**5. Anatomy and physiology**

Any member of the order Diptera has evolved a simplified structure and physiological diversity. Dipteran larvae can be differentiated from maximum of other insects by means of their absence of segmented thoracic legs. As a replacement for the customary jointed legs, several crowds have one or more couples of fleshy locomotory prolegs on abdomen and or thorax, each with curled or even hook-like spines. Fleshy tubercles arise in several species and help together in locomotory and sensory tasks. The larva head may be heavily sclerotized and exposed, as in midges, or else toughly condensed and only moderately proud (from time to time only with mouthparts expanded). The abdomen and thorax are generally fleshy, from time to time with dispersed sclerotized plates, and the whole body is usually long and

tubular, mean lengths are 2–25 mm, however can range 10 cm in several species. Always, wing pads are lacking in larvae, however existing in pupae.

At the opposite extreme are tsetse flies (*Glossina*) and three families of pupipara (females birth young ones) parasites (Nycteribiidae and Streblidae feed only on bats blood, and Hippoboscidae feed on the blood of mammals and birds). Within these families, single egg is formed at one time and it hatches internally. The larva is nourished and retained within a kind of womb, ejected out after this has matured and instantly forms a pupa. Hence, larvae of these flies have not an independent life. As pupa is immovable, the active life of fly is spent as an adult. Maximum of Streblidae and Hippoboscidae, and whole tsetse flies, bear wings and generally transfer to different hosts, however certain species of these families and entire Nycteribiidae, cannot fly and are frequently wingless. Wingless flies might be recognized as flies afterwards thorough morphological checkup only. The lifespan of an adult varies by species and may extend from a few hours to weeks or months. Even though a multivoltine life cycle is mostly prevailing, certain dipterans create one generation only in each year (univoltine) and might need many years to create a fresh generation in arctic and further cool atmospheres. The shorter generation periods illustrating this order allow dipterans to react rapidly to fresh diet or other resources and to recover quickly from critical circumstances like stream waves.

*Typical Flies: Natural History, Lifestyle and Diversity of Diptera*

*DOI: http://dx.doi.org/10.5772/intechopen.91391*

There are many different shapes of true flies and they are soft-bodied insects, most are fairly small (less than 1.5 cm long), but a few can be larger (up to 4 cm). The adult body colorations of different fruit fly species vary from black through various shades of brown to orange or yellow. **Adult** antennae are filiform, stylate or aristate, mouthparts suctorial (haustellate), mesothorax larger than pro or metathorax, one pair of wings (front), hind wings reduced (halteres) and tarsi 5-segmented. Adult fly appears from soft pupa and is lined with a colorless integument (skin), and have made perfectly (although not fully pigmented) bristles and hairs. The newly evolving adult sips air to swell its wings and body, and to power flow of blood through body. In more progressive flies of set Schizophora, in head, an expandable membranous sac ptilinum is used to help this procedure. The ptilinum shrinks away afterward it has done its job, but behind, it leaves ptilinal suture, which is a horseshoe-shaped furrow growing over and alongside antennal sockets

Mostly, flies lay eggs that hatch into minute larvae afterward a few hours or some days. The eggs number put down by one female fluctuates from 1 to around 250. But, a large number of succeeding eggs batches can be laid. Green bottle fly (*Lucilia sericata* Meigen), in confinement has set almost 2000 eggs. But, the number total is perhaps less than 1000 in ordinary environment when energy and time are gone seeing for proper places for laying eggs. Sites for egg-laying, preferred by females instinctively, are closely linked to habitats of larvae. As many larvae of fly forage into soft organic maters, several females have established telescopic ovipositors, made from either last three otherwise four segments of abdomen. The female uses an ovipositor to press its eggs within a mass of rotting matter. House flies and blow flies thrust their eggs among membranes of meat otherwise into any suitable cavity in rotting organic matter. Small fruit fly (*Drosophila* vinegar fly) that lays eggs in decomposing fruits and fermenting matters as well have this kind of ovipositor, but, large fruit fly (Mediterranean fruit fly) that lays eggs in the rind of developing fruits, bears a harder ovipositor. An elaborate ovipositors set up in robber fly is used to thrust eggs into axils of grasses and interstices of flower heads,

**6.1 Adults**

**6.2 Eggs**

**9**

and found in Schizophora only.

Various larvae breathe through the skin and minute gills exist in certain taxa. Others dipterans get oxygen using spiracles and either lengthy or small breathing tubes from the atmosphere (as in mosquitoes). Limited groups remove oxygen from plant tissues. Certain true midges like blood worms (a type of true midge), which to some extent frequent anoxic habitations, have an invertebrate form of breathing pigment hemoglobin that supports in catching of oxygen molecules.

Adult dipterans vary in size from 1 to 12 mm; however, comparative giants of 25–60 mm long are identified wherein the later contain bigger crane flies. They have a single pair of membranous wings; hind wings are rudimentary and nonfunctional for flying whereas the bodies are long and tubular. In feeding adults, the mouthparts are modified to sharp tubes for penetrating flesh and sucking up liquids as in mosquitoes or adapted for consuming liquid food using either blunt pads for sponging up liquid. Although crane flies are from time to time called 'mosquito hawks', these do not consume mosquitoes, nor they bite human being.

