Dragonfly insect. Description, features, types, lifestyle and habitat of the dragonfly

The dragonfly is an arthropod, six-legged insect, belongs to the subclass of winged insects, order of dragonflies (Odonata).

The Russian name for the insect was formed as a result of the merger of two Old Slavic words: the noun “egoza” (fidget) and the verb “strekat” (jump or jump). This name fully corresponds to the flight pattern of these fast and nimble creatures.

Description and features

Dragonflies are flying predatory insects. They belong to the order of dragonflies, which has more than 6,000 species. The sizes of insects, depending on the species, range from 1.5 to 15 cm, and the wingspan is from 2 to 19 cm. The appearance of the dragonfly is easily recognizable. The insect has a large head with large eyes, short antennae, powerful mouthparts, chest, abdomen, three pairs of legs and two pairs of wings. Body color can be very different; dragonflies of various colors are found in the world. Some of them have a metallic sheen to their body.

Appearance

The dragonfly's head is very mobile and can rotate 180⁰. The eyes consist of a large number of facets (from 10 to 27 thousand). The lower rows of eye elements can only perceive the colors of objects, and the upper ones their shape. There are 3 simple eyes located on the crown. This structure and location of the eyes makes it possible for the dragonfly to survey the surrounding space not only in front of itself, it sees what is happening from the side, above and even behind.

But with the other senses the situation is much worse. Insects have a very weak sense of smell, and hearing is practically absent. The gnawing type oral apparatus is formed by strong, durable jaws, which are covered by the upper and lower lips.

The main feature that distinguishes dragonflies from other insects is their elongated abdomen, which makes up most of the body. The wings are large, transparent, consist of 2 layers of chitin and have many overlapping veins.

The tarsi consist of 3 segments, each of which is covered with small spines. The dragonfly needs its paws for grasping and holding prey, as well as for taking off and landing. Insects practically do not use them to move. During flight, the legs fold into the shape of a basket. This helps the insect instantly grab prey that gets in its way.

Types of dragonflies, names and photographs

Today, scientists have described more than 6,000 species of dragonflies, of which about 172, forming 52 genera, live in the CIS countries.

In the classification of dragonflies, there are 3 suborders:

• heteroptera dragonflies (lat. Anisoptera);
• homoptera dragonflies (lat. Zygoptera);
• аnisozygoptera (combines the main characters of previous suborders).

Dragonflies

A characteristic feature of the suborder of heteroptera dragonflies is the perpendicular arrangement of the wings at rest and the difference in their size (the front wings of the dragonfly are much larger than the hind wings). The most famous representatives of heteroptera dragonflies are:

• Dragonfly watchman-emperor or watchman-overlord (Anax imperator)

A large insect with a wingspan of up to 11 cm and a body length of about 8 cm. The chest is green in color with black stripes. Males and females differ in the color of their wings and abdomen. Females have golden-yellow wings and bluish-green bellies with large reddish-brown spots. The male dragonfly of this species is distinguished by colorless wings and a blue belly, on which dark brown spots are visible.

Dragonflies appear in mid-June; the flight period lasts 1.5 months. They prefer to flutter near stagnant or low-flowing bodies of water. The Emperor Watcher is considered one of the largest dragonflies in Russia.

• Dragonfly Cordulegaster boltonii

The dimensions of this type of dragonfly are: body length up to 9 cm, wingspan about 10.5 cm. Oblique and transverse yellow stripes run along the abdomen and chest. The transparent wings of the dragonfly have black veins.

Throughout the summer, they fly on the edges and forest clearings, near lakes and rivers with calm currents.

• Metallic dragonfly (Somatochlora metallika)

A small insect, the body size of which does not exceed 4.5 cm, and the wingspan is only 3.5-3.8 cm. The general color of the chest and body is green with a metallic sheen. Yellow spots are visible on the first and third segments of the abdomen, and a thin yellow stripe runs along the forehead. The leading edge of the female dragonfly's wings has the same shade.

The flight period of this species of dragonfly lasts from late May to mid-autumn. Metal headstocks are found near bodies of water with stagnant or low-flowing water.

• Common dragonfly (Gomphus vulgatissimus)

A rather small insect with a wingspan of about 3 cm and an abdomen length of up to 3.7 cm. The abdomen of the dragonfly is painted black with yellow spots located on the sides and a thin longitudinal stripe of the same color running across the top of the entire body. The lifespan of dragonflies of this species does not exceed 30 days.

The dragonfly lives on forest edges and clearings near rivers, reservoirs or canals with a sandy and muddy bottom.

• Common dragonfly (Sympetrum vulgatum)

This species is a typical representative of the large family of true dragonflies (lat. Libellulidae). The color of insects can be yellow, brown or reddish and changes with age. The length of the abdomen of the common dragonfly is about 2.8 cm, the wingspan is up to 6 cm. Color is a clear indicator of gender:

• in males, the lateral parts of the chest and the flattened, expanded abdomen are red with black wide stripes;
• in females, the body is brown, and the lateral surface of the chest is yellow-brown. Black stripes cross the entire body.

Dragonflies fly near grassy swamps or ponds heavily overgrown with vegetation.

