general characteristics. Coleoptera, or beetles, occupy first place in the insect class in terms of the number of species. Currently, over 250,000 species are known. The order of beetles in the taxonomy of Coleoptera is divided into two suborders: carnivores and heterovores. However, this division is conditional. The USSR is home to more than 20,000 species of beetles, diverse in appearance, structure, lifestyle and behavior. Their study at school makes it possible to acquaint students with many biological patterns (divergence and convergence, mimicry, sexual dimorphism, defensive reactions, etc.), as well as with the role of beetles in the life of biogeocenoses and in the human economy.

The name of the order (Coleoptera) characterizes the structure of the upper pair of wings - the elytra, which are truly distinguished by their rigidity and strength, performing a protective role. In some groups of beetles, underdevelopment of the elytra (rove beetles, rove beetles, grappling beetles, longhorned beetle) or hind wings (many ground beetles, barn weevil) is observed. Usually, during flight, the elytra serve as gliding planes, but in some cases the elytra do not participate in flight. Such elytra have cutouts on the sides for the release of wings (for example, in bronze beetles, dung beetles). Among the beetles there are wingless forms that are incapable of flight (Turkish mowing elephant, T-shirts, longhorn beetles, darkling beetles - slow-moving beetles, female fireflies and cockroach fantails).

Most beetles fly quite well, and some of them carry out long-distance flights (for example, ladybugs). The absolute flight speed of beetles depends not only on the duration of the flight, but also on air temperature, wind strength, its direction and other factors. The average flight speed of the cockchafer is 3 m/s, and that of the dung beetle is 7 m/s.

Beetles move using not only wings, but also legs, the structure of which is adapted to various movements: running (predatory beetles, runner ground beetles, etc.), jumping (jumping ground beetles, jumping elephant beetles, flea beetles), swimming ( diving beetles, whirligigs), digging (dung beetles, calorie beetles, little beetles), climbing (soft beetles, click beetles). The legs of beetles that lead an active lifestyle (ground beetles, diving beetles) also have well-developed legs. Sedentary larvae (weevils, bark beetles, woodcutters) have no legs.

Many beetles are colored black, which is obtained as a result of a peculiar tanning process, when the phenol in the beetle’s body, under the influence of a special enzyme, is oxidized and converted into quinone, and this latter, when interacting with protein, forms an insoluble black product. This is a chemical type of coloring. The bright, shiny, metallic color of beetles is explained in some cases by the refraction and reflection of light rays falling on the upper layer of the cuticle, under which there is a layer of prisms (in leaf beetles, golden beetles, bronze beetles), and in other cases by the reflection of light from the scaly cover, which has refractive properties. areas of chitin (in elephants). This is a physical type of coloring.

The coloring of beetles can be either protective, if it is in harmony with the surrounding background (for example, green bugs on green leaves), or warning, i.e., warning of inedibility, if it catches the eye with bright spots, stripes and color in combination with caustic secretions , unpleasant smell, poisonous blood. As an example, in addition to the ladybug and the burying beetle mentioned in the zoology textbook, other beetles should be mentioned to show the wide distribution of this type of defense against enemies. Thus, some ground beetles, which secrete a pungent liquid with an unpleasant odor from the rear end of the abdomen, have different warning colors.

A similar combination of color with protective secretions is found in dung beetles: the aphodia and golden dung beetles have bright red elytra, and the spring dung beetle have bright blue (or green). Beetles whose warning coloration is combined with the presence of poisonous blood include rove beetles with a red pronotum and blue elytra; T-shirts and naryvniki - with blue, red or yellow elytra; goldfishes and bronzeworts - with shiny golden elytra; leaf beetles (shield beetles, iris beetles, etc.) - with a bright, shiny metallic color of green, blue and other shades, Spanish flies - with metallic green elytra; soft-bodied dark - with red spots on a dark background, etc. Many of these beetles stay open, are slow in their movements and are not afraid of attack.

The body shape of beetles usually corresponds to their habitat conditions. So, for example, beetles that live under the bark (subbark tots, Moorish boogers, narrow beetles) or live in cracks in the bark and crevices of trunks (flat beetles), as well as sitting on flowers among the petals (raspberry beetles, beetles, soft beetles), have a flat or narrow elongated body. The streamlined body shape is characteristic of swimmers and water lovers. Beetles (caryopsis) living on grains have a roundish outline, while those living on leaves (ladybugs, leaf beetles) have an oval-round or spherical body. In other beetles, the body is narrowed either at both ends (click beetles) or towards the rear (beetles).

Some beetles are suitable for demonstrating individual variability in both size and body color and can be used as an example of modifications resulting from the interaction of an organism with developmental conditions (on a topic from the general biology course - “Phenotype and Genotype”). In this regard, the two-spotted ladybug deserves attention, in which the color and pattern of the elytra are very variable. A significant range of variability in the color of the elytra is observed in gold borers and bronze beetles. For example, many narrow borers (blue, green and two-spotted) have colors ranging from bronze and olive to blue-green and blue, while bronze borers (gold and copper) range from the typical golden green through copper red, dark purple and blue. to almost black. In male large stag beetles, body size and the size of the horns (modified mandibles) are subject to variability. According to these indicators, they can be placed in the appropriate row, starting from small forms (25 mm long) to the largest (75 mm long) with intermediate individuals between them.

Some students associate insect body size with age and consider small stag beetles to be young and large stag beetles to be old. It is necessary to clarify that all beetles of one species or another, regardless of their size, have the same age, since they belong to the last stage of individual development (imago). Their youth proceeded in the larval state and ended in the pupal stage, which turned into an adult beetle that completed its growth. Among the beetles there are giants and dwarfs: for example, some pinnate wings reach only 0.3 mm in length, the Ussuri relict longhorned beetle has a length of 11 cm, and the titanium lumberjack from South America is 18 cm. These are the average body sizes, which for each species are fixed in heredity as a characteristic feature.

Beetles exhibit sexual dimorphism. For example, only males have horns in stag beetles. Males of various dung beetles (rhinoceros beetle, moon copra, bull beetle, many-horned and mobile-horned dung beetle, etc.) differ from females by the presence of one or more horns on their heads. In the Hercules beetle, the male differs from the female not only in his horn, but also in color: the male is olive green, the female is matte black. In fireflies, males have wings and females are wingless. The most pronounced sexual dimorphism is in the cockroach fan beetle: the male resembles a small fly, and the female resembles a woodlice.

In beetles, like butterflies, individual development proceeds with complete metamorphosis and, like them, the larvae perform a vegetative function with the accumulation nutrients for the imaginal stage. Due to these substances, adult beetles manage without food at all (borer, cockroach fan) or, after exhausting their reserves, switch to additional food (the vast majority of species). Both adult beetles and their larvae have gnawing jaws, which is associated with their feeding habits. In some beetles, the mouth is located at the end of the proboscis - the rostrum (in elephants or weevils). The acorn elephant at the end of the proboscis has strong jaws, which have turned into a drilling apparatus that helps it penetrate inside the acorns. In the larvae of swimmers and spinners, the upper jaws have turned into saber-shaped mandibles with channels through which they suck out their prey. All these modifications are adaptive in nature.

In many larvae, the head is highly chitinized and is adapted to withstand physical stress when moving in dense environments (soil, wood). In the soil, for example, live the larvae of May beetles, beetles, click beetles, darkling beetles, flea beetles, sow beetles, dung beetles (dung beetles and corn beetles), dark soft-bodied beetles, hairy bronze beetles, etc., and in the wood - the larvae of the house longhorned beetle, borers, and beetles. deer, some rhinoceros beetles and pied beetles, stink bugs, pine beetles (great pine beetles), bronze beetles (golden beetles), rotten elephant beetles, black longhorned beetles (spruce and pine), etc. It is noteworthy that longhorned beetles larvae, feeding on wood, are able to assimilate up to 20% this difficult to digest food. Their digestive juice contains the enzyme cellulase, which converts fiber into sugar. This kind of adaptive feature of an organism arose convergently in the process of evolution in another type of invertebrates - in mollusks (for example, in a shipworm).

The bark and under the bark are inhabited by the larvae of bark beetles, bark beetles, root beetles, sapwood beetles, elephant beetles (pine beetles, tar beetles), and gold beetles. Their larvae are inactive, soft, worm-like, and legless. The larvae of beetles living in the soil (click beetles, darkling beetles) are distinguished by an elongated, cylindrical body with a hard cover; The larvae of some weevils resemble butterfly caterpillars in appearance, but lack both thoracic and abdominal legs. The larvae of many leaf beetles, like caddisfly larvae and bagworm caterpillars, construct protective covers of various shapes, using them as building material their dried excrement. This is an example of convergence in the development of similar building instincts in insects of various orders (beetles, butterflies and caddis flies).

Beetle larvae live where they find food. For example, the predatory larvae of manticore horses hide in earthen burrows. In manure and accumulations of decomposing plant debris live the larvae of various dung beetles, geotrusses, lunar copra, dung water-lover, dung whirler (mud whirler), hairy rove beetle, scarab beetle, rhinoceros beetle, pinnacle beetle, etc. The larvae of carrion beetles, carrion eaters, and corpse eaters develop on corpses and carrion , gravediggers, predator beetles, some leather beetles, trox (sandstone beetles), etc. The larvae of swimming beetles, water lovers, spinners, water elephants, and rainbow leaf beetles live in reservoirs. In fruits and seeds, the larvae of elephant beetles (acorn, nut), caryopsis (pea, bean), cone gum, short-whiskered corn, pretend thief, etc. develop. There are beetles whose larvae penetrate into the pulp of leaves between the veins (leaf beetles) or make passages in thin stems and roots of grasses (stem longhorn beetle, etc.).

