Insects easily adapt to external conditions, therefore becoming one of the most prosperous animals on the planet. They are among the arthropods that make up more than 80 percent of all living things known to science. Among their relatives are spiders and scorpions, labiopods and bipods, as well as crustaceans, including crabs and lobsters.

Insects are amazing animals. Imagine being able to lift 50 times your own weight - for a grown man, this is the same as lifting a truck. Ants do this every time they drag crumbs, grains of sand and small pebbles into their colony. Most fleas are only a few millimeters long, but they can jump up to 18 centimeters—the equivalent of covering three football fields for the average person!

Evolution of insects

Based on fossil evidence, the first insects appeared on Earth about 440 million years ago during the Silurian period. Their ancestors were other primitive invertebrates, including marine arthropods - trilobites, which were among the predominant marine species in the Cambrian period (approximately 542 to 488 million years ago).

The first true insects descended from the land descendants of trilobites - similar to two-legged creatures that did not have wings. Winged species appeared in the Devonian period, about 70 million years later. Their wings were located at right angles to the body and provided lift by oscillating up and down. These ancient winged insects are called paleopterans, or ancient winged insects, and are considered the ancestors of modern mayflies and dragonflies.

The ability to fly gave these ancient insects a serious advantage over other animals, and they evolved rapidly. They flourished during the Carboniferous period (359 to 251 million years ago), during which they grew into huge, fearsome predators. By the end of the Permian period (299 to 251 million years ago), most modern insect groups emerged and began to spread to occupy almost every habitat on Earth.

Anatomy of insects

The general body structure of all insects is the same. All species have three pairs of legs and three main body parts: head, chest and abdomen. On the head there are appendages called antennae, with the help of which the animal orients itself in space, oral organs and simple or compound eyes. The thorax is the middle part of the insect's body and consists of three sections - metameres. Each metamer is attached to a pair of legs, of which there are six in total.

There are small openings on the chest and abdomen called spiracles. Spiracles are associated with respiratory system and supply it with oxygen. The insect's body is protected by a hard outer covering called the exoskeleton, which is made of chitin, the same substance that makes up our nails and hair. The exoskeleton performs the same functions as the internal skeleton in vertebrates: it supports muscles and protects internal organs. In addition, it can protect against predators.

Most insects have one or two pairs of wings. Even in those who apparently lack them, they are preserved in a rudimentary form on the chest. Wings give insects a significant advantage over other animals. They allow them to elude terrestrial predators and fly away when the population increases and becomes too crowded. In addition, thanks to their wings, insects were able to spread and populate the most inhospitable places on Earth.

Entomologists usually love their work for the variety of material they study and the abundance of insects. From a purely aesthetic point of view, one cannot get bored with the truly endless variety of shapes, colors and appearance options.

However, if you dig deeper, even more exciting is the world hidden in the behavior and lifestyle of insects. Although in many cases their lifestyle is formulaic, sometimes it is striking in its eccentricity.

Social insects

Although many insects are solitary, some species live in large, complex communities that resemble an idealized model of human society, with members playing different roles to help the colony thrive. However, in social insects, members of the colony are related. Typically, there is only one fertile female and an unlimited number of fertile males for the entire colony. The bulk of the inhabitants of the colony are sterile, and their role is limited to collecting food and defending the settlement from enemies.

Bees and wasps

Probably the most common social insects are bees and wasps. They build large nests with special compartments for raising young and storing food.

Interesting fact: When a bee finds a good source of nectar and pollen, when it returns home, it informs the other inhabitants of the hive. Detailed instructions about the direction and distance to a food source are conveyed through a complex bee “dance.”

Worker bees have special sacs on their hind legs. They collect pollen from flowers and transfer it to the hive, where they use it as food for growing larvae.

True to their name, paper wasps construct nests from chewed wood fibers that closely resemble paper. Each nest cell will contain an egg and subsequently a growing wasp larva.

The queen bee is fertilized once in her life, and her only job is to lay eggs for about five years. Construction and repair of the hive, caring for offspring, and collecting food are only the responsibilities of worker bees. Each worker bee plays different roles at different times in its life. Fun fact- a worker bee, having found a source of nectar and pollen, returning to the hive, can inform other members of the colony about the distance and direction in which to fly, using a kind of dance.