Common dragonfly male and female

Homoptera dragonflies

In representatives of the suborder Homoptera dragonflies, both pairs of wings are the same size, and when resting from flying, insects fold their wings and hold them in a vertical position above the body. The flight speed of these dragonflies is much lower than that of heteroptera. The most “bright” representatives of the suborder are:

• Dragonfly Beauty girl, or dark-winged beauty (Calopteryx virgo)

These are medium-sized insects with a wingspan of up to 7 cm and a body length of about 5 cm. The color of the wings of males is bluish-blue, and the body color is greenish-blue with a metallic tint. Female dragonflies are characterized by transparent wings riddled with brown veins and a bronze-green body color.

The beautiful female dragonfly lives along the vegetated banks of streams and rivers with a slow flow. The flight period begins in July and ends at the end of September. These dragonflies live in Europe, Siberia, the Far East, China, Japan, Mongolia, and Korea.

• Arrow dragonfly ( Coenagrion mercuriale )

These are rather small dragonflies with a body length not exceeding 3.5 cm and a wingspan of about 4.5 cm. The male has a bright blue body color with a dark heart-shaped spot. Females can vary in color from green to red-brown with black spots on each abdominal segment.

You can see these insects in the air both in early May and mid-September. Dragonflies fly near large bodies of water or slow-flowing rivers.

Southern Arrow dragonfly - male on the left, female on the right

• Dryad dragonfly (Lestes dryas)

A small dragonfly with a body length of about 3.5-4 cm and a wingspan of up to 3-4 cm. The color of males and females is the same - bronze-green on top, and with a yellow tint on the sides. The edges of the transparent wings are framed by a brown border.

These dragonflies begin to fly from the beginning of July to the first days of September. The lute-dryad dragonfly lives near warm and shallow, sometimes drying up reservoirs with abundant aquatic vegetation.

• Megaloprepus caerulatus is the largest dragonfly in the world.

Individuals of this species can reach 10 cm in length and have a wingspan of up to 19 cm. Adult dragonflies feed on spiders, grabbing them in flight directly from the catching web. The wings of these insects are transparent with brown veins, with a wide blue vertical stripe at the tip of the wing. This stripe contains pale blue round spots, sometimes merging into a single stripe. The wide stripe on the underside of the dragonfly's wings is black. The first and second pairs of wings are almost identical in size and structure.

The largest dragonfly in the world lives in humid and damp forests in Central and South America.

Kinds

All dragonflies are divided into 3 subspecies:

• Homoptera - this includes the smallest insects with an elegant body and wings of equal length;
• heteroptera - in this category, the rear pair of wings has an expanded base, thanks to which they can develop high speed;
• anisozygoptera is a rather rare group living in Japan, Nepal and Tibet; representatives of this subspecies combine the characteristics of the previous two.

The most common species of dragonflies belonging to Homoptera are:

• beauties;
• arrows;
• Lutki;
• planipedes.

The suborder heteroptera includes:

• grandfathers;
• grandmothers;
• rocker arms;
• club-bellies;
• Flat bellies.

Flat-bellied

All dragonflies are amphibious, that is, at different stages of development they live in water and on land. In the aquatic environment, eggs develop and larvae, which are otherwise called naiads, grow; the life activity of adults takes place in the air and on land.

Interesting facts about dragonflies

• In addition to the normal spectrum, the eyes of a dragonfly are capable of perceiving ultraviolet light.
• The ancestors of modern dragonflies appeared on the planet long before the dominance of dinosaurs and were the first creatures to conquer the air.
• Without a sufficiently developed brain, these insects are able to calculate the flight trajectory of the prey with 95% accuracy.
• Entomologists have still not found an explanation for the mysterious flights of a huge cluster of dragonflies across ocean spaces. They make such trips every 6-7 years.
• In Japan, the dragonfly is considered the standard of military valor and courage.
• On the island of Shikoku there is a park called the “Dragonfly Kingdom”. Everything in it is dedicated to this insect. In addition to the variety of species that live here, the design of the fences surrounding the clearings and the railings of the bridges thrown over artificial ponds is made in the “dragonfly” style. In the park's shops you can buy literature dedicated to these insects and see paintings depicting them.

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Lifestyle and habitat

Dragonflies live in almost all corners of the globe; they are not found only in Antarctica, Greenland, Iceland and the islands of the Arctic Ocean. The wide distribution area is due to the ancient origin of insects, their ability to move quickly and over long distances, as well as the lack of food specialization.

Insects prefer warm regions with high humidity. Dragonflies live only in those areas where periods with stable negative temperatures last no more than 90-120 days.

The habitat of dragonflies is closely related to water bodies, since it is on water that females lay their eggs. The choice of pond is largely determined by the type of insect. These can be lakes, rivers, ponds and even flooded ravines or pits. The larvae, emerging from the eggs, grow and develop in water, and the adult dragonfly, having laid a clutch, can remain nearby or fly away over a long distance, measured in hundreds of kilometers, and most often the flights are made alone.

You can meet a dragonfly in nature in any open area, for example, on a forest edge or in a meadow. This is due to the fact that it is very important for the insect to be exposed to the sun. Dragonflies are diurnal, going out to hunt in the morning or evening. As night approaches, they hide in the grass or in the crown of trees.