Having reached a certain stage of development, the beetle larvae pupate. Since they, like caterpillars, differ significantly from adult forms, at the pupal stage they undergo a corresponding restructuring of the body. The pupae of beetles are free, soft, with clearly visible legs and wings. The pupal stage lasts about a month and ends with the emergence of the beetle. The total development time of beetles from egg to adult (depending on the species) takes from 2 months to 6 years. The lifespan of adult beetles is short, only 1-2 months, but some beetles live all summer, and sometimes 2-3 years or longer. For example, slowworms with a thick cuticle can live off their own reserves for 10 years.

Dung beetles and carrion beetles are attracted to the smell of decomposing corpses and rotting manure. They smell the smell of carrion at a distance of several hundred meters and flock to its location. Among the bark beetles, there are species that use only mountain pine, without touching lodgepole pine; at the same time, they accurately find weakened trees affected by mold, viruses and other diseases. Of the false bark beetles, the oak flat beetle should be noted. Beetles of this species flock to the smell of fermenting sap flowing from recently felled oak trunks. Interestingly, beetles often confuse biologically significant odors with similar odors containing odorous components that are attractive to them. Thus, goldenrods fly not only to the smell of smoke, but also to the smell of burning oil, fried meat, tobacco smoke, and the oak flatfoot - to the smell of barrels of rum or lemon juice.

In the process of feeding, for beetles, in addition to smell, taste sensations are important, determining the suitability of the food found and its compliance with the feeding specialization of a given species. For example, the Suriname mucoed beetle willingly eats flour, grain, and dried fruits in warehouses, but does not touch fish and dried meat. The clover weevil eats clover leaves, the Colorado potato beetle eats the leaves of potatoes and other nightshade plants, and the beet weevil feeds on beet seedlings. Caryopsis beetles damage legume seeds depending on their food specialization: bean weevil - beans, pea beetle - peas, bruchidius - clover and astragalus, other weevils - china and vetch. The same can be said for bark beetles. Their names reflect the food specialization in the choice of trees, for example, elm, birch, and oak sapwood. There are sapwood trees that prefer fruit trees, bird cherry, rowan, and dogwood.

Rove beetles also feed in different ways: shaggy rove beetles - fresh cow dung, gray rove beetles - carrion, and philontes - various decomposing substances. Narrow food specialization is observed in ground beetles. For example, the odorous beetle eats gypsy moth caterpillars, the bronze beetle eats moth caterpillars, and the steppe beetle eats meadow moth and cutworm caterpillars. There are many similar examples that can be given. All of them reflect the process of differentiation of beetles by food sources, indicating the presence of versatile utilization of food resources, which is beneficial in life competition, since it reduces the level of competitive relations within various biogeocenoses.

Sighted beetles see clearly only at close range (no further than 2.5 m), which has been shown experimentally.

The study of the visual process in one of the elephants - Chlorophanus - revealed the ability of beetles to determine their own speed of movement based on the perception of the image of surrounding objects moving in the facets of the eyes. The experiment with this beetle was carried out with the aim of developing a mathematical model of a functioning eye for constructing an aircraft ground speed meter. Through the efforts of a team of bionic scientists of different specialties (zoologist, physicist, energy engineer and mathematician), it was possible to technically reproduce the work of only two facets (out of several hundred) of the eye of Chlorophanus and create on this basis an artificial speed meter (speedometer).

Beetles, like butterflies, perceive sounds in two ranges: low-frequency, within which other beetles emit sound signals, and high-frequency, which characterizes the operation of the echo sounder of bats. Both ranges are biologically significant for beetles. In the first range, they maintain contact with their own kind, and in the second, they learn in advance about the danger that threatens them from bats. Sounds in intermediate ranges, as they are not of vital importance, are not detected by beetles. If the house has old furniture damaged by grinder beetles (cabinets, tables), with holes on the surface and small sawdust around them, you can often hear sounds similar to the ticking of a clock. These beetles knock their heads against the walls of the passages in the wood and give each other special signals. The same sounds come from the dilapidated walls wooden buildings, riddled with beetle passages.

It is interesting that sound signaling by hitting the head against the walls of passages exists not only in beetles, but also in termites. According to Howes' observations, the “sentinels” inform the inhabitants of the termite mound that danger is approaching by banging their heads on the walls of the tunnel, a special alarm signal. In this similarity of instinctive behavior one can see the phenomenon of convergence, which arose in different orders of insects as a useful adaptation.

Sound information in beetles serves as one of their means of mutual communication. For example, sugar beetles and their larvae living in wood constantly “talk” using special chirping sounds. Adult beetles rub the serrated plate of the end of the wings against special hard formations on the dorsal side of the last abdominal segments, and the larvae scratch along the rough surface of the coxa of the middle legs with special appendages into which the hind legs have turned. Longhorned beetles also make sounds: this is a sharp creak produced by the friction of a rib on the posterior edge of the prothorax against the rough surface of the mesothorax. Some beetles react to touch by making scaring sounds. Thus, the heliocopra dung beetle, if you pick it up, squeaks like a bat, and the xylotrope rhinoceros beetle in this case hisses loudly and sharply. A water lover grasped with his fingers makes a creaking sound by friction of the rough area of ​​the inner surface of the elytra against the lateral edge of the first abdominal segment.

Beetles in the imaginal stage use a variety of means of defense, which were developed in the process of evolution and fixed in heredity by the action of natural selection: In addition to warning coloration; combined with caustic secretions, beetles have other methods of defense. For example, slow beetles take an unusual pose that scares away the enemy, bombardiers throw a stream of liquid towards the enemy, jumping beetles, in case of danger, take off with lightning speed, and then, having landed in another place, move jerkily, alternating running with jumping, and many other beetles simply pretend to be dead (grinder beetles, pretend beetles, little ones, ladybugs, elephants, etc.). Some beetles that visit flowers have acquired a resemblance to stinging insects and thereby protect themselves from attack by enemies. For example, the striped waxwing looks like a bumblebee, and the four-striped strangalia longhorned beetle imitates wasps in the shape and color of its body. The oak striped clit, which is found on the bark, also resembles a large wasp (it is also called the oak striped woodcutter). In general appearance and behavior, the large short-winged longhorned beetle resembles a hymenoptera insect. All of these are examples of mimicry.

Some species of beetles have luminescent organs, which they use to attract individuals of the opposite sex, and in some cases to catch prey. These beetles include our fireflies, known as “Ivan’s worms” (these are wingless, worm-like females!). The luminescence process, associated with the oxidation of lucefirin in the presence of the enzyme luciferase, occurs in luminous organs located on the abdomen. The source of energy is adenosine triphosphate (ATP) found in the firefly's body, which restores new portions of luciferin after each outbreak.

Some beetles have hygroreceptors that allow them to sense changes in atmospheric humidity associated with changing weather and respond accordingly. For example, before a storm (or thunderstorm), dung beetles behave restlessly and fly continuously, attracting attention with a characteristic hum. They are active only in good weather, and in inclement weather (rain, wind, cold) they hide. Beetles, like many other invertebrates (flies, termites, snails, worms, etc.), are able to navigate in accordance with the direction of magnetic field lines. For example, cockchafers, when landing on a horizontal surface of the substrate, are most often located in the east-west or north-south direction, which can be confirmed by direct observation of the behavior of these beetles using a compass.

It is worth noting some features of Coleoptera that increase their viability and ensure their survival. For example, golden borers have a very durable chitinous covering, making them inaccessible to birds. Longhorned beetles are distinguished by their extraordinary endurance to endure adverse conditions. There are known cases when their larvae, finding themselves in dried wood, were delayed in their development and remained alive for more than 40 years, turning into dwarfs. Lace beetle larvae tolerate temperatures up to 52° C.

Caring for offspring is of great importance in the life of beetles. U different types it is expressed in different ways. Piping elephants roll tree leaves into a conical cigar for eggs and larvae, providing them with a supply of moisture. Crawfish make several cells on the sides of the earthen burrow, where they place one egg at a time, and then fill them with plant matter such as silage, which the larvae feed on. Dung beetles store manure for their larvae in the form of sausages, pears or balls, placing them in specially built underground chambers (under a pile of manure), and protect their offspring until the beetles hatch from pupae. Sugar beetles feed their larvae with specially prepared wood and then protect the pupae and young beetles. Sinoxylon beetles (Indian hooded beetles) do not leave the uterine passages in wood with eggs, protect the larvae from enemies and die there, having fulfilled their parental purpose. Bark beetles lay eggs in special egg chambers, distributing them in the system of passages they gnaw, so that each larva is not only well protected from various harmful influences, but also receives a certain feeding territory.

