. Fly-shaped lapis lazuli beads were often worn in ancient Mesopotamia, along with other kinds of fly-jewellery.
In Prometheus Bound, which is attributed to the Athenian tragic playwright Aeschylus, a gadfly sent by Zeus's wife Hera pursues and torments his mistress Io, who has been transformed into a cow and is watched constantly by the hundred eyes of the herdsman Argus: "Io: Ah! Hah! Again the prick, the stab of gadfly-sting! O earth, earth, hide, the hollow shape—Argus—that evil thing—the hundred-eyed." William Shakespeare, inspired by Aeschylus, has Tom o'Bedlam in King Lear, "Whom the foul fiend hath led through fire and through flame, through ford and whirlpool, o'er bog and quagmire", driven mad by the constant pursuit. In Antony and Cleopatra, Shakespeare similarly likens Cleopatra's hasty departure from the Actium battlefield to that of a cow chased by a gadfly. More recently, in 1962 the biologist Vincent Dethier wrote To Know a Fly, introducing the general reader to the behaviour and physiology of the fly.
Damien Hirst's provocative 1990 artwork, titled A Thousand Years, featured a severed cow's head contained in a glass box with thousands of flies and a bug zapper, showing the life-cycle of the fly as well as the decomposition of the cow.
Flies appear in popular culture in concepts such as fly-on-the-wall documentary-making in film and television production. The metaphoric name suggests that events are seen candidly, as a fly might see them. Flies have inspired the design of miniature flying robots. Steven Spielberg's 1993 film Jurassic Park relied on the idea that DNA could be preserved in the stomach contents of a blood-sucking fly fossilised in amber, though the mechanism has been discounted by scientists.
Musical works that feature the fly:
Dipterans are an important group of insects and have a considerable impact on the environment. Some leaf-miner flies (Agromyzidae), fruit flies (Tephritidae and Drosophilidae) and gall midges (Cecidomyiidae) are pests of agricultural crops; others such as tsetse flies, screwworm and botflies (Oestridae) attack livestock, causing wounds, spreading disease, and creating significant economic harm. See article: Parasitic flies of domestic animals. A few can even cause myiasis in humans. Still others such as mosquitoes (Culicidae), blackflies (Simuliidae) and drain flies (Psychodidae) impact human health, acting as vectors of major tropical diseases. Among these, Anopheles mosquitoes transmit malaria, filariasis, and arboviruses; Aedes aegypti mosquitoes carry dengue fever and the Zika virus; blackflies carry river blindness; sand flies carry leishmaniasis. Other dipterans are a nuisance to humans, especially when present in large numbers; these include houseflies, which contaminate food and spread food-borne illnesses; the biting midges and sandflies (Ceratopogonidae) and the houseflies and stable flies (Muscidae). In tropical regions, eye flies (Chloropidae) which visit the eye in search of fluids can be a nuisance in some seasons.
Many dipterans serve roles that are useful to humans. Houseflies, blowflies and fungus gnats (Mycetophilidae) are scavengers and aid in decomposition. Robber flies (Asilidae), tachinids (Tachinidae) and dagger flies and balloon flies (Empididae) are predators and parasitoids of other insects, helping to control a variety of pests. Many dipterans such as bee flies (Bombyliidae) and hoverflies (Syrphidae) are pollinators of crop plants.
Drosophila melanogaster, a fruit fly, has long been used as a model organism in research because of the ease with which it can be bred and reared in the laboratory, its small genome, and the fact that many of its genes have counterparts in higher eukaryotes. A large number of genetic studies have been undertaken based on this species; these have had a profound impact on the study of gene expression, gene regulatory mechanisms and mutation. Other studies have investigated physiology, microbial pathogenesis and development among other research topics. The studies on dipteran relationships by Willi Hennig helped in the development of cladistics, techniques that he applied to morphological characters but now adapted for use with molecular sequences in phylogenetics.
Maggots found on corpses are useful to forensic entomologists. Maggot species can be identified by their anatomical features and by matching their DNA. Maggots of different species of flies visit corpses and carcases at fairly well-defined times after the death of the victim, and so do their predators, such as beetles in the family Histeridae. Thus, the presence or absence of particular species provides evidence for the time since death, and sometimes other details such as the place of death, when species are confined to particular habitats such as woodland.