Where do dragonflies live?

The habitat of dragonflies is very extensive. They can be found in any region of the world where the weather is warm, there is water and a large supply of food. These insects are widespread in Russia and Belarus, Germany and France, Italy and Spain, and the countries of the Balkan Peninsula. Many species of dragonflies live in the Asian region: India and Pakistan, Thailand and Azerbaijan, Armenia and Iran, Turkey and China. The dragonfly also lives in the vastness of the African continent, Australia, North and South America.

The dragonfly is an insect that prefers a solitary lifestyle. It is active during the daytime, preferring sunny hours, and waits out unfavorable cloudy weather in shelters.

Natural enemies of dragonflies include many species of birds, fish and spiders.

Nutrition

Dragonflies are aggressive predators that pose a danger to many species of insects (mostly flying ones). They even attack those larger than them, and in most cases successfully. Interestingly, most species eat prey on the fly while in the air. They are very voracious, so they eat several dozen insects per day, the total weight of which significantly exceeds their own weight.

So, what do adult dragonflies eat:

• mosquitoes;
• flies;
• midges;
• beetles;
• spiders;
• moth;
• dragonflies.

These insects can be divided into several categories according to their hunting method:

• free upper tier predators - species that can fly high, lie in wait for prey at a height of 2 - 9 m above the ground;
• free hunters of the middle tier - hunt at a height of 0.5 - 2 m above the ground, most often circling over bodies of water, only occasionally resting on the grass or plants sticking out of the water;
• lying in wait hunters - sit in ambush on blades of grass or bushes, waiting for a prey flying past, and when they notice it, they suddenly take off and attack;
• grazing predators - hunt in thickets of grass, flitting from place to place in search of prey, having caught it, they eat it while sitting on a plant.

Dragonfly larvae feed on fish fry, leeches, insect larvae, tadpoles, and small crustaceans.

What do dragonflies eat?

By the nature of their feeding, dragonflies are typical predators that catch their prey on the fly. Each individual has its own hunting grounds, which they zealously defend from strangers and, if necessary, fight for them. The main food of dragonflies is flies, mosquitoes, moths and other small flying insects. Large individuals are capable of eating small fish, spiders and frogs.

Dragonfly larvae (naiads) feed on young fish, small aquatic insects, crustaceans, and larvae of flies and mosquitoes. This diet is determined by the aquatic habitat. In addition, they clean the reservoir from decaying remains of animal and plant origin.

Reproduction and lifespan

Dragonflies are insects with incomplete metamorphosis; they skip the pupal stage. The life cycle of a dragonfly includes three stages:

• egg;
• larva;
• imago.

Larva

Depending on the species, reproduction of dragonflies can occur 1 or several times a year. Before mating, males unite in groups and begin to look for partners. Coitus occurs in the air and can last from a few seconds to 2-3 hours. The insects spend this time clinging together, hovering in the air.

The fertilized female goes to the nearest suitable body of water, where she lays eggs in an amount of from 100 to 600 pieces. Masonry is most often done on plants that rise above the water or are located under it. The larvae hatch within a few weeks. The entire life of a dragonfly larva is spent in water. They actively hunt, feed and grow. At this stage, the insect experiences from 5 to 15 molts.

The duration of development during the larval stage largely depends on the availability of sufficient food. It can take from several months to several years before becoming an adult.

When the time comes to move to the adult stage, the larva crawls out of the water (along a plant stem, stone, snag) and remains in the air from several hours to several days. At this time, she begins to breathe atmospheric air, frees herself from the shell under which the wings were hidden.

Origin of the species and description

Photo: Dragonfly

Odonata or dragonflies are predatory insects belonging to the phylum Arthropoda, subclass of winged insects and order Dragonfly. This detachment was first described by Fabricius in 1793. Dragonflies are a very large order, which includes 6,650 species. Currently, 608 species are classified as extinct, and 5899 species of these insects inhabit our planet in modern times.

The dragonfly order is divided into 3 suborders:

• heteroptera;
• Homoptera;
• anisozygoptera.

Dragonflies are a very ancient group of insects. The first dragonflies inhabited the earth back in the Carboniferous period of the Paleozoic era. These insects are descended from the giant dragonfly-like insects Meganeura. Meganeuras were large insects with a wingspan of up to 66 cm. These insects were considered the largest insects of ancient times. Meganeura later gave birth to the following groups of their descendants: Kennedyina and Ditaxineurina, these groups of insects lived in the Triassic period of the Mesozoic era. They were large; the wings of these insects were about 9 cm long. During rest, they folded under the abdomen of the insect.

Video: Dragonfly

The insect also developed a trapping basket, used for grasping prey. During the Jurassic period, the following groups came: Lestomorpha and Libellulomorpha in these insects, the larvae developed in an aquatic environment and they had an improved flying apparatus. Insects of the Libellulida group inhabited Africa, South America and Australia in the Triassic period. Meganeuras still lived in Eurasia at that time, but during the course of evolution their bodies and habits changed. In the Jurassic period, meganeurins reached the pinnacle of evolution and populated all of Eurasia. These insects had a “catching basket” and could use it to hunt during flight. Gas exchange in this group was carried out using the respiratory epithelium, but there were also lamellar gills, which changed over time, ceased to perform a gas exchange function and were replaced by internal gills.