Ants

Among those who have achieved the greatest success in social life, ants should be noted, living, like bees, in colonies. Some worker ants collect food, others gravitate towards raising larvae, and those with larger jaws become soldiers and protect the anthill. Ant colonies are divided into distinct castes, each of which plays a specific role in the general order. The winged queen is responsible for laying eggs, while the smaller workers collect food.

Termites are common in the tropics. Their striking mounds, up to 6 meters high, are a classic example of bold entrepreneurship among social insects. A termite colony contains four types of castes: the queen, fertile males, and sterile workers and soldiers.

Nutcrackers

Plants are an important source of food for all insects; all parts of the plant, from flowers and leaves to seeds and roots, with a certain degree of probability can be eaten, if not by one insect, then by another. However, not all plant-insect relationships are so straightforward, and this is best illustrated by gallworms. These tiny insects, which look like ants, affect the plant in such a way that it develops abnormal growths of tissue called galls.

The galls serve the larvae both as food and protection until the moment of pupation. Typically, the female gall moth lays one or more eggs (depending on the species) in the plant tissue. Each gallworm species is usually associated with a specific plant species and produces galls whose size, shape, and color are unique to that particular gallworm. Species with alternating generations form different galls at the sexual and parthenogenetic stages of the life cycle.

In some insect species, the lifestyle is further complicated by the alternation of generations, already described earlier for aphids. Successful mating of males and females is required first, and the next generation is parthenogenetic females that produce viable offspring without the participation of males.

Marching silkworms

The caterpillars of some silkworms sometimes go on a hike in orderly rows, following each other in single file (nose to tail). Those species whose caterpillars behave in this way are called marching silkworms. Of these, the most famous is the pine silkworm from Southern Europe. These caterpillars spend daytime inside a large silk web, which they wrap around tree branches. Stinging hairs from the body of caterpillars can be woven into this web and, combining with silk, can be an effective defense against birds. At dusk, however, the caterpillars come out to eat. By following the same line and marking their path with a silk thread, all caterpillars are able to easily find their way back home.

Sloth moth

Everyone knows three-toed sloths - slow-moving creatures that live in the forests of Central and South America.

Each of these animals is home to up to 100 moths, using its rough and matted fur. Every time a sloth climbs down from a tree to relieve itself on the ground, a moth lays eggs in its droppings. The caterpillars subsequently feed on this.

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Insects are the youngest of the invertebrates and the most numerous class of animals, numbering more than 1 million species. They have completely mastered all habitats - water, land, air. They are characterized by complex instincts, omnivorousness, high fertility, and for some, a social way of life.

During development with transformation, the habitat and food sources are divided between larvae and adults. The evolutionary path of many insects is closely related to flowering plants.

More highly developed insects are winged. Gravedigger beetles, dung beetles, and consumers of plant residues play an important role in the cycle of substances in nature, and at the same time, insects - pests of agricultural plants, gardens, food supplies, leather, wood, wool, and books - cause great damage.

Many insects are carriers of pathogens that cause diseases in animals and humans.

Due to the reduction of natural biogeocenoses and the use of pesticides, the total number of insect species is decreasing, therefore 219 species are listed in the Red Book of the USSR.

General characteristics of the class

The body of adult insects is divided into three sections: head, thorax and abdomen.

• Head, consisting of six fused segments, is clearly separated from the chest and is movably connected to it. On the head there is a pair of segmented antennae or antennae, mouthparts and two compound eyes; many also have one to three simple ocelli.

  Two compound, or facet, eyes are located on the sides of the head, in some species they are very developed and can occupy most of the surface of the head (for example, in some dragonflies, horseflies). Each compound eye contains from several hundred to several thousand facets. Most insects are blind to the color red, but they can see ultraviolet radiation and are attracted to it. This feature of insect vision is based on the use of light traps, emitting most of the energy in the violet and ultraviolet regions, for collecting and studying environmental features nocturnal insects (some families of butterflies, beetles, etc.).

