Dragonflies belong to one of the ancient groups of insects. Their fossil ancestors have been found in Paleozoic (Carboniferous) deposits. They were much larger than modern ones, reaching a wingspan of 90 cm. Currently, more than 3,000 species of dragonflies are known, of which about 200 species live in the USSR. For school studies, dragonflies are very convenient objects both in the larval and imaginal stages. Acquaintance with dragonfly larvae is possible when keeping them in an aquarium, and with adults - directly in nature (on the edges of the forest, in a meadow, in a park, near water bodies). It is not difficult to get dragonfly larvae from stagnant or slowly flowing waters from the bottom or together with aquatic plants on which they sit motionless. Since the development from the egg to the adult stage lasts 2-3 years in water, it is advisable to carry out observations on the larvae of later instars, which have the rudiments of wings and are on the eve of turning into adults, i.e. nymphs, from which already adult forms emerge.

To work, you need to have at least two types of larvae: 1) from the heteroptera suborder (rocker, grandfather, grandmother, dragonflies proper) and 2) from the homoptera suborder (lutka, arrowhead, beauty). The larvae of the first type are the largest, without leafy tracheal gills, and the larvae of the second type have leaf-like gill plates at the end of the abdomen. Comparing the larvae of these two types, one can notice both common features and differences in structure and behavior. Some larvae have a light green color (in nature, they keep among the branches of aquatic plants, clinging to them with their paws), while others have a dirty brown, inconspicuous color (these are the inhabitants of the muddy bottom). In both cases, there is a protective coloration, which makes them invisible to enemies, which, with low mobility, is important for saving life. Some larvae are heavily overgrown with green algae, with which they are in a symbiotic relationship. Such larvae are often caught in a net, and they should be shown to students by placing them in a test tube with water.

The most remarkable feature of dragonfly larvae is their "mask". This is a kind of attack organ. The mask is a modified lower lip, consisting of three joints with grasping forceps on the last one. In a calm state, she covers the lower part of the head, tightly clinging to it. If you grab the grasping claws with tweezers and pull the mask forward, you can show the segmented structure of this organ, turning the joints and folding them together during the reverse movement. The method of using the mask is found out! when observing the larva during its hunting for prey. In a jar of water containing dragonfly larvae, it is necessary to place their natural food: daphnia, water donkeys, mosquito larvae and mayflies. It turns out that dragonfly larvae (for example, yoke larvae) do not chase their prey, but lie in wait for it, sitting motionless on aquatic plants or at the bottom. They only react to moving objects. When a living object approaches and enters the field of view of the larva, it slowly turns its head and body in the desired direction. As soon as the prey is at an equal distance from both eyes, the larva, with lightning speed and without a miss, throws a mask in its direction, grabs the victim with sharp claws, like tongs; the mask immediately returns like a boomerang back to the head, bringing food to the mouth. Here the food is chewed by strong jaws of the gnawing type. It can be seen that the forceps of the mask help to keep the prey near the mouth.

Dragonfly larvae have compound eyes and binocular vision, which provides them with aiming accuracy while hunting. The rocker dragonfly larva is able to catch even the slowest movements of the prey, for example, mollusks, to which it sneaks up and then suddenly attacks. Large larvae in natural conditions hunt for fish fry, causing significant damage to fish farms. It has been established that the larvae of some species of dragonflies eat a huge amount of food per day (daphnia, fish fry, etc.), almost twice the mass of the larva itself. In turn, dragonfly larvae become prey for water beetles and bugs, they are also eaten by various fish (especially bream), newts, snakes, diving birds and other animals. However, if you put dragonfly larvae and water beetle larvae in a common vessel, you can be sure that these predators measure their capabilities and do not touch each other with equal forces.

In the process of evolution, dragonfly larvae have developed some protective reactions that are easy to detect. So, for example, the larva of the rocker, grasped by the fingers, defends itself with the help of three cerci in the form of hard spikes located at the end of the abdomen, which it vigorously bends from side to side. “In larvae that have leaf-shaped tracheal gills at the end of the abdomen, their autotomy is observed. After molting, the gills are restored. You can suggest that students conduct an appropriate experiment: pinch one of the gill plates with tweezers, provoke autotomy, and then find out how soon such a larva will regenerate the lost gill.