#### **6. Reproduction and life history**

Entirely, Diptera have a complete metamorphosis (holometabolous), meaning that they go through four life stages, for instance, egg, larva, pupa and adult. The number of eggs laid by a female varies by species, from just a few eggs to thousands of them. Mom does not have any involvement in the care of its babies, so it lays eggs on a food supply where they hatch. Females place their eggs in clumps or singly, generally near water and from time to time attached to other things. Eggs have a tendency to last only for limited days with the exception of diapause eggs, which are used to avoid unfriendly temperatures or the shortage of water in environment. Larvae, which often look like worms, hatch from the eggs and after hatching, the larvae of maximum species traverse three to four instars (six to seven in black flies) prior to pupate on land or near bottom or at water surface. The larval stage lasts for somewhere from nearly 2 weeks to some months. These larvae may have 'false legs' called prolegs that look like the little legs seen on caterpillars. But, Diptera larvae lack any truly jointed legs. As larvae are always divergent morphologically from adults and moreover live in different habitats, flies basically spend two distinct lives and thus are capable to adjust environmental changes successfully. In several flies (robber flies), neither larval nor adult stage predominates, their larvae actively forage in soil and both sexes of adult flies in flight catch other insects. Among mosquitoes, black flies and correlated blood sucking flies, larvae have distinguishing structures and spend active lives under water, and the complex mating method of adults is followed by blood sucking and egg laying (in the case of females).

There are several flies in which one stage is predominant, for example, groups of adult midges (Chironomidae), are noticeable and bothersome, however adults midge live just long enough generally fewer than a day to mate and lay eggs. The maximum of life cycle by the larval stage is occupied under water. Larvae in appearance are wormlike and certain are adjusted to oxygen-poor conditions, for example, the 'blood worm' that lives in the sludge of standing waters, usages hemoglobin as a breathing pigment. Larvae of few midges live in silken tubes, either filtering minute organisms from water for food or preying upon other creatures. Certain midge larvae have developed an elaborate mutualism or symbiosis, using other aquatic creatures, for instance, certain midge larvae and *Nostoc* (a genus of blue-green algae) utilize excreta of each other.

*Typical Flies: Natural History, Lifestyle and Diversity of Diptera DOI: http://dx.doi.org/10.5772/intechopen.91391*

At the opposite extreme are tsetse flies (*Glossina*) and three families of pupipara (females birth young ones) parasites (Nycteribiidae and Streblidae feed only on bats blood, and Hippoboscidae feed on the blood of mammals and birds). Within these families, single egg is formed at one time and it hatches internally. The larva is nourished and retained within a kind of womb, ejected out after this has matured and instantly forms a pupa. Hence, larvae of these flies have not an independent life. As pupa is immovable, the active life of fly is spent as an adult. Maximum of Streblidae and Hippoboscidae, and whole tsetse flies, bear wings and generally transfer to different hosts, however certain species of these families and entire Nycteribiidae, cannot fly and are frequently wingless. Wingless flies might be recognized as flies afterwards thorough morphological checkup only. The lifespan of an adult varies by species and may extend from a few hours to weeks or months. Even though a multivoltine life cycle is mostly prevailing, certain dipterans create one generation only in each year (univoltine) and might need many years to create a fresh generation in arctic and further cool atmospheres. The shorter generation periods illustrating this order allow dipterans to react rapidly to fresh diet or other resources and to recover quickly from critical circumstances like stream waves.

#### **6.1 Adults**

tubular, mean lengths are 2–25 mm, however can range 10 cm in several species.

Various larvae breathe through the skin and minute gills exist in certain taxa. Others dipterans get oxygen using spiracles and either lengthy or small breathing tubes from the atmosphere (as in mosquitoes). Limited groups remove oxygen from plant tissues. Certain true midges like blood worms (a type of true midge), which to some extent frequent anoxic habitations, have an invertebrate form of breathing

Adult dipterans vary in size from 1 to 12 mm; however, comparative giants of 25–60 mm long are identified wherein the later contain bigger crane flies. They have a single pair of membranous wings; hind wings are rudimentary and nonfunctional for flying whereas the bodies are long and tubular. In feeding adults, the mouthparts are modified to sharp tubes for penetrating flesh and sucking up liquids as in mosquitoes or adapted for consuming liquid food using either blunt pads for sponging up liquid. Although crane flies are from time to time called 'mosquito hawks', these do not consume mosquitoes, nor they bite

Entirely, Diptera have a complete metamorphosis (holometabolous), meaning that they go through four life stages, for instance, egg, larva, pupa and adult. The number of eggs laid by a female varies by species, from just a few eggs to thousands of them. Mom does not have any involvement in the care of its babies, so it lays eggs on a food supply where they hatch. Females place their eggs in clumps or singly, generally near water and from time to time attached to other things. Eggs have a tendency to last only for limited days with the exception of diapause eggs, which are used to avoid unfriendly temperatures or the shortage of water in environment. Larvae, which often look like worms, hatch from the eggs and after hatching, the larvae of maximum species traverse three to four instars (six to seven in black flies) prior to pupate on land or near bottom or at water surface. The larval stage lasts for somewhere from nearly 2 weeks to some months. These larvae may have 'false legs' called prolegs that look like the little legs seen on caterpillars. But, Diptera larvae lack any truly jointed legs. As larvae are always divergent morphologically from adults and moreover live in different habitats, flies basically spend two distinct lives and thus are capable to adjust environmental changes successfully. In several flies (robber flies), neither larval nor adult stage predominates, their larvae actively forage in soil and both sexes of adult flies in flight catch other insects. Among mosquitoes, black flies and correlated blood sucking flies, larvae have distinguishing structures and spend active lives under water, and the complex mating method of adults is followed by blood sucking and egg laying (in the case of females).