  The oral apparatus consists of three pairs of limbs: the upper jaws, the lower jaws, the lower lip (fused second pair of lower jaws) and the upper lip, which is not a limb, but is an outgrowth of chitin. The oral apparatus also includes a chitinous protrusion of the floor of the oral cavity - the tongue or hypopharynx.

  

  

  

  Depending on the method of feeding, the oral organs of insects have a different structure. The following types of oral apparatus are distinguished:

  • gnawing-chewing - the elements of the oral apparatus have the form of short hard plates. Observed in insects that feed on solid plant and animal food (beetles, cockroaches, orthoptera)
  • piercing-sucking - the elements of the oral apparatus have the appearance of elongated hair-like bristles. Observed in insects that feed on plant cell sap or animal blood (bugs, aphids, cicadas, mosquitoes, mosquitoes)
  • licking-sucking - the elements of the oral apparatus have the form of tubular formations (in the form of a proboscis). It is observed in butterflies that feed on flower nectar and fruit juice. In many flies, the proboscis is highly transformed; at least five of its modifications are known, from a piercing-cutting organ in horse flies to a soft “licking” proboscis in flower flies that feed on nectar (or in carrion flies that feed on liquid parts of manure and carrion).

  Some species do not feed as adults.

  The structure of the antennae, or cubs, of insects is very diverse - filamentous, bristle-shaped, serrated, comb-shaped, club-shaped, lamellar, etc. There is one pair of antennae; they bear the organs of touch and smell, and are homologous to the antennules of crustaceans.

  The sense organs on the antennae of insects tell them not only the state of the environment, they help them communicate with relatives, find a suitable habitat for themselves and their offspring, as well as food. The females of many insects attract males using scents. Male lesser night peacocks can smell a female from several kilometers away. Ants recognize females from their anthill by smell. Some types of ants mark the path from the nest to the food source thanks to odorous substances that are released from special glands. With the help of their antennae, ants and termites smell the scent left by their relatives. If both antennae pick up the scent to the same extent, then the insect is on the right track. Attractant substances released by female butterflies ready to mate are usually carried by the wind.

• Breast insects consists of three segments (prothorax, mesothorax and metathorax), to each of which a pair of legs is attached to the ventral side, hence the name of the class - hexapods. In addition, in higher insects the chest bears two, less often one, pair of wings.

  The number and structure of limbs are characteristic features of the class. All insects have 6 legs, one pair on each of the 3 thorax segments. The leg consists of 5 sections: coxa (plow), trochanter (trochanter), femur (femur), tibia (tibia) and articulated tarsus (tarsus). Depending on the lifestyle, the limbs of insects can vary greatly. Most insects have walking and running legs. In grasshoppers, locusts, fleas and some other species, the third pair of legs is of the jumping type; In mole crickets that make passages in the soil, the first pair of legs are digging legs. In aquatic insects, for example the swimming beetle, the hind legs are transformed into rowing or swimming legs.

  Digestive system presented

  • The foregut, starting from the oral cavity and dividing into the pharynx and esophagus, the posterior section of which expands, forming a goiter and a chewing stomach (not for everyone). In consumers of solid foods, the stomach has thick muscular walls and carries chitinous teeth or plates from the inside, with the help of which food is crushed and pushed into the midgut.

    The foregut also includes salivary glands (up to three pairs). The secretion of the salivary glands performs a digestive function, contains enzymes, and moistens food. In bloodsuckers, it contains a substance that prevents blood clotting. In bees, the secretion of one pair of glands is mixed in the crop with flower nectar and forms honey. In worker bees, the salivary glands, the duct of which opens into the pharynx (pharyngeal), secrete special protein substances (“milk”), which feed the larvae that turn into queens. In butterfly caterpillars, caddisfly larvae and hymenoptera, the salivary glands are transformed into silk-secreting or spinning glands, producing silky thread for the production of cocoons, protective formations and other purposes.