The presence of tracheal respiration in dragonfly larvae serves as one of the proofs of their belonging to secondary aquatic organisms. This is also evidenced by their temporary stay in the water, followed by the emergence of the nymph on land. One species of dragonflies lives in Hawaii, the larvae of which have adapted to life on land, where they get their food by crawling along the forest floor. Such an exception is not unexpected, since it is known that dragonfly larvae, in addition to tracheal gills, also have spiracles, which they use for atmospheric respiration when the reservoir dries up, as well as at the end of their larval life when leaving the water before turning into adults. During the stay of the larvae in the aquatic environment, the assimilation of oxygen occurs through its penetration into the tracheal system, which is located not only in the gills, but also in the walls of the hindgut of the larvae. Moreover, breathing through the intestines should be recognized as the main one.

Watching dragonfly larvae, you can see how they breathe. The abdomen periodically swells, absorbing a portion of water into the hindgut, and then contracts, throwing it out. Disturbed larvae quickly swim away from danger, using various methods of movement for this. The larvae, which have gill leaves, energetically hit the water with them in a horizontal plane like a fin, while bending their long abdomen from side to side, as a result of which the body acquires a rapid forward movement. Larvae that do not have gill leaves use a jet method of movement: having collected a portion of water into the hindgut through the anus, they forcefully throw it back. Here we have an example of a convergent application of the rocket mode of movement, which is also used by animals of other types (for example, jellyfish, scallops, octopuses, etc.). In order for students to be able to observe this way of moving the larva, they should be invited to place the larva of the rocker or grandfather in a saucer with water, put a thin layer of clean sand on the bottom and begin to disturb the larva. At the bottom, the movement of water will be clearly visible, displacing grains of sand along the stream ejected from the intestine. If at this moment the abdomen is raised, grabbing it with tweezers, then one can get an idea of ​​the force of the push by the power of the trickle, which is sometimes sprayed into the air at a distance of up to 1 m.

Familiarization with the characteristics of the dragonfly in the adult stage is best done on living objects under appropriate conditions. Students can carry out these observations independently on the instructions of the teacher, as well as in the pioneer camp.

Flight of dragonflies usually occurs in the second half of summer during the hottest hours of the day. At this time, they catch on the fly various mosquitoes, midges and other small insects (near water bodies). Large species chase flies, butterflies and small species of dragonflies. Hunting for insects lasts all day. It starts in the morning, as soon as the sun warms up. Thousands of dragonflies rush from their roosting places (among the branches of trees or on the stalks of reeds) to various feeding areas: to reservoirs, to the steppe and meadows, to bird nests and pastures (hunting for bloodsuckers).

Unlike larvae, adult dragonflies benefit by exterminating harmful insects in large numbers. Suffice it to say that some species of dragonflies absorb as much food in half an hour as they weigh themselves. Not all dragonflies fly continuously. Some of them are prone to rest (for example, dragonflies themselves), while they sit on stumps or tree branches. Others (for example, arrows) sit for a long time on the stems and leaves of grasses along the banks of lakes, rivers and ponds, lying in wait for prey in a state of latent activity.

It is better to consider the structure of a dragonfly by carefully taking it in your hands by the wings raised up (in order to then release it into the wild). The easiest way to do this is in the early morning, when the dragonflies are still in a state of night stupor and hold on to the needles or leaves of trees, clutching them with their paws. Attention should be paid to a number of features inherent in these peculiar insects, namely:

1) a clear division of the body into the head, chest and abdomen;

2) a movable joint of the head, allowing its free movement in different directions (check carefully!), This is important when pursuing prey;

3) a pair of large compound eyes converging on the crown;

4) the position of the chest with an inclination forward, as a result of which the legs are in front of the wings and directed forward - this facilitates the capture of food (prey);

5) the ends of the paws with claws, with which the dragonfly clings to plants during rest, and also holds the prey, bringing it to the mouth;

6) two pairs of widely spread wings, almost identical in structure, but different in shape, with a very dense network of veins. The front wing is moved away from the rear and does not come into contact with it, unlike other insects. The inability to fold wings along the body is a trait inherited from the distant ancestors of Paleozoic ancient winged insects;

7) "eye" - a thickening on the front edge of each wing near its top - pterostigma - a device for the stability of the wings in flight, eliminating their vibration.

