Diptera are a detachment of invertebrate animals from the class of insects, which are characterized by the presence of only one pair of wings and complete metamorphosis. The order unites more than 150 families and over 100 thousand species of dipterans. Everyone knows such representatives of this broad group as midges, flies, mosquitoes, horseflies.
These insects are widespread on Earth from the tundra to the deserts of the tropics. Diptera have been known since the Jurassic period.
They are not social insects, but they can gather in flocks, attracted by the smell of food or the convenient location of mating or resting places. The vast majority of these insects live solitary lives for most of their lives.
The development cycle with complete transformation includes the stages of egg, larva, pupa, and adult. The larvae have a worm-like body, lack legs, and instead of them there may be unsegmented protrusions on the abdominal segments. There is a gnawing type mouthparts. After a certain time, the larvae transform into covered pupae.
Reproduction
. Diptera are characterized by pronounced differences in the anatomical and physiological structure of larvae and adults. Thus, the life span of the larva significantly exceeds that of the imago; it is the larva that is the main feeding stage. The adult in some species may not need food at all (botflies). The main functions of adults in the life cycle are reproduction and dispersal. Under favorable conditions, dipterans develop from four to ten generations per year.
Structure of imago Diptera
. Dimensions range from 2 mm to 5 cm. Like all insects, the body has bilateral symmetry, divided into a head, chest with three pairs of limbs and abdomen. The head is round in shape with large compound eyes on both sides. The oral apparatus in most species is of the sucking type; it can be sucking-licking (flies), piercing-sucking (mosquitoes), and sometimes underdeveloped (in non-feeding adult gadflies).
Three pairs of legs are attached to the chest, and the paws have claws and suckers, with the help of which dipterans are able to crawl along vertical surfaces.
Internal structure of Diptera
. The fluid medium of the body is hemolymph, which is an analogue of blood in the circulatory system of higher animals. The circulatory system is not closed, the hemolymph freely washes the internal organs in the body cavity, then collects in the vessels. The function of the heart is performed by a thickened dorsal vessel in the back of the chest. The respiratory system is the trachea, and gas exchange takes place in the abdomen, where many tracheae are located next to the aorta. Characterized by the presence of a brain.
BI-WINGERS(Diptera), an order of insects characterized by the presence of one pair of wings. This is one of the largest and most widespread groups of insects, including approx. 100,000 species. It includes such well-known species as houseflies, mosquitoes, midges, midges, horseflies and gadflies.
Flight behavior.
Although large swarms of Diptera are often observed, they are not social insects such as termites, bees and ants. On the contrary, most of them live alone, at least for most of their lives. However, many dipterans gather in a kind of swarms, attracted by the smell of food, a convenient place for resting or mating.
Clusters. Diptera can fly to the light together with insects of other species. Mosquitoes, bells and centipedes swarm closer to dusk, usually over bushes, paths or other landmarks, near which the swarm, if frightened off, gathers again. Such groups consist mainly of males; It is believed that the sound of their wings attracts females with their characteristic tone. In experiments, by producing sounds similar to the squeaking of female mosquitoes of certain species, it was possible to induce swarming of the corresponding males. Clusters are especially characteristic of blood-sucking dipterans (gnats). If a species is active mainly in the dark, it is called nocturnal, if in the light it is called diurnal; An intermediate crepuscular group is also distinguished.
« Hanging» flight
observed in different species of Diptera, but especially developed in hoverflies and buzzers. Representatives of these families fly quickly and maneuver well in the air. You can often observe how they hover motionlessly in place, intensively working their wings, and then suddenly disappear from view.
General characteristics.
In the vast order of Diptera there is a huge variety of body sizes, shapes and colors. The length of some gall midges is only 0.4 mm with a wingspan of just over 1 mm. Australian blackbirds reach a length of 50 mm, and the wingspan of individual tropical centipedes exceeds 100 mm.
However, despite the large number of species and diversity of dipterans, they all share common characteristics. Typically, adults have only one pair of membranous wings, rather thin integuments, 5-segmented tarsi, a licking or sucking mouthpart (proboscis) and well-developed compound (compounded) eyes. Development occurs with complete transformation (metamorphosis), i.e. a larva hatches from the egg, which, after several molts, turns into a motionless pupa, and from the pupa an adult insect (imago) is born. Diptera larvae, unlike caterpillars, are always legless.
STRUCTURE
The general structure of dipterans is the same as that of other insects. The body of the imago consists of three main parts. The head bears the mouthparts, eyes and antennae. The chest includes three segments with three pairs of walking legs and a pair of wings (their second pair, the posterior one, has turned into halteres). Almost all the space inside the chest is occupied by powerful muscles necessary to activate the locomotor organs. The abdomen consists of a varying number of externally defined segments (depending on the species) and houses the reproductive organs and most of the digestive system.
EXTERIOR STRUCTURE OF A HOUSE FLY
Head.Oral apparatus. Although dipteran adults use a wide range of food sources, their oral apparatus is essentially always a sucking or licking proboscis, sometimes so hard and sharp that they are capable of piercing the skin of many vertebrates or the integument of other insects. Many dipterans, including the housefly, can often be seen with their soft proboscis extended and attached to various wet surfaces. In contact with the substrate are two extended lobes of the lower lip, or oral discs, adapted for the absorption of liquid food. Numerous thin channels (pseudotrachea) on their underside converge at the central point of the proboscis, from where liquid is drawn into the head using a bellows-like pharyngeal pump.
Horseflies not only possess licking structures, but also two pairs of hard, dagger-shaped appendages—modified upper and lower jaws—for piercing the skin of the animals whose blood they feed on. Even their upper lip turned into a stylet and became an integral part of the piercing oral apparatus. (However, male horse flies do not feed on blood, and their lower jaws are reduced.)
In mosquitoes, the lower lip does not take part in feeding, but serves only as a case for the needle-shaped stiletto jaws, which fold into a thin piercing proboscis. When these jaws penetrate the body of a vertebrate, it bends and remains on the surface. The upper lip of mosquitoes (and some other bloodsuckers, such as midges, midges and tsetse flies) is also part of the piercing mouthparts. A groove runs along its lower (posterior) side, covered by another part of the oral apparatus - a long tongue, or hypopharynx. It is pierced by a channel through which saliva is supplied to the victim's wound. The mosquito absorbs the blood diluted with it through a tube formed by the upper lip and hypopharynx.
Antennas
(antennae, or cubs) of dipterans are quite diverse in shape, which is widely used to classify these insects. It is believed that their oldest species had long multi-segmented antennae, like modern mosquitoes and centipedes, the antennae of which consist of two thick basal segments and a whip-like part formed by thin, more or less cylindrical segments numbering from two to 39. In the more advanced in evolutionary terms Diptera antennae are usually formed by two basal segments and a third - thickened, of various configurations. It often bears at the end or dorsal side a thin appendage formed by the fusion of many segments - glabrous or pubescent, bristly or ringed.
Breast insects consists of three segments: prothorax, mesothorax and metathorax. Since the main part of the pectoral muscles is responsible for flight, the middle segment, which carries the wings, is usually noticeably larger than the other two.
Legs attached to the chest, with each segment carrying one pair of them and containing the corresponding muscles. Like other insects, the typical Diptera leg consists of five parts: coxa, trochanter, femur, tibia, and tarsus. The terminal part (tarsus) is usually formed by five segments and ends with a pair of claws. Under each claw there is a soft glandular pad. The claws help move along rough surfaces. When walking, the soft pads are compressed and secrete an adhesive secretion, allowing the dipterans to hold on even where there is nothing to cling to.
Wings.
Most insects have two pairs of wings, but in dipterans one of them (the posterior one) is transformed into small club-shaped appendages, the so-called. halteres. Individuals in which they are damaged or removed partially or completely lose the ability to fly. The halteres are movably articulated with the sides of the metathorax and vibrate in the vertical plane with the same frequency as the wings, but in antiphase with them. With the help of mechanoreceptors located at their base, they give the insect the opportunity to determine and correct balance in the air.
Thin membranous wings are strengthened by cylindrical veins. Diptera have fewer of them than most other insects, and there are especially few transverse veins. Wing venation is a very important classification feature used to divide an order into lower-ranking taxa. Near the base of the wing, on its posterior (inner) edge, there may be a notch that separates a small lobe or scale from the main plate.
Abdomen primitive dipterans are elongated, almost cylindrical and consist of 10 segments, of which the two closest to the chest are very indistinctly separated from each other. In more specialized families, the number of visible abdominal segments is smaller, in particular, it has been reduced to 4 or 5 in the housefly and its closest relatives. Shortening, the abdomen becomes closer in shape to a cone or even a sphere.
Reproductive system.
The only visible abdominal appendages are the copulatory organs in males and the ovipositor in females. The latter is usually tubular or saber-shaped. In males, the expanded last segment bears special grips that serve to hold the female by the ovipositor during mating. The internal genital organs, located in the abdomen, consist of gonads (testes in males and ovaries in females), accessory glands that secrete liquid secretions, and excretory ducts. The shape of the external genital appendages in Diptera varies widely. The structure of the copulatory “captures” in males serves as the main taxonomic character in determining the species of some families.
Digestive system.
The abdomen contains most of the digestive system, mainly the intestines, sometimes forming blind outgrowths. The excretory organs are the Malpighian vessels - long thin tubes that open into the intestines. In the front part of the abdomen there is a goiter - a thin-walled sac connected by a narrow tube to the esophagus. The crop serves as a temporary reservoir for liquid food. Filling with air, it probably facilitates the emergence of an adult insect from the pupa shell.
Diversity.Sexual dimorphism. One of the surprising phenomena that is often found in Diptera is sexual dimorphism, i.e. significant differences in appearance between males and females of the same species. For example, as noted above, the males of many species have holoptic compound eyes, i.e. touch each other, whereas in females they are separated by a frontal stripe (dichoptic). In female mosquitoes, the antennae are sparsely pubescent, while in males they are densely covered with long hairs. Sexual dimorphism can also be expressed in size: males are usually smaller. In females of some species, the wings are absent or greatly reduced, while in males they are normally developed. In one of the families of Diptera, in females, two veins of the wing merge at its edge, and in rare males they are separated along the entire length. In another group, the legs, antennae, or other body parts of males often bear tufts of hairs with a metallic sheen that are absent in females. The legs of the males of some mosquitoes are trimmed with a wide scaly fringe; females do not have it. Differences in color between the sexes are common, but usually not noticeable. However, sometimes this difference is quite significant; for example, males of one American centipede are pale reddish, while females are almost black.
Mimicry and protective coloration.
Many species of harmless dipterans are strikingly similar in appearance to other insects, especially bees and wasps, which humans and probably other animals try to avoid. This phenomenon is called mimicry. A typical example of this is the appearance of a number of hoverflies; they are so similar to wasps that even an entomologist will not always immediately correctly identify the insect. Other hoverflies mimic the appearance of bees. Some flies are more or less like bumblebees. This similarity is reflected in the nomenclature of dipterans: the entire family Bombyliidae (buzzers) is named in Latin after bumblebees ( Bombus); there are bee-like hoverflies, bumblebee hoverflies, hornet-shaped moths, etc.; one of the clans of ktyrs is called Bombomima(“bumblebee imitator”).
Some dipterans avoid predators with the help of protection, i.e. camouflage, coloring. The dark color of fungus gnats makes them invisible as they sit motionless in crevices under fallen trees. Other dipterans have “dismembering” coloration. For example, in liriopids, bright black and white stripes on the body are arranged in such a way that these insects, flying against a light or dark background, simply look like sets of spots that do not form a single whole.
FOUR STAGES OF THE LIFE CYCLE common housefly. A - A housefly lays an egg on the surface of a food substrate, such as a garbage heap. b- A whitish, relatively inactive larva (maggot) hatches from the egg. V- After a period of feeding and growth, accompanied by two changes of skin (molting), the larva pupates inside its skin, which hardens and turns brown, turning into the so-called. pupary. At the pupal stage, the organs of an adult insect (imago) are formed. G- An adult fly emerges from the puparium, spreads its wings and flies away. The egg, larva, puparium and young adult are shown enlarged to the same scale.
LIFE CYCLE
Like other higher insects, the life cycle of dipterans is complex and includes complete metamorphosis. The eggs of most species are oblong and light-colored. They hatch into larvae that are usually elongated, roughly cylindrical, soft-bodied and legless. In most cases, the hard parts of their heads are greatly reduced; Such worm-like larvae are called maggots. The larva feeds intensively and periodically molts as it grows. The number of larval molts varies among dipterans, but usually there are two or three. This is followed by the pupal stage. In some dipterans it is formed inside the larval skin, which turns into the so-called. "puparium". Eventually the shell of the pupa ruptures, and an adult insect (imago) is born.
Life cycle of a housefly.
Using the example of the housefly, we can trace the development of dipterans. To lay eggs, the female searches for accumulations of decaying organic matter, such as manure or garbage heaps. Thus, the fly instinctively leaves the clutch where the sedentary larva will be provided with a sufficient amount of food. At one time, the female can lay 120 or slightly more narrow whitish eggs of approx. 1 mm long. Huge masses of them are found in places where several females leave their clutches at the same time. At summer temperatures of 24-35° C, egg development takes approx. 8 ocloc'k. The worm-like larvae that hatch from them are approx. 2 mm begin to feed voraciously. They grow so quickly that the first moult occurs after 24-36 hours, and the second about a day later. The third stage larva feeds for another 72-96 hours and grows to a length of approx. 12 mm and then pupates.
An oblong pupa forms inside the last larval skin, which becomes the pupal case (puparium). This shell changes its dirty white color to brown and hardens. Within 4-5 days, inside the apparently inactive pupa, the larval tissues disintegrate and rearrange themselves, forming the structures of an adult insect. In the end, the imago comes out with the help of a special frontal bladder, which, under the pressure of “blood” (hemolymph) pumped into it, protrudes into the frontal part of the head. Under its pressure, the “lid” of the puparia opens, releasing the adult insect. It crawls out of the decaying debris or soil in which it pupated, spreads its initially crumpled wings and flies off to feed and mate, starting a new life cycle.
Another curious form of reproduction found in some dipterans is pedogenesis, i.e. the appearance of offspring in apparently immature individuals. Thus, in gall midges, an adult female lays only 4 or 5 eggs, from which large larvae are formed. Inside each of them, from 5 to 30 (depending on the species and individual) daughter larvae develop. They feed on the mother's body and then reproduce themselves in the same way. After several such cycles, successive larvae pupate, and a generation of adults is formed. Larvae reproduce without mating. This development of unfertilized eggs is called parthenogenesis. This phenomenon, in the absence of pedogenesis, has been found in other dipterans, for example, in some midges. Females lay unfertilized eggs, from which only females emerge. Parthenogenesis can be cyclic, constant or sporadic. Cm. REPRODUCTION.
GEOGRAPHICAL DISTRIBUTION
There is, perhaps, no corner on land where dipterans do not live. This is the most widespread order of insects, although the ranges of many of its families are not fully known. Each of the large zoographic regions is characterized by its own set of taxa, but the genera and families to which they belong can be cosmopolitan, i.e. meet almost everywhere. About two dozen species of Diptera are also cosmopolitan. About half of them were unwittingly dispersed throughout the planet by humans. These species include the ubiquitous housefly, the squeak mosquito ( Culex pipiens), the gastric horse botfly and the autumn fly. Among approximately 130 families of Diptera, less than 20 are truly cosmopolitan, although the ranges of many others are not much narrower, i.e. they are distributed subcosmopolitanly.
Diptera abound in the humid tropics. The distribution of most families is limited to this natural zone, while many others reach their maximum diversity and abundance here. In temperate or cold areas, fewer species of Diptera are found per unit area, but the number of individuals is often no lower than in the tropics. In the windswept Arctic desert, on mountaintops and among dunes, where harsh climatic conditions are unsuitable for most insects, Diptera remain the most prominent representatives of this group of invertebrates. In the north of Greenland, several hundred kilometers from the North Pole, there are centipedes, carrion flies, flower flies, bell flies and fungus gnats. On the other side of the Earth, on the Antarctic islands, there are several species of midges, hoverflies, centipedes, gall midges and some other groups. In Antarctica itself, only one species of wingless mosquitoes has so far been recorded, but it is likely that other dipterans will be found there.
Diptera of mainland islands are usually close to those living on the nearest continents, but on more isolated oceanic islands they, even belonging to widespread groups, are often very peculiar. Apparently, a single, accidental arrival of some species on such islands in the distant past led in the course of evolution to the appearance of a whole set of diverse forms. This may explain, for example, the fact that almost a third of Hawaii's 246 dipteran species belong to just one family.
ECOLOGY
Having thin integuments, most dipterans are not able to effectively retain water in their bodies. They would constantly be in danger of drying out if they did not live in more or less humid conditions. Although the larvae in many cases lead an aquatic lifestyle, the adults are almost always terrestrial. The only exception is sea centipedes Limonia monostromia, whose entire life cycle takes place in the warm sea waters off the coast of Japan.