Some species of maggots such as blowfly larvae (gentles) and bluebottle larvae (casters) are bred commercially; they are sold as bait in angling, and as food for carnivorous animals (kept as pets, in zoos, or for research) such as some mammals, fishes, reptiles, and birds. It has been suggested that fly larvae could be used at a large scale as food for farmed chickens, pigs, and fish. However, consumers are opposed to the inclusion of insects in their food, and the use of insects in animal feed remains illegal in areas such as the European Union.
Fly larvae can be used as a biomedical tool for wound care and treatment. Maggot debridement therapy (MDT) is the use of blow fly larvae to remove the dead tissue from wounds, most commonly being amputations. Historically, this has been used for centuries, both intentional and unintentional, on battlefields and in early hospital settings. Removing the dead tissue promotes cell growth and healthy wound healing. The larvae also have biochemical properties such as antibacterial activity found in their secretions as they feed. These medicinal maggots are a safe and effective treatment for chronic wounds.
The Sardinian cheese casu marzu is exposed to flies known as cheese skippers such as Piophila casei, members of the family Piophilidae. The digestive activities of the fly larvae soften the cheese and modify the aroma as part of the process of maturation. At one time European Union authorities banned sale of the cheese and it was becoming hard to find, but the ban has been lifted on the grounds that the cheese is a traditional local product made by traditional methods.
Some authors draw a distinction in writing the common names of insects. True flies are in their view best written as two words, such as crane fly, robber fly, bee fly, moth fly, and fruit fly. In contrast, common names of non-dipteran insects that have "fly" in their names are written as one word, e.g. butterfly, stonefly, dragonfly, scorpionfly, sawfly, caddisfly, whitefly. In practice, however, this is a comparatively new convention; especially in older books, names like "saw fly" and "caddis fly", or hyphenated forms such as house-fly and dragon-fly are widely used. In any case, non-entomologists cannot, in general, be expected to tell dipterans, "true flies", from other insects, so it would be unrealistic to expect rigour in the use of common names. Also, exceptions to this rule occur, such as the hoverfly, which is a true fly, and the Spanish fly, a type of blister beetle.
Nearly every element in the universe may be thus personalized, and even the least of these such as tiny Chipmunk and those little insect helpers and mentors of deity and man in the myths, Big Fly (Dǫ’ soh) and Ripener (Corn Beetle) Girl (’Anilt’ ánii ’At’ ééd) (Wyman and Bailey 1964:29–30, 51, 137–144), are as necessary for the harmonious balance of the universe as is the great Sun.
Amanita muscaria, commonly known as the fly agaric or fly amanita, is a basidiomycete of the genus Amanita. It is also a muscimol mushroom. Native throughout the temperate and boreal regions of the Northern Hemisphere, Amanita muscaria has been unintentionally introduced to many countries in the Southern Hemisphere, generally as a symbiont with pine and birch plantations, and is now a true cosmopolitan species. It associates with various deciduous and coniferous trees.
Arguably the most iconic toadstool species, the fly agaric is a large white-gilled, white-spotted, usually red mushroom, and is one of the most recognizable and widely encountered in popular culture.