Wood beetles enter into symbiosis with fungi developing on the walls of the passages, which receive favorable conditions for their development and, in turn, deliver food to the beetle larvae. The female woodcutter beetle, drilling a hole in the wood, brings in a fungus, which softens the hard wood fibers, making them more accessible to the larvae. When laying eggs, the female carefully places fungal spores on each of them, which ensures the preservation of mutually beneficial cohabitation in the next generation. Both females and males usually take part in caring for the offspring, obeying an innate instinct, which is based on unconditioned reflexes. At the same time, beetles are also capable of forming conditioned reflexes, in particular food reflexes. This can be seen from the results of experiments with swimming beetles, which, after training, are able to distinguish sweet from bitter. In addition, they can be taught to climb out using a stick, which is lowered into the water, always in the same place, for a piece of meat.

Beetles are pests of forestry and agriculture

Beetles cause great damage to forestry and agriculture. But among them there are many useful species that students should know about.

Many types of ground beetles are very useful; they feed on caterpillars and larvae of harmful insects, slugs and other snails; ladybugs and their larvae that destroy aphids; subbark little ones that eat bark beetles and borers; motley ant beetles, whose larvae destroy bark beetle larvae; Moorish booger, whose larvae eat grain moth caterpillars and granary weevil larvae; Blisters, the larvae of which destroy eggs in locust capsules, etc.

Ground beetle and click beetle. These beetles are easy to find in the summer in a field, meadow or on the edges of a forest. They are convenient for demonstrating the characteristics of beetles leading different lifestyles. Ground beetles and their larvae are predators and are natural enemies of herbivorous click beetles (adults and larvae). For work, you can use the bread nutcracker (7.5-10.0 mm long) and the hairy ground beetle (14-16 mm long) or other species found in fields and meadows, in the garden and vegetable garden. It is better to examine beetles and larvae by placing them in glass cylinders. The adult click beetle appears in the spring and during the summer feeds on grasses and foliage of trees and shrubs, where it should be looked for. The ground beetle hides under stones, planks and lumps of earth, crawling out to prey at night, so during the day it can be found by turning over objects that serve as its shelter.

In each species of beetles under consideration, it is not difficult to identify their specific structural and behavioral features. The click beetle stays calmly on plants, crawling from one shoot to another, while the ground beetle quickly runs along the ground, looking for caterpillars and small insects. The clicker has short legs, and when it falls on its back, it is difficult for it to roll over and take a normal position. A unique device comes to the rescue. If a bug is placed on the palm with its belly up, it immediately bends its head and straightens it sharply, resting against the palm. A click is heard and the beetle jumps up, turning its belly down. If it doesn't hit the target the first time, the clicks are repeated. The sound is produced because a special process of the prothorax, which enters the fossa of the mesothorax and rests against its edge, jumps off the stop at the moment of sharp bending of the body and imparts a strong push to it, which throws the beetle upward. For this feature, the beetles were called click beetles. A click beet caught by a bird may be released from its beak in this way, but this must be verified by observation under experimental conditions.

Comparing the ground beetle with the click beetle, it should be noted that it has more developed legs with tenacious paws, on which claws are visible. With them, the ground beetle rests on uneven soil and pushes off when running. The upper jaws are capable of grasping and firmly holding prey. (The click beetle has less strong jaws.) The mouthparts of each beetle are adapted to the characteristics of their food, but in both they are of the gnawing type. If you pick up a ground beetle, it will immediately release a pungent-smelling liquid. This is a defensive reaction that serves as a means of protection against attack by enemies. The larvae of both beetles also deserve attention. They live in the soil, from where they can be extracted when excavating the ground. Ground beetle larvae are mobile, so they can only be examined by placing them in a test tube. You need to pay attention to the attack organs - hard jaws, similar to tweezers, as well as long antennae and three pairs of strong legs with two claws on each paw. Behind the legs stretches a segmented abdomen with two processes at the posterior end of the body. Quickly moving their paws and pushing off lumps of earth, the ground beetle larvae quickly run away and hide in secluded corners. The same agility helps them quickly find prey.

The larvae of click beetles, known as wireworms, living in the soil, gnaw the roots of grasses and bore into potato tubers. Their cylindrical body is distinguished by a durable chitinous covering of red-brown color and looks a bit like a piece of rusty wire. The head is flat on top and, together with the jaws, forms a wedge-shaped protrusion that loosens the soil, and at the end of the body there are special outgrowths that prevent the larva’s body from moving backward. Thus, there is a complex of adaptations to living conditions in the thickness of the earth. Wireworms, unlike ground beetle larvae, are slow in their movements, which is due to the nature of their feeding, which does not require rapid movements. When assessing the importance of the activities of ground beetles and click beetles for humans, it is necessary to emphasize the difference between them: ground beetles are mostly useful beetles, and click beetles are pests of field and garden crops. Only a few ground beetles are harmful (for example, grain and millet ground beetles), which eat seedlings and grains of cereals. On the other hand, among click beetles there are species that do not cause much harm. For example, the red-winged click beetle lives in forests, whose larvae feed on rotten wood.

Swimming beetle. To keep adult beetles and their larvae in the corners of wildlife, it is advisable to take the largest representative: the fringed diving beetle (up to 3.5 cm long).

The diving beetle has a number of adaptations to water image life, in particular the streamlined shape of the body and hairs on the legs, increasing the rowing surface of the limbs. In addition, it has a protective dark color on the dorsal side, making it hardly noticeable to birds from above, and the diving beetle is also invisible from below, since its ventral side is light yellow. Its color blends with the light background of the sky, protecting the swimmer from attack by fish.

The diving beetle has a clearly expressed functional differentiation of its limbs. Just look at how it swims: only its hind legs, covered with wide, strong hairs, work; they swing like oars. If the movements of the hind legs occur with equal force, the beetle swims in a straight line, and turns with one-sided strokes of each leg. The front and middle pairs of legs do not participate in swimming, but do not interfere with movement, since the beetle presses them. These legs are used for crawling, but they also perform other functions. With its front legs, the swimmer grabs and holds prey, and with the help of its middle legs it rises to the surface of the water. In addition, with its middle legs the beetle clings to underwater plant stems, staying at depth. Average density diving beetle less water, therefore, it floats up passively if it does not use its legs as attachment organs. The diving beetle can dive only by overcoming the pushing force with energetic swings of its hind legs.

The swimmer is a predator that hunts live prey, the pursuit of which requires agility. Its food is tadpoles, fish fry, crustaceans, snails, and various aquatic insects (larvae of mayflies, dragonflies, caddis flies, etc.). Being hungry, the diving beetle dares to attack frogs, newts and even relatively large fish (8-10 cm long). In the absence of suitable food, it eats carrion and plants. In captivity, swimming beetles must be kept isolated, as they can attack each other and destroy the living population of the aquarium.

The taste organs of swimming beetles are well developed: when catching prey, they perfectly recognize it with the help of chemoreceptors - sensitive papillae on the antennae, palps and partly in the pharynx. If you let a drop of blood into the aquarium, the swimmer becomes extremely excited and rushes about in search of imaginary prey, which indicates that the leading importance for it is not vision, but smell. That's why he doesn't pay attention to the tadpole in the test tube and grabs the gauze bag in which the tadpole was wrapped. In captivity, swimming beetles are fed pieces of meat and earthworms.

The swimmer breathes atmospheric air, periodically rising to the surface of the water and exposing the end of its abdomen. Fresh air enters the trachea through the last two pairs of abdominal spiracles, and exhaust air exits through the first four. As for the pectoral spiracles of the diving beetle, it breathes with them only on land during flights. Air accumulates under the elytra of the diving beetle, the bubbles of which sometimes come out and float to the surface, which is easy to observe when keeping the beetle in an aquarium. However, for the diving swimmer this air is a reserve and is gradually used for breathing under water. The presence of air under the elytra prevents the beetle from diving into the depths of the reservoir, so when diving it has to partially free itself from the air, pressing the elytra to the dorsal side of the body.

Swimming beetles exhibit the phenomenon of dimorphism, which is expressed in two forms: sexual and “female”. Males have suckers on their front legs, which are absent in females. These suckers serve to hold females during mating, as well as to attach the beetle to underwater objects with a smooth surface (stone, glass). Female diving beetles are distinguished by their biformity: in some, the elytra are smooth, like in males, while in others they are covered with longitudinal grooves. In the spring, an overwintered female swimmer makes cuts on the surface of aquatic plants with her ovipositor and lays one egg there. This process lasts one to two months, and during this time the female manages to lay from 500 to 1500 eggs. The eggs hatch into larvae that live in the water for 2-3 months, feed, grow, and then crawl onto land and pupate somewhere on the shore in a hole under stones or under lumps of earth. Thus, among diving beetles leading an aquatic lifestyle, the connection with land is not interrupted, which indicates their origin from terrestrial ancestors.

Having become true aquatic insects and, in the process of evolution, having acquired the adaptations necessary for life in water, these beetles retained their wings as normally functioning organs. For example, at night (especially when there is a moon) they leave bodies of water and fly for some time. That is why aquariums containing swimming beetles must be covered with mesh, glass or gauze. When water bodies dry up, swimmers fly to other places. In flight, they are guided by sight. Observations have shown that beetles, when descending, are guided by the mirror-like surface of water bodies. However, there are times when they mistakenly land not on the water, but on the glass frames of greenhouses or on the shiny surface of an iron roof and in the process they break (an example of relative fitness).