Larvae. The habitats of dipteran larvae are much more diverse than those of adults and include almost all types of ecological niches. Some attack aphids or nibble the leaves of mosses and other plants, i.e. live openly. However, in most cases they develop in the thickness of a moist substrate, for example, inside the leaves, stems and roots of plants. Larvae of many species make tunnels in rotting wood, fungi or soil, feeding on organic debris or microscopic invertebrates.
They often live in standing and flowing bodies of water of any size, where they feed on vegetation, microorganisms or insects of other species. Most of these aquatic larvae prefer shallow places, but in some bell mosquitoes they dive to a depth of more than 300 m. If their development requires a good supply of oxygen, they attach to the stones of river rapids or mountain streams. The larvae and pupae of some dipterans prefer water with a high content of alkalis or salts, and in one Californian species they live in oil puddles. Others are found in hot springs and geysers, where the water temperature reaches 50 ° C. The larvae of one of the mosquitoes survive even in the liquid filling the pitcher leaves of insectivorous plants, where other insects drown and are digested.
EVOLUTIONARY HISTORY
Judging by fossil finds, insects existed already in the Devonian period, i.e. OK. 300 million years ago. However, until the Upper Triassic (about 160 million years ago), no remains of dipterans were found among them. The most primitive representatives of this order are similar to centipedes and are united in the extinct family Architipulidae. Many different dipterans, close to modern forms, are found in Baltic amber - the resin of coniferous trees, fossilized in the Upper Oligocene, i.e. about 35 million years ago. The Miocene shales from Florissant, Colorado, contain many fossils of centipedes, fungus gnats, and other dipterans characteristic of marshy habitats. Among them, even the tsetse fly is noted, although at present this genus is found only in Africa. The study of Baltic amber and Florissant fossils showed that by the middle of the Cenozoic era, dipterans had passed through most of their evolutionary development.
MEANING IN HUMAN LIFE
Many dipteran species are best known as disease vectors, nuisance bloodsuckers, and crop pests. Chemical methods of combating them are the most effective, but even the newest insecticides cannot be considered a panacea, since insects quickly become resistant to them.
Vectors of human diseases.
Listed below are just a few of the medically important dipterans.
Housefly
mechanically transports pathogens of bacterial dysentery; it is possible that it can also spread the bacteria of typhoid fever, paratyphoid fever, cholera and the polio virus.
Horseflies can transmit from an infected animal the causative agents of tularemia, as well as one of the filariasis - loiasis.
Cereal flies
from the family Hippelates When feeding near the eyes, they easily introduce bacteria into them, causing acute epidemic conjunctivitis.
Blood sucking.
Blood-sucking dipterans, even if they are not carriers of diseases, such as biting midges, autumn flies, many mosquitoes and midges, when attacked en masse, worsen human health, causing itching and allergic reactions, sharply reducing performance. In addition, all of these species remain potential spreaders of pathogenic agents.
Pests of agricultural plants.
Compared to beetles, butterflies, herbivorous bugs and representatives of some other orders of insects, dipterans cause relatively little damage to agricultural plants. Representatives of only 5-6 families have a certain significance in this sense. The Hessian fly from the gall midge family is a serious pest of grain crops. This species mainly damages wheat, but is also dangerous for barley and rye. Hessian fly larvae feed on plant sap at the base of stems, causing stunted growth and lodging. With the development of wheat varieties resistant to such damage, the importance of this agricultural pest has decreased. The variegated fly family includes many species that feed on the succulent fruits of various plants, but only a few of them cause serious damage. Thus, the larvae of the apple moth fly spoil apples, damage the fruits of citrus and other fruit trees, significantly reducing the yield. The larvae of other dipterans gnaw tunnels in various plants. As an example, we can cite three species from the family of flower flies: sprout flies, cabbage flies and onion flies. Representatives of the family of cereal flies, living in many parts of the world, damage grain crops.
CLASSIFICATION
The order Diptera (Diptera) is divided, according to different systems, into 121-138 families, which are grouped into two or three suborders. When classifying, the most commonly used characters are the venation of the wings, the length of the antennae and the number of segments in them, the number and location of bristles and spines on the body and legs, the configuration of the external genital appendages, the presence or absence of simple ocelli and the shape of the hole through which the imago leaves the pupal skin or puparia. Coloration, size and body shape do not always allow us to judge the degree of relationship, because natural selection often leads to external similarity between representatives of very distant groups. The scheme proposed below, including only the most important families, is only one of the possible ways of classifying the approximately 100 thousand species of Diptera; the number of species in families is indicated approximately.
Suborder Nematocera
(long mustache). These insects are characterized by long antennae with more than three segments. The group includes 36 families. The antennae of the imago consist of 6 or more approximately identical, movably connected segments, and the mandibular palps usually consist of 4 or 5. The larvae have a well-developed dark-colored head capsule. The pupa is not enclosed in a larval skin, i.e. no puparia is formed.
Bibionidae (centipedes): 500 species, mainly in Eurasia and North America.
Simuliidae (midges): 600 species, subcosmopolitan, but especially numerous in Eurasia, North and South America.
Blepharoceridae (reticular wings): 75 species, found in highlands.
Suborder Brachycera
(short-whiskered) includes approximately 100 families. The antennae of adult insects consist of three segments, of which the last (distal) is thickened and bears an appendage in the form of a seta or rod on the dorsal side or apex. Palpi of one or two segments. The head of the larva is poorly formed or rudimentary. Representatives of some families (straight-suture) have a free pupa; in other cases (round-suture dipterans) it develops inside the puparia.
Tabanidae (horseflies): 3000 species, mainly in the tropics and subtropics.
Diptera insects are the most highly organized order, the representatives of which have one (front) pair of membranous transparent or colored wings. The hind wings are vestigial and transformed into halteres. Mouth parts piercing or licking. According to the structure of the cows, they are divided into two suborders: long-whiskered ( Nematocera), which include mosquitoes, midges, mosquitoes, long-legged mosquitoes, bells, or bloodworms, gall midges, etc., and short-whiskered mosquitoes ( Brachycera), including horseflies, flies, gadflies, tachines, tyres, bloodsucker and many others. Transformation complete. The larvae are legless and often (in flies) without a separate head. Pupae are free or barrel-shaped. Its larvae are found on sea coasts and in all types of inland water bodies of all landscape zones - flowing and stagnant, cold and warm, weakly and highly mineralized, clean and heavily polluted. They inhabit all parts of water bodies, ranging from the moist soil of the shores, aquatic plants and the surface film of water down to depths of several hundred meters. Predatory or herbivorous forms. There are a number of specialized bloodsuckers (midges, mosquitoes, horseflies, some flies - tsetse flies, bloodsuckers and some others). Larvae of many forms live in water (mosquitoes, midges, etc.). In many flies they develop in rotting organic matter, which they also feed on. The digestive enzymes secreted by the larvae promote the rapid decomposition of organic residues and transform them into a semi-liquid state. This “food gruel” is absorbed by the larvae. The larvae of a number of dipteran species lead a parasitic lifestyle (botflies, tachynes). The larvae of aquatic dipterans vary in shape, most often elongated cylindrical, worm-shaped, with a narrowed anterior or both ends. Sometimes only the anterior end is narrowed, and the posterior end is widened. Some have a widened anterior end, a weakly widened anterior end, and a club-shaped thickened posterior end. Body may be flattened dorsoventrally. Body segments are smooth or with projections of various shapes. The most characteristic feature of dipteran larvae, which distinguishes them from all other orders of insects, is the absence of true articulated thoracic legs articulated with the body. The larvae are either legless, or the latter are functionally replaced by soft outgrowths - pseudopods, often equipped with hooks or spines, crawling ridges - special thickenings of the body wall bearing transverse rows of tubercles and spines. Some larvae have pseudopods equipped with suckers. The larvae swim, quickly and alternately moving the anterior and posterior ends of the body, with quick jerks due to sharp bends of the abdomen or smooth wave-like, serpentine movements, which is very typical for most larvae of the subfamilies Palpomyunae serves as a good distinguishing feature from all other families. The body of the larvae is most often clearly segmented and consists of 3 pectorals, sometimes merging into a single complex, and 8-9 abdominals. Sometimes secondary segmentation of the body is observed. The cuticle of the larvae is transparent, except in cases where it is densely covered with various kinds of outgrowths or impregnated with lime and other substances. Larvae Diptera are often colored. The color depends on the pigment located in the parietal or internal fat body. The external pigment may be diffuse or concentrated into spots and stripes. Sometimes the color depends on the pigment located in the hemolymph. In dipteran larvae, all transitions take place from a fully developed, sclerotized, often pigmented head capsule to its complete reduction and replacement with a pseudocephalon (false head). In a number of forms, the head is partially or almost completely retracted into the prothoracic segment. The main parts of the oral organs are mandibles and maxillae. The first are well developed, sclerotized. Of great importance are the various formations around the posterior pair of stigmas in meta- and peripneustic forms, which together represent the stigma plate, the structure of which is often a very good systematic feature. The stigma plate serves aquatic larvae breathing atmospheric air to overcome the elasticity of the surface film of water when establishing contact between the respiratory system and atmospheric air and to maintain the larvae on the surface of the water. In larvae leading a burrowing lifestyle, it also serves as a support when moving forward. It usually consists of several lobe-shaped processes surrounding the stigmata and often giving the plate a star-shaped shape. In some larvae these processes are functionally replaced by hairs. When the larva is on the surface, the plate with hairs lies open on the surface film. When immersed, the stigma larvae are drawn inward, the lobes or hairs are bent, forming a cavity under the stigmas into which an air bubble is captured. In addition to the respiratory function, the tracheal system often also performs a hydrostatic function. Diptera, as well as Hymenoptera, play an important role in nature and human economic activity. The negative value of Diptera is great. A number of forms harm plants, including agricultural crops. Mosquitoes (fam. Culicidae) have long antennae and piercing-sucking mouthparts. Male mosquitoes feed on nectar or plant sap, and females of many species feed on the blood of humans and animals. Larvae and pupae live in stagnant bodies of water. Malaria mosquitoes ( Anopheles) spread malaria. Mosquitoes ( Phlebotomus) - small dipterous insects whose body length usually does not exceed 3 mm. The body is covered with hairs. Males suck plant juices. Females feed on the blood of humans and warm-blooded animals. Very numerous in tropical countries. In the CIS they are found in Crimea, Central Asia, and the Caucasus. Mosquito bites are very painful and cause itchy skin. They spread pathogens of a number of human diseases: leishmaniasis, summer influenza (a disease like temporary fever). Midges (fam. Simuliidae) are well known to the inhabitants of the taiga. They make up the bulk of the midges - huge clusters of small blood-sucking insects. Midges, the length of which does not exceed 5 mm, are distinguished by a short body with a raised front breast with a hump. Their antennae are shorter than those of mosquitoes, but longer than those of flies. Only females feed on the blood of warm-blooded animals and humans. Midges transmit pathogens of a number of diseases to humans and farm animals. Gall midges (family Cecidomyiidae) include a large number of species of small mosquitoes with an elongated body, long legs and thin wings with few longitudinal veins without transverse joints. Gall midge larvae, settling in plant tissues, often cause the formation of growths - galls. Some species of gall midges cause significant damage to agricultural plants. Such, for example, is the Hessian fly (or rather, a mosquito) ( Mayetiola destructor), the larva of which lives in the stems of cereals. Flies (fam. Muscidae) are distinguished by a wide flattened body, a hemispherical head with short antennae. The common housefly is dangerous because it carries the eggs of parasitic worms and pathogens of various diseases on its legs and proboscis. Equally dangerous as disease spreaders are large green and blue carrion flies. Horseflies (fam. Tabanidae) - large or medium-sized blood-sucking flies with huge iridescent eyes. Horsefly bites bother livestock. They are carriers of anthrax. Gadflies (family Oestridae) are among the important parasites of farm animals. They differ from horse flies by their short, hairy body and small eyes. Adult gadflies have underdeveloped oral organs, and they do not eat anything during their short lives. Bovine gadfly larvae ( Hypoderma bovis) and cattle gadfly ( Hypoderma lineata) parasitize the body of cows and bulls, accumulating under the skin in the last stages of their development. Sheep botfly larvae ( Oestrus) live in the nasal cavity and frontal sinuses of sheep, causing false “whirl”. Gastric gadflies (fam. Gasterophilidae) are similar to skin gadflies. Their larvae parasitize the intestines and duodenum of horses and donkeys, often causing severe inflammation of the mucous membrane of these organs. Adult gadflies lay eggs on horses' fur, from where they are licked off by the owner. Botflies cause great damage to livestock production. These are quite large hairy flies that lead a free lifestyle and visit their hosts (horses, cattle, sheep, etc.) only to lay eggs or larvae. The larvae are thick, somewhat narrowed in front, hard, usually with spinous rings, with a pair of spiracles strongly chitinized along the edges at the posterior end and with another pair of spiracles near the anterior end of the body. The larvae settle in the stomach, under the skin, in the nasopharynx, frontal and maxillary sinuses. A serious pest is the Wohlfarth fly ( Wohlfahrtia magnified), which lays larvae - it is viviparous - in the nose, ears, anus of mammals, as well as on wound and ulcerative surfaces. The larva feeds on living tissue, then emerges and pupates in the ground. There are known cases of human infection with Wohlfarth fly larvae. Flies lay larvae mainly on people sleeping in the open air during the day. The larvae live in a person's ears, nose, frontal sinuses, gums, eyes and cause severe suffering. The positive significance of dipterans is also very significant, many of which are important pollinators of flowering plants. Predatory (ktyri) and parasitic (tachyna) destroy harmful insects. Larvae of bell mosquitoes, or bloodworms (family. Chironomidae), serve as food for many
Order Diptera, or flies and mosquitoes (Diptera) (B. M. Mamaev)
Among the 33 modern orders of insects, the order Diptera occupies one of the first places in terms of the number and diversity of representatives, second only to beetles, butterflies and Hymenoptera in this regard. To date, 80,000 species are known in this order. Undoubtedly, in the near future this figure will increase significantly, since the study of Diptera is still very far from being completed.
The main features that separate Diptera from other orders of insects are, firstly, the preservation in the adult stage of only the first pair of wings - organs of fast and perfect flight and, secondly, a radical transformation of the larval stage, expressed in the loss of legs, and in higher Diptera also in the reduction of the head capsule and, ultimately, in the development of extraintestinal digestion.
The body shape of adult dipterans is very diverse. Everyone knows slender, long-legged mosquitoes and stocky, short-bodied flies, but only experts will classify the microscopic wingless “bee louse” or the female of one of the humpback species found in anthills, which looks more like a very small cockroach, into this order.
The organs of vision - large compound eyes - in dipterans often occupy most of the surface of their rounded head. Additionally, on the crown there are, although not all, 2-3 pinpoint ocelli.
The antennae, or antennae, are located on the frontal surface of the head, between the eyes. In mosquitoes they are long and multi-segmented, which is one of the most distinct features that distinguish the suborder of long-whiskered dipterans (Nematocera). In flies belonging to the other two suborders, the antennae are greatly shortened and usually consist of only three short segments, the last of which bears a simple or feathery seta. Antennas are mainly organs for sensing smells. On the surface of each of the segments there are olfactory tubercles specially adapted for this purpose. Often the antennae of male dipterans are much more complex than the antennae of females. These secondary sexual differences are usually observed in mosquitoes; in flies they appear more often in the size of the eyes.
The oral parts of dipterans (Fig. 407) are greatly modified and are suitable for receiving mainly liquid food. The most perfect device for this is the proboscis of higher flies, formed by the lower lip and ending with sucking blades.
In blood-sucking mosquitoes, the mouthparts are highly elongated, the lower lip forms a groove in which piercing stylets are located: needle-shaped upper jaws (mandibles) and lower jaws (maxillae). Between them there is a subpharyngeal gland through which the duct of the salivary glands passes. The groove of the lower lip is covered from above by the upper lip.
In some blood-sucking flies, mandibles do not develop and the proboscis is structured differently than in mosquitoes. Their lower lip forms a stiletto-shaped hard groove, the cutout of which is covered by an upper lip of the same shape, linked to the lower lip by special outgrowths. The denticles, which in the proboscis of higher flies are located on the sucking blades and serve most species for scraping off solid food particles, are greatly enlarged in bloodsuckers and are used to open the integument of animals. In this case, the fly places its proboscis vertically against the skin of the animal and sets in motion the rollers on which the preoral teeth are located. Having cut the upper protective layer of the skin, these teeth quickly drill out the wound. Such proboscises are found in flies, tsetse flies, and other related species of dipterans. When the integument of insects is pierced by predatory flies - blackbirds and greenflies - the lower lip along with the subpharyngeal cavity plays the main role. In bloodsuckers such as horseflies, the wound is caused mainly by the mandibles.