At the same time, the descendants of the family Calopterygoidea have evolved greatly from the original state. The wings of these insects narrowed, became stalked and the size of the wings became the same. In the Jurassic period, insects of the suborder Anisozygoptera become the most common; their numbers sharply decrease during the Cretaceous period, but this group remains widespread throughout the entire polygenic period. During this period, such species of dragonflies as Coenagrionidae, Lestidae and Libelluloidea, etc. almost disappear. The Cenozoic fauna is already inhabited by modern species of dragonflies. During the Neocene, the ethnofauna was no different from the modern one. The Zygoptera population declined sharply, but Coenagrionidae and Lestidae became the most common species.

Natural enemies of dragonflies

Due to the fact that larvae and adult insects live in different environments, their enemies are also different. The danger for larvae is:

• predatory and omnivorous fish;
• birds living on shallows and near bodies of water (herons, waders, etc.);
• swimming beetles and their larvae;
• some species of water bugs.

Adult dragonflies are hunted by:

• orb-weaving spiders, tetragnathid spiders, hobo spiders;
• blackflies;
• birds (including bee-eater, white wagtail, gulls, ducks, swifts, woodpeckers).

Enemy of the dragonfly

In addition, dragonflies can become prey for carnivorous plants. Most often these are varieties of sundews growing in sphagnum and peat bogs. To date, no enemies of dragonflies have been found among mammals and reptiles.

Considering that adult insects are quite cautious, fly quickly and maneuver deftly in the air, it is not easy to catch them. A predator can eat a dragonfly only if it takes the insect by surprise, which does not happen often.

Population and species status

Photo: What a dragonfly looks like

The population of the order Odonata is large and diverse. There are more than 6,650 species of these insects in the world. These insects are found on all continents and migrate. Many species of these insects live and reproduce well in the wild. However, today some species of dragonflies are on the verge of extinction and their populations are rapidly declining. This is due to human pollution of dragonfly habitats.

A number of species are listed in the Red Book. At the end of 2022, there are more than 300 species listed in the Red Book. Of these, 121 species are on the verge of extinction, 127 subspecies have the status of insects in a vulnerable position, and 19 subspecies are already extinct. The species Megalagrion jugorum is considered extinct. In the global population, about 10% of all dragonfly species are on the verge of extinction.

Dragonflies are a very important group that indicates the condition of water bodies, since dragonfly larvae react strongly to any changes in water quality. Dragonfly larvae die in polluted waters. In order to maintain the population of these insects, it is necessary to be more careful about the environment. Install cleaning equipment at enterprises, create protected areas in dragonfly habitats.

The benefits and harms of dragonflies

Like many other insects, dragonflies cannot be called clearly beneficial or harmful. Their benefit is that adult individuals feed on insects, and therefore play a significant role in the regulation of certain types of blood-sucking insects (including such dangerous ones as horseflies or tsetse flies), pests of agricultural crops and forests. In addition, dragonflies participate in pollination. Flying from flower to flower, they carry pollen on their legs. Fish and crustaceans feed on the larvae of these insects. Fishermen often use them as bait.

Damage is caused mainly by dragonfly larvae. They eat the fry of some fish species or compete with them for food, which leads to a decrease in the population. In addition, the larvae are hosts for parasites, in particular helminths. Birds (including domestic birds) eating larvae can become infected with prostagonymosis. This is a serious disease that affects the bird's ability to lay eggs. Without timely, competent treatment, there is a high risk of death.

Features of character and lifestyle

Photo: Blue Dragonfly

In our country, dragonflies live from late April to October. In warm and tropical countries, these insects live all year round. Dragonflies are diurnal insects. They are most active in sunny and warm weather.

In the morning, dragonflies try to bask in the sun, sitting on stones or pieces of wood. During the midday heat, they adopt a “glow” position, in which the luminous tip of the abdomen is directed towards the sun. This reduces the insect's body exposure to sunlight and helps avoid overheating.

Interesting fact: Dragonflies practically do not use their legs for movement; they are used only during takeoff and landing. The hind limbs are used to capture prey.

Dragonflies go hunting in the morning and evening. Some species are more active at dawn. During the daytime, dragonflies are busy procreating their species. At night, insects hide among thickets of foliage and grass. Mostly dragonflies live alone.

Interesting fact: Thanks to the structure of their wings, dragonflies can fly very quickly, make interesting turns in the air, and migrate long distances. Due to the fact that dragonflies are good at the art of flight, they are very difficult for predators to catch.

Groups of dragonflies

Scientists have found and described more than 6 thousand species of dragonflies. They are divided into two large groups:

1. Various dragonflies - the suborder includes about 3 thousand species, including the common dragonfly. A characteristic feature is that the wings are placed perpendicular to the axis of the body during rest. The front pair of wings is larger than the back. This group includes the fastest predators, with a record speed of up to 100 km/h. Nymphs live in stagnant water.
2. Homoptera dragonflies - a group of insects with equal sizes of front and rear wings. Their flight is smooth and measured. At rest, the wings are folded like a roof over the abdomen. The larvae live in standing and flowing water bodies.