Although classified as poisonous, reports of human deaths resulting from its ingestion are extremely rare. After parboiling—which weakens its toxicity and breaks down the mushroom's psychoactive substances—it is eaten in parts of Europe, Asia, and North America. Amanita muscaria is noted for its hallucinogenic properties, with its main psychoactive constituents being the compounds ibotenic acid and muscimol. The mushroom was used as an intoxicant and entheogen by the peoples of Siberia, and has a religious significance in these cultures. There has been much speculation on possible traditional use of this mushroom as an intoxicant in other places such as the Middle East, Eurasia, North America, and Scandinavia.Asilidae
The Asilidae are the robber fly family, also called assassin flies. They are powerfully built, bristly flies with a short, stout proboscis enclosing the sharp, sucking hypopharynx. The name "robber flies" reflects their notoriously aggressive predatory habits; they feed mainly or exclusively on other insects and as a rule they wait in ambush and catch their prey in flight.Black fly
A black fly (sometimes called a buffalo gnat, turkey gnat, or white socks) is any member of the family Simuliidae of the Culicomorpha infraorder. They are 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 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 the Americas (S. callidum and S. metallicum in Central America, S. ochraceum in Central and South America).Botfly
Botflies, also known as warble flies, heel flies, and gadflies, are a family of flies technically known as the Oestridae. Their larvae are internal parasites of mammals, some species growing in the host's flesh and others within the gut. Dermatobia hominis is the only species of botfly known to parasitize humans routinely, though other species of flies cause myiasis in humans.Crane fly
Crane fly is a common name referring to any member of the insect family Tipulidae, of the order Diptera, true flies in the superfamily Tipuloidea. Cylindrotominae, Limoniinae, and Pediciinae have been ranked as subfamilies of Tipulidae by most authors, though occasionally elevated to family rank. In the most recent classifications, only Pediciidae is now ranked as a separate family, due to considerations of paraphyly. In colloquial speech, crane flies are sometimes known as mosquito hawks or daddy longlegs, a term also used to describe opiliones or the family Pholcidae, both of which are arachnids. The larvae of crane flies are known commonly as leatherjackets.Crane flies are found worldwide, though individual species usually have limited ranges. They are most diverse in the tropics, and are also common in northern latitudes and high elevations.The Tipulidae is one of the largest groups of flies, including over 15,000 species and subspecies in 525 genera and subgenera. Most crane flies were described by the entomologist Charles Paul Alexander, a fly specialist, in over 1000 research publications.Dragonfly
A dragonfly is an insect belonging to the order Odonata, infraorder Anisoptera (from Greek ἄνισος anisos, "unequal" and πτερόν pteron, "wing", because the hindwing is broader than the forewing). Adult dragonflies are characterized by large, multifaceted eyes, two pairs of strong, transparent wings, sometimes with coloured patches, and an elongated body. Dragonflies can be mistaken for the related group, damselflies (Zygoptera), which are similar in structure, though usually lighter in build; however, the wings of most dragonflies are held flat and away from the body, while damselflies hold the wings folded at rest, along or above the abdomen. Dragonflies are agile fliers, while damselflies have a weaker, fluttery flight. Many dragonflies have brilliant iridescent or metallic colours produced by structural coloration, making them conspicuous in flight. An adult dragonfly's compound eyes have nearly 24,000 ommatidia each.
Fossils of very large dragonfly ancestors in the Protodonata are found from 325 million years ago (Mya) in Upper Carboniferous rocks; these had wingspans up to about 750 mm (30 in). There are about 3,000 extant species. Most are tropical, with fewer species in temperate regions.
Dragonflies are predators, both in their aquatic larval stage, when they are known as nymphs or naiads, and as adults. Several years of their lives are spent as nymphs living in fresh water; the adults may be on the wing for just a few days or weeks. They are fast, agile fliers, sometimes migrating across oceans, and often live near water. They have a uniquely complex mode of reproduction involving indirect insemination, delayed fertilization, and sperm competition. During mating, the male grasps the female at the back of the head, and the female curls her abdomen under her body to pick up sperm from the male's secondary genitalia at the front of his abdomen, forming the "heart" or "wheel" posture.
Loss of wetland habitat threatens dragonfly populations around the world. Dragonflies are represented in human culture on artifacts such as pottery, rock paintings, and Art Nouveau jewelry. They are used in traditional medicine in Japan and China, and caught for food in Indonesia. They are symbols of courage, strength, and happiness in Japan, but seen as sinister in European folklore. Their bright colours and agile flight are admired in the poetry of Lord Tennyson and the prose of H. E. Bates.Emirates (airline)
Emirates (Arabic: طَيَران الإمارات DMG: Ṭayarān Al-Imārāt) is an airline based in Dubai, United Arab Emirates. The airline is a subsidiary of The Emirates Group, which is owned by the government of Dubai's Investment Corporation of Dubai. It is the largest airline in Middle East, operating over 3,600 flights per week from its hub at Dubai International Airport, to more than 150 cities in 80 countries across six continents. Cargo activities are undertaken by Emirates SkyCargo.Emirates is the world's fourth largest airline in scheduled revenue passenger-kilometers flown, the fourth-largest in terms of international passengers carried, and the second-largest in terms of freight tonne kilometers flown. From March 2016 to February 2017 Emirates had the longest non-stop commercial flight from Dubai to Auckland.