The three thoracic segments of dipterans are tightly fused together, forming a strong thoracic region - a container of powerful muscles. It serves as a reliable support for the wings during fast flight. The halteres are also located here - short club-shaped appendages, which are a modified second pair of wings. They are considered organs of balance. The mesothorax, the most powerful thoracic segment, is equipped on the posterior edge with a semicircular outgrowth - a scutum.
At rest, the wings are folded over the abdomen in a roof-like manner, horizontally one above the other, or simply retracted back and to the sides. Many families of dipterans are best distinguished by their wing venation - the pattern that is formed on the transparent wings by their framework - the veins. In good flyers, the leading edge of the wing is especially strongly reinforced with veins. The surface of the wings is often covered with large and small hairs or scales, and sometimes has additional sensory pores. At the base of the wing, many flies have separate chest and wing scales, as well as a winglet.
The structure of the legs of dipterans is closely related to their lifestyle. Agile, fast-running flies have short, strong legs. Mosquitoes, which usually hide among vegetation during the day, have long limbs adapted for climbing among the tangle of grass stems or in the foliage of trees and shrubs. The paws of the legs end in claws, at the base of which 2-3 special suction pads are attached. With their help, dipterans can move freely on a completely smooth surface.
Ingenious experiments have proven that in flies these pads serve not only for movement, but are additional taste organs that signal the edibility of the substrate on which the fly has landed. If a hungry fly is brought to a sugar solution so that it touches it with its paws, the fly extends its proboscis to suck. When the sugar solution is replaced with water, the fly does not react in any way.
Both the chest and abdomen, which in dipterans consist of 5-9 visible segments, often have a characteristic color and are lined with hairs and setae. The arrangement of these setae is often used as a character to distinguish individual families, genera and species of the order.
The idea of dipteran larvae as whitish, legless and headless “worms” swarming in manure and garbage dumps does not at all reflect the true diversity of their forms and is based on the most superficial acquaintance with the order.
First of all, it should be emphasized that the larvae of all long-whiskered dipterans have a well-developed head and are often equipped with strong jaws, with the help of which the larvae feed on plant roots or rotting organic matter. The only exception is the rare family of long-whiskered dipterans - hyperoscelididae. Hyperoscelidid larvae completely lack a head capsule; their head segment bears only a pair of antennae and a mouth opening. These larvae live in decaying wood and feed exclusively on liquid food.
The head capsule never develops in the larvae of higher flies, whose entire oral apparatus is usually represented by only two sclerotized hooks.
The loss of the head capsule, so characteristic of the larvae of higher dipterans, is associated with the development in them of a unique method of digestion, which is called extraintestinal. With this type of digestion, food is first digested outside the larva’s body under the influence of the digestive juices it secretes, and only then is it swallowed and assimilated.
The body shape of the larvae is varied. It is usually worm-shaped, but sometimes it is so unusual that it can baffle an inexperienced taxonomist. Very bizarre, for example, are the flat larvae that live in fast mountain streams. deuterophlebiid(Deuterophlebiidae) - a small family distributed in the Altai, Tien Shan, Himalaya and Rocky Mountains of North America. Each segment of the larvae bears a long outgrowth on its sides with a sucker at the end. By alternately moving these outgrowths, the larvae are able to slowly move along the stones at the bottom of the fastest streams. They completely lack a tracheal system - a rare case not only in dipterans, but also in insects in general, and they breathe using anal gills.
The larvae are very remarkable ptychopterid(family Ptychopteridae), developing in fresh water bodies. They have a well-developed head, dense integument, equipped with dense rows of spines, and a long respiratory tube formed from the last two segments of the abdomen. There are spiracles at the end of the tube, and two respiratory filaments are attached to its middle part. The significance of the tube in the life of the larvae is clear: with its help, the larva can, without losing contact with the atmospheric air, search the bottom of shallow water or underwater parts of plants in search of food.
Very interesting are the slug-like larvae of mosquitoes of the genus ceroplatus(Ceroplatus family Ceroplatidae), found openly on the surface of fungi and mold. They have a rare ability among dipterans to emit weak phosphorus light in the dark, the source of which is their fat body. The glow continues in the pupa, but disappears in the adult mosquito.
Perhaps the only constant feature of dipteran larvae is the absence of thoracic (true) legs. The absence of legs in fly larvae in some cases is compensated by the development of various body outgrowths, reminiscent of the “false legs” of butterfly caterpillars. With the help of these outgrowths, the larvae can move relatively quickly along the surface of the substrate. Such larvae are known, for example, in the family snipe(Leptidae), numbering more than 400 species. Most of them have worm-shaped larvae and do not differ in appearance from housefly larvae. But in the larvae of the ibis fly (Atherix ibis), which live among stones at the bottom of fast-flowing rivers, on each body segment there is a pair of “false legs” equipped with hooks, which serve as perfect organs of movement.
In an abundant food substrate, dipteran larvae are found in large clusters. Common places for the mass development of larvae of higher flies are decomposing animal corpses, garbage dumps, latrines, etc.
Fungus gnat larvae (Mycetophilidae) bring a lot of frustration to mushroom pickers. In most cases, it is their long white larvae with a black head that swarm on the fractures of “wormy” mushrooms, making them completely unsuitable. True, fungus gnats cannot be considered exclusively inhabitants of mushrooms; some of their groups are associated with rotting wood, plant debris, etc., where they also form large colonies.
Also found in large clusters are leaf mosquito larvae ( family Sciaridae). In some cases, when food is scarce, these masses of larvae may undertake mass migrations. Larvae military mosquito(Sciara militaris) are grouped into a long ribbon up to 10 cm, which, slowly wriggling, moves in search of a favorable place. The appearance of such “snakes” aroused superstitious fear among people; they were considered a harbinger of crop failure, war and other disasters. Hence the name of the mosquito - “military”.
The process of transformation of an adult larva into a pupa in Diptera has its own characteristics. Typically, in insects with complete metamorphosis, after a pupa has formed under the integument of the larval skin, these integuments are shed and the pupa is completely released.
Long-whiskered dipterans are no exception to this rule. But a whole group of higher flies has a special additional protective device that protects the pupa from damage and is called puparia. In this case, the skin of the adult larva not only does not shed like an unnecessary shell, but, on the contrary, hardens, takes on a barrel-shaped shape and is strengthened by various deposits. The pupa is formed inside this skin, and the adult fly, in order to be free, breaks out a round exit hole in it (Table 55).
This biological feature is the basis for identifying Diptera in the order, except suborderlong-moustached, or mosquitoes(Nematocera), two more suborders: short-crested straight-stitched dipterans(Brachycera-Orthorrhapha), without a puparium, and short-crested round-suture dipterans(Brachycera-Cyclorrhapha), developing with the puparium. It is interesting that the larvae of some groups of Diptera, although they do not form a typical puparium, still pupate inside the larval skin. Among long-whiskered dipterans, this method of pupation is typical for a small family scatopsid(Scatopsidae), numbering about 130 species, and for a few species of the family gall midge(Cecidomyiidae), such as the Hessian fly and some others. Lionfly larvae pupate from short-haired straight-sutured dipterans inside a slightly modified larval skin.
The adaptability of dipterans to various living conditions is unusually wide. Their larvae have mastered a wide variety of habitats: fast streams and stagnant waters, clean, transparent bodies of water, including seas with salt water, and fetid sewers, thick soil, various rotting plant substances entering the soil, tissues of living plants and, finally, , the body cavity of insects and other invertebrate animals, as well as the intestinal tract, subcutaneous tissue and respiratory tract of vertebrate animals, and in some cases of humans.
Diptera larvae lead a hidden lifestyle and are incapable of long-term movements. To place their offspring in suitable conditions is the task of adult flies, which are therefore good flyers. Many of them have interesting adaptations that increase the survival rate of the larvae. It is enough to recall the birth of live larvae, common among higher dipterans, and in some cases the feeding of the larvae with secretions of special glands, when the larva leaves the mother’s body when it is already fully grown.
However, it is usually not adult flies that feed their larvae, but, on the contrary, the larvae store the nutrients necessary for the life of the adult phase.
There are often cases when adult dipterans live solely on the nutrients that the larva has accumulated and do not feed at all. Other species only need to drink water, flower nectar, or sweet sap flowing from wounded trees. But not all adult dipterans are so harmless. Mosquitoes, horseflies, biting midges, midges, sand flies are annoying bloodsuckers. However, only females suck blood from them, while males are completely harmless. If the females of these dipterans do not drink blood, they will remain infertile. Their bloodthirstiness is also explained by the fact that they need to drink a lot of blood, otherwise only part of the eggs will develop in the ovaries or the supply of nutrients will not be enough at all.
One of the families of Diptera - fruit flies(Drosophilidae) - forever entered the history of science, since its representatives served as one of the main objects in studying the role of the smallest structures of the cell nucleus - chromosomes in the phenomena of heredity. And this is no coincidence: under experimental conditions, Drosophila larvae develop very quickly on artificial media, and after 7-10 days the results of the experiment can be assessed. When adult flies or their larvae are exposed to X-ray or radioactive radiation, numerous changes occur in their offspring - eye pigmentation disappears, wings are underdeveloped, sometimes an ugly limb grows instead of one of the antennas, etc. In the experiment, it was possible to obtain flies that were several times larger than normal ones, ugly specimens were also obtained in which one half of the body had the characteristics of a male, and the other of a female, or many of the characteristics of the individual were of an intermediate nature. The results of all these experiments formed the basis for many important scientific conclusions about the laws of heredity, which are the study of genetics.
Diptera are one of the most numerous groups of insects and therefore represent a great force of nature. And this force, if we evaluate the importance of dipterans as a whole, causes enormous damage not only to the economy, but also to human health.
In nature, there are numerous foci of various diseases that affect wild animals. In many cases, these diseases are not dangerous to humans, but some of them pose an extremely serious threat to humans. There are also diseases that are not transmitted from person to person, but are nevertheless very widespread. Blood-sucking dipterans that attack animals and humans, along with other blood-sucking arthropods, widely spread these diseases, transmitting the pathogen during blood sucking.
The main danger from a malaria mosquito is not that it inflicts a painful bite, but that at the same time it can introduce malaria pathogens into the blood, and this disease alone has claimed many more human lives than all the wars in human history combined.
Equally dangerous carriers of infections are synanthropic dipterans, i.e. species that live in human dwellings. Visiting garbage and feces, they carry pathogenic microorganisms and worm eggs on their body and in the intestines, leaving them on dishes, food, furniture, etc. It is not without reason that many teams of scientists are working to study the biology of one of these insects - the housefly - with the aim of its destruction.
Diptera larvae can also be serious pests of food supplies. For example, a lot of harm comes from a nondescript cheese fly(Piophila casei), belonging to the family pyophilide(Piophilidae). Its white, shiny larvae develop in old cheese, ham, lard, and salted fish, destroying these products. Adult larvae emerge from food and look for places to pupate in dark corners, crevices and cracks in the garbage. They are sometimes called “jumpers” for their ability to curl up in a ring and suddenly straighten up to make jumps.
Cheese fly larvae pose a danger to human health when foods contaminated by them are eaten. In the human intestine, the larvae are able to remain viable for a long time, causing ulceration of the intestinal wall, with symptoms reminiscent of typhus.
One cannot underestimate the negative significance of those dipterans that attack a person during his work in the field, significantly reducing labor productivity, and in some cases making this work impossible during certain periods.
The positive role of dipterans in nature and in the human economy is small compared to the harm they cause. They are tireless orderlies, cleaning the surface of the land from the waste that accumulates here. Some groups of dipterans are known as soil formers and as enemies of harmful insects, inhibiting their reproduction.
Diptera are distributed very widely: from the tropics to the ice boundaries in the north and in the mountains. But even among the tropical representatives of the order there are almost no particularly large and brightly colored species. Insect lovers pay little attention to them, preferring beetles and butterflies, although biologically dipterans are no less interesting and unique.
Suborder Long-whiskered Diptera (Nematocera)
Mosquitoes have a slender, elongated body and thin, usually long legs; less often they are dense, squat, with short legs. Their antennae consist of more than three segments. In larvae the head capsule is well developed. Covered type pupae.
centipedes (family Tipulidae) are those large mosquitoes that fly out from under your feet in a wet meadow or forest clearings and, lazily flying several tens of meters, hide again among the grass.
Representatives of this family are distinguished by their slender body, long wings and very long, thin and weak legs, which serve them not only for climbing among vegetation, but also as a kind of protection from enemies. When a mosquito sits, its legs are spread wide apart, and an approaching predator grabs the centipede by the legs. But it is impossible to hold these mosquitoes by the legs; their limbs are immediately torn off, and instead of large prey, the predator ends up with only one or two convulsively shuddering legs. This method of protection is widespread in nature. Suffice it to recall the haymakers, who also flee from the enemy, leaving him with several of their limbs, lizards, who leave only the end of their tail in the teeth of the pursuer, octopuses, sacrificing their tentacles, etc.
Centipede larvae are inhabitants of moist environments: soil, litter, rotting wood or fresh water bodies. They have a large, dark, well-developed head and strong gnawing jaws. Most species feed on decaying plant debris, but some also gnaw on living plant roots.
The digestive process of these larvae is interesting. Plant foods, consisting mainly of very persistent substances - fiber and lignin, are difficult to digest. Single-celled animals come to the aid of centipedes. They multiply en masse in the intestines of the larvae, secreting enzymes that facilitate the digestion of fiber. As a result, the food is enriched with substances that are absorbed by the centipede larvae. Interestingly, the intestines of the larvae are equipped with special blind outgrowths where food is retained and where especially favorable conditions are created for the proliferation of microorganisms. This type of digestion, when plant food is digested in the intestines with the participation of symbiotic microorganisms, is found not only in insects, but also in vertebrates, for example, in a horse, whose stomach is also very complicated.
Among the few harmful species of centipedes, mention should be made garden centipede(Tipula paludosa) is an extremely widespread species, the larvae of which gnaw at the roots of plants, including cultivated ones. In total, there are more than 2,500 species in the family.
Familyreticulum(Blepharoceridae), which includes a total of 160 species, is famous for the uniqueness of its larvae that live in fast mountain streams. The head of the larvae merged with the thoracic region into a single whole, as well as the end segments of the abdomen. On the middle abdominal segments there are six powerful suckers of complex structure, the soles of which are lined with strong bristles. With the help of suction cups, the larvae slowly move along the stones in jets of a fast flow, scraping off various growths from them.
Before pupation, the adult larva firmly attaches itself to the stone, the skin on its dorsal side bursts and its fragments are quickly carried away by the streams, exposing the delicate pupa. The covers of the pupa soon harden, it darkens and becomes inconspicuous.
Mosquitoes emerging from pupae emerge from the bottom of the stream and fly to damp, shaded places, usually into rock crevices, where for the most part they hang calmly, clinging to ledges with their long and thin legs.
In all zones of the globe, from the tundra to the tropics, with the exception of sultry deserts, one of the most annoying insects in warm weather are real mosquitoes (family Culicidae). In swampy areas, these insects chase animals and humans in clouds, inflicting painful injections with their long proboscis (Table 56), from which even the fabric of clothing does not protect a person if it is not thick enough. Perhaps no other group of dipterans has such a perfect blood-sucking instrument as this stylet, which essentially consists of several stylets: two needle-shaped mandibles and two maxillae, the upper lip and the subpharyngeal, enclosed in a case - the lower lip. By the presence of a proboscis, it is easy to distinguish true mosquitoes from jerk mosquitoes, whose oral organs are not developed.
However, not all types of mosquitoes are aggressive. Many of them use their proboscis only to feed on nectar. In blood-sucking species, blood saturation is also obligatory only for females, while males are content with plant juices.
The environment for the development of mosquito larvae is small stagnant bodies of water or microponds - forest puddles, accumulations of water in hollows, rain barrels and even cans with rainwater. This is where the overwintered females of our common bloodsuckers from the genera Culex, Aedes, and Anopheles lay their eggs.
Common eggs malaria mosquito(Anopheles maculipennis) swim alone on the surface of the water. After 2-3 days, larvae emerge from the eggs, all of whose further development takes place at the surface of the reservoir. The larvae spend most of their time in a horizontal position, attached to the surface film with non-wettable humeral lobes, groups of special hairs on the abdominal segments and a stigmal plate; at the surface they are held by surface tension forces. In this position, the larvae feed on organic debris or small aquatic organisms that are constantly present in standing water. The air necessary for breathing enters the tracheal system through the stigmatic openings brought to the surface. An additional method of breathing is gas exchange through the skin and gills, two pairs of which surround the anus. Food is actively obtained by the larva. Its upper lip is equipped with brushes, the main purpose of which is to direct the flow of water with food particles to the mouth, where the food is captured by a filter of hairs of the oral apparatus. In addition to this method of feeding, the larvae are able to scrape food from plants and other objects submerged in water.
