Types of Flies: True flies are insects of the order Diptera. The name is derived from the Greek δι- di- “two”, and πτερόν pteron “wings”. Insects of this order use only a single pair of wings to fly. The hind wings have evolved into advanced mechanosensory organs known as halteres. They act as high-speed sensors of rotational movement and allow dipterans to perform advanced aerobatics. Diptera is a large order containing an estimated 1,000,000 species including horse-flies, crane flies, hoverflies and others. Although researchers describe only about 125,000 species.
All types of 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. Their wing arrangement gives them great maneuverability in flight, and claws and pads on their feet. It enables them to cling to smooth surfaces. These types of flies undergo complete metamorphosis. They lay eggs on the larval food-source and the larvae, which lack true limbs, develop in a protected environment. They develop often inside the source of their food.
The pupa is a tough capsule from which the adult emerges when ready to do so. All types of flies mostly have short lives as adults. Diptera is one of the major insect orders and is of considerable ecological and human importance. Many types of flies are important pollinators, second only to the bees (Hymenoptera) and their Hymenopteran relatives. These types of flies may have been among the evolutionarily earliest pollinators responsible for early plant pollination.
Researchers use fruit flies as model organisms. But less benignly, mosquitoes are vectors for malaria, dengue, West Nile fever, yellow fever, encephalitis, and other infectious diseases. And also for houseflies spread food-borne illnesses. Flies can be annoyances especially in some parts of the world. They can occur in large numbers, buzzing and settling on the skin or eyes to bite or seek fluids.
Other types of flies are Larger flies such as tsetse flies and screwworms cause significant economic harm to cattle. In fishing bait and as food for carnivorous animals, they use blowfly larvae, known as gentles, and other dipteran larvae, known more generally as maggots. Doctors use them in medicine in debridement to clean wounds.
Diversity and types of flies
All terrestrial habitats in the world apart from Antarctica has flies in abundance. They include many familiar insects such as house flies, blow flies, mosquitoes, gnats, black flies, midges and fruit flies. Researchers describe more than 150,000 types of flies. The actual species diversity is much greater, with 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 a total of about 19,000 species of Diptera in Europe, 22,000 in the Nearctic region, 20,000 in the Afro-tropical 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. The largest fly in the world is Gauromydas heroes (Asiloidea), with a length of up to 7 cm (2.8 in). While the smallest is Euryplatea nanaknihali, which at 0.4 mm (0.016 in) is smaller than a grain of salt. Brachycera is ecologically very diverse, with many being predatory at the larval stage and some being parasitic. Animals parasitized 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. Researchers believe some of the earliest pollinators of plants may have been flies.
Flies, principally the family Cecidomyiidae (gall midges) has the greatest diversity of gall-forming insects. 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. Fungus feeding flies that visit fungus infected male flowers pollinate some plants. 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
Life cycle and development
Diptera goes through a complete metamorphosis with four distinct life stages – egg, larva, pupa and adult. In different types of 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 they reduce or modify those of Brachyceran larvae. 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 inTermitoxenia (Phoridae) females have incubation pouches, and a fully 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. Oviduct retains single fertilised egg 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. Particularly the Nematocera, the pupa is intermediate between the larval and adult form; They describe these pupae 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 aren’t 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 female flies is 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.
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; 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 sand flies (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.
Uses of flies in Scientific Research
Model organism in research uses Drosophila melanogaster, a fruit fly. Because it is easy to breed and rear it in the laboratory. It has a small genome and the fact that many of its genes have counterparts in higher eukaryotes. This species has a large number of genetic studies undertaken; these have had a profound impact on the study of gene expression, gene regulatory mechanisms and mutation. Other studies have investigated physiology, microbial 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 forensics. Researchers identify maggot species by their anatomical features and by matching their DNA. Maggots of different species and types of flies visit corpses and carcasses 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. People breed some species of maggots such as blowfly larvae (gentles) and bluebottle larvae (casters) 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. Researchers suggest that they use fly larvae at a large scale as food for farmed chickens, pigs, and fish.
Use of Fly Larvae
However, consumers oppose the inclusion of insects in their food. And the use of insects in animal feed remains illegal in areas such as the European. Medicals use fly larvae as a biomedical tool for wound care and treatment. Maggot debridement therapy (MDT) is the use of blowfly larvae to remove the dead tissue from wounds, most commonly being amputations. Historically, doctors used this 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. They expose Sardinian cheese casu marzu to flies known as skippers such as Piophila casei. They are the members of the family Piophilidae. The digestive activities of fly larvae soften the cheese and modify the aroma as part of the process of maturation. At one time European Union authorities banned the sale of the cheese and it was becoming hard to find. But lifted the ban on the grounds that the cheese is a traditional local product and people use traditional methods.
Everyone realizes that flies aren’t the cleanest of the pest! There are different types of flies, they might be little in measure yet their germ-carrying potential is actually stunning. That is on account of they feed on excrement, liquids from injuries, and rotting matter, for example, garbage. Keep in mind that flies are an unsafe pest! Monitor house fly pollution and be aware of what and where you eat when heading out to locales influenced by fly-borne illnesses. Hicare is India’s No.1 Pest control service providers. Call Hicare for Flies control and other pest control services.