  • The midgut at the border with the foregut is covered from the inside with glandular epithelium (pyloric outgrowths of the intestine), which secretes digestive enzymes (insects lack liver and other glands). Absorption of nutrients occurs in the midgut.
  • The hindgut receives undigested food debris. Here water is sucked out of them (this is especially important for desert and semi-desert species). The hindgut ends with the anus, which leads excrement out.

  

  Excretory organs are represented by Malpighian vessels (from 2 to 200), which look like thin tubes that flow into the digestive system at the border between the midgut and hindgut, and the fat body, which performs the function of “storage buds”. The fat body is loose tissue located between the internal organs of insects. It has a whitish, yellowish or greenish color. Cells of the fat body absorb metabolic products (uric acid salts, etc.). Next, the excretory products enter the intestines and are excreted together with excrement. In addition, fat body cells accumulate spare nutrients- fats, proteins and carbohydrate glycogen. These reserves are spent on the development of eggs during wintering.

  Respiratory system- trachea. This is a complex branching system of air tubes that directly deliver oxygen to all organs and tissues. On the sides of the abdomen and chest there are most often 10 pairs of spiracles (stigmas) - holes through which air enters the trachea. Large main trunks (tracheas) begin from the stigmas, which branch into smaller tubes. In the chest and anterior part of the abdomen, the trachea is expanded and forms air sacs. Tracheas permeate the entire body of insects, intertwine tissues and organs, and enter individual cells in the form of tiny branches - tracheoles, through which gas exchange occurs. Carbon dioxide and water vapor are removed to the outside through the tracheal system. Thus, the tracheal system replaces the functions of the circulatory system in supplying tissues with oxygen. The role of the circulatory system is reduced to the delivery of digested food to the tissues and the transfer of decay products from the tissues to the excretory organs.

  Circulatory system in accordance with the characteristics of the respiratory organs, it is relatively poorly developed, not closed, consists of the heart and a short, unbranched aorta extending from the heart to the head. The colorless liquid containing white blood cells circulating in the circulatory system is called hemolymph, in contrast to blood. It fills the body cavity and the spaces between organs. The heart is tube-shaped, located on the dorsal side of the abdomen. The heart has several chambers capable of pulsating, into each of which a pair of holes equipped with valves opens. Through these openings, blood (hemolymph) enters the heart. The pulsation of the heart chambers is caused by the contraction of special pterygoid muscles. Blood moves in the heart from the rear end to the front, then enters the aorta and from it into the head cavity, then washes the tissues and flows through the cracks between them into the body cavity, into the spaces between the organs, from where through special openings (ostia) it enters the heart. The blood of insects is colorless or greenish-yellow (rarely red).

  Nervous system reaches an exceptionally high level of development. It consists of the suprapharyngeal ganglion, peripharyngeal connectives, the subpharyngeal ganglion (it was formed as a result of the fusion of three ganglia) and the abdominal nerve cord, which in primitive insects consists of three thoracic ganglia and eight abdominal ones. In higher groups of insects, adjacent nodes of the ventral nerve chain merge by combining three thoracic nodes into one large node or abdominal nodes into two or three or one large node (for example, in true flies or lamellar beetles).

  The suprapharyngeal ganglion, often called the brain, is especially complex. It consists of three sections - anterior, middle, posterior and has a very complex histological structure. The brain innervates the eyes and antennae. In its anterior section, the most important role is played by such a structure as the mushroom bodies - the highest associative and coordinating center of the nervous system. The behavior of insects can be very complex and has a clearly defined reflex nature, which is also associated with significant development of the brain. The subpharyngeal node innervates the oral organs and the anterior intestine. The thoracic ganglia innervate the organs of movement - legs and wings.

  Insects are characterized by very complex forms of behavior, which are based on instincts. Particularly complex instincts are characteristic of the so-called social insects - bees, ants, termites.

  Sense organs reach an exceptionally high level of development, which corresponds to high level general organization of insects. Representatives of this class have organs of touch, smell, vision, taste and hearing.

  All sense organs are based on the same element - the sensilla, consisting of one cell or a group of sensitive receptor cells with two processes. The central process goes to the central nervous system, and the peripheral one goes to the outer part, represented by various cuticular formations. The structure of the cuticular sheath depends on the type of sensory organs.