During the mid-1980s, Gulf Air began to cut back its services to Dubai. As a result, Emirates was conceived in March 1985 with backing from Dubai's royal family, with Pakistan International Airlines providing two of the airline's first aircraft on wet-lease. With $10 million in start-up capital it was required to operate independently of government subsidy. Pakistan International Airlines provided training facilities to Emirates' cabin crew at its academy. The airline was headed by Ahmed bin Saeed Al Maktoum, the airline's present chairman. In the years following its founding, the airline expanded both its fleet and its destinations. In October 2008, Emirates moved all operations at Dubai International Airport to Terminal 3.Emirates operates a mixed fleet of Airbus and Boeing wide-body aircraft and is one of the few airlines to operate an all-wide-body aircraft fleet (while excluding Emirates Executive). As of February 2019, Emirates is the largest Airbus A380 operator with 109 aircraft in service and a further 14 on order. Since its introduction, the Airbus A380 has become an integral part of the Emirates fleet, especially on long-haul high-traffic routes. Emirates is also the world's largest Boeing 777 operator with 151 aircraft in service.Fly Me to the Moon
"Fly Me to the Moon", originally titled "In Other Words", is a song written in 1954 by Bart Howard. Kaye Ballard made the first recording of the song the year it was written. Frank Sinatra's 1964 version was closely associated with the Apollo missions to the Moon.
In 1999, the Songwriters Hall of Fame honored "Fly Me to the Moon" by inducting it as a "Towering Song".Fly ash
Fly ash or flue ash, also known as pulverised fuel ash in the United Kingdom, is a coal combustion product that is composed of the particulates (fine particles of burned fuel) that are driven out of coal-fired boilers together with the flue gases. Ash that falls to the bottom of the boiler's combustion chamber (commonly called a firebox) is called bottom ash. In modern coal-fired power plants, fly ash is generally captured by electrostatic precipitators or other particle filtration equipment before the flue gases reach the chimneys. Together with bottom ash removed from the bottom of the boiler, it is known as coal ash. Depending upon the source and composition of the coal being burned, the components of fly ash vary considerably, but all fly ash includes substantial amounts of silicon dioxide (SiO2) (both amorphous and crystalline), aluminium oxide (Al2O3) and calcium oxide (CaO), the main mineral compounds in coal-bearing rock strata.
The minor constituents of fly ash depend upon the specific coal bed composition but may include one or more of the following elements or compounds found in trace concentrations (up to hundreds ppm): arsenic, beryllium, boron, cadmium, chromium, hexavalent chromium, cobalt, lead, manganese, mercury, molybdenum, selenium, strontium, thallium, and vanadium, along with very small concentrations of dioxins and PAH compounds. It also has unburnt carbon.In the past, fly ash was generally released into the atmosphere, but air pollution control standards now require that it be captured prior to release by fitting pollution control equipment. In the United States, fly ash is generally stored at coal power plants or placed in landfills. About 43% is recycled, often used as a pozzolan to produce hydraulic cement or hydraulic plaster and a replacement or partial replacement for Portland cement in concrete production. Pozzolans ensure the setting of concrete and plaster and provide concrete with more protection from wet conditions and chemical attack.
In the case that fly (or bottom) ash is not produced from coal, for example when solid waste is incinerated in a waste-to-energy facility to produce electricity, the ash may contain higher levels of contaminants than coal ash. In that case the ash produced is often classified as hazardous waste.Fly fishing
Fly fishing is an angling method that uses a light-weight lure -- called an artificial fly -- to catch fish. The fly is cast using a fly rod, reel, and specialized weighted line. The light weight requires casting techniques significantly different from other forms of casting. The flies may resemble natural invertebrates, baitfish, or other food organisms.