Having completed a comprehensive examination of dragonflies, they must be released into the wild and observe their behavior in flight. The nature of flight in different species is peculiar. Rocker arms and headstocks are distinguished by sharp and fast movements; hatchlings, shooters and beauties have a light fluttering flight, which is in harmony with their graceful slender body and elegant coloring, etc.

Particular attention should be paid to the work of the organs of vision in connection with the flights of dragonflies. The compound eyes of a dragonfly have up to 28,000 facets. In the upper part, the facets are larger, with a smaller number of ommatidia, and vice versa in the lower part; the vigilance of the eye from below is greater, and the color perception is richer than in the upper half. It has an important adaptive value. G. M. Mazokhin-Porshnyakov found that the upper part perceives only two colors - blue and cyan, and the lower one distinguishes several colors of the spectrum: yellow, green, orange, red. This feature has developed in dragonflies in the process of evolution and has been fixed by natural selection as a useful feature of the visual analyzer, acting rationally on the principles of economical functioning. In the conditions of life of dragonflies, while hunting for living objects located above, one has to look at them and visually perceive them against the background of the blue sky. To do this, it is enough to see the prey in the form of a dark silhouette, i.e. here the color does not matter much. When the dragonfly looks down, flying over the surface of the earth covered with flowering plants, it needs to find its prey against a colorful background, orienting itself in shape and light contrast, which requires more complex color orientation. It is these conditions that have found their satisfaction in the specificity of dragonfly vision.

Compound eyes can only function properly in good light. When a dragonfly flies into shady forest areas (in twilight), its simple eyes come into action, with the help of which it finds its way into space with optimal lighting for it. If you paint over one eye of a dragonfly flying towards the light, then the trajectory of its flight will turn out to be spiral, since there will be a violation of coordination of movement. Adult dragonflies, like their larvae, react only to moving objects.

If you look closely at the flight of a dragonfly, you can notice the difference in the work between the front and rear wings. The front ones, as it were, stand motionless, only occasionally arching up and down. At this time, the dragonfly then decreases, then takes off, holding in the air. These wings support the dragonfly at a certain height. The hind wings move like a propeller, flicker, buzz and rustle. They rake in the air, starting from it, and move the dragonfly forward. Sometimes a dragonfly seems to float silently in the air if its wings become a rib and act like a sail in a fair wind.

Dragonflies can soar for 4-5 minutes, rising to a height of 3-4 m and using currents of hot air rising from the soil heated by the sun. They are also able to move in flight not only forward, but also backward, while revealing extraordinary maneuverability: they make sharp turns, slide sideways, describe loops, rapidly rise up and fall down like a stone. The virtuosity of the flight is provided by an accurate system of coordination of movements based on feedback. There are two sensitive pads on the chest of dragonflies, with the help of which the slightest changes in the position of the head are recorded during the flight. In this case, the dragonfly's brain picks up signals about ongoing deviations in symmetry between the body and wings and sends appropriate impulses to the motor muscles.

Dragonflies fly at a speed of 10-30 m / s, making up to 80-100 wing flaps during this period of time. The highest speed of horizontal flight was observed in a patrolman (from the rocker family), which, as observations showed, repeatedly accompanied a training aircraft flying at a speed of 144 km / h, and sometimes overtook it.

Massive flights of dragonflies from north to south over long distances are noteworthy. They have been known for a long time and have been observed in different countries, including our country. So, in the spring of 1939, a mass flight of dragonflies was noted in Leningrad, and in the autumn of 1969, dragonflies flew at an altitude of 15 m above the Tien Shan ridge.

Mass migrations of dragonflies were observed in Ireland and Sweden, and flights between the islands of Japan, 50-60 km apart, were also recorded. The reasons for such migrations and their final points remain unclear. It is only firmly established that flocks of dragonflies fly south every year through the passes of the Pyrenees and the Alps, which indicates their ability to climb very high and fly far. Flights have been recorded only for some species: from the family of the dragonflies proper and from the family of the yoke.

It is interesting that our usual large rocker dragonfly in its airy way of life surpasses not only other dragonflies, but insects in general. She performs almost all her vital functions in the air sphere: she catches prey on the fly and immediately eats it, mates in flight and lays eggs directly into the water, flying over its surface. Following the prey, it moves in the air at different hours to different heights. In the morning it stays high, in layers of dry air, where small insects fly, and in the evening it descends to the surface of the earth, since at this time many insects (mosquitoes, midges, flies, butterflies) decrease closer to the vegetation cover. At nightfall, dragonflies hide in the crowns of trees and grass, falling into a night stupor until sunrise.