The larvae of diving beetles are slender, flexible, mobile, swim well and quickly, bending their long abdomen and working with their legs covered with a stiff fringe of hairs. The jaws of diving beetle larvae look like long narrow sickles with deep grooves on the inside. With them they pierce the body of the prey and suck out the juices of their victim, after liquefying its tissues with the released digestive fluid. Being a very energetic and aggressive creature, the diving beetle larva rushes at any moving objects. The first reaction is to grasp the object, and then recognize edibility using the palps. You can offer the larva a sliver, stick or other inedible object, which it will first grab onto and then release. You have to be careful not to put your fingers in, so as not to get injured. If the larva pierces the hand, the jaws will penetrate so deeply into the muscle tissue that it will be possible to free oneself from the predator only by tearing off its head. Thus, from the above characteristics it is clear that among diving beetles, the adult beetle and its larva lead the same, predatory lifestyle.

In nature, larvae feed on any aquatic insects, as well as fish fry, newts, tadpoles, leeches, snails and other inhabitants of water bodies. They do not touch fish eggs, since the eggs are immobile. The larvae attack anything that moves or has the smell of life with the speed of lightning. Pursuing prey, they dive under it, make sharp movements with their heads and pierce the body. Through the jaw canals, a portion of toxic liquid is first regurgitated from the esophagus, which paralyzes the prey, and then a second portion is injected into the wound from the digestive stomach - this is a black liquid that can liquefy body tissues. This method of feeding should be considered as an evolutionary acquisition of diving beetles, making it possible for their larvae to eat food under water. The larvae of the diving beetle are so voracious that they manage to eat up to 50 tadpoles per day, and in the absence of food they begin to devour relatives, even those of equal size (which other predators do not do). When attacking each other, success is determined by whoever manages to grab the opponent first and let the juice into his body.

Laboratory studies by Indian scientists have shown that some species of diving beetles can be used for biological control of mollusks (pond snails and squids) - intermediate hosts of trematodes. However, swimming beetles cause significant harm to fish farms. There are known cases when these beetles and their larvae destroyed all the offspring of whitefish and carp in nursery ponds. The enemies of swimming swimmers include various large fish that can capture them in their mouths. A protective agent against these enemies for swimming swimmers is a milky-white liquid that smells of almonds and licorice, containing 10% cortexone. It is secreted between the head and pronotum from the paired mammary gland at the moment the beetle is swallowed by the fish and causes shock in the latter. While the fish is in a daze, the beetle manages to escape from its mouth to freedom.

Towards the end of life, swimming beetles show signs of aging: chitin becomes brittle (when swimming, the beetle's legs and antennae break off); the secretion of secretions that cleanse the surface of the body decreases, as a result of which colonies of protozoa develop on different parts of the body; general activity decreases and sexual intercourse stops; the waterproof layer (epicuticle) wears out and other changes appear that reduce the viability of the beetle. All this is apparently connected with the relatively long life expectancy of the beetle in the imaginal stage and the influence of various unfavorable environmental influences on its body.

Habitats, structure, lifestyle

Insects are the largest class of animals. It includes more than 1 million species. Insects live everywhere: in forests, gardens, meadows, fields, vegetable gardens, on livestock farms, in human homes. They can be found in ponds and lakes, on the body of animals.

The body of insects consists of a head, thorax and abdomen. There are a pair of compound eyes on the head, a pair of antennae, three pairs of legs on the chest, and most have one or two pairs of wings, and spiracles on the sides of the abdomen.

Insects differ in the shape of their body parts, the size of their eyes, the length and shape of their antennae and other characteristics. Their antennae, mouthparts, and legs are especially diverse. Some insects have lamellar antennae (many beetles), others have filamentous antennae (grasshoppers), others have feathery or club-shaped antennae (butterflies), etc. The mouthparts can be gnawing, like those of cockchafers, piercing-sucking, like mosquitoes, sucking, like butterflies, etc. The hind legs of grasshoppers are jumping, while those of swimming beetles are swimming; The front legs of the mole cricket are digging. All these and other structural features have developed in insects in connection with adaptation to certain living conditions.

Rice. Bombardier (beetle). Family - ground beetles

The internal structure of insects is mainly related to the respiratory, excretory and nervous systems. The respiratory organs of insects - the trachea - are highly branched. In small insects, gas exchange occurs by diffusion. Large insects ventilate the trachea (when the abdominal walls relax, air is sucked into the trachea, and when contracted, it is released into the external environment). The excretory organs of insects are numerous tubes, the free ends of which are closed. The excretory products entering them flow into the posterior intestine. Insects have fat cells that store nutrients and water. Some substances unnecessary for the body are deposited in them.

Differences in the nervous system of insects are associated with the enlargement of the suprapharyngeal nerve ganglion (it is often called the brain), a decrease in the number and enlargement of the nodes of the ventral nerve chain. The more complex structure of the nervous system is manifested in the complexity of insect behavior. A bee, for example, having found flowering nectar-bearing plants, upon returning to the hive, crawls on the honeycomb, “dances,” describing certain figures, by which other bees establish the direction to the place of honey collection. The ants close the entrances to the anthill at night, bring wet needles to the surface, and after drying, drag them into the depths of the anthill.

Types of insect development

Insects are dioecious animals. In some insects (locusts, bedbugs), fertilized eggs laid by females develop into larvae that are similar in appearance to adults. Feeding heavily, they grow, molt several times and become adult insects. In other insects (butterflies, beetles, flies), the larvae are not similar in appearance and nutrition to adults. The larvae of the cabbage butterfly, for example, are worm-like and do not feed on nectar, like butterflies, but on cabbage leaves. Their mouthparts are not sucking, but gnawing. After several molts, the caterpillars turn into pupae that do not feed or move, but complex changes occur under their chitinous cover. After some time, the cover of the pupa’s body bursts and a adult insect.

Development that occurs in three phases, and the insect larvae are similar to adults, is called incomplete transformation. The development of insects, which occurs in four phases (including the pupal phase), and the larvae do not resemble adults, is called complete metamorphosis.

Development with transformation makes it possible for insects to survive unfavorable conditions life (low temperature, lack of food) at one or another less vulnerable stage of development. Insects with complete metamorphosis have the greatest advantages. Their larvae do not compete with adults: they usually use different food and develop in different habitats.

The main orders of insects

In the class of insects there are from 30 to 40 orders. The largest of them are the orders of Orthoptera, Homoptera, Hemiptera, Coleoptera, Lepidoptera, Hymenoptera, and Diptera.

Orders of insects with incomplete metamorphosis. The order Orthoptera includes locusts, grasshoppers, crickets, and mole crickets. They are characterized by gnawing oral apparatus, two pairs of wings with longitudinally arranged veins and (usually) a hopping hind pair of legs. Many Orthoptera produce and perceive sounds (in grasshoppers, the sound apparatus is located on the front wings, and the auditory apparatus is on the shins of the front legs). Their antennae are thread-like. Females of many species have an ovipositor. The order Homoptera includes aphids, cicadas, etc., feeding on plant sap, having a piercing-sucking proboscis and 2 pairs of transparent wings.

The order Hemiptera, or bugs, includes terrestrial and aquatic insects with piercing-sucking mouthparts, two pairs of wings (semi-rigid upper and membranous lower), and highly developed scent glands. Of the representatives of this order, the most common are green forest bugs and long-legged water strider bugs. The same order includes the bedbug, which feeds on the blood of people and animals living in human housing.

Orders of insects with complete transformation. The order Coleoptera, or beetles, includes insects with rigid front wings and membranous hind wings. In most beetles, when at rest, hard wings completely cover the membranous wings and protect them from damage. Beetles have gnawing mouthparts. The order Coleoptera includes chafer beetles, ground beetles, ladybugs, and weevils.

Butterfly Papilio demoleus. Photo: Jeevan Jose

The vast majority of insects of the order Lepidoptera, or butterflies, are characterized by two features: scaly cover on two pairs of wings and a sucking mouthpart, usually coiled. The antennae of daytime butterflies are usually club-shaped, while those of nighttime butterflies are feathery. Worm-like butterfly larvae (caterpillars), in addition to three pairs of jointed legs, have false legs - outgrowths of the body. Caterpillars have gnawing mouthparts.

Diptera - flies, mosquitoes, horseflies, etc. - have one pair of membranous wings. The hind wings are transformed into flask-shaped organs - halteres. The mouthparts of dipterans are piercing-sucking or licking. Larvae have no legs. They develop in water, soil, rotting remains of plants, living animals and corpses.

Insects are the most numerous class of animals; there are more than 1 million species. There are about 40 orders of insects, which are divided into two groups - insects with incomplete transformation and insects with complete transformation.

Examples of insect orders with incomplete transformation are Orthoptera, Homoptera, and Hemiptera. Examples of orders with complete transformation are Coleoptera, Diptera, Lepidoptera, Hymenoptera.

Features of the order Orthoptera

Representatives: grasshoppers, locusts, crickets.

• Gnawing mouthparts.
• The wings of the first pair are narrow with longitudinal venation, the wings of the second pair are fan-shaped.
• The hind legs are of the jumping type (not for everyone).
• Many can make sounds and perceive them (grasshoppers make sounds with their front wings, and their hearing organ is on their legs).

Features of the order Homoptera

Representatives: aphids, copperheads, shield insects.

Aphids live on the shoots of trees, shrubs and grasses, forming clusters. There are usually a lot of copperheads on the leaves fruit trees.

• They feed on plant sap.
• Piercing-sucking mouthparts with proboscis.
• Two pairs of soft transparent wings (not for everyone).