The common dragonfly belongs to the family of true dragonflies. Its representatives are small in size (3-5 cm). They are found everywhere except Antarctica.

Meaning for humans

Dragonflies and humans rarely have conflicts. Representatives of the Odonata family bring great benefits. They keep the number of blood-sucking insects – mosquitoes, gadflies, mosquitoes – under control. Adults destroy pests on land, and nymphs in water. Dragonflies are absolutely safe for people. They have stings and do not carry disease. Many species are sensitive to water conditions. They die when water bodies are polluted.

Human economic activities often threaten populations of certain dragonfly species. Representatives of Sympetrumvulgatum are safe for now. While near a pond, with sufficient patience and caution, you can wait until you come into close contact with a dragonfly. The insect will land on your hand.

General characteristics of dragonflies

General characteristics help to understand what each unit is.
Dragonflies are the largest flying insects on Earth. They are predators. The order of dragonflies includes suborders: heteroptera and homoptera.

Like the dragonfly, the louse's characteristics are quite simple.

These insects are blood-sucking parasites. They belong to the order of lice eaters. The general characteristics of lice do not form any suborders. By parasitizing on humans, they cause lice, or lice are scientifically the causative agents of pediculosis. Beetles are the most numerous inhabitants in the world. There are about 300 thousand species of them. All of them form the order Coleoptera. Bedbugs are numerous representatives of the order Hemiptera.

Reproduction of dragonflies

The main feature of living beings is reproduction - the reproduction of their own kind, which can be different for each species.
Dragonflies reproduce sexually. Mating occurs directly during flight. To scare away other males, the male performs a ritual flight around the female.

Lice also reproduce sexually. After fertilization, the female, fed with blood, crawls through the hair, laying eggs along with secretions. Hardening after some time, it ensures strong attachment of the nit to the hair.

Next begins the life cycle of lice, which was mentioned earlier. Male beetles can fight for a female. Also, in order to find each other, the couple releases a smelling substance - a pheromone. The reproduction of bedbugs has the following feature: the female is fertilized without her desire, that is, by force.

Now everything has become known about lice and nits, dragonflies, beetles and bedbugs, their habitat, existence and nutrition. This knowledge will help us better understand the world around us.

Features of dragonflies

The structure of these organs is most clear in some Haplogynae, for example in Segestria (Fig. 83) and Scytodes. Proximally, on the tarsal segment of the pedipalp, a large pear-shaped appendage (bulbus genitalis), elongated into a thin spout (embolus), develops.

At the end of the spout lies a small hole leading into a long, spirally coiled, chitin-lined sperm reservoir, or spermophore. During mating, the embolus is inserted into the female's seminal receptacle.

The proximal position of the bulb appears to be secondary. In many other primitive spiders (Aviculariidae, Hypochilusy Oonopidae, etc.), the copulatory apparatus is almost as simple, but the bulb is located subterminal or even completely terminal. In Hypochilus it is partially immersed, while in Filistata it is entirely immersed in the invagination at the end of the tarsal segment.

With the complication of the copulatory apparatus (Fig. 84), a second appendage develops next to the embolus - the conductor, which serves as a vagina or sheath for the embolus and facilitates the introduction of the latter into the copulatory opening of the female (Atypus, Caponia, etc.).

The base of the bulbus, already in Segestria and Scytodes, is movably articulated with the tarsus by means of an articular membrane.

Growing strongly in Aviculariidae, Atypus and other forms, the latter acquires the ability to swell with blood. In Entelegynae, the articular membrane turns into a special sac-like organ - a blood receptacle, or haematodocha, which folds at rest, but at the moment of mating it expands, swelling like a bubble under blood pressure.

The blood receptacle is located in a deep hole (alveolus) on the surface of the tarsus, which is called the boat (cymbium). Sometimes the tarsus is shortened to the size of a small scale (Nephila). Often in Entelegynae the copulatory apparatus reaches extraordinary complexity. One of its significant changes is the spiral twisting of the inflated blood receptacle and the bulb itself. The spermophore, which already in Segestria has a spiral course, here is strongly elongated and twists repeatedly; in addition, its individual sections can be differentiated in the form of special glandular organs (Linyphiidae).

Complications in the chitinized parts of the apparatus are also significant, and most importantly, very diverse and serve in taxonomy as an excellent criterion for distinguishing species. The bulb can take various shapes and become very complicated due to the formation of special sclerites or membranous parts on it.

The first are represented by the so-called retinacula (hetinacula) - chitinous appendages of various shapes that serve to attach the bulb to the female copulatory organs during mating. The second, called hematodochulae, are membranous areas that are functionally similar to a blood receptacle and can, like it, swell when filled with blood.

Quite often the embolus becomes more complicated. In Entelegynae, it forms a sharply isolated chitinized appendage and often turns into a flexible, spirally twisted hollow thread, the length of which can exceed the length of the body (Delena, Isopoda - from Sparassidae, Hyptiotes - from Uloboridae, Tegenaria - from Agelenidae and Labulla - from Linyphiidae).