Fly fishing can be done in fresh or salt water. North Americans usually distinguish freshwater fishing between cold-water species (trout, salmon, steelhead) and warm-water species, notably bass. In Britain, where natural water temperatures vary less, the distinction is between game fishing for trout and salmon versus coarse fishing for other species. Techniques for fly fishing differ with habitat (lakes and ponds, small streams, large rivers, bays and estuaries, and open ocean.)
Author Izaak Walton called fly fishing "The Contemplative Man's Recreation".Horse-fly
Horse-flies or horseflies (for other names, see common names) are true flies in the family Tabanidae in the insect order Diptera. They are often large and agile in flight, and the females bite animals, including humans, to obtain blood. They prefer to fly in sunlight, avoiding dark and shady areas, and are inactive at night. They are found all over the world except for some islands and the polar regions (Hawaii, Greenland, Iceland). Both horse-flies and botflies (Oestridae) are sometimes referred to as gadflies.Adult horse-flies feed on nectar and plant exudates; the males have weak mouthparts and only the females bite animals to obtain enough protein from blood to produce eggs. The mouthparts of females are formed into a stout stabbing organ with two pairs of sharp cutting blades, and a spongelike part used to lap up the blood that flows from the wound. The larvae are predaceous and grow in semiaquatic habitats.
Female horse-flies can transfer blood-borne diseases from one animal to another through their feeding habit. In areas where diseases occur, they have been known to carry equine infectious anaemia virus, some trypanosomes, the filarial worm Loa loa, anthrax among cattle and sheep, and tularemia. They can reduce growth rates in cattle and lower the milk output of cows if suitable shelters are not provided.
Horse-flies have appeared in literature since Aeschylus in Ancient Greece mentioned them driving people to madness through their persistent pursuit.Housefly
The housefly (Musca domestica) is a fly of the suborder Cyclorrhapha. It is believed to have evolved in the Cenozoic era, possibly in the Middle East, and has spread all over the world as a commensal of humans. It is the most common fly species found in houses. Adults are grey to black, with four dark, longitudinal lines on the thorax, slightly hairy bodies, and a single pair of membranous wings. They have red eyes, set farther apart in the slightly larger female.
The female housefly usually mates only once and stores the sperm for later use. She lays batches of about 100 eggs on decaying organic matter such as food waste, carrion, or faeces. These soon hatch into legless white larvae, known as maggots. After 2 to 5 days of development, these metamorphose into reddish-brown pupae, about 8 mm (0.3 in) long. Adult flies normally live for 2 to 4 weeks, but can hibernate during the winter. The adults feed on a variety of liquid or semiliquid substances, as well as solid materials which have been softened by their saliva. They can carry pathogens on their bodies and in their faeces, contaminate food, and contribute to the transfer of food-borne illnesses, while, in numbers, they can be physically annoying. For these reasons, they are considered pests.
Houseflies have been used in the laboratory in research into ageing and sex determination. Flies appear in literature from Ancient Greek myth and Aesop's The Impertinent Insect onwards. Authors sometimes choose the fly to speak of the brevity of life, as in William Blake's 1794 poem "The Fly", which deals with mortality subject to uncontrollable circumstances.Hoverfly
Hoverflies, sometimes called flower flies, or syrphid flies, make up the insect family Syrphidae. As their common name suggests, they are often seen hovering or nectaring at flowers; the adults of many species feed mainly on nectar and pollen, while the larvae (maggots) eat a wide range of foods. In some species, the larvae are saprotrophs, eating decaying plant and animal matter in the soil or in ponds and streams. In other species, the larvae are insectivores and prey on aphids, thrips, and other plant-sucking insects.
Aphids alone cause tens of millions of dollars of damage to crops worldwide every year; because of this, aphid-eating hoverflies are being recognized as important natural enemies of pests, and potential agents for use in biological control. Some adult syrphid flies are important pollinators.
About 6,000 species in 200 genera have been described. Hoverflies are common throughout the world and can be found on all continents except Antarctica. Hoverflies are harmless to most other animals, despite their mimicry of more dangerous wasps and bees, which wards off predators.Mayfly
Mayflies (also known as Canadian soldiers in the United States, and as shadflies or fishflies in Canada and the upper Midwestern U.S.; also up-winged flies in the United Kingdom) are aquatic insects belonging to the order Ephemeroptera. This order is part of an ancient group of insects termed the Palaeoptera, which also contains dragonflies and damselflies. Over 3,000 species of mayfly are known worldwide, grouped into over 400 genera in 42 families.