Features of the order Hemiptera (bugs)

Representatives: green forest bugs, water strider bugs, bed bugs.

• They lead a terrestrial or aquatic lifestyle.
• Piercing-sucking mouthparts.
• A pair of semi-rigid upper wings and a pair of membranous lower wings.
• Scent glands are developed.

Features of the order Coleoptera (beetles)

Representatives: ladybugs, weevils, dung beetles, ground beetles, chafers.

• Rigid front wings protect the hind wings from damage.
• The mouthparts are gnawing type.

Features of the order Diptera

Representatives: flies, mosquitoes.

• One pair of membranous wings. The hind ones are modified into halteres.
• The oral apparatus is piercing-sucking or licking.

  Characteristics of the insect order

• Legless larvae that develop in soil, water, plant and animal remains.

Features of the order Lepidoptera (butterflies)

• Scaly cover of wings.
• The sucking mouthparts are coiled.
• Feathery (in nocturnal) or club-shaped (in diurnal butterflies) antennae.
• Butterfly larvae are caterpillars.

  They have body outgrowths - false legs. The mouthparts are gnawing type.

Features of the order Hymenoptera

Representatives: bees, wasps, ants, riders.

• Two pairs of membranous transparent wings.
• The mouthparts are gnawing or licking.
• Females have an ovipositor at the end of the abdomen, which in some species is transformed into a sting and is associated with poisonous glands.
• Worm-like, most often legless, larvae.

Order Coleoptera, or beetles

Their front wings, or elytra, are very rigid and durable.

They cover the upper side of the abdomen and the membranous wings of the second pair located here. It is these membranous wings that are used for flight.

They are slightly longer than the elytra and in a calm state are folded and hidden under them.

The mouthparts of beetles are of the gnawing type. The main tools for crushing food are the upper jaws, often called mandibles or mandibles. Sometimes they turn into decorations, reaching extraordinary development in males ( bug—deer).

The elytra and wings of beetles are attached to the mesothorax and metathorax. The prothorax forms a wide ring, the upper part of which is called the pronotum.

Attached below to the three thoracic segments are three pairs of legs, which are extremely diverse in beetles. Usually they are long, running, in aquatic forms - swimming, in those living in the soil - digging; sometimes the hind legs increase in size, their hips thicken - the legs become jumping. The legs end in tarsi, the segments of which bear pads from below, and in some species - suckers.

Beetles are fully metamorphosed insects that lay eggs after mating.

The eggs hatch into larvae whose body consists of 3 thoracic and 10 abdominal segments. The development of larvae is completed in a few months, less often it lasts for three to five years. Next, the larva turns into a pupa, and from the pupa into an adult insect.

This order includes beetles that damage a wide variety of cultivated plants (Chafer, bread beetle, nutcrackers, the larvae of which are called wireworms, Colorado beetle, apple blossom beetle), forest plants ( beetles—bark beetles, beetles—lumberjacks,); beetles destroy food products (barn weevil, bread fleas).

Predatory beetles destroy agricultural pests ( ground beetles, ladybugs), beetles that eat animal excrement and dead parts of plants are of great sanitary importance ( beetles—dung beetles) and animal corpses ( beetles—carrion eaters). Some beetles switched to life in fresh water bodies (beetles—swimmers, beetles—water lovers).

Over 30 thousand species.

Order Lepidoptera, or butterflies

Of all insects, butterflies are the most famous. The most important feature of the order is that they are covered with scales, the structure and arrangement of which determine the whimsicality and variety of colors. That's why butterflies are called lepidoptera.

Insects. Orders of Dragonflies, Mayflies

Scales are modified hairs. Along the edge of the wing there are very narrow scales, almost like hairs. Closer to the middle they are widened, but their ends are sharp. And even closer to the base of the wing there are wide scales in the form of a flattened, hollow inside sac, attached to the wing by means of a short stalk.

The scales are located on the wing in regular rows across the wing: the edges of the scales face the lateral edge of the wing, and their bases are covered in a tiled manner by the ends of the previous row.

Lepidoptera usually have all four wings developed; however, in females of some species the wings may be underdeveloped or completely absent.

The front wings are always larger than the hind wings. In many species, both pairs of wings are linked to each other using a special hook, or “bridle.”

The oral limbs are sucking. They are represented by a soft proboscis, capable of curling and unfolding like a clock spring. The basis of this oral apparatus is made up of highly elongated internal lobes of the lower jaws, which form the valves of the proboscis. The proboscis is elastic and mobile.

Lepidoptera are insects with complete metamorphosis.

Their larvae are very diverse in shape. Butterfly larvae are called caterpillars; their body consists of a head, 3 thoracic and 10 abdominal rings. They use a silk-like thread to build a cocoon, inside which pupation occurs.

And only after a few weeks the butterflies fly out.

This group includes silkworm, leafrollers, glassware, moths, scoops, blueberries, cabbages, moths, hawkmoths and others. About 140 thousand species.

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All about insects

Insect - what does this name mean? It indicates that his body is divided into parts. Insecta is a Latin word that literally means “divided, dissected.” The Russian word “insects” is also explained by the fact that the wasp’s body is divided into three segments (parts of the body) - notches.

Class Insects, their orders, main characteristics and meaning (Table)

The ancient Greek word entomon, with a similar meaning of “divided,” is preserved in the name of the science of insects - entomology. The scientific name of species is based on the principle of binary nomenclature: genus name + species name. For example, the name of the honey bee consists of the name of the genus Apis and the name of the species mellifera. Thus, the scientific name of the honey bee is Apis mellifera.

Many species of insects live in the tropics, but in Europe there are currently at least 30,000 species.

In order to somehow understand such diversity, biologists 200 years ago began to systematize knowledge about animals, relying on their typical characteristics. They classified those similar to each other and capable of reproduction as one species. Species that shared common ancestors and are therefore related were grouped into genera.

Many genera form a family, several families form an order, several orders form a class, and classes are combined into types, which, in turn, belong to the animal kingdom. Thus, each species receives its own place in the natural system.

In 2002, scientists discovered an unknown insect in the rock canyons of Namibia. It looked like a cross between a praying mantis, an Annam stick insect and a grasshopper. Not long before this, similar insects were discovered in amber frozen 45 million years ago; they were classified as long-extinct species.

Orders of insects

Currently, the class of insects is divided into more than 30 orders.

At the same time, the orders of cockroach crickets, zoraptera and macroptera include less than one hundred species, hymenoptera, butterflies and coleoptera - more than a hundred thousand species. The first two orders are not found in Europe. Representatives of other, less well-known orders, although they are found in our area, live secretly, and their sizes are so small that in order to see them you will need a microscope.

The insects presented here can be encountered during a regular walk in the field and forest.

Mayfly

Mayflies die a few hours after hatching; The maximum lifespan of a fly is several days.

Adult mayflies do not feed. Their only task now is to find a partner and lay eggs. As larvae, mayflies spend one to three years at the bottom of streams, rivers and lakes. All this time they feed on algae, parts of plants and small invertebrates (crustaceans).

Beetles

Coleoptera is the largest order of insects, which includes more than 300,000 species.

They have mastered all areas of habitat - from land to fresh water. Among them there are herbivores and predators, some feed on dung and carrion. In beetles, hard forewings (elytra) cover the flying hind wings. Usually, before taking off, beetles raise their hard elytra and straighten their hind wings.

Silverfish and forktails

In many orders of insects there are wingless species that have lost their wings during the process of evolution.

These are, in particular, forktails and silverfish. Forktails are no more than 1-2 millimeters in length and live in the ground, where they feed on rotting plant and animal debris. These insects owe their name to the special jumping fork on the underside of the abdomen. If they are disturbed, they may jump far away in an attempt to protect themselves.

The most famous silverfish is the common silverfish, Lepisma saccharina, which can sometimes be found in our kitchens and bathrooms.

Locusts and grasshoppers

Locusts and grasshoppers need strong hind legs to quickly hide from the enemy.

When locusts use their wings, they are able to cover appreciable distances at lightning speed. By their long hind legs, powerful body, strong head and leathery wings, locusts and cicadas can be easily distinguished from other insects.

The Italian locust feeds almost exclusively on plants; true grasshoppers and crickets are omnivorous. For them, animal food (insects and their larvae) can make up more than half of the diet.

Characteristics of orders of insects with different variations of sucking mouthparts.

Order Diptera (diptera) The appearance of dipterans is characteristic, primarily due to the reduction of the hind wings, which are transformed into short halteres.

However, these are not useless rudiments. Covered with a large number of sensitive receptors, the halteres stimulate the nervous system and ensure the rapid activation of the fore wings and the start of dipterans, while at the same time serving as flight stabilizers.

Diptera usually have a large, often spherical head with large eyes, which in males may touch on the forehead.

The most common orders of insects

Antennae are of two types: multi-segmented in the suborder long-whiskered dipterans and three-segmented in the suborder short-whiskered dipterans. The mouthparts are transformed into various proboscis. In those that feed on liquid organic substances these are sucking or licking-sucking organs, in bloodsuckers - piercing-sucking.

Due to dipterus, the mesothorax is especially developed.

There is noticeable costalization of the wing, i.e. thickening of the anterior veins and moving them to the anterior edge. The flight of dipterans is very perfect, especially in hoverflies, with quick start and hovering in the air.