There are several flies in which one stage is predominant, for example, groups of

adult midges (Chironomidae), are noticeable and bothersome, however adults midge live just long enough generally fewer than a day to mate and lay eggs. The maximum of life cycle by the larval stage is occupied under water. Larvae in appearance are wormlike and certain are adjusted to oxygen-poor conditions, for example, the 'blood worm' that lives in the sludge of standing waters, usages hemoglobin as a breathing pigment. Larvae of few midges live in silken tubes, either filtering minute organisms from water for food or preying upon other creatures. Certain midge larvae have developed an elaborate mutualism or symbiosis, using other aquatic creatures, for instance, certain midge larvae and *Nostoc* (a genus of

blue-green algae) utilize excreta of each other.

**8**

Always, wing pads are lacking in larvae, however existing in pupae.

pigment hemoglobin that supports in catching of oxygen molecules.

human being.

**6. Reproduction and life history**

*Life Cycle and Development of Diptera*

There are many different shapes of true flies and they are soft-bodied insects, most are fairly small (less than 1.5 cm long), but a few can be larger (up to 4 cm). The adult body colorations of different fruit fly species vary from black through various shades of brown to orange or yellow. **Adult** antennae are filiform, stylate or aristate, mouthparts suctorial (haustellate), mesothorax larger than pro or metathorax, one pair of wings (front), hind wings reduced (halteres) and tarsi 5-segmented. Adult fly appears from soft pupa and is lined with a colorless integument (skin), and have made perfectly (although not fully pigmented) bristles and hairs. The newly evolving adult sips air to swell its wings and body, and to power flow of blood through body. In more progressive flies of set Schizophora, in head, an expandable membranous sac ptilinum is used to help this procedure. The ptilinum shrinks away afterward it has done its job, but behind, it leaves ptilinal suture, which is a horseshoe-shaped furrow growing over and alongside antennal sockets and found in Schizophora only.

#### **6.2 Eggs**

Mostly, flies lay eggs that hatch into minute larvae afterward a few hours or some days. The eggs number put down by one female fluctuates from 1 to around 250. But, a large number of succeeding eggs batches can be laid. Green bottle fly (*Lucilia sericata* Meigen), in confinement has set almost 2000 eggs. But, the number total is perhaps less than 1000 in ordinary environment when energy and time are gone seeing for proper places for laying eggs. Sites for egg-laying, preferred by females instinctively, are closely linked to habitats of larvae. As many larvae of fly forage into soft organic maters, several females have established telescopic ovipositors, made from either last three otherwise four segments of abdomen. The female uses an ovipositor to press its eggs within a mass of rotting matter. House flies and blow flies thrust their eggs among membranes of meat otherwise into any suitable cavity in rotting organic matter. Small fruit fly (*Drosophila* vinegar fly) that lays eggs in decomposing fruits and fermenting matters as well have this kind of ovipositor, but, large fruit fly (Mediterranean fruit fly) that lays eggs in the rind of developing fruits, bears a harder ovipositor. An elaborate ovipositors set up in robber fly is used to thrust eggs into axils of grasses and interstices of flower heads, and from time to time even into plant tissues, to protect and conceal them from drying. Once hatched, the larvae drop to the ground and burrow below the soil.

as decay develops from newly deceased carcass through thoroughness and decomposition to mummification. Though several maggots only appear during a noticeably definite stage of animal decomposition, the greedy large maggots of various blow flies nourish on any animal material, comprising living tissues [40].

*Typical Flies: Natural History, Lifestyle and Diversity of Diptera*

*DOI: http://dx.doi.org/10.5772/intechopen.91391*

The number of instars or larval stages is six or seven in black flies (Simuliidae) and four in most other Nematocera. Alongside the second line of evolution of flies, Brachycera have from five to eight instars, while Cyclorrhapha maggots of the most advanced flies have only three instars. Three economically important free-living instars exist for tephritid fruit flies. The *Urophora jaceana* (Hering) and *Urophora cardui* (Linnaeus) have the first instar remaining in the egg and exits as a second instar. One or two species have no molts and from time to time molts arise earlier to the larva hatches from the egg. Muscidae, for instance, are organized in three groups according to whether they are monomorphic (pass the first two instars in the egg, have one free larval instar), dimorphic (pass the first instar in egg, have two free larval instars) or trimorphic (have three free larval instars). Monomorphic larvae are constantly predatory; however, dimorphic and trimorphic larvae feed first on decaying matter (saprophagous) and, on the other hand, they may or may

Larval breathing is adjusted to the medium wherein larvae live. Even though limited parasitic larvae (Pipunculidae, parasite in Drosophilidae and froghoppers, internal parasite of scale insect) take oxygen by the skin and maximum dipterous larvae require tracheal system to allocate oxygen. Basically, tracheal system possibly is exteriorly opened on each body segment by paired spiracles. The soil occupiers, Scatopsidae and Bibionidae, hold this system, even though maximum families have retained spiracles only on thorax (one pair) and one at the abdomen tip. These are even sealed in several aquatic larvae (larvae of biting midges and luminous larvae of some fungus gnats). On the other hand, larvae of mosquitoes and many other water-living fly larvae repeatedly come to surface for renovation of their oxygen provisions. Certain larvae of flies pierce twigs of underwater plants to get oxygen made by photosynthesis activity. In Cyclorrhapha, maggots heavily depend on posterior spiracles complex. Pupae take breaths by prothoracic spiracles, which are from time to time furnished with long tubes extending outside the puparium or