Mayflies exhibit a number of ancestral traits that were probably present in the first flying insects, such as long tails and wings that do not fold flat over the abdomen. Their immature stages are aquatic fresh water forms (called "naiads" or "nymphs"), whose presence indicates a clean, unpolluted environment. They are unique among insect orders in having a fully winged terrestrial adult stage, the subimago, which moults into a sexually mature adult, the imago.
Mayflies "hatch" (emerge as adults) from spring to autumn, not necessarily in May, in enormous numbers. Some hatches attract tourists. Fly fishermen make use of mayfly hatches by choosing artificial fishing flies that resemble the species in question. One of the most famous English mayflies is Rhithrogena germanica, the fisherman's "March brown mayfly".The brief lives of mayfly adults have been noted by naturalists and encyclopaedists since Aristotle and Pliny the Elder in classical times. The German engraver Albrecht Dürer included a mayfly in his 1495 engraving The Holy Family with the Mayfly to suggest a link between heaven and earth. The English poet George Crabbe compared the brief life of a daily newspaper with that of a mayfly in the satirical poem "The Newspaper" (1785), both being known as "ephemera".Rugby union positions
In the game of rugby union, there are 15 players on each team, comprising eight forwards (wearing jerseys numbered 1–8) and seven backs (numbered 9–15). In addition, there may be up to eight replacement players "on the bench", numbered 16–23. Players are not restricted to a single position, although they generally specialise in just one or two that suit their skills and body types. Players that play multiple positions are called "utility players".
The scrum (a contest used to restart play) must consist of eight players from each team: the "front row" (two props, a loosehead and tighthead, and a hooker), the "second row" (two locks), and a "back row" (two flankers, and a number 8). The players outside the scrum are called "the backs": Scrum Half, Fly Half, Inside centre, Outside centre, two wings, and a fullback.
Early names, such as "three-quarters" (for the wings and centres) and "outside-halves" (for fly-half) are sometimes used in the Northern Hemisphere, while in the Southern Hemisphere the fly-half and inside centre are colloquially called "first five-eighth" and "second five-eighth" respectively, while the scrum-half is known as the "half-back".
The backs play behind the forwards and are usually more lightly built and faster. Successful backs are skilful at passing and kicking. Full-backs need to be good defenders and kickers, and have the ability to catch a kicked ball. The wingers are usually among the fastest players in a team and score many of the tries. The centres' key attacking roles are to break through the defensive line and link successfully with wingers. The fly-half can be a good kicker and generally directs the back line. The scrum-half retrieves the ball from the forwards and needs a quick and accurate pass to get the ball to the backs (often firstly to the fly-half). Forwards compete for the ball in scrums and line-outs and are generally bigger and stronger than the backs. Props push in the scrums, while the hooker tries to secure the ball for his team by "hooking" it back with his heel. The hooker is also the one who is responsible for throwing the ball in at line-outs, where it is mostly competed for by the locks, who are generally the tallest players on the team. The flankers and number eight are expected to be the first players to arrive at a breakdown and play an important role in securing possession of the ball for their team.
There are a maximum of 15 players from each team on a rugby field at one time. The players' position at the start of the game are shirts, 1 to 15. The positions are divided into two main categories; forwards (numbered 1 to 8) and backs (numbered 9 to 15). In international matches, there are eight substitutes that can replace an on-field team member. The substitutes, numbered 16 to 23, can either take up the position of the player they replace or the on-field players can be shuffled to make room for this player in another position. Typically, the replacement players will have a number that corresponds with their intended replacement position with the numbers from 16 to 20 being forwards and 21 to 23 being backs (depending on the composition of the reserves). There are no personal squad numbers and a versatile player's position and number may change from one game to the next. Players can also change positions with players on the field during the match, and, as long as the laws are followed, any player can change positions with another player during the match. Common examples are the fly-half playing the full-back's position in defence or a prop taking the hooker's position at line-outs.