Disturbed larvae quickly dive, making sharp movements with the end of the abdomen. After stopping at the bottom or in the water column, the larvae begin to rise to the surface with their tail first, making the same movements. In about a month, the larva molts three times and increases in length by more than 8 times. Adult larvae turn into characteristic humpback pupae, which also stay at the surface of the water and breathe through a pair of respiratory tubes located on the dorsal side of the cephalothorax. In case of danger, however, the pupae quickly dive, flapping the end of the abdomen several times, and then passively rise to the surface again.
The skin of a mature pupa bursts on the back, and through the gap, first the head with antennae appears, and then the chest of the mosquito, the wings and limbs are released, and the mosquito, having grown stronger, flies into the coastal vegetation.
In the evening, you can observe a swarm of mosquitoes: many dozens of males mill around in the air, forming a kind of “singing” cloud, while the females, one after another, fly into the swarm and immediately leave it, carrying away one of the males.
In fertilized females, the blood-sucking instinct awakens. A hungry female is capable at a distance of up to 3 km determine the location of large concentrations of warm-blooded animals and humans and quickly overcome this distance. In one act of sucking, the female absorbs an amount of blood that exceeds the initial weight of her body. In the process of digesting this blood, due to the incoming nutrients, the first portion of 150-200 eggs is formed in the female’s ovaries. The female becomes aggressive again only after she lays these eggs in the nearest body of water. From now on, if for the first time a female drinks the blood of a person with malaria, she becomes dangerous, since her saliva is now teeming with sporozoites - the initial stage of the development of malarial plasmodium.
Having re-fed the blood, the female again loses interest in food until the next batch of eggs matures and is laid. The female lives for about 2 months in the summer. By autumn, females appear, preferring to feed on nectar. Their ovaries do not develop, but reserve fatty substances accumulate in the body. These females climb into cool and empty shelters, caves, hollows, holes, basements, where they spend the winter. The development cycle of other species of blood-sucking mosquitoes is very similar.
From a practical point of view, it is important to distinguish mosquitoes that are harmless to humans from those that carry malaria. Our ordinary squeak mosquito(Culex pipiens), an annoying but harmless bloodsucker, differs well from the malarial mosquito in its position (Fig. 410): it holds its body almost parallel to the surface on which it sits, while the abdomen of the malarial mosquito deviates at an angle of 30-40°. The larvae of the squeak mosquito hang vertically at the surface of the water, upside down (Table 57); the larvae of the malaria mosquito hang horizontally.
Mosquitoes are of great importance as carriers of pathogens of such serious diseases as malaria in its various forms, yellow fever caused by a virus, Japanese encephalitis, encephalomyelitis, etc. Only a well-developed scientific system for the prevention of these diseases in the USSR and some other countries has made it possible to sharply reduce the incidence of human diseases. Not only chemical but also biological control measures have been successfully used to control mosquitoes. The small viviparous fish Gambusia, brought from America, acclimatized in Central Asia, where it became one of the main enemies of mosquito larvae. Interestingly, the larvae of some harmless mosquito species are predatory, destroying the larvae of blood-sucking mosquitoes. One larva toxorhynchitis mosquito(Toxorhynchites splendens), common in the tropics, destroys up to 150 larvae of other mosquitoes. This species has been successfully introduced to some Pacific islands to control harmful mosquitoes. In total, there are about 2000 species in the mosquito family.
Mosquitoes are the first of five main families of blood-sucking dipterans, the complex of which is aptly named "gnus". Together with horse flies, biting midges, midges, and in the south also mosquitoes, mosquitoes form hordes of dipterans, which, especially in swampy taiga places, do not give a moment of rest in the summer months, attacking animals and humans.
This is how zoologists who visited the taiga describe this phenomenon.
“In summer and autumn, on a bright sunny day and in cloudy weather, from morning to evening, humans and animals are besieged by myriads of mosquitoes and especially midges. Midges get into the eyes, mouth, and fill the ears and nose. It’s difficult to breathe, there’s a ringing in the ears, the eyes are clouded with tears. Calves and foals sometimes die, eaten by midges. Large wild animals, for example, in the summer, make long migrations to the mountains and to the sea, where they escape from the midges thanks to the wind. In taiga villages, field work is often stopped during the day. , which are transferred to the night. Pets stop eating and gather under the canopy, where smokers are raised to drive away the midges.
A person takes shelter indoors, and outdoors uses smoke, nets, and ointments to protect himself. But neither the room, nor the tent, nor the clothes protect against bloodsuckers: attacking annoyingly, the insects pierce the fabrics, get under the clothes and into the room. A person besieged by midges will have drops of blood appear on his face and hands within a few minutes. You rub dozens of insects swollen with blood, hundreds of new ones land on you.
At night, the midges subside, but mosquitoes and midges are still active; biting midges, due to their insignificant size, penetrate through the smallest cracks in tents, doors and windows and attack sleeping people; their injections are especially painful."
Blood-sucking dipterans are most numerous in the virgin, untouched taiga. With its development, the number of bloodsuckers decreases, but even large-scale systematic measures to combat the midges do not yet produce such an effect that one can talk about a final victory over this army of enemies of animals and humans.
Extensive, numbering over 3000 species familymosquitoes, or bells(Chironomidae), closely associated with large and small bodies of water. On quiet warm evenings, over the banks of ponds and small rivers overgrown with reeds, you can hear a subtle melodic ringing. This ringing is produced by swarming mosquitoes, which either suddenly fly up or passively fall down. The bells are usually pale yellow or light green, less often dark in color, their forelimbs are greatly elongated, raised and serve as organs of touch, the oral organs are not developed, and the male antennae are densely feathery.
By washing a portion of sludge from the bottom of the pond on a sieve, you can almost always find the larvae of bell-bellied mosquitoes. These larvae have no need for atmospheric air: the absorption of oxygen dissolved in water and the release of carbon dioxide occur through their tracheal gills and partially through the integument of the body. Red larvae live in the silt of various reservoirs, including heavily polluted ones with low oxygen content in the water. bloodworm(Chironomus plumosus) and a number of related species. These larvae intensively feed on microorganisms that populate the sludge, hiding in arachnoid tubes from their numerous enemies. They are very readily eaten by fish, for which they serve as one of the main food sources, and are well known to fans of aquarium fish farming. The respiratory pigment hemoglobin is dissolved in their hemolymph - a useful adaptation to life in conditions of lack of oxygen.
In some lakes, bell larvae descend to a depth of over 300 m, at such a depth they are the only representatives of insects. In some Arctic lakes, which freeze to the bottom in winter, the larvae of these mosquitoes successfully overwinter in the thickness of frozen silt, that is, in conditions that would be destructive for many other insects.
Larvae have adapted to living in seawater pontomy(Pontomyia natans). The females of this species have lost their wings and legs, turning into worm-like animals that do not leave the water. Males look for females by running along the surface of the water.
Mokretsy (family Ceratopogonidae) - small mosquitoes, their body length rarely exceeds 3-4 mm. They are close to ringing mosquitoes, from which they differ in the good development of the oral apparatus in adult mosquitoes. Let us remember that adult bell mosquitoes do not feed and their oral organs are underdeveloped. There are over 1,000 members of the midling midge family, but only a few hundred species of bloodsuckers have been well studied. Most of these species have variegated wings and, by this feature, are well distinguished from such blood-sucking dipterans as mosquitoes and midges.
The environment for the development of midge larvae can be very diverse, but always moist. Most often, larvae can be found in a layer of silt along the banks of fresh water bodies, in swampy soil, in temporary micro-reservoirs, such as puddles on roads, rainwater in tree hollows, midge larvae are often found in flowing tree sap, wet, rotten wood, etc. .
Thin and long larvae of midges, white or pinkish in color, with a dark brown head and a naked, smooth body, are able to move quickly in the mud or swim in the water, wriggling like a snake. The development time of various species ranges from two weeks to two months. Pupation occurs amicably, and after 5-7 days adult mosquitoes begin to emerge from the pupae, and in terms of timing of emergence, males are slightly ahead of females.
Hatched biting midges usually stay near the breeding sites among grass, bushes and in the crowns of trees. Many species swarm in the evenings or early mornings in calm weather, and the swarm consists predominantly of males. Blood-sucking midges often penetrate en masse into livestock premises.
Adult biting midges feed on plant sap and are often found on flowers. Only representatives of some genera, primarily the genus Culicoides, are vicious mass bloodsuckers. Like many other blood-sucking insects, feeding on blood in these species of midges is typical only for females. Blood-sucking midges attack people, domestic and wild animals, not only warm-blooded mammals and birds, but also amphibians and reptiles. There are known cases of attacks even on other insects, most often mosquitoes and butterflies.
Mid-latitude mid-latitudes appear in May - June and, developing in several generations, reach their highest numbers in July - August. Most blood-sucking species are active in the morning and evening; on cool, cloudy days, biting midges also attack during the day.
A single saturation with blood is enough for the complete development of eggs in the ovaries of the female. After laying the first batch of eggs, the females again attack the animals and, if bloodsucking is successful, lay eggs again.
The harm caused by biting midges is not limited to the toxic effect of their saliva, which is especially severe during a mass attack. Although the role of biting midges as carriers of pathogens has not yet been fully elucidated, it has been proven that some species of this family are intermediate hosts of filariid nematodes; biting midges are considered one of the possible carriers of the hemosporidia tularemia microbe, as well as some viral diseases - Japanese encephalitis, equine encephalomyelitis, etc.
The most common and widespread of the blood-sucking midges, not found only in the tundra, is burning biting midge(Culicoides pulicaris), producing several generations over the summer. Its larvae are found in polluted fresh water bodies.
TO familymidges(Simuliidae) are small humpback mosquitoes whose body length does not exceed 6 mm. They are easily distinguished from real mosquitoes by their shorter, stronger legs and short proboscis. Their wings at rest fold horizontally one above the other, short antennae usually consist of 9-11 segments.
Midges are known as annoying bloodsuckers. Together with mosquitoes and biting midges, they form hordes of midges and equally readily attack wild animals, livestock and humans. There are especially many midges where there are fast rivers that serve as places for the development of their larvae.
Female midges are experienced divers. To lay eggs, they descend under water, clinging to rocks and plant stems. Some species of midges, however, prefer a calmer coastal strip for laying eggs or drop their eggs into the water while flying over the stream.
The larvae emerging from the eggs are immediately attached to the substrate by the rear end of the body, where there are hooks and powerful muscles. Females lay eggs in groups, often with several females in one location. Therefore, midge larvae often form large colonies in the stream bed. Under particularly favorable conditions on 1 cm 2 surfaces account for up to 200 midge larvae.
The appearance of these colonies is peculiar. The fast, changeable flow of the stream rhythmically oscillates the larvae, which passively obey the streams and resemble small aquatic plants more than living creatures. Only periodically contracting “fans” located near the mouth opening of the larvae indicate that intense life flows inside these organisms.
Fans are complex formations consisting of numerous hairs and bristles and serve to trap food. They were formed from the lateral sections of the upper lip. The food of the larvae - organic residues suspended in water or small aquatic organisms - is filtered out of running water like a sieve and accumulates in the fans of the larvae. Then the fans contract, and the food bolus is driven to the mouth and enters the intestines. With this method of feeding, the faster the current, the more water is filtered through the fans and the more food is captured. Therefore, midge larvae colonize areas of the riverbed with the fastest flow. This is all the more necessary because midge larvae are very sensitive to lack of oxygen and quickly die in stagnant or low-flow water with a high content of rotting organic residues.
It is difficult to imagine that these legless larvae can move in fast currents. However, an experienced observer will immediately notice at the anterior end of the larva’s body a cone-shaped outgrowth, the sole of which bears rows of hooks.
The significance of this outgrowth, called the “leg” of the larvae, becomes clear only when the larvae begin to crawl. In this case, the larva lubricates the nearest surface area with sticky cobweb secretion, attaches itself to it with its thoracic “leg” and pulls up the rear end of the body. Having secured the rear end of the body on the web site, the larva releases the thoracic “leg” and, straightening up, looks for a new site for attachment. Along the entire path of movement, the larva weaves a cobweb thread, on which it holds on if it is torn off by the current.
When there are sudden disturbances in the conditions of a reservoir, the larvae of some midges release cobwebs up to 2 m and stay on it for some time in the currents. When the reservoir regime is restored, they return along the web to their original place.
The entire colony of larvae pupates very amicably. Before pupation, the adult larva weaves a cocoon, which looks like a cap from which the pupa sticks out. On her cephalothorax there are branched respiratory tubes that provide gas exchange. Adult midges emerge from pupae after 1.5-2 weeks. Leaving the pupal skin, the midge is enveloped in an air bubble, in which it rises to the surface and comes out of the water completely dry.
Adult midges feed only on hot sunny days; in cloudy weather, at dusk and at night they are inactive. Only females are bloodsuckers; males feed on flowers.
The short proboscis of midges with sawing mandibles and tearing maxillae is well adapted for piercing the skin of animals. It would seem that blood sucking is the most natural way of feeding for all midges. However, this is not the case. In some areas, despite the significant abundance of midges, they do not attack animals or humans. Specially conducted experiments showed that female midges can successfully feed on flowers, while the eggs in their ovaries mature normally.
The activity of adult bloodsuckers also varies in different zones of their distribution: it decreases from north to south. So, broad-legged midge(Eusimulium latipes), decorated midge(Odagmia ornata), creeping midge(Simulium repens) in the tundra are a scourge of humans and animals, and further south - in the forest-steppe and steppe zones they are not at all registered as bloodsuckers. It is quite likely that the need for blood feeding arises in adult midges if their larvae developed in unfavorable conditions and did not accumulate sufficient reserves of nutrients. Among midges, however, there are species for which blood sucking is a necessary stage in the life cycle. It is these species that pose the greatest danger.
A midge injection is a whole surgical operation. At the time of the injection, saliva containing anesthetic substances is injected into the wound. Therefore, the pain quickly disappears and appears again only after the midge has sucked blood and flies away. At the same time, substances that prevent blood clotting are injected into the wound.
The saliva of midges is poisonous. Swelling develops at the injection site within a few minutes, burning and itching appear. With numerous bites, body temperature rises, signs of general poisoning appear, hemorrhages and swelling of internal organs begin, which can lead to rapid death.
The scourge of livestock farming in the Danube countries is Columbian midge(Simulium columbaczene). The larvae of this species develop in large rivers and are especially numerous in the Danube. The larvae of the Columbus midge pupate in the first half of May, and by the end of this month the coastal bushes are covered with swarms of emerging mosquitoes. After fertilization, the males die, and the females fly away from the shore 5-20 km in swarms and attack livestock. In some years, tens of thousands of livestock died from this midge.
In the USSR, bloodsucking midges are most diverse in the taiga zone. The most malicious bloodsuckers here are tundra midge(Schoenbaueria pusilla), Kholodkovsky midge(Gnus cholodkovskii), decorated midge(Odagmia ornata) and a number of other species. These midges attack at temperatures from 6 to 23 ° C, and in the fall the Kholodkovsky midge is active even after snow has fallen.
The harm from midges is aggravated by the fact that they are carriers of such serious diseases as anthrax, glanders, tularemia, plague, and leprosy. The causative agents of these diseases are transmitted by a female who has interrupted feeding on a sick animal and quickly attacks a healthy one. In Africa, midges transmit human filariasis.
Butterflies (family Psychodidae) are very peculiar small mosquitoes, distinguished by a densely hairy body and wide, hairy wings with a dense network of longitudinal veins.
In damp and dark rooms it is often found on windows and is harmless. ordinary butterfly(Psychoda phalaenoides), extending far to the north.
The southern relatives of butterflies are not so harmless - mosquitoes(Phlebotomus), common in the tropics and subtropics, and in the USSR found in Central Asia. Beginning in April, female mosquitoes, like female mosquitoes, leave their daytime shelters at dusk and attack various mammals, birds, and reptiles, causing many difficult moments for people. Blood feeding is absolutely necessary for females, otherwise they will not leave offspring. Flower nectar, although consumed by mosquitoes as food, fully provides only males, while female mosquitoes are particularly bloodthirsty. Having sucked on the blood, the females begin to digest it. At the same time, eggs begin to mature in the ovaries.
Unlike mosquitoes, mosquitoes are not associated with water. Their larvae develop in various organic residues, but at a sufficiently high humidity. In populated areas, places where mosquitoes develop are spaces under the floor, garbage pits, latrines, barnyards, in nature - caves, hollows, damp pits and, especially in desert areas, turtle and rodent burrows. The duration of development of one generation of mosquitoes is about 2 months.
A person should carefully guard against the bites of these small insects. With their saliva, pathogens of serious diseases can be introduced into the blood - the papatachi fever virus, as well as leishmania, which causes visceral and cutaneous leishmaniasis-Pendine ulcer. Visceral leishmaniasis is especially dangerous, which affects the internal organs of a person - the liver, spleen, and bone marrow.
Gall midges(Cecidomyiidae) - family Diptera, numbering over 3000 species. These include small mosquitoes, mostly orange in color, with long antennae and legs and very weak wings, strengthened by only 3-4 longitudinal veins. Adult gall midges do not feed and live only 2-3 days, so the prosperity of this family is explained by the many useful adaptations that their larvae have developed.