The pupal stage of a true fly is enclosed within a hard capsule (skin). It may have some of its legs and body parts visible or it may be hidden inside a larval skin and just looks like a brown capsule. Dipteran pupae have non-functional mandibles (adecticous) and may have the appendages free from the body (exarate) or glued to the body (obtect). In exarate type, the pupa is concealed inside the hardened skin (puparium) of the last larval instar. The external structures of adult fly (antennae, eyes, legs, wings) are obviously noticeable in the pupa. However, the pupa, is not every time visible to the sight, it may be encircled either in a puparium that is a case formed by toughening of the larval skin or in a cocoon of extraneous matter (silk, soil or a mixture of the two). In flies of Stratiomyidae family and others, which have maggots like larvae (whole Cyclorrhapha), a puparium is formed. Many fly families sporadically form cocoons and cocoon has developed an adaptive tool, which delivers an extra safety to the pupa. Pupae of mosquitoes, black flies (Simuliidae) and limited aquatic midges swim vigorously. Several pupae that lie in wood or in soil have evolved spines in order to aid them for effort to have their way to the

not be predatory in their final instar [41].

surface just before appearance of adult insects.

cocoon.

**11**

**6.4 Pupae**

#### **6.3 Larvae**

The larvae of true flies look like thick segmented worms, but they have many different shapes. They do not have jointed legs, unlike beetle larvae. Some larvae have mouthparts and a distinct head, but most do not bear typical structures. Larvae of fly have single joint characteristic, wherein all have lack of jointed true thoracic legs. Several larvae of flies have 'false legs' (pseudopods or prolegs) related to those that care fleshy abdomen of caterpillars. Flies are greatly more adjustable than caterpillars in this respect, and around anybody segment can have prolegs. The prolegs aid larvae to push through soil or crawl into narrow spaces.

The evolutionary tendency among larvae of fly has been in the direction of structural simplification, so, usually, primitive flies larvae are extra structured than larvae of further importantly evolved flies that display better physiological adaptability. Most members of suborder Nematocera or Brachycera larvae bear a wellbuilt head having antennae, complex mouthparts and palpi related to several adult insects. Frequently they are so structurally modified to their distinctive mode of life that these are not capable to adjust any other. It is particularly true among aquatic larvae such as mosquitoes and possibly reaches at extreme in larvae of mountain midge that live in roaring torrents and creep on immersed rocks. Segments of their body are furnished with suckers and clinging processes. The maggots of Cyclorrhapha have tiny external structure other than the posterior spiracles and black mouth hooks.

In comparison to very specialized larvae, nearly half species of flies have larvae called maggots. The maggots have missing the complex head capsule of primitive flies. Their sharp anterior ends comprise one or a couple of mouth hooks. The rounded posterior end has one couple of spiracles posteriorly (outer air holes), which look as black spots to the naked eye. Microscopically, spiracles are recognized as pores or a complex arrangement of slits, which are valuable in differentiating of species.

Even though maggots display structural homogeneity, they are dissimilar physiologically. Maximum of maggots feed upon rotting organic material, however in forensic studies; there are wide dissimilarities in the food likings of various flies. Larvae of gout fly of barley and frit fly of oat are maggots of flies that fit into plantfeeding family Chloropidae. The hessian fly of wheat is the destructive larva of *Mayetiola destructor* (Say) (gall midges) in nematoceran family Cecidomyiidae. Even though external structure of maximum nematoceran larvae is diverse, the structure of gall midges that live totally submerged in plant tissue, has developed in the direction of simplification. Gall midges fly larvae are known as well gall gnats for the reason that feeding larvae result in the development of disfiguring galls on stems or leaves and harm to several kinds of plants. So, they have developed physiological diversity and simplified structure concerning food floras as have maggots of further progressive flies.

The greatest well-known blow flies existing are sheep blow flies, essentially species in *Lucilia* genus. Maggots of *L. sericata*, forage on tiny deceased animals, and in garbage and abattoirs cans, oviposit in dirty wool around anus of sheep otherwise in pus oozing from wounds and scratches, wherein these are essential means of sheep strike illness. These maggots from time to time occur in soil adjacent to buildings in towns and their diet basis is not recognized. Eight 'waves' of worms have been well-known, and each wave assaults deceased animals in a severe series

#### *Typical Flies: Natural History, Lifestyle and Diversity of Diptera DOI: http://dx.doi.org/10.5772/intechopen.91391*

as decay develops from newly deceased carcass through thoroughness and decomposition to mummification. Though several maggots only appear during a noticeably definite stage of animal decomposition, the greedy large maggots of various blow flies nourish on any animal material, comprising living tissues [40].

The number of instars or larval stages is six or seven in black flies (Simuliidae) and four in most other Nematocera. Alongside the second line of evolution of flies, Brachycera have from five to eight instars, while Cyclorrhapha maggots of the most advanced flies have only three instars. Three economically important free-living instars exist for tephritid fruit flies. The *Urophora jaceana* (Hering) and *Urophora cardui* (Linnaeus) have the first instar remaining in the egg and exits as a second instar. One or two species have no molts and from time to time molts arise earlier to the larva hatches from the egg. Muscidae, for instance, are organized in three groups according to whether they are monomorphic (pass the first two instars in the egg, have one free larval instar), dimorphic (pass the first instar in egg, have two free larval instars) or trimorphic (have three free larval instars). Monomorphic larvae are constantly predatory; however, dimorphic and trimorphic larvae feed first on decaying matter (saprophagous) and, on the other hand, they may or may not be predatory in their final instar [41].