Of the other features of the behavior of dragonflies, one additional feature can be noted, which is characteristic of species that imitate the stinging hymenoptera in their appearance (for example, microstigma maculata). Such dragonflies, being grabbed by their hands, bend their abdomen and scrape its end along the finger, as if about to sting, although they have no sting. In this case, there is one of the instincts that have developed in the process of evolution, hereditarily fixed by the action of natural selection, aimed at increasing the survival of a defenseless species, when completely harmless individuals of this species scare away their enemies not only due to their external resemblance to a well-armed animal, which they imitate, but also create the appearance of dangerous actions for the attacking predator, which are actually used by a species adapted for defense. This phenomenon is widespread among insect mimics that are similar to their models in both appearance and behavior (an example of convergence).

The jumping dragonfly sang red summer... Indeed, these beautiful creatures can be found, basically, only in summer. For example, I see them every year. Or hear them flapping their wings loudly. :) I don't know if they sing in the red summer, but they definitely like to communicate with the opposite sex. :) I very often see not lonely dragonflies in the country, but couples in love.

With what feed these amazing creatures? Maybe they bring each other coffee in bed? More on this later. :)

What do dragonflies eat

Dragonflies are a separate detachment of the insect class. Science knows more six and a half thousand different types these creatures . When compared with other insects, dragonflies are much larger.

The life cycle of dragonflies is similar to that of butterflies. Both beings have it occurs with the presence of a transformation, however dragonflies it is incomplete. This means that they, before becoming an adult, they go through egg and larval stages. Moreover, development at these stages occurs entirely in the aquatic environment.

Now to the main thing. Dragonflies are predators. Basically, they feed on other small insects(flies, wasps, mosquitoes) . They catch them right on the fly.

Some large individuals are able to hunt even small ones. amphibians and reptiles(frogs, lizards, etc.)

Being a dragonfly larva, these animals consume small river creatures- small crustaceans, tadpoles, etc.

I have prepared a small selection of interesting facts about dragonflies:

• Earlier, I read about a butterfly that can reach speeds of up to 50 km / h. However, dragonflies are not impressed with such results. Most species can flyat a speed of 60 km/h.

• The process of hunting these creatures is very interesting and reminds me of a war in the air, when the plane sits on the tail of another plane. It's pretty much the same here, but they hunt from above. And then abruptly swoop down on their prey.
• Man can thank these creatures for being kill a lot how simple annoying insects, as well as real garden pests.

These amazing dragonflies

These amazing dragonflies Odonata

There are about 6500 species in the order Odonata, united in over 600 genera. Adult dragonflies are brightly colored medium to large diurnal insects that hunt in the air for prey that they notice with their huge eyes. They are found near fresh water sources, although some species of dragonflies can be found in a wide range, away from breeding areas. Dragonfly larvae are an aquatic predator found in all types of inland waters.

ancient dragonflies

In the Cretaceous, giant dragonflies lived, with a wingspan of about 0.7 m.

huge eyes

The head of the dragonfly is large, the neck is movable. When examining a dragonfly, attention is drawn to the huge eyes that occupy most of the head, which are divided in the middle. The eye consists of 28 thousand facets (ommatidia), each of which is served by 6 light-sensitive cells. For comparison: the number of facets in the eye of a fly is 4 thousand, of a butterfly - 17 thousand. The facets located in different areas of the eye have an unequal structure, which determines the ability to perceive objects of different degrees of illumination and different colors. There are dark spots that block the areas responsible for vision. The image originates in the lobe of the brain that lies just below the surface of the eye. Eyelashes on the eye can be compared with antennas, their function is to capture the light source, to carry out orientation during the flight. The ability of the antennas is so high that the dragonfly never loses its light source during the flight, which makes it possible to accurately target its movement (and, as you know, the speed of the dragonfly is one of the highest in the world of insects).

Balance

A thin rod-shaped abdomen during the flight acts as a balancer.

Insect speed record
Dragonflies are the fastest flying insects. The usual flight speed of a dragonfly is 30 km/h. But the maximum speed of their movement reaches 57 km / h.