In parallel with the embolus, the conductor is lengthened and usually twisted. From a simple embolus case, it turns into a special targeting device. Twisting of the embolus and conductor occurs in one direction (Isopoda) or in different directions (Dictyna, Tegenaria ferruginea).

Sometimes the entire copulatory apparatus reaches a very significant size. Thus, in Theridiosoma and in some related genera of Araneidae, the bulbus is the same size as the entire cephalothorax.

Finally, often (Tetragnathidae, Araneidae, Linyphiidae) a special outgrowth also develops on the tarsus - paracymbium, which serves for attachment during mating; sometimes attachment hooks even develop on the tibia and femur of the pedipalp.

The male copulatory apparatus of Pholcidae stands apart.

In simpler cases (Ninetis, Modismus, etc.) the bulb has a simple pear-shaped shape, but in other genera it is very complex. Thus, in Pholcus phalangoides, in addition to the embolus, the bulb bears two more outgrowths. One of them, the uncus, is covered with peculiar scales, the other, the T-shaped appendix, is heavily chitinized. The tarsus also forms a distal outgrowth called procursus, which carries a soft membrane stretched between the teeth, which swells at the moment of mating.

In the question of the phylogenetic development of the male copulatory apparatus, decisive importance belongs to observations of its formation in ontogenesis.

As Burrows (1925) and Harm (1931, 1934) showed, in the ontogeny of Segestria and Salticidae the bulbus develops from the pretarsal segment, and the embolus from the claw. Accordingly, in Mugalomorphae (Eurypelma), the tendons of two muscles are attached to the base of the copulatory organ, in which it is easy to recognize the usual levator of the claw segment, attached, as in the unmodified pedipalp, in the tarsal segment, and the depressor, lying, as usual, in the tibia (Snodgrass, 1952). Obviously, the most primitive types of the copulatory apparatus should be sought in those spiders in which it is located terminally, such as, for example, Aviculariidae, Hypochilus, Filistata, Oonopidae (Comstock, 1913; Berland, 1932).

In Lipistius, on the contrary, the position of the apparatus is secondarily changed, and its high specialization indicates a special path of evolution of this genus.

In general, three types of copulatory apparatus are distinguished: a simple type Segestria, a complicated type characteristic of most Entelegynae and others, and a special type characteristic of Pholcidae. The first two represent successive stages of development; the formation path of the third type was probably special and independent.

There are 5,000 species of dragonflies in the world.