The smaller the insect, the more enemies it has. But the larvae of gall midges, which can only be examined in detail through a magnifying glass, are not afraid of enemies - they are reliably hidden inside the gall both from predators and from the adverse effects of the external environment.
Galls are abnormally modified parts of organs, and sometimes entire plant organs (flowers, fruits, shoots, leaves), transformed by larvae into a more or less closed chamber (Table 58). In such a chamber, the larvae have nutritious food at their disposal - plant juice; they are not afraid of the vicissitudes of the weather - the walls of the gall reliably isolate them from adverse influences.
The process of gall formation is very complex. Gall midge larvae do not gnaw plant tissue; their tiny heads and piercing mouthparts are unsuitable for this. The larva acts differently: it releases specific growth substances onto the surrounding tissues, under the influence of which plant cells begin to rapidly grow and divide. As a result of the close and precise interaction of the larva and the plant, a gall of a strictly defined characteristic shape is formed, so that the type of gall midge can be easily determined by the shape of the gall. Adult larvae sometimes pupate in the gall, and sometimes fall into the soil, where they weave a silky cocoon for themselves.
Inside the cocoon, the larva quickly turns into a pupa. Adult gall midges emerging from pupae must find a plant suitable for the development of larvae. There are a lot of phytophagous gall midges, but each species is strictly confined to a specific type of plant. If the female makes a mistake, the larvae that emerge from the eggs will not be able to form a gall on the alien plant and will die. But such mistakes are very rare, since gall midges distinguish plants very accurately, guided by the subtle characteristics of their odors.
Many species of gall midges are common and very widespread. In forests, reddish round galls are found on the petioles of aspen leaves in summer. aspen gall midge(Syndiplosis petioli, table 58, 2). The tops of willow shoots are transformed into a characteristic gall, reminiscent in structure of a rose flower, larvae willow roseate gall midge(Rhabdophaga rosaria, table 58.5). The galls caused by saxaul gall midges in deserts are especially diverse.
Gall midges periodically reproduce in incredible numbers. Species that damage cultivated plants are especially dangerous during periods of mass reproduction. Common in Europe, Asia and North America Hessian fly(Mayetiola destructor) - the scourge of grain breads. The females of this gall midge lay eggs on the leaves of wheat, rye or barley seedlings. The larvae develop in the leaf sheaths, damaging the stem so much that it breaks off from the wind. Fields affected by Hessian grass look as if they have been trampled by cattle.
However, not all groups of gall midges develop in plant tissues. Primitive gall midges still retained a strong connection with their primary habitat - soil, litter, rotting wood. Particularly noteworthy are the gall midges of the genus, living in rotting plant debris and wood. miastor with a single species - Miastor metraloas. Colonies of larvae of this species number thousands of individuals (Table 58, 12), and each colony originated from one egg. Miastor is distinguished by its ability, rare among insects, to reproduce at the larval stage. As soon as the larva of this species has time to reach maturity, numerous daughter larvae quickly form inside it, which, eating the insides of their parent, tear the wall of her body and come out. They eventually suffer the same fate and the colony of larvae grows rapidly. Only after greatly multiplying, all the larvae of the colony finally pupate together, and the adult gall midges scatter in search of new habitats.
This rare method of reproduction, first studied by N. Wagner in these gall midges, was called pedogenesis. Further pedogenesis in the class of insects was also discovered in one of the North American beetles.
Familypachypodes(Bibionidae) includes about 400 species, the importance of which in nature lies in the active processing of organic substances entering the soil and improving the properties of the soil. This processing is carried out by large, up to 1.5 cm, gray larvae with a large head, strong jaws and numerous fleshy outgrowths on the body. The larvae live in separate colonies, each of which is the offspring of one female, which laid the entire supply of her eggs in a given place. Only some dilophus (Dilophus) feed on living plants, the larvae of which gnaw at the roots.
Adults emerge very amicably during the warm spring months. They often accumulate en masse on flowers, grass, leaves of bushes, or fly lazily in the rays of the sun. The eyes of thick legs are unique. In males, each eye is divided into two parts, with the facets in the upper half being much larger than those in the lower half. Usually the eyes are densely covered with hairs. The antennae are short and consist of 9-12 segments. The tibiae of the front legs are thickened and equipped with spines. Males and females often differ in color. U garden skein(Bibio hortulanus) the male is black, the female is red-brown, but her head, scutellum and legs are black.
The expressive appearance of slow, clumsy shiny black or brown mosquitoes from familiesaximied(Axymyiidae) recalls those distant times when dipterans were just in their infancy.
Indeed, many structural features of these mosquitoes were inherited from their distant ancestors. First of all, attention is drawn to their wings, adapted for slow and difficult flight, sluggish, clumsy legs, and the whole appearance of the insect, unable to quickly fly away, or run away, or in any other way protect itself from enemies. Only the eyes of these mosquitoes have reached a high degree of perfection: they occupy almost the entire surface of the head and in males each consists of two sections - the upper, of large facets, and the lower, of smaller facets. The mouth parts of mosquitoes are reduced, and the antennae are greatly shortened, but they have a large number of short segments, of which there are from 13 to 17.
How did such helpless insects survive to this day? This became possible because the almost complete defenselessness of adult mosquitoes was compensated by the development of very advanced adaptations in their larvae, which went on to live in wet, rotten wood. They have a large head and strong jaws, with the help of which they grind short passages. Their thick whitish body ends in a long respiratory tube, at the base of which 2-4 clear-shaped outgrowths with a dense plexus of trachea inside are attached. All this is a complex breathing apparatus in wood saturated with water. Other insects were unable to adapt to life in such an environment, and therefore aximiids have very few enemies and competitors. But even under these conditions, only 4 species of this family have survived to this day, distributed only in the northern hemisphere.
More recently, in 1935, when it seemed that all families of Diptera were already known, a description of a strange mosquito discovered in the mountains of Japan was published. This find immediately attracted the attention of scientists, since the described insect could not be included in any of the known families of the order. This is how the first information about the new familynymphomiids(Nymphomyiidae), representatives of which have recently been discovered in North America.
White nymphomy(Nymphomyia alba) differs from other dipterans primarily in its large elongated triangular wings with very weak venation. The anterior and especially the posterior margins of the wings are lined with dense rows of very long hairs, increasing the total area of the wing. The head of mosquitoes is directed straight forward, the underdeveloped eyes merge not from the top, but from the bottom, the mouth parts are underdeveloped, and the antennae consist of only 3 segments with a small appendage at the end.
Even more amazing is the white nymphomia pupa, which has a free, movable head. All that is known about the larvae of this amazing mosquito is that they live along the banks of mountain streams. This was established because insect pupae were found there, but no one had ever seen the larvae themselves.
Among modern dipterans there were no forms with which nymphomiids could be related. They cannot rightfully be considered long-whiskered dipterans, since their antennae consist of only 3 segments. They are also very different from the short mustache ones. Fossil dipterans with a similar structure are known only from Upper Triassic deposits studied in Central Asia. When the nymphomiid larvae are studied, it may be possible to answer the question of which modern dipterans are their closest relatives. In the meantime, this family occupies a separate position in the order Diptera.
Suborder Brachycera-Orth0rrhapha
These are typical flies with a compact short body and wide, strong wings. Their antennae consist of 3 segments, but the last of them may retain traces of additional segmentation. The head capsule of the larvae is greatly reduced. The larval skin is usually shed during pupation. The pupa is covered; when the fly emerges, its thorax cracks along a T-shaped line.
Horseflies (family Tabanidae) are large blood-sucking dipterans. A female horsefly is capable of taking up to 200 mg of blood in one blood suck, i.e., as much as 70 mosquitoes or 4,000 midges drink. If we add to this that in swampy areas during the hot summer months, herds of domestic animals are attacked by tens of thousands of horseflies, the enormous negative significance of horseflies in nature and human economy becomes clear. Their harmfulness is further aggravated by the fact that when horseflies suck blood, they carry pathogens of anthrax, tularemia, polio and other serious diseases, and also transmit some diseases caused by nematodes.
There are great losses in livestock production from horse flies. Often the most productive pastures along the shores of lakes and in river valleys are empty in the summer months, as they cannot be used due to the abundance of bloodsuckers. Even with a moderate attack of horseflies, cows reduce their milk yield by 10-15% and quickly lose weight. Scientists have calculated that in one day the loss of strength in animals that are bothered by horseflies and flies is equivalent to malnutrition of 400 G oats per head of livestock. And this is understandable, since the largest of the horse flies reach a length of 2-3 cm, their bites are extremely painful and are accompanied by swelling, which is caused by saliva entering the wound during blood sucking.
Horseflies are sometimes incorrectly called gadflies. However, it is enough to make sure that a fly caught on an animal has a short, piercing proboscis in order to confidently classify it as a horsefly. The large eyes of horseflies are beautiful - golden, shimmering with all the colors of the rainbow. Their wings are sometimes transparent, sometimes with smoky spots, and their abdomen is always flattened.
The life cycle of horse flies has much in common with the basic features of the life cycle of other bloodsuckers. Males feed exclusively on the nectar of flowers and the sugary secretions of aphids, scale insects, and also sweet juice flowing from wounded trees.
Unfertilized females also follow the same diet, but after fertilization there is no limit to their aggressiveness. They attack animals and humans on hot days from the morning until sunset; rainflies are also active in cloudy weather, especially before rain. Among their victims, large animals come first: deer, elk, roe deer and especially livestock. Horseflies are also capable of attacking small animals - rodents, birds, especially fledgling chicks, and even lizards - monitor lizards, takyr roundheads, etc. They do not even neglect animal corpses in the first 2-3 days after death, which makes horseflies particularly dangerous carriers infections.
At close distances, horseflies are guided by vision and perceive the contours and movement of objects. They often make mistakes and pursue moving cars, boats, ships for a long time, even flying into train cars.
Horseflies are usually not selective about food. However, in complex plant communities, for example in multi-tiered tropical forests, individual species complexes are found predominantly in one particular plant layer. In the rainforests of Cameroon, for example, Ethiopian pieds(Chrysops silvacea, Ch. centuriones) stay in the treetops and chase herds of monkeys.
Females that have sucked blood quickly digest it. After just 24 hours, the blood clot in the stomach is significantly reduced, and the absorbed nutrients go to feed the gradually enlarging ovaries. After 48 hours, only a small amount of semi-digested blood remains in the intestines, and the maturing egg cells have grown greatly. After 76 hours, digestion ends and the eggs finally ripen. Thus, eggs are laid on average 3-4 days after bloodsucking. Female horse flies, as a result of repeated blood sucking, can complete up to five such cycles, ultimately laying over 3,500 eggs. The fertility of different horsefly species can, however, vary greatly.
Eggs are laid on plants, usually over the water of lakes and swamps. The larvae that emerge from the eggs fall into the water and live in the moss cover, root plexuses or in the upper layers of moist soil, in some species feeding on decaying plant debris, in others they are actively predating. Their victims include larvae of other insects, amphipods, and earthworms.
Bullfly(Tabanus bovinus) is one of the largest species. It is dark brown, the chest has dark stripes and yellowish hairs, the abdomen is bordered by a yellow-brown border with a strip of light triangular spots in the middle part.
Brightly colored smaller ones common lacewing(Chrysops caecutiens), which actually has bright emerald-golden eyes. The abdomen of this species has yellow spots at the base. More modestly colored ordinary raincoat(Chrysozona pluvialis), whose wings are distinguished by a complex smoky pattern. In total, there are over 3,500 species in the horsefly family.
Long proboscis(Nemestrinidae) - small family Diptera, distributed mainly in tropical and subtropical regions. Adult flies resemble horse flies, but are clearly distinguished from them by their strongly elongated proboscis, which is usually much longer than the body. With its help, flies suck the nectar of flowers. However, it is not so easy for long-proboscis to get to nectar - their proboscis does not bend, and the fly, especially in windy weather, has to work hard to satisfy its hunger.
North American females trichopsidea(Trichopsidea clausa) lay eggs in cracks in tree trunks or telegraph poles. The fertility of females is very high - several thousand eggs, and this is understandable, since the original larvae emerging from the eggs, equipped with numerous outgrowths, are simply carried in different directions by the wind. The meeting with the host, which is the locust, largely depends on chance, so most of the larvae die without reaching the goal. But if this meeting occurs, the larva penetrates the locust’s body through one of the spiracles and, feeding on the host’s tissues, completes its development by the fall and overwinters. Adult flies emerge in the spring.
In total, about 250 species are known in the long-proboscis family.
Large familylittle lion(Stratiomyiidae), which includes about 2000 species, is distributed mainly in the humid tropics. Only about a hundred species are found in the northern forests of Eurasia.
Lion flies can be easily distinguished by their wide, flattened body, usually painted in bright colors, often with a metallic sheen, by short transparent wings and peculiar antennae with a ringed last segment.
This is exactly what it looks like common soldier fly(Stratiomyia chamaeleon), which is often found on flowers. Its black abdomen with yellow spots, brown chest with a yellow shield and red-yellow legs harmonize well with the bright color of the flower corollas, hiding the insect from enemies.
The larva of this fly is unique, living in shallow polluted water bodies. Its fusiform body, reaching a length of 20 in an adult larva mm, ends with a long “tail”, which is formed from several elongated last segments of the abdomen. At the end of the “tail” there is a stigma plate with two holes for breathing. There is also a corolla of long, non-wettable hairs. The larva breathes by hanging from the rear end of the body to the surface of the water. In this case, the non-wettable hairs straighten, the stigmas open, and the larva itself is passively held by surface tension forces. Having inhaled, the larva bends sharply, breaking away from the surface film. At the same time, the hairs fold and cover the stigma area. The larva then slowly sinks to the bottom, where it burrows among silt and algae, ingesting decaying organic matter. The pupa forms inside the skin of an adult larva.
Many species of lion flies develop in soil, manure, and rotting wood. Among them, metallic green or blue ones are especially distinctive. geosargus(Geosargus), the larvae of which are common in manure. The integument of the larvae is impregnated with calcium carbonate and serves as good protection for both the larva and the pupa, which forms inside the larval skin.
About 5000 species familiesktyry(Asilidae) - predominantly inhabitants of open spaces - steppes and deserts. These slender flies, whose bodies are covered with dense, short hairs, usually bask in the sun, ready to instantly take off when danger appears or in pursuit of prey. Everything in their appearance speaks of adaptation to predation. The sharpness of the bulging eyes, deeply separated by the crown of the head, is so great that it is difficult to approach sitting birds without being noticed. Although their proboscis lacks mandibles, other parts of the oral apparatus - maxillae, subpharynx and lower lip - form a very sophisticated piercing organ. The saliva of insects contains a strong poison, from which insects die instantly. A bird caught by hand sometimes bites a person. This sting is as painful as a bee sting.
The speed and accuracy of the ktyr’s reaction is surprising: an instant, a short takeoff, and the lifeless insect is already sucked out by the ktyr, which has returned to its original place. The aggressiveness of ktyrs is so great that they emerge victorious in a fight with such well-armed insects as bees, wasps, and jumping beetles; the extraordinary gluttony of these flies forces them to hunt continuously.
Moth larvae are also predators. In the soil they pursue the larvae of other insects, and can withstand prolonged starvation. But if the hunt is successful, they grow very quickly.
The larvae are peculiar Lafriy(Laphria), pursuing the larvae of longhorned beetles or lamellar beetles in wood. Their body bears numerous outgrowths that help the larva move in the passages. Adult frogworts sit on the bark of trees. Sometimes they are painted in bright colors, such as gold red laffria(L. flava).
Large murmurs reach a length of 4-5 cm. That's how giant ktyr(Satanas gigas), found in the steppes.
Among Diptera there are few other groups whose representatives could compare in speed and flight agility with flies from familiesbuzzed(Bombyliidae). The appearance of most buzzers is very peculiar: a short stocky body covered with long thick hairs, wings directed to the sides and back at rest, reminiscent of the position of the wings of high-speed aircraft, and, finally, a needle-shaped proboscis, which in some species is not inferior to the length of the body.
The proboscis is an excellent device for sucking nectar from flowers with a deep corolla, which are inaccessible to many insects. But the buzzers would not have been able to take advantage of this advantage if they were not excellent flyers. With amazing dexterity, feeding flies literally hang in the air above the flowers, while plunging their proboscis into the nectaries, and without sitting on the flower, they suck out the nectar.
In the modern fauna, the buzzer family is one of the thriving ones and includes about 3,000 species.
Adult flies are predators familiespushers(Empididae) and their larvae living in the soil. The nectar of flowers on which adult flies are often found serves as an additional source of nutrition for them. The long, needle-shaped proboscis of pushers is equally well adapted for sucking insects and for absorbing plant juices. Prey - small dipterans - is captured by the front legs, the thighs of which are lined with spines, and the tibia are tightly attached to them, forming strong forceps.