Why do dragonflies need forceps on their abdomens?

Males have "tweezers" at the top of their abdomens, with which they hold the female by the neck during mating. Such "tandems" of dragonflies can often be observed near water bodies. Dragonfly females drop their eggs into the water or place them in the tissues of aquatic plants using a piercing ovipositor. The legs of the dragonfly are weak, they are able to keep an insect on a blade of grass or keep prey, but they are not adapted for walking. The abdomen of the dragonfly is long, in rare species it is shorter than the length of the wings and very flexible. In both sexes, 10 segments can be counted. Males of the genus Zygoptera have secondary genitalia (genital appendages) on 2-3 segments below, while females have an ovipositor opening on 9-10 segments.

What kind there are wings

Large wings with reticulate venation in large dragonflies are always spread to the sides, in small ones (arrows, buttercups) at rest they can fold along the body. In some dragonflies, the wings are the same in shape, narrowed towards the base (suborder Homoptera), in others, the hind wings are wider than the front ones, especially at the base (suborder Hemoptera). Blue, green, yellow tones predominate in the coloration of dragonflies, bright metallic luster is less common. Some wings are spotted or darkened. In dried specimens, the color fades and changes greatly.

Two hearts

At the initial stage of development, the dragonfly larva has 2 hearts: one in the head and the second in the back of the body. A more mature dragonfly larva has 5 eyes, 18 ears, and an 8-chambered heart. Her blood is green.

Hindgut: organ of movement and respiration

The hindgut of the dragonfly larva, in addition to its main function, also performs the role of an organ of movement. Water fills the hindgut, then it is thrown out with force, and the larva moves according to the principle of jet propulsion by 6-8 cm. The hindgut also serves as a nymph for breathing, which, like a pump, constantly pumps oxygen-rich water through the anus.

The biggest dragonfly

Dragonfly fossils date back to the Jurassic period. They cannot be assigned to any of the currently existing three suborders, so they are classified as fossil orders: Protozygoptera, Archizygoptera, Protanisoptera and Triadophlebiomorpha. The separate order Protodonata, sometimes placed as a suborder in the order Odonata, contains many large dragonflies, among which there are impossibly large individuals. The largest of the giant dragonflies, Meganeuropsis permiana, has a wingspan of 720mm.

For modern species, this figure is more modest, large species have a wingspan of less than 20 mm (Nannodiplax rubra species, Libellulidae family) or more than 160 mm (Petalura ingentissima species, Petaluridae family): some modern dragonflies of the genus Zygoptera have a wingspan of 18 mm (species, Agriocnemis pygmaea, family Coenagrionidae) up to 190 mm (species Megaloprepus caerulatus, family Pseudostigmatidae). The largest of modern dragonflies is recognized Megaloprepus caeruleata, living in Central and South America, it has a body length of 120 mm and a wingspan of 191 mm. A rare giant Australian dragonfly with a wingspan of 110 - 115 mm (females up to 125 cm). And although the giants of the insect world live in the tropics, the rocker dragonflies found in our country are considered one of the largest insects.

Rocker arms

The largest dragonflies in our country belong to the rockers (Aeschnidae). One of the common types blue rocker (Aeschna juncea), body length up to 70 mm, and in wingspan up to 95 mm. Males are brighter, with a predominance of blue coloration, especially on the abdomen. In females, green and yellowish tones predominate. These are wonderful flyers, capable of covering tens and even hundreds of kilometers, settling in new water bodies. Sometimes it is possible to observe the process of the dragonfly emerging from the larva, which for this purpose is selected from the water onto the protruding parts of plants. The wings of a young dragonfly are still fragile, cloudy, the integument is palely colored. But an hour after hatching, the dragonfly is ready to fly.

grandmother

The family of butterflies (Corduliidae) includes medium-sized dragonflies, in the coloration of which there is a bright metallic sheen.