Larval breathing is adjusted to the medium wherein larvae live. Even though limited parasitic larvae (Pipunculidae, parasite in Drosophilidae and froghoppers, internal parasite of scale insect) take oxygen by the skin and maximum dipterous larvae require tracheal system to allocate oxygen. Basically, tracheal system possibly is exteriorly opened on each body segment by paired spiracles. The soil occupiers, Scatopsidae and Bibionidae, hold this system, even though maximum families have retained spiracles only on thorax (one pair) and one at the abdomen tip. These are even sealed in several aquatic larvae (larvae of biting midges and luminous larvae of some fungus gnats). On the other hand, larvae of mosquitoes and many other water-living fly larvae repeatedly come to surface for renovation of their oxygen provisions. Certain larvae of flies pierce twigs of underwater plants to get oxygen made by photosynthesis activity. In Cyclorrhapha, maggots heavily depend on posterior spiracles complex. Pupae take breaths by prothoracic spiracles, which are from time to time furnished with long tubes extending outside the puparium or cocoon.

### **6.4 Pupae**

and from time to time even into plant tissues, to protect and conceal them from drying. Once hatched, the larvae drop to the ground and burrow below the soil.

The larvae of true flies look like thick segmented worms, but they have many different shapes. They do not have jointed legs, unlike beetle larvae. Some larvae have mouthparts and a distinct head, but most do not bear typical structures. Larvae of fly have single joint characteristic, wherein all have lack of jointed true thoracic legs. Several larvae of flies have 'false legs' (pseudopods or prolegs) related to those that care fleshy abdomen of caterpillars. Flies are greatly more adjustable than caterpillars in this respect, and around anybody segment can have prolegs. The

The evolutionary tendency among larvae of fly has been in the direction of structural simplification, so, usually, primitive flies larvae are extra structured than larvae of further importantly evolved flies that display better physiological adaptability. Most members of suborder Nematocera or Brachycera larvae bear a wellbuilt head having antennae, complex mouthparts and palpi related to several adult insects. Frequently they are so structurally modified to their distinctive mode of life that these are not capable to adjust any other. It is particularly true among aquatic larvae such as mosquitoes and possibly reaches at extreme in larvae of mountain midge that live in roaring torrents and creep on immersed rocks. Segments of their

prolegs aid larvae to push through soil or crawl into narrow spaces.

body are furnished with suckers and clinging processes. The maggots of

Cyclorrhapha have tiny external structure other than the posterior spiracles and

In comparison to very specialized larvae, nearly half species of flies have larvae called maggots. The maggots have missing the complex head capsule of primitive flies. Their sharp anterior ends comprise one or a couple of mouth hooks. The rounded posterior end has one couple of spiracles posteriorly (outer air holes), which look as black spots to the naked eye. Microscopically, spiracles are recognized as pores or a complex arrangement of slits, which are valuable in differentiating

Even though maggots display structural homogeneity, they are dissimilar physiologically. Maximum of maggots feed upon rotting organic material, however in forensic studies; there are wide dissimilarities in the food likings of various flies. Larvae of gout fly of barley and frit fly of oat are maggots of flies that fit into plantfeeding family Chloropidae. The hessian fly of wheat is the destructive larva of *Mayetiola destructor* (Say) (gall midges) in nematoceran family Cecidomyiidae. Even though external structure of maximum nematoceran larvae is diverse, the structure of gall midges that live totally submerged in plant tissue, has developed in the direction of simplification. Gall midges fly larvae are known as well gall gnats for the reason that feeding larvae result in the development of disfiguring galls on stems or leaves and harm to several kinds of plants. So, they have developed physiological diversity and simplified structure concerning food floras as have

The greatest well-known blow flies existing are sheep blow flies, essentially species in *Lucilia* genus. Maggots of *L. sericata*, forage on tiny deceased animals, and in garbage and abattoirs cans, oviposit in dirty wool around anus of sheep otherwise in pus oozing from wounds and scratches, wherein these are essential means of sheep strike illness. These maggots from time to time occur in soil adjacent to buildings in towns and their diet basis is not recognized. Eight 'waves' of worms have been well-known, and each wave assaults deceased animals in a severe series

**6.3 Larvae**

*Life Cycle and Development of Diptera*

black mouth hooks.

maggots of further progressive flies.

of species.

**10**

The pupal stage of a true fly is enclosed within a hard capsule (skin). It may have some of its legs and body parts visible or it may be hidden inside a larval skin and just looks like a brown capsule. Dipteran pupae have non-functional mandibles (adecticous) and may have the appendages free from the body (exarate) or glued to the body (obtect). In exarate type, the pupa is concealed inside the hardened skin (puparium) of the last larval instar. The external structures of adult fly (antennae, eyes, legs, wings) are obviously noticeable in the pupa. However, the pupa, is not every time visible to the sight, it may be encircled either in a puparium that is a case formed by toughening of the larval skin or in a cocoon of extraneous matter (silk, soil or a mixture of the two). In flies of Stratiomyidae family and others, which have maggots like larvae (whole Cyclorrhapha), a puparium is formed. Many fly families sporadically form cocoons and cocoon has developed an adaptive tool, which delivers an extra safety to the pupa. Pupae of mosquitoes, black flies (Simuliidae) and limited aquatic midges swim vigorously. Several pupae that lie in wood or in soil have evolved spines in order to aid them for effort to have their way to the surface just before appearance of adult insects.