Today, from 3,600 to 4,500 species are known in the world fauna, with most species found in the tropics and subtropics. Dragonflies are the most ancient insects, having retained primitive features in the process of evolution. The most ancient remains of dragonflies date back to the Carboniferous period, and the most ancient of them only resemble modern species in appearance. Dragonflies are medium or large in size (up to 13 cm) and are always predatory insects characterized by incomplete metamorphosis. In its development, an insect goes through three stages - egg, larva (nymph, naiad), flying imago. The order Dragonfly (Odonata) includes three types of insects; they differ sharply in their appearance and behavior, but the number of diagnostic signs by which they differ from each other is small. Modern forms of one of the suborders - Anisozygoptera - are very rare and distributed only in Southeast Asia. In modern taxonomy, the order includes two suborders: homoptera (Zygoptera) and heteroptera (Anisoptera). The suborder Zygoptera are slender and delicate insects with a fluttering flight that contrasts sharply with the fast and purposeful movements of heteroptera dragonflies. The imago of homoptera dragonflies is distinguished by an originally constructed thorax: the mesothorax, together with the metathorax, has the appearance of an approximately rectangular prism located at approximately an angle of 70-80 degrees relative to the longitudinal axis of the body. The wings at rest are directed all together backwards and upwards at right angles to the upper edges of the mesothorax and metathorax. Due to the fact that the latter are inclined to a certain extent, the wings folded in this way lie parallel to each other and are located directly above the abdomen. Most dragonfly adults are dark-colored, but some have red or black wing bands or metallic green or bronze bodies and wings. Nymphs also have a slender body and three large caudal tracheal gills. They live among the stems of aquatic plants, and not at the bottom of reservoirs. The suborder includes three families - Calopterygidae, Agrionidae, Lestidae. Representatives of the genus Calopteryx are very beautiful - the brilliant beauty (Calopteryx splendens), the beautiful girl (Calopteryx virgo), listed in the Red Book of the Chelyabinsk region. Representatives of this suborder are also the following species: Arrow-girl (Agrion puella), Lute-bride (Lestes sponsa). The suborder Anisoptera includes insects with a more robust physique and are characterized by powerful, graceful and excellently controlled flight. The chest is not inclined as in representatives of homoptera dragonflies and the wings at rest are directed to the sides. Many species are brightly colored and have a striking pattern on their wings - mottled or spotted. Older individuals often develop a pale blue waxy coating on the body and wings, which masks the original color and pattern. Dragonfly nymphs are also densely built, and many live in the mud or mud at the bottom of stagnant bodies of water. They do not have external gills, but they have a rectal respiratory chamber in which gas exchange occurs. No such respiratory chamber has been found in any other order of insects. This suborder includes the following species - the emperor watchman (Anax imperator), listed in the Red Book, and a huge, extinct dragonfly found in France, reaching 75 cm with spread wings - Meganeura monyi, which, along with Meganeuropsis permiana, is one of the largest insects on Earth. Dragonflies are characterized by an incomplete type of transformation. Imago dragonflies have a slender or stocky body, with two pairs of similarly constructed wings with reticulate venation. There are 2 large compound eyes on the head and three simple ocelli. The antennae are short, bristle-like, consisting of 4–7 segments. The mouthparts are of a gnawing type with strong mandibles. The first pair of wings has a pterostigma, which dampens harmful wing vibrations. The wings can be transparent or colored. The legs are running, the first pair is designed for holding prey. The dragonfly's auditory organs are located in the antennae, and the organs for producing sound are located at the base of the wings. Dragonfly larvae of the naiad type with tracheal gills live from one to three years. They molt up to 25 times during development. The larvae have gnawing type mouthparts with a strongly elongated and knee-bending lower lip, which is the strongest grasping organ capable of catching and holding prey; legs are strong; Representatives of the suborder Zygoptera have three leaf-shaped caudal gills, the loss of which is not critical. The size of the egg, depending on the species, varies from 0.5 mm to 2 mm. Adult dragonflies feed on insects caught in flight. Dragonflies are typical active predators. Each individual has its own territory on which it feeds, which it protects from other dragonflies and, if necessary, fights for it. According to ethology, dragonflies can be called predators - sentinels. Dragonflies eat mosquitoes, horseflies and other insects, which they are able to catch and defeat, and at the same time bring benefits by exterminating blood-sucking species. Dragonfly nymphs lead an aquatic lifestyle, living mainly in stagnant and slow-flowing bodies of water: lakes, ponds and oxbow rivers. Many of them cannot swim, but they walk along the bottom among decaying debris or vegetation. Nymphs are also predators: they catch aquatic invertebrates by grabbing them with their retractable lip (mask), equipped with spines. Among the prey of dragonfly naiads there are also many larvae of blood-sucking insects. Dragonfly eggs are laid in various ways in or near water. Some species immerse them in plant tissue or rotten wood, others place them in the form of lumps on some objects directly below the surface of the water, others deposit them in the water in ribbons or rings, and sometimes place them in wet mud near the water's edge. Females of many species dive into the water and wash the eggs from the end of the abdomen. Others crawl underwater, laying eggs. When laying eggs, some females fold their wings into a fan shape. A female can lay from 200 to 1600 eggs in her life. Some species reach several tens of thousands. Nymphs of smaller species develop throughout the year. In large species, from two to four years. Wintering occurs at the nymph stage. Having reached full size, the dragonfly nymph crawls out of the water and climbs onto a plant stem or some other object protruding from the water to molt for the last time. At the same time, many species of dragonflies must take a vertical position. After molting dragonflies, specific skins remain - exuviae, suitable for determining the species. The covers of newly emerged adults harden and acquire color relatively slowly: many species of dragonflies require one or two days to do this. Dragonflies often have pronounced sexual dimorphism; males and females can be distinguished by the intensity of their color: males are brightly colored, while females are inconspicuous. At the top of the abdomen of males there are paired upper and unpaired lower outgrowths - appendages, while females have only paired upper ones. A unique feature of the order of dragonflies is their mating method. The credit for this goes to the male individual: unlike other insects, the male dragonfly has secondary reproductive organs, which are located on the second sternum of the abdomen - the bladder-shaped receptacle. The genital opening itself is located on the 9th sternum of the abdomen. Having such genitals, the male has to do the following before mating: the male bends the end of the abdomen forward and transfers the sperm to a bladder-shaped receiver. During mating, the male uses his caudal gonopods to clasp the female's neck; after this, the female bends her abdomen forward to the second sternite of the male and in this position the actual transfer of sperm takes place. Such an unusual procedure is unknown outside the order Odonata . The importance of dragonflies in nature is determined by their predatory nature of behavior, aesthetic appearance, as well as the habitat of the larval phase of development: dragonflies maintain species balance in ecosystems not only by eating various representatives of the animal world, but also by the fact that their larvae are intermediate hosts of various diseases ( up to 160 species), including such diseases as prostagoniasis. With their graceful form, and many species and their coloring, dragonflies play a large role in the aesthetic perception of the world by humans.

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Red Book of the Chelyabinsk region

Structural features

The same parts of the body can perform completely different functions in different animals. They depend on the animal’s lifestyle and environmental conditions.

Structural features of dragonflies

The eyes of dragonflies have a complex structure.
Their good vision is due to the fact that their upper part recognizes the shape of objects, and the lower part recognizes colors. To ensure the strength of the wings, veins are located along their entire length, and at the end you can see dark spots that reduce vibration during flight, thereby preventing wing fracture.

Dragonflies can make various beats of their hind and front wings for balance and synchronized ones for speeds that can reach 50 km/h. The lower lip is well developed and very long. It allows you to deftly grab prey. To hunt, the dragonfly compresses its legs while flying.

Features of the structure of lice

Lice have a sucking type oral apparatus, represented by two tubes: one for piercing the skin, and the second for sucking blood.
Another feature of the structure of lice is that during a puncture, a substance is released that stops blood clotting. The structure of the eyes is simple.