Small equal-winged dragonflies: beauties, notches and arrows

Beauty Family - Calopterygidae, Buttercups - Lestidae, Arrows - Coenagrionidae

Near any stagnant reservoirs, the dryad buttercup (Lestes dryas) and a similar species, the bride buttercup (L. sponsa), which differs only in the structure of the genital appendages, are very common. Females are lighter. Like dragonflies, their small, poorly flying relatives are. predators, their main prey are mosquitoes and midges. Nymphs eat water fly larvae. The body length of small dragonflies is from 25 to 50 mm. They hold their wings vertical to their abdomen because they cannot spread them in a different plane. They themselves can become victims of large dragonflies, birds, or even insectivorous plants. The related family of arrowheads (Coenagrionidae) includes graceful dragonflies up to 40 mm long, folding wings at rest with a short pterostigma along the body. They have a weak flight and preferentially keep in thickets of adventitious plants. More often than others, we have a blue arrow (Enallagma cyathigerum), which has pear-shaped blue spots on the back of the head.

The smallest dragonfly
... this is Agriocnemis paia from Myanmar (Burma). One copy, stored in the Natural History Museum in London, had a wingspan of 17.6 mm in life with a body length of 18 mm.

Air and water predators

Dragonflies are aerial predators that hunt in the air, visually detecting potential prey, in order to catch it, dragonflies sometimes have to perform miracles of aerobatics. Often they eat prey right on the fly. Some species of dragonflies are excellent fliers and are very difficult to catch. Eating mosquitoes, horseflies and other bloodsuckers, dragonflies are of great benefit. The development of all dragonflies necessarily passes through the aquatic stage - the nymph (the so-called insect larvae with rudiments of wings). Nymphs are even greater predators, because they eat not only any prey that is smaller than their size, but they are able to overcome the enemy and their own height. They also attack aquatic vertebrates; small fish also cannot resist these predators. All dragonfly nymphs are voracious predators, grabbing their prey with a modified lower lip - a mask that rapidly opens and throws forward, while the claws on its front end, like stilettos, pierce deeply into the victim. When the mask is folded, the prey is pulled up to the mouth and chewed calmly.

Larvae and nymphs

Dragonfly larvae and nymphs are found in all types of fresh water reservoirs. They can be found in ponds and rivers, drying up puddles, and even in tree hollows filled with water. Larvae of some species are able to survive in conditions of moderate salinity, other larvae lead a semi-aquatic lifestyle, crawling out to the surface of the earth at night, they can be found along the banks of swamps and on the branches of semi-flooded trees. Larvae of six species lead a completely terrestrial lifestyle.

During development, the larva molts 10 to 20 times at the age of 3 months to 6-10 years, depending on the species. The number of molts depends on natural conditions and food availability. During 6-7 molts, the rudiments of wings begin to actively develop. The metaphor is direct, bypassing the pupal stage, the adult insect leaves the water and sometimes moves away to a considerable distance from the place of its birth. During the absence, which lasts several days, the dragonfly actively feeds and acquires physical maturity. A sign of the onset of maturity will be the bright color of the dragonfly. Young dragonflies are recognized by the glassy sheen of their wings. With age, the coloration of dragonflies becomes more intricate, additionally colored areas appear, which are absent in juveniles.

Lifespan

Most adults live for a long time. In areas with a cold climate, dragonflies hibernate, choosing secluded places for wintering; in the tropics, dragonflies wait out the dry season and come to life with the onset of rain. Some dragonflies undertake long flights, including the transatlantic route, but most species live near breeding sites.

Pairing

In the process of mating, the couple performs a complex trick. The male holds the female by the head (genus Anisoptera) or the prothorax (genus Zygoptera). The pair flies entangled (male in front, female in back), often they rest on the bushes in the same position. The female bends her abdomen to form a wheel and connects with the secondary genitalia located on segments 2-3 of the male, which were previously coated with sperm from the primary genital opening from segment 9. In different species, mating lasts from several seconds to several hours. Some species of dragonflies also lay eggs together, because by this time the male and female do not separate. In others, the male hovers over the female while she lays her eggs. Third males leave the female amoy to cope with this process: they either return to their site or sit on a bush nearby.

Gathering in flocks

It is known that dragonflies (Odonata) can gather in flocks, the size of which in some cases can be considered huge. So, males gather in flocks and patrol the breeding grounds, they can sit on nearby bushes or fly up and down in search of females. The area where they gather is very small. The fact is that in many species, females stay far from water, appearing near a pond or lake only for mating or in order to lay eggs. In some cases, males and females stay in place and fly in one flock. So, for example, on June 13, 1817, dragonflies flew over Dresden for two hours. July 26, 1883 flock four-spotted dragonflies (Libellula quadrimaculata) flew over the Swedish city of Malmo from 7 hours 30 minutes. Morning until 8 o'clock. Evenings. In 1900, a flock of dragonflies was observed in Belgium, which was 170 m long and 100 km wide.