Mosquitoes can beat their wings up to 1,000 times per second, although they fly relatively slowly.

Diptera larvae are legless and rarely have false abdominal limbs. Longwhiskers have a separate head, but in most fly larvae the head capsule is reduced, and the oral appendages are represented by a pair of retractable hooks. The pupae are free, or in a false cocoon - puparia. When the fly emerges from the puparia, its shell at the apex is either torn longitudinally (in straight-suture dipterans) or in a circle, and folds back in the form of a small lid (in round-suture dipterans).

Order Hymenoptera (Hymenoptera). This order includes both rather primitive sawflies, whose pseudo-caterpillars, similar to butterfly caterpillars, feed on plants, and insects with the most highly organized nervous system and extremely complex biology - ants, bees and wasps.

Adult insects have two pairs of membranous wings covered with relatively sparse veins, and small forms are usually almost or completely devoid of veining. The rear pair of wings is smaller and has a subordinate importance during flight.

In living insects, both pairs of wings are usually attached to each other using hooks and work as one plane. The mouthparts are gnawing or licking-gnawing. In the latter case, the lower lip and lower jaws are extended and form a proboscis with a tongue at the end.

This mouthpart is used to suck nectar from flowers. The mandibles are well developed in all species and are used not only for feeding, but also for building nests, digging soil, etc.

d. The antennae are simple, club-shaped, comb-shaped, feathery, and can be either straight or geniculate. The tibia and tarsus of the foreleg sometimes bear a special apparatus for cleaning the antennae and tarsi, formed by a comb spur at the end of the tibia and a notch on the first segment of the tarsus.

Lepidoptera or butterflies (Lepidoptera) differ from other orders of insects by such features as sucking mouthparts that look like a thin, coiled proboscis, colored scaly cover of the wings, as well as development with complete transformation, i.e.

the presence in their development of a caterpillar, which is a worm-like larva, and a pupa.

The smallest scales located on the wings of butterflies served as the basis for assigning the name to the order of these insects - “Lepidoptera”, since they are their main distinguishing feature.

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A beetle is an insect that belongs to the kingdom animals, phylum arthropods, class insects, order Coleoptera, or beetles (lat. Coleoptera).

The Latin definition of the vast order of beetles comes from the fusion of two ancient Greek words: "κολεός", meaning "sheath", and "πτερόν", corresponding to the concept of "wing". Thus, a name appeared for an insect that, in a calm state, retracts its wings into a “sheath.” The Russian concept of “beetle” was formed from the ancient Slavic word “žukъ”, which arose as a sound imitation of the noise that an insect makes during flight.

Beetle - description, characteristics, structure, photo. What do beetles look like?

A characteristic feature of Coleoptera, or beetles, is the presence of hard chitinous or leathery elytra formed from the upper pair of wings. This kind of armor protects the folded flying wings of the insect from damage when it is not in the air.

The body shape of beetles depends on their habitat and species. In aquatic inhabitants it is slightly flattened, streamlined and compact (swimmers, whirligigs).

Beetles living in the soil are characterized by a slightly convex body shape with a powerful, widened anterior part (scarabs, dung beetles).

Beetles that live on the surface of the earth have a strongly convex upper part and rather long limbs (ground beetles).

The body structure of adult individuals is divided into three main sections: head, chest and abdomen.

The beetle's head is round, slightly flattened, although in some families it has the appearance of an elongated tube. It can enter deeply into the prothorax and be practically invisible, or it can be connected to it freely with the help of a movable neck. In some beetles, the head is a rostrum, at the end of which there is a mouthparts (weevils, moths, tubeworms).

The beetle's head can be:

1. Prognathic (mouthparts and antennae directed forward),
2. Orthognathic (hypognathic) (mouth parts point downwards),
3. Opisthognathic (mouth parts directed backwards).

On the upper surface of the head there are beetle antennae of varying lengths, consisting of individual segments that perform the functions of the olfactory organs.

The fantail beetle's whiskers, Rhipicera femorata, look like long eyelashes.

On the sides are well-developed, complex compound eyes of the beetle, sometimes consisting of 25 thousand individual lenses, creating a mosaic image.

Some species have additional simple eyes on the crown, and underground and cave dwellers may have no visual organs at all.

The oral apparatus of most beetles, designed for grinding food, consists of paired mandibles (upper jaws) and maxillae (lower jaws). On the lower lip and jaws of beetles there are small palps, which are the insect’s original organs of touch and taste.

The largest mandibles are observed in stag beetles (stag beetles and Hercules beetles).

In the structure of the thorax of beetles, three segments are distinguished: the prothorax, movably connected to the mesothorax and fused with the metathorax. On the dorsal side, the segments are called pronotum, mesonotum and metanotum. Each segment is formed by two semirings (superior tergite and inferior sternite), movably connected to each other. Hard elytra are attached to the mesonotum tergites, and membranous wings are located on the metanotum of the beetle. Three thoracic sternites bear a pair of limbs.

The shape and sculpture of the pronotum is very diverse, and its structure plays an important role in the classification of beetles. It can be either smooth or with lateral spikes or growths of various shapes.

The limbs of beetles consist of 5 parts: coxa, trochanter, femur, tibia and tarsus.

Distinctive feature beetles is the presence of special spurs on the top of the tibia, which can be paired or single. The beetle's feet are covered with small dense hairs and have two claws of various shapes and lengths.

Depending on the lifestyle of the beetle (Coleoptera), the appearance of the limbs may vary slightly and perform running, grasping, digging, swimming or jumping functions.

In the process of evolution, the forewings of beetles turned into hard elytra, not inferior in hardness to the chitinous exoskeleton of an insect.

When folded, the beetle's elytra serve reliable protection mesonotum, metanotum and upper abdomen.

In species with reduced lower wings, the elytra usually grow together to form a monolithic frame. Some bark beetles have a depression on the surface of the elytra, intended for transporting wood waste formed when gnawing a system of passages in the body of the tree.

The surface of the elytra is smooth, covered with various depressions, growths, grooves and spines.

The lower membranous wings of beetles are usually transparent and may be faintly colored or completely colorless.

Depending on the genus and species, the veins can have different textures, both with the formation of transverse cells and with medial veins and branches from them.

The color of beetles is often a characteristic feature by which insects are divided into separate species.

Usually the color of the beetle is uniform, dark brown, red-brown, black, green, yellow or red, often with a metallic tint. However, there are species with characteristic bright patterns on the surface of the body or with a bioluminescent glow.

Sexual dimorphism of beetles is usually expressed in the size and color of individuals of the opposite sex.

In most species, male beetles are smaller than females and have a more elongated body. However, in some genera, due to overly developed mandibles resembling horns, the size of male beetles is much larger than females. Also, the length of the antennae or front legs may indicate belonging to a certain sex.

Some species of beetles are characterized by sound communication, which allows them to maintain relationships within one population, and for males to find females and scare away insects of another species. Sound vibrations arise due to the friction of the prothorax against the mesothorax.

The sizes of beetles included in the order Coleoptera vary over a wide range. Among these insects there are both real giants and little ones, which can only be clearly seen under a microscope. For example, the size of the titan woodcutter beetle (lat. Titanus giganteus) can reach 22 cm in length, relic woodcutter (lat. Callipogon relictus), living in Russia - 11 cm, and the length of the baby Scydosella musawasensis does not exceed 352 microns.

Beetles live in almost all corners of the globe, from sultry deserts and humid equatorial forests to the vast expanses of the tundra, with the exception of the eternal snow zone of high mountain peaks, as well as the ice fields of Antarctica and the Arctic.

The numerous order of Coleoptera includes species of beetles that settle in the near-surface fertile soil layer, inhabiting the bark, wood or roots of trees, as well as flowers or foliage.

Inhabitants of deserts and semi-deserts have adapted to the conditions elevated temperatures, therefore they lead an active nocturnal lifestyle. Many beetles live in fresh or slightly salted water bodies with abundant coastal and bottom vegetation.

Among the insects included in the order Coleoptera, there are representatives of almost all known types of nutrition characteristic of arthropods. There are carnivorous beetles that feed on other insects and their larvae, herbivorous beetles that feed on mushrooms, leaves, roots, fruits and seeds, and beetles that eat wood or bark. various plants. Many beetles are pests of agricultural crops and eat leaves, beets, cabbage, as well as other vegetables, fruits and fruit trees. One of the most famous pests is the Colorado potato beetle, which feeds on the leaves of nightshade crops.

There are even species that are, in fact, forest orderlies, since these beetles feed on dry and rotting parts of plants or decaying animal remains.

In addition, the food of beetles depends on the stage of development of the insect.

The adults of some species, feeding on wood, the pulp of green shoots, pollen or sap, being at one time larvae, ate decaying organic remains, or were predators. There are families that accumulate a sufficient supply of nutrients in the larval stage, allowing adult individuals to go without food for the rest of their lives.

Coleoptera, through their vital activity, have a positive impact on the ecosystem in their habitats. Both adult beetles and their larvae process dried wood, as well as parts of plants affected by various fungal diseases, actively participating in the process of humus formation. In addition, beetles can act as pollinators of flowering plants.

At the same time, some types of beetles are capable of causing significant damage to most agricultural crops and forests, the leather and tobacco industries, museums and libraries, as well as wooden structures and furniture.