A disproportionately small round head and slightly pubescent body complement the characteristic appearance of representatives of this family. But the “dances” of the pushers during the mating flight are especially unique. They are not only quite complex in their execution, but are also notable for the fact that the males at this time drag around silky “parachutes” or elliptical “balloons” with foamy walls, inside of which lies dead prey - a small fly or mosquito. Before mating, the male offers this prey to the female and thereby saves his own life, since aggressive females often eat males after copulation. Such “dances” are observed among representatives of the most common genera - empis(Empis), Gilara(Hilara) ts etc.
Greenflies (family Dolichopodidae) are metallic shiny or grayish small dipterans with long legs and a laterally compressed body. In total, the family contains more than 3,500 species. Greenfinches are often found in damp meadows, along the banks of ponds and rivers, but they are difficult to notice against the background of green parts of plants. They attack small mosquitoes and midges, killing them with a proboscis consisting of pointed appendages of the lower lip and subpharyngeal spines; The mandibles of these dipterans are not developed.
Most closely related to water water strider greenfinches(Hydrophorus), sliding along its surface like water bugs. They hunt for small insects that often stick to the surface of the water. Their larvae, like those of most other greenfinch species, prey in moist soil.
Useful honeydew greenfinches(Medetera), the larvae of which destroy bark beetles in their passages under the bark of trees. Adult grayish flies are often found on forest trunks.
Suborder Brachycera-Cyclorrhapha
Typical flies with a short compact body and wide, strong wings. Their antennae are shortened, 3-segmented, with a seta on the third segment. The head capsule of the larvae is completely reduced, only the mouth hooks are preserved. The larval skin does not shed during pupation, takes on a barrel-shaped shape and hardens, becoming saturated with special secretions, forming a false cocoon - puparia. The doll is free. When the adult fly emerges, the puparium opens along a rounded line under the pressure of the head or frontal bladder, which in most cases is well developed.
Gorbatki(family Phoridae) are very small, inconspicuous flies with a swollen hump-shaped chest, strong legs, and thickened thighs. The transparent wings are strengthened along the anterior edge by two thick, closely spaced veins; the remaining veins of the wing are much thinner; there are no cross-veins in the wing.
Representatives of the genus are found in anthills platyphora(Platyphora). The winged male of these flies retains all the characteristics of the family, but the female is wingless, her body is flattened, like that of a cockroach, and in appearance she in no way resembles a fly.
In termite mounds live peculiar termite mounds(Termitoxenia, Termitomyia), which are sometimes classified into a special family Termitoxeniidae. They have a soft elongated body, an elongated head with a piercing proboscis, short antennae and tenacious legs (Fig. 420, 3). The wings are represented by small stumps, by which termites usually drag them; The abdomen is soft, unusually strongly swollen.
On the flowers of umbelliferous and asteraceae, flies from very similar species often sit next to wasps and bumblebees. familieshoverflies(Syrphidae, table 59). Although these flies are completely harmless, birds do not dare to touch them, mistaking them for hymenoptera armed with a sting. There are about 4,500 species in the hoverfly family.
The flight of these flies is original. Along with normal flights, hoverflies can hang in the air for a long time, continuously working with their wings, but without moving. The study of such a “standing” flight showed that only when the wing is lowered is its plane directed horizontally - the lifting force that arises in this case balances the weight of the insect. In the down position, the wing rotates 45° and returns upward, cutting the air with its sharp leading edge. Naturally, no forward force arises in this case.
The lifestyle of hoverfly larvae is unusually diverse, in contrast to adult flies, which part with nectar-bearing flowers only to lay eggs in a suitable place. Females of some species fly to dirty, stinking streams to do this, others rush under the forest canopy, looking for trees with fermenting sap flowing from wounds, others look for colonies of aphids or nests of bumblebees, others fuss around anthills, etc.
Of the syrphid larvae developing in water, the larva is especially noteworthy common beekeeper(Eristalis tenax), which is figuratively called “rat”. The body of this larva is barrel-shaped, vaguely segmented, with outgrowths - “false legs” - on the ventral surface. The last three segments of the abdomen form a characteristic “tail” - a respiratory tube. These segments are thin, and each subsequent one can be retracted into the previous one or, conversely, quickly move out of it. At the end of this device are two spiracles, and inside the tube are two thick trachea. The fully extended respiratory tube of adult larvae reaches a length of 12-15 cm(Fig. 421, 5).
Rice. 421. Hoverflies: 1 - Conosyrphus volucellum; 2 - decorated spherophoria (Sphaerophoria scripta); 3 - baccha (Baccha elongata); 4 - chrysotoxum (Chrysotoxum festivum); 5 - “rat” - larva of the common bee (Eristalis tenax); 6 - larva of the wasp-shaped hoverfly (Temnostoma vespiforme)
Its significance in the life of the larvae becomes clear if you move the bottom of the reservoir in which they live with a stick. From there, silt and undecomposed organic matter will rise and bubbles of foul-smelling gases will appear. Meanwhile, the bee larva boldly descends into this rotting mess, where it finds abundant nutrition - after all, on the surface of the water it leaves the end of a breathing tube through which gas exchange occurs. When the larva dives into deeper layers, it is forced after some time to rise to the surface to breathe. The larva pupates in the soil next to the pond. The pupa forms inside the larval skin. An adult fly with a brownish chest and a yellow-black spotted abdomen is very similar to a bee (Table 59, 2). It was on this similarity that the assertion, which arose in the early stages of the development of science, was based that bees could be born from mud. Now such a statement can only bring a smile.
Adult hoverflies of the genus are very similar to wasps darkostoma(Temnostoma). Their larvae are active wood destroyers of wet stumps and dead trunks. How can these larvae of higher dipterans, which, as is known, lack a head capsule and gnawing jaws, make passages in wood? To achieve this, the larvae had completely unexpected adaptations: the bases of their prothoracic spiracles greatly increased, partially separated and turned into two powerful scrapers, the edges of which are lined with rows of teeth. They scrape wood in the same way as a mollusk - a shipworm - uses the remains of its underdeveloped shell for the same purpose.
However, the most common of hoverflies are those that live in aphid colonies. It is difficult to imagine that the greenish or gray larvae resembling small leeches crawling in aphid colonies belong to the same family as the “rat”, but this is so. Just look at the adult hoverflies of the genus sirfov(Syrphus). Their appearance is quite typical: a dark chest with a metallic tint and the same abdomen, on each segment of which there are two crescent spots.
The larvae of our common syrphs (Syrphus balteatus, S. ribesii) are serious enemies of cabbage aphids (Table 59, 16). One adult larva sucks out over 200 aphids in just one day. Considering that the feeding period lasts about 20 days, it can be calculated that each larva will destroy up to 2000 pests during this time, and there are several hundred such larvae in the offspring of just one female. By attracting syrphids to fields by sowing nectar-bearing flowers, you can successfully combat many harmful species of aphids.
Hoverfly larvae of the genus microdon(Microdon), living in anthills, were first mistaken for mollusks and described as a special genus of these invertebrate animals. This error is not accidental: the larva has a rounded body with a flat lower surface without any traces of articulation and even some semblance of a shell, which is formed by its hemispherical hardened outer covers, bearing layers of dust and dirt. However, these larvae eventually produce bronze-green flies, whose belonging to hoverflies is beyond doubt.
Various species have achieved the greatest success in imitating stinging Hymenoptera bumblebee, or shaggy(Volucella), which are similar to bumblebees both in body shape and in the arrangement of thick fluffy hairs, colored, like bumblebees, in various colors (Table 59, 8). This similarity most likely arose because woolly bees are biologically closely related to bumblebees. Their larvae develop in bumblebee nests, feeding on the corpses of dead larvae or the always available feces and waste.
It is difficult to imagine that the sticky resin oozing from wounded spruce trees could harbor living larvae. But hoverflies have adapted to this habitat. Larvae black chylosis(Chilosia morio) develop only in resin. The whitish body of these larvae is immersed in its thickness, and a short breathing tube is brought to the surface, providing an unhindered supply of air. In the spring, also without leaving the resin, these larvae pupate in a kind of puparia. The emerging completely black hoverflies lay their eggs in the wounds with fresh resin.
Another interesting example of imitation of stinging Hymenoptera is found by representatives familiesbig-headed(Conopidae), numbering over 600 species. The abdomen of adult flies is slender, weakly stalked, slightly curved downwards - features that give the henheads a resemblance to wasps. The head of flies is very large, the antennae are often elongated; the proboscis is long, thin, with one or two geniculate bends, the body is colored black, brown and yellow.
One of the largest species of the family - yellowlegged bighead(Conops flavipes), up to 15 long mm. Its body is black, its head has yellow spots, and its abdomen also has 2-3 yellow bands.
Cereal flies (family Chloropidae) have become notorious as pests of grain crops, no less dangerous than the Hessian fly. Almost all representatives of this extensive family, numbering over 1300 species, develop on wild and cultivated grasses. Adult flies are common in meadows, forest clearings, and on the boundaries of agricultural fields, where they can be collected in large numbers with a regular net. The size of grain flies does not exceed 3-5 mm, body naked, shiny black, yellow or greenish; in many species the chest is on top with longitudinal dark stripes on a yellow background.
The larvae damage the apical part of the stem of cereals, often resulting in a characteristic spindle-shaped cluster of leaves. As a result, the plant either dies or begins to bush, developing weak adventitious stems.
Most species of grain flies are food selective; each of them develops successfully on a few, strictly defined plant species. The most economically important species of this family, although they are also found on wild cereals, show a clear preference for cultivated ones.
One of the most dangerous pests of grain bread is swedish fly(Oscinella frit). New studies of these flies suggest, however, that this is not one species, but a whole complex of species, each of which prefers one of the grain crops - wheat (O. vastator), barley (O. pusilla) or oats (O. frit ).
Damage to cultivated cereals by the Swedish fly varies widely depending on the time of oviposition. If the pest attack coincides with the tillering phase of spring grains, then the larva lives under the leaf sheaths at the ear bud, which is destroyed. When the next generation of Swedes flies, the grain is already earing. In this case, the eggs are laid directly in the ear and the larvae eat the grains.
Another harmful species from this family is green-eyed(Chlorops pumilionis) - yellow fly with black stripes on the chest. In spring, it most often affects spring wheat and barley, and in autumn - seedlings of winter wheat and winter rye. The green-eye larva lives under the leaf sheaths, causing shortening and thickening of the internodes.
Piedwings (family Trypetidae) are small or medium-sized flies with a unique pattern on the wings, characteristic of each species. The pattern is made either with dark stripes and spots on transparent wings, or one or another number of light spots appear on a general dark background. The abdomen is also often spotted. In total, about 2,500 species are known in the family.
Adult flies feed on flower nectar or aphid secretions. Their larvae are typical phytophages, that is, they feed on living plant tissues. Many species of variegated flies have adapted to develop inside the baskets of Asteraceae plants, where they eat away the ovaries of flowers and the receptacle. By breaking large burdock (Arctium) baskets, you can often find dirty white larvae orellias(Orellia tussilaginis). Variegated fly larvae are also found in the juicy fruits of cherries, barberries and other plants.
cherry fly(Rhagoletis cerasi) brown-black with a yellow head and shield, legs, except for the thighs, also yellow. Females lay eggs under the skin of ripening cherries, the larvae feed on the pulp of the fruits, causing them to rot and fall off.
Some species of variegated flies enter into more complex relationships with plants, causing the formation of pathological growths - galls.
In all cases, representatives of this family have well-expressed food selectivity - certain species of the family are capable of developing not on any, but only on strictly defined plant species.
Extremely interesting from a biological point of view mining flies (family Agromyzidae). Representatives of this relatively large family, which includes 1000 species, like variegated flies, develop in living plant tissues. Just like with variegated flies, the nature of the damage caused by the larvae of leafminers is varied. The family includes gall-forming species, there are species that inhabit the inflorescences of Asteraceae or their seeds, pests of grass stems, and even species that have come to live in the trunks and branches of trees. But the most flourishing species are the miner species, the larvae of which eat away large slit-like cavities in the leaf parenchyma, called “mines.”
Most leafmining flies are characterized not only by the type of plant they damage, but also by the shape of the mine, which is sometimes so specific that it makes it possible to accurately determine the type of pest. It is interesting to note that representatives of this family have adapted to life on almost all groups of plants - from primitive ferns and horsetails to the historically youngest Compositae.
Some species of leafminer flies, which have switched to feeding on cultivated plants, have established themselves as serious pests. Harmful to cabbage and other cruciferous vegetables phytomysis(Phytomyza atricornis), which, unlike most species of the family, is characterized by significant indifference to food. About 300 species of plants from 30 different families are known on which larvae of this fly have been found. The appearance of adult specimens is typical for the family: body length - 2-3 mm, the back is shiny black, the legs and sides of the chest are yellow.
In some places in the forest zone, leaf miners of the genus dysygomisa(Dizygomyza) associated with tree species. Willows, birches and some fruit trees are especially affected by them.
Familyshorebirds(Ephydridae), which includes more than 1000 species, reaches its peak in the forest zone. These very small, inconspicuous flies, colored in gray and black tones, are remarkable for their biology.
A completely unusual way of feeding larvae oil psylops(Psilopa petrolei), found in oil springs in California. Numerous bacteria were found in the oil, as well as in the intestines of the larvae, that can decompose paraffin and are believed to provide the larva with food. It is not yet clear, however, how the larvae obtain the nitrogenous substances necessary for protein synthesis.
Harmful species of the family include barley coast(Hydrellia griseola). The larvae of this small gray fly with transparent wings develop in mines on the leaves of cereals, including barley, wheat and rice, and sometimes cause significant damage.
Dung flies (family Scatophagidae) got their name because their most abundant species are common on animal excrement, i.e. they are coprobionts. This is red dung beetle(Scatophaga stercoraria) - large fly, up to 10 mm, yellow-brown in color with thick rusty-yellow hairs and slightly lighter wings of the same shade (Table 60, 8). Its larvae feed on manure and feces.
However, paradoxically, most dung fly species are not associated with dung. Among them, especially interesting are plant pests whose larvae, like the larvae of leaf miners, develop in leaf mines or live in the generative organs of plants.
Pests of ears of wild and cultivated cereals (rye, timothy) are the larvae of ear flies (Amaurosoma).
There are over 500 species in the family. Many of them are associated with accumulations of decaying plant debris.
There are over 3000 species in familyreal flies(Muscidae). It’s easy to imagine their appearance by remembering the well-known housefly.
Many species of true flies are synanthropic, that is, more or less closely related to humans. Some of them, for example housefly(Musca domestica, Fig. 423) are no longer found in the wild, outside towns and cities. Manure, feces, various garbage - these are the wastes where the larvae of the housefly, a constant companion of human settlements, develop. The reproduction rate of this species is amazing. At one time, the female lays on average about 100-150 eggs, but with sufficient nutrition, oviposition is repeated at intervals of 2-4 days, so that her total fertility is ultimately 600, and in countries with a hot climate 2000 or more eggs. If the larvae, pupae and flies themselves did not die, then the offspring of just one female by the end of summer could exceed 5 trillion (5,000,000,000,000) copies.
Housefly larvae, like other higher flies, do not have a head. They liquefy food by releasing digestive juices onto it; this method of digestion is called extraintestinal. As a result, the entire colony of fly larvae finds itself floating in a liquefied semi-digested medium, which they constantly swallow (Table 55). As a result, food is used with amazing economy. In one liter of horse or cow manure or in the same amount of kitchen waste, from 1000 to 1500 fly larvae can simultaneously develop, and in pig manure - up to 4000.
Houseflies are dangerous spreaders of infections. Each of them, having been exposed to feces and various kinds of waste, carries about 6 million microorganisms on the surface of its body and at least 25-28 million in the intestines. But it must be said that the pathogenic bacteria in the intestines of the fly are not digested and are excreted quite viable. Typhoid and paratyphoid bacilli, dysentery bacillus, Vibrio cholera, tuberculosis bacillus, anthrax spores, the causative agent of diphtheria, and worm eggs were found on the flies. Therefore, the fight against houseflies is an important link in the overall system of combating human diseases.
Along with housefly larvae, many other species of this family develop in manure and waste. Larvae housefly(Muscina stabulans) also begin their lives as consumers of decaying plant matter, but then, having grown stronger, they begin to feed on the larvae of other dipterans, i.e. they become predators. One of the most active predators in manure are larvae. common toothpole(Hydrotaea dentipes), which destroy the larvae of houseflies, flies and other species of dipterans.
Competition among dung inhabitants is usually extremely fierce. Some species of flies have developed a special life rhythm that allows them to avoid large losses in this competition: they lay not eggs, but live larvae, often quite large, in manure. Thus, the larvae of some species of the genus dasiphora(Dasyphora) develop in the mother’s body up to the third stage, that is, they enter the manure when they are almost adults.