Usually camouflage is associated with immobility, however dragonflies (Hemianax papuensis), rivals for territory, on the other hand, use movement to hide from each other. It turned out that dragonflies in flight with the highest accuracy concentrate their shadow in the enemy's retina, and the lack of optical flow makes the enemy perceive the dragonfly as a static object that does not pose a threat. How dragonflies manage to do all this remains a mystery.

Dragonfly flight speed– up to 96 km/h; bumblebee - 18 km / h.

dragonflies in folklore different countries

In some countries (especially Japan), dragonflies are an image of beauty along with butterflies and birds. In European culture, attitudes towards dragonflies are less favorable. They are considered the "goad of horses" and the "devil's sting".

Of course, dragonflies are not able to sting or bite. All types of dragonflies are absolutely harmless. Moreover, they are beneficial insects because they destroy harmful insects. The presence of many dragonflies near the reservoir indicates its ecological attractiveness and the presence of many aquatic inhabitants in it.

Giant extinct dragonflies

Giant dragonflies that lived during the Cretaceous period had a wingspan of 0.7 m.

The animal world that surrounds man is rich and varied. Knowledge about some creatures will help to understand and realize what is around each of us. This article discusses the orders of dragonfly insects, lice, bugs, which are most common in people's lives.

A general description helps to understand what each squad is. Dragonflies are the largest flying insects on Earth. They are predators. The order of dragonflies includes suborders: heteroptera and homoptera.

To date, more than 6 thousand species of dragonflies are known. They differ in their color, which can be very different, and in size, which can be from 3 to 12 centimeters. There are several thousand species of lice. But among this huge variety of lice, only three types are dangerous for humans: head, body and pubic. They differ in habitat.

The whole variety of beetles can be divided into 6 families: predators, weevils, barbels, leaf beetles, ground beetles and lamellar. The variety of bedbugs is very large. The most famous of them are those that feed on human blood.

Appearance

Most often, we distinguish representatives of the animal world by their appearance. Dragonflies have a long and thin body, which is connected to a round small head with a chest. On the body there are 3 pairs of paws, as well as 2 pairs of long transparent wings, which can have the same shape in homoptera dragonflies and different in heteroptera. Large eyes and antennae are clearly visible on the head.

The appearance of beetles can be very different. They come in different colors. Their sizes vary from a few millimeters to 15 centimeters.

All beetles have a large elongated body, a small head, a three-segmented chest, and 3 pairs of five-segmented legs extending from the body.

Bedbugs in nature can also be found in different sizes and colors. Their body is mostly rounded, the head is small.

Structural features

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

Structural features of dragonflies

The eyes of dragonflies have a complex structure. Their good eyesight is due to the fact that their upper part recognizes the shape of objects, and the lower part recognizes colors. For durability, the wings are veined throughout their length, and dark spots can be seen at the end, which reduce vibration during flight, thereby preventing wing fracture. Dragonflies can flap their hind and front wings in different ways for balancing and synchronized for speeds that can reach up to 50 km/h. The lower lip is well developed and very long. It allows you to deftly grab prey. For hunting during the flight, the dragonfly compresses its paws.

Features of the structure of lice

Features of the structure 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 sinewy. This structure protects the body of the beetle. They have chewing-gnawing mouthparts.

Features of the structure of bedbugs

On the chest, bed bugs have glands that secrete a smelling enzyme. It is unpleasant to humans and resembles the smell of almonds. It serves to scare off enemies.

Habitat

All animals settle in such places, the conditions of which are favorable for them. Dragonflies live almost everywhere. But the main factor of their habitat is a humid climate. Therefore, you can meet dragonflies near rivers and lakes. A large variety of them live in tropical and subtropical climates.

Beetles live everywhere. There are especially many of them in the tropical regions of the planet. You can not meet them in the Arctic and Antarctica. In small numbers they live on the tops of mountains. Bed bugs are also ubiquitous. Some species can be found even beyond the Arctic Circle.

Food

All representatives of the animal world can be predators, herbivores and omnivores. Dragonflies are predatory animals. They feed on various small insects, and their larvae can even eat fish fry. Lice feed on the blood of warm-blooded animals. This happens only when the life cycle of lice reaches the adult stage.