They may be completely absent. This suggests that lice do not use vision to move; their sense of smell helps them in this. This structure of lice is determined by their parasitic lifestyle.

Structural features of beetles

The main feature of beetles is their wings. They are double: the upper pair hardened during evolution and formed a chitinous shell, while the lower pair remained transparent and veiny.

This structure protects the beetle's body. They have a chewing-gnawing mouthparts.

Features of the structure of bedbugs

Bedbugs have glands on their chests that secrete an odorous enzyme. It is unpleasant to humans and resembles the smell of almonds. It serves to scare away enemies.

Dragonfly larva and brief characteristics of the order

Dragonflies are a group of flying predatory insects. Representatives of this group of animals are distributed in the tropics, subtropics and areas with temperate climates. To date, about six thousand representatives of this order are known. These insects are characterized by an indirect mode of development, which includes a transitional stage (dragonfly larva) and an imago stage (adult). Both larvae and adults form the basis of the diet of some fish species. What are dragonflies?

What do adults look like?

Before the dragonfly larva is considered, it is necessary to learn more about the way of life of these insects. The adult is quite large, with a pronounced and mobile head. The organ of vision is the huge compound eyes, which occupy the entire upper part of the head. The insect's body is elongated and consists of a thoracic and abdominal part. The dragonfly's limbs are not very well developed, but they have bristles arranged in rows that act as a hunting basket, making it possible to hunt in flight.

Representatives of this group have two pairs of wings, which are almost the same size and actively participate in flight.

What do dragonflies eat? As already mentioned, these are predatory insects. Smaller species become their prey. Mostly these are midges, mosquitoes and other insect pests. The dragonfly itself usually becomes food for fish.

Reproduction and development of dragonflies

These insects mate in flight. On the abdomen you can see developed copulatory organs - in this way it is easy to distinguish a male from a female. Another interesting feature is that the male removes foreign sperm from the female’s copulatory apparatus before placing his own there. This phenomenon has no analogues in the wild.

The female then lays fertilized eggs. As a rule, oviposition is carried out either in water or on aquatic plants and much less often in moist soil. From each egg a dragonfly larva emerges.

The larvae of these insects live in water. Their body is olive-brown in color. They breathe using rectal gills and through the integument of the body. These creatures are inactive, but the way they move is worthy of attention. First, a portion of water is sucked through the anus, which is then sprayed out from there under high pressure. The recoil force pushes the insect in the opposite direction. In addition, the dragonfly larva can swim using gill plates, which perfectly replace fins.

Another feature of the larva is the presence of a so-called mask, which is represented by an overgrown lower lip. The mask plays the role of a grasping apparatus. Insects at this stage of development do not actively hunt - most of the time they sit on the bottom or attach themselves to an aquatic plant, waiting for prey, which they then grab, quickly throwing the mask forward.

The dragonfly larva feeds mainly on daphnia, mosquito larvae and other insects. Before the last molt, the insect climbs ashore and attaches itself to a plant. It is here that the larva transforms into an adult form - an adult.

It is worth noting that dragonflies are a fairly common group of insects. The order is further divided into two main suborders:

1. Homoptera dragonflies. Representatives of this order have pairs of wings of equal size. Thanks to this structure, insects are characterized by a soft, fluttering flight. The larvae of such dragonflies live in flowing or stagnant bodies of water.
2. Varied dragonflies. These insects have two pairs of large, almost transparent wings. In a calm state, their wings are placed perpendicular to the abdomen. It is worth noting that representatives of this group are considered one of the fastest insects. The larvae live either in a pond or in a swamp.

Interestingly, experienced fishermen quite often and successfully use these insects as bait.

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It is very typical for the entire order of spiders to replace the primary copulatory organs absent in males with peculiarly modified pedipalps, or gonopalps, as V. Dogel (1940) calls them. Among arachnids, similar sperm transfer organs are present only in Ricinulei (on the third pair of legs), and in general are very rare (for example, the hectocotylated tentacle of Cephalopoda males).

The copulatory organs reach full development only after the last molt of the male; Before this, there are no particularly significant differences in the pedipalps of the male and female.

Structure of a dragonfly

The dragonfly has an amazing eye structure that allows it to see danger from all sides at a distance of 10 meters. Two large eyes located on the head look disproportionate with the body.

But in fact, on both sides of the dragonfly’s head there are not two, but several dozen small eyes, working autonomously from each other and separated by pigment cells.

The dragonfly's body contains a head, a thoracic part and an elongated body, the limb of which consists of two special tweezers. The wings are strengthened with the help of transverse and longitudinal veins. In the modern world, dragonflies are found in different shades and reach from 3 to 14 cm in length.

Basically, dragonflies move in the air at a speed of 5-10 km/h, but in some categories of these insects the flight speed reaches 100 km/h. Dragonflies hunt for prey with the help of six tenacious legs covered with protective bristles.

It is noteworthy that when developing aircraft designs, engineers adopted the distinctive structural features of the wings of dragonflies.

In the photo of the dragonfly below, you can see that there are dark spots on the wings. They help the insect overcome air vibration.