It is often said that by autumn flies become angry and begin to bite. This folk sign arose because it is in the fall that burner flies appear, first of all. autumn burner(Stomoxys calcitrans). This fly, equipped with a piercing proboscis, is a bloodsucker and causes harm as a mechanical carrier of anthrax, tularemia and other diseases.
Another blood-sucking fly that carries a special type of trypanosome, the causative agent of “sleeping sickness,” common in Africa, has become notorious. Trypanosomes themselves are constantly found in the blood of antelopes, which do not cause harm. Tsetse fly(Glossina palpalis), having drunk the blood of such an antelope, often then bites a person, transmitting trypanosomes to him. The disease is expressed in deep exhaustion and usually ends in death.
Another species from the same genus, Glossina morsitans, spreads a similar disease, which, however, only affects animals. Interestingly, in these flies the larva develops completely inside the swollen abdomen of the female, feeding on special secretions of the accessory glands. After leaving the mother's body, the larva immediately pupates in the soil.
Very serious pests are true flies that develop in living plant tissues. Plants affected by flies usually rot and die. Cabbage flies, whose grayish color gives them a strong resemblance to a housefly, greatly harm cabbage and other cruciferous vegetables. Their larvae make passages in the roots of damaged plants, contributing to the spread of root rot. Particularly dangerous spring cabbage fly(Chortophila brassicae), the first generation of which attacks seedlings, causing plant death.
Similar to cabbage, but lighter in color onion fly(Ch. antiqua). The larvae of this pest eat away the insides of bulbs in vegetable gardens. Beets are damaged by larvae beet fly(Regomyia hyosciami), which eat away bubble-like cavities in the leaf parenchyma. Lives in the stems of cereals winter fly(Hylemyia coarctata). Its larvae cause damage resembling that of the Swede. Larvae spring fly(Phorbia genitalis), also living in the stems of wheat and barley, gnaw spiral-shaped passages in them.
* (The Sakharov locust eater described below is sometimes classified as a separate family Acridomyiidae or included in the family Anthomyiidae.)
Carrion flies(Calliphoridae) is a predominantly tropical family with about 900 species, some of its representatives are common up to the northernmost regions. Like many tropical insects, they are brightly colored green or blue with a metallic sheen (Table 60).
In tropical countries, related species also attack humans. Typically, the females of these species lay eggs on the dirt floor of a hut where people live, and the larvae then actively burrow under the skin of humans and domestic animals.
During the First World War, an incident occurred that helped to discover the completely unexpected beneficial effect of carrion fly larvae settling in festering wounds. Two seriously wounded German soldiers were picked up only seven days after the battle, and the wounds of each of them were infested with carrion fly larvae.
After the wounds were washed, they were in such good condition that this fact attracted the attention of surgeons, especially since such wounds usually ended in death.
Study of the action of fly larvae, such as green carrion flies(Lucilia), blue carrion flies(Calliphora), and others have shown that by feeding on decaying wound tissues, they not only remove these tissues and small bone fragments, but also prevent the proliferation of pathogenic bacteria with their secretions. In addition, they secrete allantoin into the wound, a substance that promotes healing.
However, the use of flies from natural environments does not always end successfully, since they can introduce tetanus bacilli or gangrene bacilli into wounds. Therefore, for the clinical treatment of difficult-to-heal wounds, flies are bred in the laboratory and completely sterile larvae are obtained, that is, free from any pathogenic microbes.
Larger familygray blow flies(Sarcophagidae), numbering over 2000 species, is poorly represented in the tropics and reaches its peak in the more temperate zones of the northern hemisphere.
The body of these flies is most often colored ash-gray with a black checkerboard pattern or rounded spots.
In the forest zone, larvae develop on carrion common blowfly(Sarcophaga carnaria). Adult flies, gray with a black pattern, can be found on flowers, their sizes reach 20 mm, but there are also dwarfs with a length of only 6-8 mm.
Common in Southern Europe and Central Asia Wohlfarth's fly(Wohlfahrtia magnifica), distinguished from other species by the presence of three rows of dark spots on the gray abdomen. Females of this species, like most other species of the family, are viviparous. They forcefully throw larvae into ulcers and wounds, as well as into the eyes, ears and nostrils of various animals. The larvae feed on living tissue, causing severe suffering, often ending in death. This species is especially harmful in pastoral areas.
There are many cases where a person became a victim of Wohlfarth fly larvae, in whom they usually caused long-term suppuration (myiasis) on the head or penetrated into the nasal cavity. By making passages in the tissues, the larvae not only give rise to painful sensations: the damaged areas swell and fester, the tissues partially die, and bleeding begins from the nose. After removing the larvae, all these phenomena disappear.
Familysubcutaneous gadflies(Hypodermatidae), as reflected in its name, includes species whose larvae develop in nodules under the skin of animals.
Of interest are the adaptations of subcutaneous gadflies to ensure that, in strictly defined periods, a high number of adult individuals is created in nature, which is important for the successful reproduction of the species. Although botfly larvae fall out of the fistulas into the soil at different times, the first pupae formed in the spring develop more slowly compared to those that form somewhat later. Therefore, the vast majority of pupae complete their development almost simultaneously, and within a few days a large number of adult flies emerge from them at once. Moreover, gadflies emerge from their pupae at a strictly defined time of day, in the temperate zone usually from 7 o'clock. 30 min. until 8 o'clock 30 min. morning. All emerging individuals flock from large territories to the same points, constant from year to year, usually to the tops of some hills or mountains, to certain sections of roads, paths, etc. There are significantly more males in these clusters than females. If the gadflies are scared away from these places, then after a while they return there again. Based on these observations, even proposals were made to combat adult gadflies in places where they gather.
Females of subcutaneous gadflies, laying eggs, behave very actively and for a long time in whole flocks chase animals, which take flight in panic. It is possible to milk cows during the flight of the gadflies only when they are standing in the water - the gadflies do not attack them at this time. The amount of milk produced in tired animals is halved, and their fatness drops sharply. Reindeer husbandry suffers huge losses from subcutaneous gadflies, as the value of skins perforated by larvae is greatly reduced.
Sometimes, though very rarely, a person becomes a victim of subcutaneous gadflies. These are usually people caring for pets. The migration of subcutaneous gadfly larvae in the human body often ends with their penetration into the head - after all, the larvae migrate upward, like in animals. The most severe diseases are caused by the introduction of larvae into the eye. In this case, to remove the larva, surgery is necessary, which leads to partial loss of vision.
Bull Gadfly(Hypoderma bovis) is distributed in Europe, North Africa and Asia. Females of this species lay eggs on the hair of animals, mainly on the legs. Cattle are mainly affected. After 4-6 days, the larvae emerge from the eggs and, having penetrated the skin, begin complex migrations. First, they rise through connective tissue layers to the esophagus and penetrate its walls, then descend into the chest and here they reach the place of their final development, which occurs under the skin in the intercostal spaces, where nodules are formed.
An adult gadfly reaches a length of 14 mm, its body is covered with thick hairs. On the chest in the anterior half the hairs are yellowish-gray, in the posterior half they are black; the abdomen in the middle part is covered with black hairs, its end is reddish, and the base is even lighter.
Deer can be very heavily infected with northern hypoderm. On average, 200 botfly larvae develop on one deer, and the maximum infestation is estimated at 1000-1500 larvae.
Larvae of different types gastric gadflies (family Gastrophilidae) develop not only in the stomach, but also in other parts of the intestinal tract. At the same time, females lay eggs on the animal’s hair, but in strictly defined places - most often on the hairs of the lips, cheeks or intermaxillary space. In this case, the larvae emerging from the eggs independently reach the oral cavity and descend into the intestines. Some gastric gadflies lay eggs on the hair of those parts of the animal's body that it scratches with its teeth. In this case, the larvae do not leave the egg shell, remaining viable for 90-250 days - a period of time sufficient for the animal to accidentally lick the eggs of the gadflies while scratching, from which larvae immediately appear in the oral cavity. Further migration of the larvae to the stomach or some other part of the intestine occurs quickly. Here the larvae attach to the walls with mouth hooks, feed on the secreted mucus and blood, and, having reached maturity, are carried out along with the feces. They pupate in the soil.
Gadfly-hook(Gastrophilus intestinalis) is one of the most numerous gastric botflies. This is a large yellowish-brown species, up to 15 mm, with spotted wings. The chest of the fly is covered with protruding light yellow or brownish hairs; on the abdomen the hairs are straw-yellow with some admixture of dark ones.
The female lays eggs on the hairs of the host's lips. There is evidence that the female is also capable of sticking eggs into the skin of the animal with a sharp attachment process. The larvae that emerge from the eggs develop in the oral cavity before the first molt and then descend into the stomach. At the end of development, the larvae are carried into the rectum, where they reattach to the walls and live for a long time.
The development cycle of representatives is interesting familiesnasopharyngeal gadflies(Oestridae), Females of all species of this group are viviparous, but by the time they emerge from the pupae, the larvae in the eggs do not have time to develop. Females spend almost three weeks in complete immobility, waiting for the moment when young larvae appear in their abdomen from eggs. After this, a period of active search for host animals begins. The female sprays several larvae each time directly into the nasal cavity of the animal, where they develop due to mucous and blood pathological secretions. Along with the larvae, the female also squirts out a certain amount of liquid. The larvae are very sensitive to drying and even before this liquid evaporates, they must reach the mucous membrane of the nasopharynx. Some animals, such as deer, during an attack by gadflies, inhale dust and fine sand, thereby drying out the nasal cavity and to some extent protecting themselves from the larvae.
In temperate climates, young larvae of gadflies overwinter, and their development is completed in spring and summer. Adult larvae emerge through the host's nostrils.
There are known cases of nasopharyngeal gadflies attacking humans. In this case, females usually spray larvae into the eye. The larvae quickly crawl and scratch the mucous membrane of the eye with their hooks, causing inflammation (conjunctivitis).
Causes great harm to livestock breeding kruchak, or sheep gadfly(Oestrus ovis), which develops in the nasal cavity, frontal sinuses and cavities at the base of the horns of sheep. The female of this species lives up to 25 days, and the first 12-20 days are necessary for the final formation of the larvae. Then the female energetically searches for a host and quickly places the offspring, since even a slight delay in laying larvae leads to the fact that the larvae crawl into the female’s body and cause her death. In total, the female can lay up to 500 eggs.
The losses caused by the twister are very large. With the development of more than 50 larvae in the nasal cavity and frontal sinuses, sheep experience “false whirling” - a disease in which sheep spin in one direction and die after a few days. When the larvae penetrate the respiratory tract, death occurs from pneumonia.
The harm caused by gadflies is extremely great. Huge amounts of money are spent annually on the fight against these dipterans, but the fight against gadflies is effective only when it is carried out as planned and over large areas. In the USSR, in the last decade, as a result of the use of a complex of chemical and preventive control measures, significant progress has been achieved in the extermination of gadflies.
The body of adult flies, especially the abdomen, is usually lined with strong bristles; the last segment of the antennae is laterally compressed. Tachins are sun-loving insects; in summer they can most often be found on flowers, where flies feed on nectar or honeydew. However, they avoid high temperatures and hide in shelters during the hottest hours of the day. Only a few species of tahini have a twilight period of activity.
Although fertilization occurs in the first hours after the females emerge from the puparia, eggs are not laid immediately. In different species of tahini, it takes from 8 to 25 days for the eggs to mature in the ovaries. After this, the entire behavior of the females changes dramatically, as the period of feeding on plants is replaced by a period of intensive searches for the host.
Among the representatives of the family there are relatively few species of monophages that develop exclusively at the expense of any one animal species. Most tachinas successfully establish their offspring on a large number of different hosts, which, however, belong to any one family or order, that is, more or less related. Larvae emerging from eggs swallowed with food drill through the intestinal wall and, with a flow of hemolymph, reach certain organs where their development takes place. In some species, the larvae are located in the suprapharyngeal nerve ganglion, in others they penetrate the salivary glands or linger in the muscle tissue.
As the larvae grow, they begin to experience difficulty breathing and are usually attached with the rear end of the body to one of the tracheal trunks of the host so that the spiracles of the larva extend into the lumen of the trachea.
Having successfully penetrated the host's body, the larvae begin to feed on its tissues, but during the first period they spare vital organs. Only at the final stage of development the larva secretes a large amount of digestive juices into the host tissue, causing their complete digestion. Having finished feeding, adult larvae most often emerge through the integument and pupate in the soil.
The bloodsucker eggs mature in the female’s body, and the larvae hatch from them there. The larvae feed on the secretions of special accessory glands. The eggs in the ovaries are formed alternately, and therefore the female feeds one larva in each subsequent period of time. The larva grows quickly on nutritious food and leaves the mother’s body only to immediately pupate, having climbed into the soil. Therefore, the bloodsucker and some other dipterans that give birth to larvae ready for pupation are often combined into the group of “puppet-bearers”.
Avian bloodsuckers can generally live successfully on many species of birds. When birds come into contact with each other, flies often change hosts. The species composition of bloodsuckers on birds of prey that hunt other birds is especially diverse: while the predator eats its prey, all the bloodsuckers that lived on it move to a new host.
In bloodsucking bats, two methods of attachment of born larvae are noted. During this period, the females of most species leave the host and attach the larvae to some substrate - on the stone walls of caves, on the bark of trees, on the walls of attics where mice hide during the day, etc. The bloodsucker emerging from the puparia independently searches for the owner. Only a few species attach the newly born larvae to the fur of bats.
In total there are about 150 species in the family. All of them are relatively small - length common bloodsucker of bats(Nycteribia pedicularia) total 2-3 mm. Despite some external similarities, bloodsuckers of bats are not considered closely related to the family Hippoboscidae discussed above. It is believed that they arose independently of dipterans, which initially developed on waste in the shelters of bats, and then adapted to feeding on their blood.
And etc.). However, at the same time, they are of great importance for agriculture, since they are pollinators of various plants, including cultivated ones.
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✪ Life of insects (narrated by entomologist Andrey Matalin)
In most cases the head, thorax and abdomen are well separated and each bears specific appendages.
The head is movably articulated with the chest by a thin stalk of soft cuticle. The legs have a typical structure. The tarsi of most Diptera are five-segmented; at the end they bear two claws, under which there are suction cups, with the help of which dipterans can crawl along smooth, vertical surfaces. The abdomen is usually sessile, rarely stalked, and consists of 4-10 visible segments.
Head
Holoptic eyes are characteristic of those groups that are characterized by swarming and mating on the fly, and occur more often in males, and in representatives of the families of reticularis ( Blephariceridae), Thaumaleidae, buzzed ( Bombyliidae), sharovok ( Acroceridae), bigeye ( Pipunculidae) in both sexes. In Acroceridae, the eyes may touch both above and below the antennae; in most detrituses ( Sciaridae) and some gall midges ( Cecidomyiidae) they merge and form the eye bridge above the antennae on the dorsal side of the head, at Nymphomyidae- on the ventral.
Dichoptic eyes in some representatives of the families Retinoptera ( Blephariceridae), Axymyidea and gall midges ( Cecidomyiidae) can be divided into ventral and dorsal parts by a stripe that does not contain facets.
The color of the eye is very different, modern species sometimes have bright stripes, for example, in horseflies ( Tabanidae) .
The individual parts of the head are given corresponding names. The forehead is located between the eyes ( frons), which passes upward into the crown ( vertex). The lower border of the forehead is determined by the position of the antennae ( antennae). In the suborders short-whiskered and long-whiskered, the forehead is a more or less uniformly scleritized plate. Sometimes (horseflies - Tabanidae, liars - Therevidae) on the forehead, individual, more scleritized shiny areas stand out, which are called calluses. U Cyclorrhapha-Schizophora(except for some tennis courts - Sciomyzidae) an arcuate suture passes over the base of the antennae, which is called the ptilinum suture ( ptilinal fissure), falling down onto the face.
Ptilinum ( ptilinum) turns inside out like a sac and swells from the pumped hemolymph during the period when it needs to be born from the puparium. With its help, the fly breaks through the puparia and comes to the surface. Throughout the rest of life, the ptilinum is retracted into the head and is not visible. In some dipterans, for example, in mining flies ( Agromyzidae), between the arcuate suture and the bases of the antennae there is a clearly visible plate called the lunula ( lunule) .
Most lower dipterans have a forehead that is a scleritized plate. Representatives Schizophora the central part of the forehead is usually more or less membranous and forms the frontal plate ( frontal vitta, interfrins, seumesofrons). On the sides there are more scleritized parafrontal (frontoorbital) plates ( orbitis, seuparafrontalia). Either they run along the edge of the eye along the entire forehead, or they are shorter and are divided into upper orbital plates, which can sometimes be called parietal plates, they are located on the sides of the ocellar triangle and lower frontal plates, called zygomatic plates. In variegated wings ( Tephritidae) frontal plates are sometimes greatly enlarged, in Calytratae always merged with the orbital ones. In some representatives of cereal flies ( Chloropidae) and milichiids ( Milichiidae) the central part of the forehead is occupied by the large ocellar, also called parietal, triangle.