Different positions on the field suit certain skill sets and body types, generally leading to players specialising in a limited number of positions. Each position has certain roles to play on the field, although most have been established through convention rather than law. During general play, as long as they are not offside, the players may be positioned anywhere on the field. It is during the set pieces, scrum and line-out, when the positions are enforced.Tsetse fly
Tsetse ( SEET-see, US: TSEET-see or UK: TSET-see), sometimes spelled tzetze and also known as tik-tik flies, are large biting flies that inhabit much of tropical Africa. Tsetse flies include all the species in the genus Glossina, which are placed in their own family, Glossinidae. The tsetse are obligate parasites that live by feeding on the blood of vertebrate animals. Tsetse have been extensively studied because of their role in transmitting disease. They have a prominent economic impact in sub-Saharan Africa as the biological vectors of trypanosomes, which cause human sleeping sickness and animal trypanosomiasis. Tsetse are multivoltine and long-lived, typically producing about four broods per year, and up to 31 broods over their lifespans.Tsetse can be distinguished from other large flies by two easily observed features. Tsetse fold their wings completely when they are resting so that one wing rests directly on top of the other over their abdomens. Tsetse also have a long proboscis, which extends directly forward and is attached by a distinct bulb to the bottom of their heads.
Fossilized tsetse have been recovered from the Florissant Fossil Beds in Colorado, laid down some 34 million years ago. Twenty-three extant species of tsetse flies are known from Africa.
Tsetse were absent from much of southern and eastern Africa until colonial times. The accidental introduction of rinderpest in 1887 killed most of the cattle in these parts of Africa and the resulting famine removed much of the human population. Thorny bush ideal for tsetse quickly grew up where there had been pasture, and was repopulated by wild mammals. Tsetse and sleeping sickness soon colonised the whole region, effectively excluding the reintroduction of farming and animal husbandry. Sleeping sickness has been described by some conservationists as "the best game warden in Africa".United Airlines
United Airlines, Inc., commonly referred to as United, is a major American airline headquartered at Willis Tower in Chicago, Illinois. United operates a large domestic and international route network, with an extensive presence in the Asia-Pacific region. It is a founding member of the Star Alliance, the world's largest airline alliance with a total of 28 member airlines. Regional service is operated by independent carriers under the brand name United Express. United was established by the amalgamation of several airlines in the late 1920s, the oldest of these being Varney Air Lines, which was founded in 1926.United has seven hubs, with Chicago–O'Hare being its largest in terms of passengers carried and the number of departures. The company employs over 86,000 people. Through the airline's parent company, United Airlines Holdings, it is publicly traded under NYSE: UAL with a market capitalization of over US$21 billion as of January 2018.Venus flytrap
The Venus flytrap (Dionaea muscipula) is a carnivorous plant native to subtropical wetlands on the East Coast of the United States in North Carolina and South Carolina. It catches its prey—chiefly insects and arachnids—with a trapping structure formed by the terminal portion of each of the plant's leaves, which is triggered by tiny hairs (called "trigger hairs" or "sensitive hairs") on their inner surfaces.
When an insect or spider crawling along the leaves contacts a hair, the trap prepares to close, snapping shut only if another contact occurs within approximately twenty seconds of the first strike. Triggers may occur if one-tenth of the insect is within contact. The requirement of redundant triggering in this mechanism serves as a safeguard against wasting energy by trapping objects with no nutritional value, and the plant will only begin digestion after five more stimuli to ensure it has caught a live bug worthy of consumption.
Dionaea is a monotypic genus closely related to the waterwheel plant (Aldrovanda vesiculosa) and sundews (Drosera), all of which belong to the family Droseraceae.Zelina Vega
Thea Megan Trinidad (born December 27, 1990) is an American professional wrestler, professional wrestling manager and actress currently signed to WWE, where she performs on SmackDown brand under the ring name Zelina Vega.
She previously worked in Total Nonstop Action Wrestling (TNA) as Rosita, and for various independent promotions under her real name. In TNA, she was a one-time Knockouts Tag Team Champion with Sarita.
Extant Diptera families