All living beings go through several stages of development during their lives. Dragonflies have an incomplete development cycle. Throughout their life, they go through 3 stages: egg, larva and imago (adult). They can develop over 5-7 years, and in adulthood they live no more than 1 month. Eggs are laid by the female mainly in water or on aquatic plants, less often in wood or soil.

The larvae hatched from the eggs live in the water, feeding on insects and fry. They already have large eyes and a long developed lower lip for food. After several molts, they get out onto land, where they molt for the last time and turn into an adult dragonfly. Only a few go through the entire development cycle, since most of the larvae are eaten by predatory inhabitants of lakes and rivers.

The development cycle of lice is incomplete and is represented by three stages. The type of development of lice and dragonflies is similar, since they have the following stages: egg, larva and adult. called nits, they are firmly attached to the hair by the secret of the mother. Under favorable conditions, after some time, a larva appears through the lid of the nit shell. Soon she grows to an adult. How long the louse lives depends on the favorable environmental conditions.

Beetles have a complete life cycle consisting of eggs, larvae, pupa and adults.

Beetle eggs are predominantly light in color. Larvae emerge from them, the body of which is covered with a chitinous shell. With an open lifestyle, they have a dark color, and with a closed lifestyle, they are light. All larvae are divided into 3 categories: campodeoid, erucoid, wireworms. Pupation takes place on land. The pupa does not have a chitinous shell. She is motionless and colorless.

The female bugs lay their eggs in secluded places, from which the larvae hatch after a few days. Outwardly, they are similar to adults, but are small in size. Shedding occurs every week. And after a month, the larva turns into an adult.

reproduction

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 right during the flight. To scare away other males, the male performs a ritual flight around the female.

Lice also reproduce sexually. After fertilization, the female, refreshed with blood, crawls through the hair, laying eggs along with the secret. Hardening after a while, it provides a strong attachment of the nits to the hair. Then the lice life cycle begins, which was discussed earlier. Male beetles may fight for the female. Also, in order to find each other, the couple releases a smelling substance - a pheromone. has the following feature: the fertilization of the female occurs 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.

In antiquity for their flight and the type of wings that are horizontally spread in the air. Today, the dragonfly population is rapidly declining, this is due to both poor ecology and climate change. Dragonflies are thermophilic: they need a high temperature of water and air for life and reproduction. They are demanding on the flora of the area, prefer marshy and flooded meadows, where there is a lot of food.

Not likely, but true: a dragonfly can hunt an object many times larger than itself. Large individuals attack even small frogs or fry.

Dragonfly is a predator. It eats the flying midge, which inhabits in abundance the coastal territories of rivers and lakes. Thanks to its huge eyes and wide-angle capture, it can see the victim at a distance of up to 12 meters. At the same time, the location of the latter does not actually matter, because the dragonfly can fly backwards and see everything that is happening in its tail area.

The jaw of the dragonfly is relatively powerful, and the teeth resemble files, so mosquitoes and flies that are captured by the dragonfly die almost instantly, being bitten in half. On the fly, the dragonfly catches the victim with its paws, which, thanks to the movable bristles, seem to lock it in the vise of its own body. An insect cannot eat in flight. Therefore, it lands with prey on the nearest large grass or leaf.

The main diet of dragonflies consists of:
- mayfly,
- springflies,
- caddisflies,
- lacewings,
- Lepidoptera.

However, dipterous insects still occupy a large share in the diet.

Nymph nutrition

The dragonfly reproduces by laying eggs, which hatch into nymphs. They lead an exclusively underwater lifestyle for a year and a half, feeding exclusively on water fleas, tadpoles, and larvae of other underwater inhabitants. The "child" of the dragonfly is extremely voracious due to the fact that it consumes a large amount of energy, moving quickly, rapidly. In addition, larvae and nymphs change their skin 10-15 times during their life, and this is a colossal waste of energy.

Unique nymphs live longer than dragonflies. The life cycle of a dragonfly is 6 weeks, a nymph is 5 years.

It is not the paws or the ability to swim in jerks due to the ejection of water from the body, as many people think, that help the nymphs to hunt, but a unique organ - the lip, which is located under the "chin". With a lip, a nymph literally captures a small insect and sends it into its mouth.