Types of beetles, photos and names

The order Coleoptera is one of the most numerous groups living on the planet today. It includes about 390 thousand species of beetles, most of which have been little studied, since their descriptions were compiled from single specimens found in a separate area.

Among the variety of families included in the order Coleoptera, the most famous are the following:

• Ground beetles (lat. Carabidae) , including about 30 thousand species.

The body length of beetles from this family ranges from 1 mm to 10 cm. The body is colored dark colors, often with a rainbow tint, usually elongated-oval, although there are varieties that resemble the shape of a biconvex lens or plant leaf. According to the way they feed, the species of beetles included in the family can be both predators and herbivores.

One of the representatives of this family is ground beetle, or humpback peon (lat. Zabrus gibbus , Zabrus tenebrioides ) having an oval shaped body. The color of the beetle is rich black with a metallic tint. The size of an adult ground beetle can reach 12-18 mm. Well-developed mandibles enable the ground beetle to easily navigate the hard surfaces of plants in search of food. The slender legs of the insect are adapted for fast running. Large elytra almost completely protect the abdomen.

This beetle lives in areas with moderate air temperatures and high humidity, so it can be found in Egypt, Morocco, Tunisia and other North African countries, Italy, Spain, France, the European territory of Russia, Great Britain and Sweden. The largest populations of this species are found in Moldova and Ukraine.

• Weevils or elephants (lat. Curculionidae) , numbering about 60 thousand species of beetles in their ranks.

A distinctive feature of representatives of this family is the special shape of the front part of the head, resembling a tube in shape. The size of adult individuals, depending on their habitat, can reach 30-50 mm. This family is characterized by a wide variety of body shapes, which can be almost cylindrical, pear-shaped, rhombic, hemispherical or flattened. The color of beetles can be yellow, brown or black, sometimes with spots of a lighter or darker tone. All beetles in the family feed on plant foods.

A typical representative of the family is rice weevil (lat. Sitophilus oryzae), having an elongated, slightly convex body up to 2.5-3.5 mm long with a thin elongated rostrum. The beetle's matte or slightly shiny chitinous covers are brown. The surface of the pronotum is covered with rather large pits. The elytra are marked with frequent thin grooves, between which small dots are visible, forming short rows.

Bug rice weevil lives throughout almost the entire territory of Europe, Asia, Australia, North and South America, as well as in Africa.

• Predatory beetles (lat. Staphylinidae) , including almost 48 thousand species.

A characteristic feature of the beetles included in this family is the presence of short elytra. The sizes of beetles vary from 0.5-50 mm, but the body length of most species does not exceed 8 mm. The outer integuments are colored red-brown or brownish-black, often with indeterminate spots of red or yellow color. These beetles live on almost all continents. Predatory insects live in the Czech Republic, Canada and Alaska, Japan, Europe, China, as well as North America. According to the method of feeding within the family, not only predators or scavengers are distinguished, but also species whose diet consists of decaying plant debris or pollen, algae and plant sap.

One of the brightest representatives of the family can be considered Rove rove beetle (coastal bluewing) (lat. Paederus riparius). Adults of this species grow up to 10 mm in length. The elongated spindle-shaped body of an adult beetle is yellow-orange or red, except for the blue elytra, as well as the head and the awl-shaped end of the abdomen, which are colored black.

The beetle lives throughout almost the entire territory of Eurasia, North and South America, North Africa and Australia. Prefers to settle near water bodies or in damp grass litter on personal plots, where it destroys agricultural pests.

• Lamellar (lat. Scarabaeidae) , which include about 28 thousand species of beetles.

Numerous representatives of this family are characterized by average sizes, ranging from 2 to 60 mm, although larger beetles are also found. The body of individuals of most species is oval, but there are subfamilies with an almost square or cylindrical shape. The color of the chitinous covers is dark green or dark brown, and their surface can be covered with all kinds of growths and spines. Most species of the family feed on manure or rotting plant remains.

The most famous representative of the lamellar beetle family is rightfully considered to be the beetle. sacred scarab (lat. Scarabaeus sacer) . These beetles have a smooth, strongly convex round-oval body, painted black, the length of the beetle is up to 25-37 mm. A distinctive feature of the scarab is the presence of large teeth on the surface of the tibia of the front legs.

The distribution area of ​​the beetle covers part of the countries of North Africa, Spain and western Georgia, Yugoslavia, Bulgaria, Cyprus, Ukraine and Sicily. Individuals of this species of beetles feed not only on plant foods, but also on animal dung.

• Leaf beetles (lat. Chrysomelidae)

This family includes more than 36 thousand species. The body shape of leaf beetles can be either oval-flattened or highly spherical, and the color of the beetles is bright green, greenish-blue, bronze-yellow, etc. The size of an adult insect rarely exceeds 15 mm.

One of the most famous representatives of this family is green mint leaf beetle (lat. Chrysolina herbacea). It's pretty small insect, with a smooth convex body that is colored bright blue-green color with a clear golden tint. The adult size rarely reaches 11 mm. The beetle's food is the tender leaves of the aromatic mint plant, which gives the species its name.

• Barbels, or lumberjacks (lat. Cerambycidae), numbering about 26 thousand species in their ranks.

A distinctive feature of beetles from the longhorned beetle family is their long whiskers, which can exceed the length of the insect’s body several times.

The Great Oak Longhorned Beetle is a beetle with very long antennae. The whiskers of this beetle are 2 times longer than the insect itself!

Depending on the species, the shape and length of the beetle’s body, as well as the sculptural design of the elytra and pronotum, vary. Despite the fact that most species in the family are medium in size, there are also giants among them, one of which is the beetle lumberjack titan (Titanus giganteus) . This is the largest beetle in the world. His maximum dimensions can reach 22 centimeters in length, and the weight of the beetle exceeds 25 grams.

The insect's body is elongated, slightly flattened, and when viewed from the side it resembles a lens. The color is brownish-brown or tarry black. Three sharp spines located on each side are clearly visible on the pronotum. The lifespan of males does not exceed 35-38 days. The largest beetle in the world, the titan lumberjack, lives in South America.

In the name of the squad - Coleoptera- reflects one of the most significant characteristics of the insects included here. Their fore wings, or elytra, are very hard and durable; they cover the soft upper side of the abdomen and the membranous wings of the second pair located here. It is these membranous wings that are used for flight. They are much longer than the elytra and in a calm state are folded and hidden under them.

In some groups of beetles, the elytra are sometimes greatly shortened and almost do not cover the abdomen. Then the membranous wings either fold even more strongly and still hide under the elytra, or lie open on the surface of the abdomen. Some beetles, on the contrary, lose their second pair of wings and are unable to fly.

These beetles are often called wingless, although they always retain the first pair of wings - the elytra. The elytra of wingless species are sometimes fused.

Compounded eyes are absent only in those species that constantly live in the dark - in caves, termite mounds, anthills. Antennae are attached in front of the eyes, in the vast majority of cases consisting of 11 segments. The antennal segments can be uniform, thin and long - then the antennae are called filamentous. Sometimes the last few segments thicken and form a rounded club (club-shaped antennae). Sometimes, on the contrary, they turn into flat lateral projections, as is observed in lamellar beetles. If these projections are not collected into a club, but are present on all segments, the antennae resemble a comb and are called comb-shaped.

The mouthparts of beetles are of the gnawing type. The main tools for crushing food are their upper jaws, often called mandibles or mandibles. Sometimes they turn into decorations, reaching extraordinary development in males.

The elytra and wings of beetles are attached to the mesothorax and metathorax. The prothorax forms a wide ring, the upper part of which is called the pronotum. Attached below to the three thoracic segments are three pairs of legs, which are extremely diverse in beetles. Usually they are long, running, in aquatic forms - swimming, in those living in the soil - digging; sometimes the hind legs increase in size, their hips thicken - the legs become jumping. The legs end in tarsi, the segments of which bear pads from below, and in some species - suckers.

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Usually the beetles are brightly and beautifully colored (Tables 39, 40), often in metallic blue or green tones. Many species have additional sculptural decorations in the form of appendages on the head and antennae or peculiar protrusions and outgrowths on the elytra. Some beetles imitate other insects, most often Hymenoptera, in body shape and coloration.

The body of beetle larvae consists of 3 thoracic and 10 abdominal segments, of which the tenth is very small and is often shifted to the underside of the ninth. They always have a well-developed head, which is much more chitinized than the integument of the body, and is colored more dark color.

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The body color of the larvae (Fig. 248) depends on their lifestyle. The larvae, living openly on plant leaves or running along the surface of the soil, are brown, green or black. Those of them that live in the soil or inside plant tissues have a fleshy, white body. Mobile, flattened beetle larvae, equipped with long legs and antennae, as well as cerci, are called campodeoid, while sedentary, thick and outwardly awkward inhabitants of the thickness of various solid media are called erucoid. However, the diversity of beetle larvae is not limited to these two examples. Therefore, names derived from the names of the most typical families are often applied to individual groups of larvae: curculionoid, scarabeoid, daedambicoid, etc. larvae. The head of the larvae is equipped with a pair of strong jaws, which can be either gnawing or piercing. Some predatory larvae have a channel inside their piercing jaws through which digestive juice flows into the body of the victim. The liquefied, semi-digested tissues of the animal are then absorbed by the larva. This type of digestion is called extraintestinal, although the main digestive processes always take place in the intestine itself.