The part of the head below the antennae is called the face ( face). Most long mustaches ( Nematocera) there is practically no face, and in blood-sucking forms, that is, mosquitoes ( Culicidae), midge ( Ceratopogonidae), midges ( Simuliidae), horseflies ( Tabanidae), this part of the head is occupied by a large clypeus ( clypeus). In most higher dipterans, part of the face is occupied by the facial plate, which is limited by the frontobuccal or frontogenal suture. U Schizophora an arcuate suture runs outside the front one. That part of the face that is located between the arcuate suture and the eyes is called the cheekbones, or otherwise parafacialia. The strip between the cheekbones and the frontal suture is convex and represents the facial or vibrissal carina ( parafacialia), ending at the bottom with a vibrissal angle. The face can be concave, convex, with more or less developed tubercles, for example in hoverflies ( Syrphidae), fruit flies ( Drosophilidae). The frontal plate is usually bare, but sometimes (in the ktiri - Asilidae) bears a tuft of long hairs called a “beard.” The face may have two deep furrows or antennal pits ( antennal foveae), in which the antennae seem to be partially hidden, the ridge separating them is called the facial carina ( facial carina). At the bottom of the head there is a clypeus (prolabrum), which is separated from the face by a suture. In higher dipterans ( Muscomorpha) clypeus is reduced to a small sclerite in the upper part of the proboscis and is not visible from the outside. The lower edge of their face is called epistome.
Under the eyes on the side there are cheeks ( genae), which consist of the cheek itself and a narrow strip below, the so-called cheeks, or postgena ( postgenae). The back of the head is convex, flat, less often concave, in the families Bombiliidae and Pipunculidae, and this part is called postcarinoma ( postcarinum). In its central part there is the actual back of the head ( occiput), in the lower part is called the cheek part ( postgena) .
On the head there are paired segmental appendages, the so-called antennae, or antennae. In dipterans, the structure of the antennae is very diverse. They consist of a scape ( scapus) - the very first segment, pedicel ( pedicellus) - the second segment, and the so-called antennal flagellum, or flagellum ( flagellum), the number of segments of which varies quite greatly.
The scape is often short, sometimes reduced and poorly visible. The pedicel is enlarged and elongated, and its structure includes Johnston's sensory organ, which perceives the movement of the antennal flagellum. In some Muscomorpha the pedicelium has a suture on top. The flagellum of Nematocera initially consists of fourteen segments, in primitive short-whiskers ( Brachycera) out of eight, y Asilomorpha out of three and Cyclorrhapha out of four. In long mustaches ( Nematocera) segments of the flagellum can be thin cylindrical or shorter massive, or comb-shaped with one or several projections (some representatives of long-legged mosquitoes Tipulidae, brachycerid Brachiceridae), or bead-shaped with one or two rounded extensions. Sometimes, at Thaumaleidae, the segments at the apex are narrower than in the main part of the flagellum. In male mosquitoes ( Culicidae) and bell mosquitoes ( Chironomidae) segments of the flagellum are often covered with short or very long hairs and are called pinnate; the flagellum of gall midges ( Cecidomyiidae) there are loop-shaped sensory filaments.
In higher dipterans, the first segment of the flagellum, that is, the third segment of the antennae, is usually enlarged and designated as the first flagellomere, and the rest are greatly reduced and transformed into a rod-shaped appendage - the stylus ( stylus) or thread-like appendage - aristu ( arista). The stylus is usually located at the apex of the first flagellomere or near it, and the arista can be located both at the apex and on the dorsal side. The arista in Cyclorrhapha consists of three segments, but in Syrphidea and some Empidoidea of two segments. Arista can be naked, short or long pubescent, or with a number of long sparse rays. In some cereal flies ( Chloropidae) arista flattened and thickened. The stylus can be divided into segments. U Scenopinidae, Cryptochetidae and some humpbacks ( Phoridae) aritsa and stylus are reduced.
Oral cavity and oral organs
In most higher dipterans, the lower part of the head is occupied by the subcranial, or oral cavity, into which the proboscis is retracted. In forms with a piercing proboscis, bloodsuckers (mosquitoes - Culicidae, biting midges - Ceratopogonidae, midges - Simuliidae, horseflies - Tabanidae) and some predators - Asilidae, the oral cavity is not developed, the proboscis does not retract and is directed forward or downward.
The proboscis of dipterans differs in origin from similar adaptations of butterflies and bugs. It consists mainly of the lower lip ( labium) - representing a semblance of a groove, open at the top and ending in sucking lobes (they are believed to be homologues of the labial palps). The upper lip (labrum) and the hypopharynx, more or less firmly fused to it, cover the groove of the lower lip from above. The salivary gland channel runs inside the hypopharynx. The maxillary palps are attached to the base of the proboscis.
However, it cannot be said that this structure of the mouthparts is characteristic of all Diptera: in different families its peculiar modifications arise. The channel through which food is absorbed is formed by the hypopharynx and upper lip in most representatives of the order.
Breast
Wings
For the most part, the wings are covered with small hairs, the so-called microtrichia, sometimes in addition to them with large hairs - macrotrichia, and in some families they are often bare. The veins may contain large setae, some of them (on the costal vein and on R 1) have taxonomic significance. Some members of the mosquito family ( Culicidae) and butterflies ( Psychodidae) there are scales on the veins. The wing membrane is transparent, uncolored, entirely grayish, brownish to almost black, or with a varied pattern of dark stripes or spots.
The venation of modern species of Diptera is represented by the following venation. A costal vein runs along the anterior edge of the wing - C, sometimes it goes around the entire wing, in this case it is thinner along its rear edge. The costal vein contains small hairs, sometimes, especially in some families Acalyptratae, in place of the hairs there are spiny bristles. In the same group of families, the costal vein may have thinning and breaks: the first subcostal break is at the confluence of the subcostal or radial vein with the costal vein (if the apex of the subcostal vein is reduced), the second subcostal break is distal to the humeral vein. The humeral crossvein connects the costal vein with the subcostal vein and is located near the base of the wing. Less common is the third costal break, which is located proximal to the humeral transverse vein. The costal vein is followed by the subcostal vein - Sc, which usually does not branch and flows into the costal in the middle or in the anterior third of the wing. Sometimes the subcostal vein is completely reduced. Some long-moustached ( Nematocera) Sc at the top it divides into two branches Sc 1 and Sc 2, near the swamps ( Limoniidae), sometimes ends freely, without reaching the costal, less often, in long-legged mosquitoes ( Tipulidae) and parts of mining flies ( Agromyzidae), as if flowing into the radial vein following it. The subcostal vein may be connected to a subsequent radial separate crossvein Sc-R(some authors designate it as Sc 2) .
Radial vein system - R, begins with one trunk, which can later split three times. The first branching vein is designated as radius one - R 1, the rest as radius sectors - Rs, with full branching there are four veins of a sector of radius - R 2 , R 3 , R 4 , R 5 . This generalized state persists among representatives Tanyderidae and butterflies ( Psychodidae), the remaining dipterans retain three or fewer branches of the radius sector - R 2+3 , R 4 , R 5 or R 4+5. In small dipterans, in gall midges ( Cecidomyiidae), there is often only one branch of the radius sector. The radial veins are connected to the system of medial veins of the transverse r-m(previously designated ta- anterior transverse vein). The base of the common trunk of the medial veins is atrophied and they seem to branch off from the following cubital veins. It is believed that of the two primary branches medial to the vein in Diptera, only the posterior one is preserved; the anterior one remains in the basal part of the wing in the form of a small process. The medial vein has three branches M 1 , M 2 and M 3 where between M 2 and M 3 cross vein passes m-m. The anterior cubital vein has two branches - CuA And CuA 2. Vein CuP is walking behind CuA 2, close to it and sometimes does not reach the edge of the wing. Following the system of cubital veins in a heiralized form there are two anal veins - A 1 and A 2 ; A 2 ends without reaching the edge of the wing in all dipterans, with the exception of long-legged mosquitoes ( Tipulidae) and winter mosquitoes ( Trichoceridae). A 1 in many is complete and reaches the edge of the wing, but is often shortened or completely reduced. There is another pepper vein in the main part m-cu, which connects the system of medial and cubital veins and is located closer to the base of the wing than the transverse m-m .
The last of the radial veins, the medial and anterior cubital cell were not previously designated as closure - p, their maximum number is five. Some wing cells, due to the fact that the veins merge in the apical part, do not extend to the edge of the wing and are considered closed; cells that extend to the edge of the wing are considered open. In the main part of the wing, between the radial and medial trunks, lies the anterior main, or basal radial - br, distally closed by a transverse r-m. Behind the anterior main cell, between the medial and cubital trunks, lies the posterior main, or basal medial cell - bm, distally closed by a transverse vein m-cu. Closer to the apex, in the middle of the wing, between the trunks of the medial veins lies the discodial cell - d, distally closed by a cross-vein m-m .
Thus, initially dipterans have three cells in the main part of the wing, the most distal of which is the true discodial cell - d. Although some long-moustached ( Nematocera) And Brachycera-Orthorrhapha and everyone Mescomorpha discodial medial, or discomedial, are formed - dm, The formation of this cell is due to the fact that the vein M 3 disappears or connects with the transverse m-m and form the posterior cross vein dm-cu (tp) and connects with CuA 1 near its base, and the cell m 3 disappears. In this case, the distal cell dm is closed by the transverse dm-cu, and not m-m, since it connects M And CuA 1 and not M 2 and M 3 .
halteres
Limbs
The coxae are often short, the fore coxae are more elongated, and sometimes, in the family of flat antennae ( Mycetophilidae), all coxae are elongated. The coxae of the middle legs are divided into two parts: the anterior one - the coxa itself, and the posterior one - the meron, which is more or less connected to the epimeron.
The thighs are long and usually more or less thick, often with tubercles, spines and setae, especially on the front and hind legs. The hind thighs of some representatives of the order are thicker than the front and middle ones. On the middle thighs of some cereal flies ( Chloropidae) there are special special organs made of enlarged or modified bristles, similar organs in mining flies ( Agromyzidae) and silverfish ( Chamaemyiidae) are located on the hind thighs and are associated with stridulation.
The tibiae are usually the same length as the femurs, but thinner, with spines and setae, in many Diptera with spurs on the apex. In centipede mosquitoes ( Bibionidae) apical spurs on the front tibiae are very large, can reach the length of the tibia itself. Some Muscomorpha the tibia have large setae, the name of which is determined by their location on the anterior, ventral dorsal, anterodorsal, posterodorsal, anteroventral or posteroventral surface of the tibia, Acalyptratae there is a separately projecting preapical dorsal seta, important for identifying families. In cereal flies ( Chloropidae), anteater ( Sepsidae), greenfinches ( Dolichopodidae) on the hind legs, at Ocydromyidae The sensory organ is located on the front.
Most dipterans have a tarsi formula of 5-5-5. The first segment of the tarsus is usually longer and is often called the metatarsus. In sharouski ( Sphaeroceridae), centipede mosquitoes ( Bibionidae) and some others, the first segment of the hind legs is thickened; in some gall midges ( Cecidomyiidae) - very short and more or less merged with the second segment. The tarsal segments may be thickened, for example in mushroom flies ( Platypezidae) and others, sometimes, especially on the front and hind legs of males, they are modified, armed with ridges of bristles or long hairs, most often this affects the first segment. A reduction in the number of tarsal segments, characteristic of many insects, is very rare in Diptera: in some gall midges ( Cecidomyiidae), detritus ( Sciaridae) and humpbacks ( Phoridae).
The legs of dipterans are predominantly walking; in some (long-legged mosquitoes - Tipulidae, swamps - Limoniidae, gall midges - Cecidomyiidae and stilts - Micropezidae), very long and thin, easily broken off by long-legged mosquitoes and swamp mosquitoes. It is believed that thickened thighs (in some cereal flies - Chloropidae, hoverflies - Syrphidae, Megamerinidae etc.) enable their owners to make jumps. In predatory forms (some midges - Ceratopogonidae), Empidoidea, Ochthera from the family of shorebirds ( Ephydridae) etc.) the front legs are grasping, with highly developed hips and characteristic setae and outgrowths. The structure of the legs often shows sexual dimorphism. In males (antbirds ( Sepsidae), tennis ( Sciomyzidae), dung flies ( Scathophagidae), real flies ( Muscidae) etc.) there are special outgrowths and bristles on the thighs and shins of the front and hind legs, with the help of which the female is restrained during copulation.
Morphology of infraimaginal stages
Morphology of pupae
The last abdominal segment bears various projections, including oar-shaped swimming blades in most mobile pupae of some aquatic forms. In some pupae, for example from the family Cylindertomidae ( Cylindrotomidae), the skin of the last instar larva remains at the end of the body. Some gall midge larvae ( Cecidomyiidae) pupate inside the modified larval skin, forming a brown puparia. Larvae of the family Stratomyiidae also pupate inside the larval skin of the last instar, while their larval skin, impregnated with calcium, has almost no shape, only the respiratory organs are visible on the prothorax. Other types of pupae - pupae exaratae characteristic of higher dipterans Cyclorrhapha. They have free appendages and are always located inside the puparia - the modified skin of the third instar larva.
Unlike larvae, pupae are mostly propneusewage, especially in aquatic forms with spiracles only on the prothoracic segment. In long mustaches ( Nematocera) prothoracic spiracles are often located on long projections called prothoracic organs, processes, horns or filaments, which often branch. Among Brachycera-Orthorrhapha long prothoracic respiratory organs are developed only in the greenfinch family ( Dolichopodidae) .
Development
Diptera eggs come in different shapes (from round to elongated). The chorion is cellular or spongy in structure.
The larvae are worm-like in shape, often with a narrowed anterior end. Completely lacking true (jointed) pectoral legs. Locomotion is carried out using false legs (body outgrowths containing a cavity), crawling ridges (thickening of the body wall) or movements of the whole body. The number of larval segments is less than or equal to 13 (3 thoracic and 10 abdominal). In some, secondary segmentation may appear. Within the order Diptera, there is a clearly observed tendency towards reduction of the head in larvae, from a well-developed, non-retractable head capsule in some Nematocera (family Bibionidae, etc.) to its complete absence in Cyclorrhapha.
The pupa of Nematocera and Orthorhapha is free. When the imago emerges, the pupa shell breaks along a straight seam. In Cyclorrhapha, the pupa is enclosed in a puparium (the hardened shell of the last instar larva), which breaks apart at hatching along a circular suture.
Biology
A separate biological group of larvae Diptera are the inhabitants of cap mushrooms. These are mainly fungus gnats (family. Mycetophilidae), less commonly - mosquitoes of the family. Limoniidae and flies Helomyzidae, sem. Drosophilidae and etc.
There is also a large number of dipteran species in a heterogeneous group characterized by the presence of saprobiont larvae. Most synanthropes belong to this group. Often these dipterans are distributors of various gastrointestinal infections and helminthiases.
Diptera imagoes are inhabitants of the air. Most of them eat nectar or pollen, but also among them there are predators (non-specific) and bloodsuckers (mainly mammals, less often birds and insects). The group of bloodsucking dipterans is not phylogenetically united: it also includes some families Nematocera(family Culicidae, family Ceratopogonidae, sem. Simuliidae), and primitive Brachycera(family Tabanidae), and representatives Cyclorrhapha(family Muscidae, sem. Hyppoboscidae and etc.).
Classification
Squad Diptera previously traditionally divided into three suborders - Nematocera, Orthorhapha And Cyclorrhapha. The last two are combined into a group Brachycera(short-whiskered, or flies), which is opposed to the suborder Nematocera(long-whiskered, or mosquitoes): for Nematocera characterized by multi-segmented (more than 6) antennae, for Brachycera- three-segmented. Sometimes the term " Brachycera" is used as a synonym " Orthorhapha» .
Representatives Cyclorrhapha(literally: “round-sutured”), unlike other dipterans, they have a puparia - a detached and hardened shell of the last stage larva, inside of which there is a pupa. When the adult emerges, the puparia membrane opens along a circular suture. U Orthorhapha(literally: “straight-seam”) the pupa opens with a straight longitudinal seam.
Most of the representatives Cyclorrhapha- groups Schizophora at the moment of emergence from the pupa, the frontal vesicle protrudes above the antennae ( ptilinum) - a special thin-walled formation. With its pulsation it helps to break the shells of the pupa and puparia. Subsequently, the frontal bladder is retracted into the head. So the head Schizophora turns out to be the most complexly arranged within Diptera.
According to modern views, the groups Nematocera, Orthorrhapha and Aschiza are recognized as artificial (paraphyletic). They include a group of basal lineages from which other monophyletic categories (Brachycera, Cyclorrhapha and Schizophora, respectively) evolved. The order Diptera includes about 10,000 genera, 150 families, 22-32 superfamilies, 8-10 infraorders and 2 suborders (Yeates & Wiegmann, 1999). Cladogram (Yeates et al., 2012):