#### **6.5 Wings**

Adult flies are usually active during the day when it is warmer and they also sometimes detect the vibrations of wing beats. Adult flies have only one pair of wings on the mesothorax or second thoracic segment. The hind wings, modified into small club-like halteres behind the much larger forewings, have a knob or club and a stalk, which may be big and thick comparative to the size of fly. The halteres vibrate above and below in time with wings and in flight perform as gyroscopes (maintain or measure motion). If fly rolls, yaws or pitches in the course of flight, halteres maintain their original plane of movement, twist at their roots, where special nerve cells identify the twist and cause fly to accurate its flight attitude. The base of halteres is elastic and when these are stirred, a fly is capable to control its flying. As the halteres curve at the base, a fly can change flight direction or speed thus making them well controllable in comparison to various other flying insects.

Many flies have maxillae, most have also mandibles and stretched blades that cover a furrow in labium and arranged as tubular channel for sucking liquids. In many females (mosquitoes, blood sucking flies), for drawing blood, mandibles act as piercing stylets. Mandibles have been lost relatively entirely early in fly evolution or became functionless and as a result families of blood sucking insects, which afterward evolved have to develop other methods of piercing the hosts. Stable flies and tsetse flies usage toughened labium, dance flies and robber flies practice hypopharynx, and Dolichopodidae (metal green flies having very large legs) crush their prey with especially evolved teeth by wrapping in spongy labella of labium. Many flies suck their diet, whereas with few exceptions have condensed mouthparts and probably do not forage at all as adults. Therefore, diet of flies might be liquid, otherwise solids, which may be dissolved by stomach juices and saliva. Flies as well bear a couple of labial palpi fitted with sensory cells, which act as organs to detect smell, taste and touch. The antennae and palpi are important for scrutinizing of

Entirely, flies bear antennae and great antennal structural differences occur among related species and genera. Members of suborder Nematocera (crane flies, midges and gnats) have whip-like antennae with two basal segments (scape and pedicel) and apical flagellum of many similar segments. Altogether in other flies, accurately called Brachycera, flagellums are contracted into a compound third segment and have remnants of the terminal flagellar segments remaining as a bristle-

Diptera are such a diverse group that they can be found just about anywhere and these are most common in humid or moist environments, but can also be found in deserts, forests, mountains and even polar regions. They are also common in both fresh and saltwater environments such as lakes, ponds, streams, marshes and swamps. There is hardly any life-supporting medium in which dipterous larvae have not been observed. Species of Diptera can be gathered in wide range of habitats from most polluted to most pristine environments, from fast flowing water to stagnant water or from saline water to freshwater. Pupae and larvae are found among aquatic vegetation, organic debris, problematic habitats, sand, fine sediments, gravel, mud, cobbles or bedrock. They might be restricted to and sometimes closely associated with water surface, water column, any of aquatic zones, main water flow, benthic, littoral or interstitial and hygropetric zones. However, maggots are the utmost essential larvae, for the reason that they perform a crucial part in restructuring and breaking down organic material. The waste produces expelled by the larvae offer nutrients for molds, fungi and other types of plants. Additionally, bodies of larvae, pupae and a lot of adult flies are essential diet sources for higher animals. Cases in point are aquatic larvae of mosquitoes and midges that are basic diet for fish. Also, the terrestrial maggots of various flies have a part in nutrition chains. Meanwhile, a blow fly is able to lay one to two thousand eggs; their density would upsurge terribly if more than a few of them stay alive. Maximum of the larvae pass away owing to desiccation, malnutrition and sinking or are used up by birds. Adult flies are snapped up by small mammals, birds, toads and frogs. Martins, swifts and swallows consume huge numbers of flies that have been brought into the air by convection currents. So, their density is conserved at a persistent level.

probable diet sources and appropriate spots for laying eggs.

*Typical Flies: Natural History, Lifestyle and Diversity of Diptera*

*DOI: http://dx.doi.org/10.5772/intechopen.91391*

**6.8 Antennae**

like arista or a pencil-like style.

**7. Ecology of Diptera**

**13**

The wings of flies have a well-defined pattern of veins; each has a characteristic location and name, and often has taxonomic significance. A small number of true flies have a reticulation (network of small veins), nearly resembling to various other insects, which are called flies (dragonflies, mayflies, dobsonflies) mistakenly. Primitive flies tend to have complex wing venation, whereas advanced ones have simplified and reduced venation. Some of the small midges (Sciaridae, Cecidomyiidae, Mycetophilidae) have also reduced wing venation. Reduction or losses of wings take place in several families, predominantly, which dwell windy dwellings (islands, mountains) or caves, or those are exterior parasites among feathers and furs.

#### **6.6 Eyes**

Most adult flies have large eyes, to help them see when they are flying. Flies use vision more than most insects do and like all insects, they use their sense of smell a lot. The eyes of most flies often lodge on much surface area of head, particularly in males, where eyes may well come across in the middle line (holoptic). With few exceptions, in female flies, the eyes do not normally meet (dichoptic). In certain families, notably both sexes of small acalyptrate flies and robber flies are dichoptic. Parasitic flies or those that living in sheltered dwellings can have very little eyes or none of any kind. Characteristically, on the other hand, compound eyes of flies comprise several facets, for instance, house fly in each eye has 4000 facets and some *Drosophila* sp., has 700 facets per eye that help them to see.