The respiratory organs of larvae are more diverse than those of adult beetles. Some inhabitants of the aquatic environment breathe, for example, with the help of tracheal gills - special outgrowths of the body penetrated by tracheae.

During the development period, the larvae molt several times. Larvae of different ages are usually similar to each other, but cases of complex transformation are known, when the appearance of the larvae completely changes after molting.

The reproductive biology of the small American beetle is most unique and complex. microsmallpus(Micromalthus debilis), allocated to a special family Micromalthidae. It has three known larval instars. The first instar larvae have long legs and a large head. They are very mobile, but do not feed and, apparently, serve for settlement. After molting, they turn into fleshy, legless second-instar larvae; their main function is nutrition; They chew wood and can cause harm. Having accumulated enough nutrients, these larvae turn into third instar larvae, which do not feed, but are capable of reproduction and give birth to many first instar larvae. Adult beetles are also known from this species, which develop from feeding larvae of the second instar, although this process has not yet been fully studied. In Micromalthus, therefore, there is the only case among insects of a combination of complex hypermetamorphosis with the reproduction of larvae - pedogenesis (which also occurs in some dipterans from the gall midge family).

The development of larvae in beetles is usually completed in a few months, less often it lasts for 3-5 years. The pupae of beetles, with rare exceptions, are of the free type; their limbs are not glued to the body and are similar to the limbs of an adult insect.

Pupation occurs in a unique way in some larvae that have a long and thin body. Larvae living in rotten wood tree eaters(Eucnemidae) before pupation, they prepare cradles where they can place their long body only by folding in half. This strange position of the larvae before pupation is also typical for narrow-bodied borers. Gradually, the entire contents of the rear half of the larva moves to the front, and eventually a pupa is formed from the long and thin larva, the dimensions of which exactly correspond to the size of the cradle prepared for it.

Beetles are the most diverse and species-rich order of insects. Already, more than 250,000 species have been described, but thousands of previously unknown forms are added to this number every year. More than 20,000 species of beetles are known on the territory of the USSR.

The detachment is divided into two suborders: carnivorous beetles(Adephaga) and heterovorous beetles(Polyphaga).

The vast majority of representatives of the order are land dwellers, inhabiting a wide variety of habitats; beetles are found in forests and meadows, in deserts and swamps, in valleys and high in the mountains.

The main reserves of nutrients that ensure life and reproduction of the adult stage are accumulated by the larva. However, for most beetles, additional feeding of young females and males is also necessary, during which the beetles finally mature. Often, after laying the first batch of eggs, the female begins to feed again, ensuring the accumulation of the necessary reserves for further reproduction.

The adaptability of beetles to a wide variety of living conditions is unusually high.

The lack of water in deserts is an insurmountable obstacle for many animals, but here, too, beetles turn out to be the most abundant group among the inhabitants of these spaces. Adaptations for the strictest water conservation allow desert beetles to subsist on the water that they absorb when feeding on living plant tissues, and is also formed as a result of metabolism in their bodies. During the day, to escape the scorching rays of the sun, desert beetles burrow into the soil, but at night they lead an active life.

In the forest zone, on the contrary, there is enough moisture, but not enough heat, and therefore sunny weather is one of the most important conditions daily activity of many insects, including beetles. Forest species of this order are remarkable in another respect - they were able to successfully adapt to development in environments that were inaccessible to most other insects. It is characteristic, for example, that in dead wood, especially on initial stages its decomposition, all its inhabitants are almost exclusively beetle larvae. It is interesting that here we find not only those species whose larvae are able to feed on wood, the main components of which - fiber and lignin - are digested with great difficulty. Many beetles that live in wood do not use it as food, but only as a medium for breeding fungi, which are specially introduced into the wood by females when laying eggs and subsequently serve as food for the larvae.

Wood-eating beetles have developed complex instincts for caring for offspring, which in their perfection are not inferior to well-known facts from life dung beetles. Dung beetles store food for their larvae in the form of dung sausages, balls or pears of strictly defined shapes, which are made in specially built underground chambers. Wood-eating beetles plant “mushroom gardens” for their larvae on the walls of passages specially gnawed into wood, and some of them, e.g. sugar beetles(Passalidae), the larvae are fed with specially prepared wood, since the larvae themselves cannot feed.

No less perfect instincts are developed in beetles that have adapted to life at the expense of other animals, most often at the expense of insects. Most of these species are found in anthills. The behavior of myrmecophilous beetles is such that ants do not distinguish them from other ants and often feed their larvae as if they were their own. They do not even interfere with their tenants when the beetles destroy the eggs and larvae of the anthill owners in addition to the food that they receive directly from the ants.

Some myrmecophilous beetles have special glands, the secretions of which are eaten by ants. In representatives close to ground beetles paussid family(Paussidae) everywhere on the body - on the antennae, frontal region, prothorax, on the elytra and abdomen - there are glands that secrete a thick liquid that attracts ants. The places where the glands open are covered with thick hairs, through which the secretion rises due to capillarity and from here is licked off by ants.

The relationships between beetles and plants often reach great complexity. This is reflected not only in the high precision of the beetles' actions when drilling a hole in a nut or when rolling a leaf into a “cigar” - all of these actions are examples of caring for the offspring - but also in the ability of the larvae of some beetles to stimulate the growth of plant tissues with the subsequent formation of galls.

Galls caused by beetles can occur in response to gnawing larvae, as is observed in some longhorned beetles developing in thin branches of trees and shrubs. Elephant larvae cause larger galls, and although the formation of these galls is still poorly studied, their occurrence should be considered the result of not only mechanical, but also complex biochemical effects of the larvae on plant tissue.

No less interesting and varied are the adaptations of beetles to protect themselves from numerous enemies. This purpose is served not only by their durable covers and, in many cases, well-defined protective coloring that camouflages the insect, but also by biochemical defenses, which are also produced by many beetles. Typically, toxic substances, which often have a strong unpleasant odor, are dissolved in the hemolymph of beetles and are released through the joints of the body when the beetle is disturbed. Some beetles, defending themselves from enemies, “shoot” a caustic liquid, which quickly evaporates in the air and scares off the pursuer. U bombardier beetles this liquid contains nitrogen oxide and nitrate salts, and the entire mixture explodes when it comes into contact with air.

Beetles deprived of more effective means protection, when irritated, they fall into a state of shock, tighten their antennae and paws and fall down. Finding such a “playing dead” beetle is not easy.

The importance of beetles in the economics of nature and the human economy is enormous. Huge amounts of money are spent annually on pest control in agriculture and forestry. There are much fewer beneficial species among beetles. They are usually predators that destroy harmful insects.

Collecting beetles is one of the most fascinating pastimes of naturalists. Together with butterflies, these original insects adorn collections and bring lovers many pleasant moments.

Animal life: in 6 volumes. - M.: Enlightenment. Edited by professors N.A. Gladkov, A.V. Mikheev. 1970 .

Coleoptera (or beetles) are the most numerous order of insects, including more than 300 thousand species. Representatives of Coleoptera include ladybugs, chafers, ground beetles, rhinoceros beetles, stag beetles, weevils, Colorado beetles, jumping beetles, dung beetles, bark beetles and many others. The size of the beetles varies from less than a millimeter (for the featherwing) to almost 20 centimeters (for the titan lumberjack). Body coloration can be very different, from protective to repellent to predators.

Coleoptera are distributed almost everywhere, including some that have switched to an aquatic lifestyle (diving beetles). There are especially many species of beetles in the humid tropics.

The main distinguishing features of Coleoptera are the rigid, venation-free elytra (fore wings) and membranous hind wings used for flight. In some species, the wings may be underdeveloped; such insects do not fly (ground beetles, weevils, etc.). The elytra protect the wings and the relatively soft body. Many beetles fly, but not very well, primarily due to their heavy wing covers. When flying, in most flying species, the elytra spread to the sides and serve as a kind of load-bearing planes. The hind wings play the role of peculiar propellers.

In Coleoptera, the first thoracic segment (prothorax) is enlarged and movably attached to the second thoracic segment (mesothorax). Various spines, outgrowths, etc. are formed on the dorsal side of the prothorax. From these, the type of beetle can be determined. The number of abdominal segments varies from 6 to 10 depending on the species.

The mouthparts are gnawing type. In its inner and external structure beetles are typical representatives of insects.

Vision is not very well developed; they orient themselves mainly through their sense of smell (the olfactory organs are located on the antennae).

Among Coleoptera there are both herbivorous (most representatives) and predatory species (ground beetles, jumpers), as well as saprophages (dung beetles, gravediggers) that feed on organic remains. Predatory beetles eat mainly invertebrates.

A number of beetles are pests of agriculture and forestry (Colorado beetles, bark beetles, longhorned beetles, May beetles). On the other hand, there are those that bring benefits by destroying pests (ground beetles, ladybugs).

Coleopterans are characterized by sexual dimorphism (usually females are slightly longer and wider than males). Development occurs with metamorphosis. In many beetles, the larvae are worm-shaped with three pairs of small limbs on the first segments (in some species they may be completely absent). The larvae can develop for several years, after which they turn into a pupa (in some species this stage lasts more than a year), from which an adult insect emerges (the adult stage). Such larvae usually live in soil or wood and move poorly. In predatory species, the larvae are also predators and are able to move quickly, as they have well-developed running or swimming limbs.