#### **6.7 Mouthparts**

Characteristically, flies have suctorial type of mouthparts and several bear large fleshy pads along with drainage canals called pseudotracheae for proficient uptake of liquid. Mouthparts of certain flies are modified for piercing and stabbing of other insects, for instance, predatory dance flies (Empididae) and robber flies (Asilidae). Mosquitoes and certain other ectoparasitic insects have modified mouthparts for penetrating into vertebrate host skin, and take out blood and other body fluids. In various families, rostrum (proboscis) is altered for lapping and or sponging. These flies live on nectar, honeydew or exudates of different plants and animals (alive or dead). In further families, proboscis is amended for piercing or cutting the tissues of hosts. Many of these flies are outer parasites (mosquitoes and deer flies) that feed on the blood of their vertebrate hosts, including humans, and most wild and domestic animals [42].

*Typical Flies: Natural History, Lifestyle and Diversity of Diptera DOI: http://dx.doi.org/10.5772/intechopen.91391*

Many flies have maxillae, most have also mandibles and stretched blades that cover a furrow in labium and arranged as tubular channel for sucking liquids. In many females (mosquitoes, blood sucking flies), for drawing blood, mandibles act as piercing stylets. Mandibles have been lost relatively entirely early in fly evolution or became functionless and as a result families of blood sucking insects, which afterward evolved have to develop other methods of piercing the hosts. Stable flies and tsetse flies usage toughened labium, dance flies and robber flies practice hypopharynx, and Dolichopodidae (metal green flies having very large legs) crush their prey with especially evolved teeth by wrapping in spongy labella of labium. Many flies suck their diet, whereas with few exceptions have condensed mouthparts and probably do not forage at all as adults. Therefore, diet of flies might be liquid, otherwise solids, which may be dissolved by stomach juices and saliva. Flies as well bear a couple of labial palpi fitted with sensory cells, which act as organs to detect smell, taste and touch. The antennae and palpi are important for scrutinizing of probable diet sources and appropriate spots for laying eggs.

#### **6.8 Antennae**

**6.5 Wings**

*Life Cycle and Development of Diptera*

flying insects.

feathers and furs.

**6.7 Mouthparts**

and domestic animals [42].

**12**

**6.6 Eyes**

Adult flies are usually active during the day when it is warmer and they also sometimes detect the vibrations of wing beats. Adult flies have only one pair of wings on the mesothorax or second thoracic segment. The hind wings, modified into small club-like halteres behind the much larger forewings, have a knob or club and a stalk, which may be big and thick comparative to the size of fly. The halteres vibrate above and below in time with wings and in flight perform as gyroscopes (maintain or measure motion). If fly rolls, yaws or pitches in the course of flight, halteres maintain their original plane of movement, twist at their roots, where special nerve cells identify the twist and cause fly to accurate its flight attitude. The base of halteres is elastic and when these are stirred, a fly is capable to

control its flying. As the halteres curve at the base, a fly can change flight direction or speed thus making them well controllable in comparison to various other

simplified and reduced venation. Some of the small midges (Sciaridae,

some *Drosophila* sp., has 700 facets per eye that help them to see.

Cecidomyiidae, Mycetophilidae) have also reduced wing venation. Reduction or losses of wings take place in several families, predominantly, which dwell windy dwellings (islands, mountains) or caves, or those are exterior parasites among

Most adult flies have large eyes, to help them see when they are flying. Flies use vision more than most insects do and like all insects, they use their sense of smell a lot. The eyes of most flies often lodge on much surface area of head, particularly in males, where eyes may well come across in the middle line (holoptic). With few exceptions, in female flies, the eyes do not normally meet (dichoptic). In certain families, notably both sexes of small acalyptrate flies and robber flies are dichoptic. Parasitic flies or those that living in sheltered dwellings can have very little eyes or none of any kind. Characteristically, on the other hand, compound eyes of flies comprise several facets, for instance, house fly in each eye has 4000 facets and

Characteristically, flies have suctorial type of mouthparts and several bear large fleshy pads along with drainage canals called pseudotracheae for proficient uptake of liquid. Mouthparts of certain flies are modified for piercing and stabbing of other insects, for instance, predatory dance flies (Empididae) and robber flies (Asilidae). Mosquitoes and certain other ectoparasitic insects have modified mouthparts for penetrating into vertebrate host skin, and take out blood and other body fluids. In various families, rostrum (proboscis) is altered for lapping and or sponging. These flies live on nectar, honeydew or exudates of different plants and animals (alive or dead). In further families, proboscis is amended for piercing or cutting the tissues of hosts. Many of these flies are outer parasites (mosquitoes and deer flies) that feed on the blood of their vertebrate hosts, including humans, and most wild

The wings of flies have a well-defined pattern of veins; each has a characteristic location and name, and often has taxonomic significance. A small number of true flies have a reticulation (network of small veins), nearly resembling to various other insects, which are called flies (dragonflies, mayflies, dobsonflies) mistakenly. Primitive flies tend to have complex wing venation, whereas advanced ones have

Entirely, flies bear antennae and great antennal structural differences occur among related species and genera. Members of suborder Nematocera (crane flies, midges and gnats) have whip-like antennae with two basal segments (scape and pedicel) and apical flagellum of many similar segments. Altogether in other flies, accurately called Brachycera, flagellums are contracted into a compound third segment and have remnants of the terminal flagellar segments remaining as a bristlelike arista or a pencil-like style.

#### **7. Ecology of Diptera**

Diptera are such a diverse group that they can be found just about anywhere and these are most common in humid or moist environments, but can also be found in deserts, forests, mountains and even polar regions. They are also common in both fresh and saltwater environments such as lakes, ponds, streams, marshes and swamps. There is hardly any life-supporting medium in which dipterous larvae have not been observed. Species of Diptera can be gathered in wide range of habitats from most polluted to most pristine environments, from fast flowing water to stagnant water or from saline water to freshwater. Pupae and larvae are found among aquatic vegetation, organic debris, problematic habitats, sand, fine sediments, gravel, mud, cobbles or bedrock. They might be restricted to and sometimes closely associated with water surface, water column, any of aquatic zones, main water flow, benthic, littoral or interstitial and hygropetric zones. However, maggots are the utmost essential larvae, for the reason that they perform a crucial part in restructuring and breaking down organic material. The waste produces expelled by the larvae offer nutrients for molds, fungi and other types of plants. Additionally, bodies of larvae, pupae and a lot of adult flies are essential diet sources for higher animals. Cases in point are aquatic larvae of mosquitoes and midges that are basic diet for fish. Also, the terrestrial maggots of various flies have a part in nutrition chains. Meanwhile, a blow fly is able to lay one to two thousand eggs; their density would upsurge terribly if more than a few of them stay alive. Maximum of the larvae pass away owing to desiccation, malnutrition and sinking or are used up by birds. Adult flies are snapped up by small mammals, birds, toads and frogs. Martins, swifts and swallows consume huge numbers of flies that have been brought into the air by convection currents. So, their density is conserved at a persistent level.

Within more primitive families in suborder Nematocera, larvae of flies have well-built head capsules having mouthparts of mandibulate type. These arrangements are absent or reduced in more progressive Brachycera and Cyclorrhapha suborders wherein larvae are recognized as maggots, having worm-like bodies and a couple of mouth hooks only for nourishing. The abdomen, thorax and legs of adult flies differ from short to long and appearance of fly is well-designed along with decorative style. From time to time, bright color and pattern of several flies (blow flies) is metallic, on the other hand, most often fly is concealed with a good coating called dusting or tomentum. Numerous flies, principally those of more greatly evolved families, are bristly and the strongest bristles have an accurate location, mostly on thorax. The identification of bristles, their arrangement and the method established on them is known as chaetotaxy [43, 44].

blood at all are anautogenous. One species may have both types, probably as a result of unstable populations otherwise races rising from usual selection. Such as far north, great densities of biting flies (horse flies, black flies, biting midges mosquitoes) arise for the period of small Arctic summer and there are noticeably inadequate amounts of warm-blooded animals to offer diet. If flies clip blood, they

The adults do not feed and most flies visit flowers, which provide water, nectar and pollen. Although the name *Drosophila* means 'lover of dew', this insect sucks water and any other obtainable fluid. Nectar from flowers contains carbohydrates and most adult flies use this syrupy liquid. Pollens are tougher to obtain for a sucking insect than blood, which is rich in protein and a vital source of this nutrient. Several hover flies love pollen grains among hardened portions of labella prior to swallow them and certain flies actively probe into flowers, covering their eyes and heads with pollen grains. Although their role in pollination is less well known than that of bees, flies are important pollinators of flowers. Some plants (spurges) are often covered with small flies of different families. Small flies also feed on honeydew from aphids or whiteflies. Flies forage on dung and fluid produces of either vegetable decay or animal. They get nutrients from garbage dumps and farmyard manure heaps. These dwellings as well harbor several larvae, which nourish either right on biological diet available or feed on other larvae as carnivorous. Yellow dung fly larvae and adults, is a familiar example that target on other insects coming to

Adaptableness of flies is obvious on a widespread range of foods consumed by the larvae. Aside from parasites, the maximum specific feeders are those larvae, which live in plant tissues (leaf mining Agromyzidae, may be limited to group of plants or one plant species). Commonly, pests of horticulture and agriculture (cabbage root fly) are multipurpose species, nourishing on a diversity of wild type hosts and altering their foods while offered with intense plantings of marketable crops. Numerous carnivorous larvae of fly (asilids) most likely reside in soil and consume animal or vegetable material, whatsoever is accessible. Meanwhile adult robber flies (asilids), forage on various insects, their larval diet is recognized to be insufficient. Certain maggots, predominantly young insect, which forage on plant material for the duration of second and first instars, turn into carnivorous in the course of third

Adult flies escape from predators with their alertness and speed. Likewise, several flies mimic stinging insects, for instance, bees or wasps, therefore predators will avoid them. Larvae habitually live in dwellings that are hard to reach by predators. Well-known predators of flies are shrews (eat larvae and pupae), rodents (pupae), moles (larvae and pupae), toads (mostly adult flies), frogs (mostly adult flies), birds, ants, wasps, other flies, spiders, ground beetles (larvae and pupae) and

In many cases, only the adult females of biting flies under certain circumstances get blood diet, Culicidae family of mosquitoes, possibly spreads dengue, malaria, filariasis, encephalitis, yellow fever and other illnesses. Tabanidae (deer flies/ horse flies) can transmit loiasis, trypanosomiasis, tularemia and some other sicknesses. Simuliidae family of black flies feasibly spread onchocerciasis of human and leucocytozoon contaminations in poultry. Moth flies of Psychodidae can transmit leishmaniasis, sand fly fever and further diseases. Family Ceratopogonidae having punkies and no-see-ums are small and on the other hand vicious biters associated to

transmit some protozoan, roundworms and virus pathogens in animals and humans. Muscidae family of house flies is among the utmost cosmopolitan than all other insects. Particular species have piercing mouthparts while some others are

consume it; however, these still stay alive, if not availed.

*Typical Flies: Natural History, Lifestyle and Diversity of Diptera*

*DOI: http://dx.doi.org/10.5772/intechopen.91391*

instar, where maximum of development occurs.

true bugs (larvae and pupae).

**15**

dung [35, 36, 46].