  The organs of touch are represented by sensitive hairs scattered throughout the body. The olfactory organs are located on the antennae and mandibular palps.

  The organs of vision play a leading role in orientation in external environment along with the olfactory organs. Insects have simple and compound (compound) eyes. Compound eyes consist of a huge number of individual prisms, or ommatidia, separated by a light-proof layer. This eye structure gives “mosaic” vision. Higher insects have color vision (bees, butterflies, ants), but it differs from human vision. Insects perceive mainly the short-wave part of the spectrum: green-yellow, blue and ultraviolet rays.

  Reproductive organs are located in the abdomen. Insects are dioecious organisms; they have well-defined sexual dimorphism. Females have a developed pair of tubular ovaries, oviducts, accessory gonads, spermatic receptacle and often an ovipositor. Males have a pair of testes, vas deferens, ejaculatory duct, accessory sex glands and copulatory apparatus. Insects reproduce sexually, most of them lay eggs, there are also viviparous species, in which the females give birth to live larvae (some aphids, gadflies, etc.).

  After a certain period of embryonic development, larvae emerge from the laid eggs. Further development of larvae in insects of various orders can occur with incomplete or complete transformation (Table 16).

  Life cycle. Insects are dioecious animals with internal fertilization. According to the type of postembryonic development, insects are distinguished with incomplete (in highly organized) and complete (in higher) metamorphosis (transformation). Complete metamorphosis includes the stages of egg, larva, pupa and adult.

  In insects with incomplete metamorphosis, a young individual emerges from the egg, similar in structure to the adult insect, but differing from it in the absence of wings and underdevelopment of the genital organs - a nymph. They are often called larvae, which is not entirely accurate. Its living conditions are similar to adult forms. After several molts the insect reaches size limits and turns into an adult form - an imago.

  In insects with complete metamorphosis, the eggs hatch into larvae that differ sharply in structure (they have a worm-like body) and habitat from the adult forms; Thus, mosquito larvae live in water, and imaginal forms live in the air. The larvae grow and go through a series of stages, separated from each other by molts. During the last molt, a stationary stage, the pupa, is formed. The pupae do not feed. At this time, metamorphosis occurs, the larval organs undergo decay, and imago organs develop in their place. Upon completion of metamorphosis, a sexually mature, winged individual emerges from the pupa.

  Table 16. Development of insects	Type of development
  	Superorder I. Insects with incomplete metamorphosis	Superorder 2. Insects with complete metamorphosis
  Number of stages	3 (egg, larva, adult insect)	4 (egg, larva, pupa, adult insect)
  Larva	Similar to an adult insect in external structure, lifestyle and nutrition; differs in smaller size, wings are absent or incompletely developed	Differs from an adult insect in external structure, lifestyle and nutrition
  Doll	Absent	Yes (in the immobile pupa, histolysis of larval tissues and histogenesis of adult tissues and organs occurs)
  Squad	Order Orthoptera (Orthoptera)	Order Coleoptera, or beetles (Coleoptera) Order Lepidoptera, or butterflies (Lepidoptera) Order Hymenoptera (Hymenoptera)

  Class Overview

  The insect class is divided into more than 30 orders. The characteristics of the main groups are given in Table. 17.

  Beneficial insects

  Honey bee or house bee [show] A family usually lives in a hive, which consists of 40-70 thousand bees, of which one is the queen, several hundred male drones, and the rest are worker bees. The queen is larger in size than other bees; she has well-developed reproductive organs and an ovipositor. Every day the queen lays from 300 to 1000 eggs (on average this is 1.0-1.5 million over a lifetime). Drones are slightly larger and thicker than worker bees, and they do not have wax glands. Drones develop from unfertilized eggs. Worker bees are underdeveloped females that are unable to reproduce; their ovipositor turned into an organ of defense and attack - a sting. The sting consists of three sharp needles, between them there is a channel for removing the poison produced in a special gland. In connection with feeding on nectar, the gnawing mouthparts have changed significantly; when eating, they form a kind of tube - the proboscis, through which nectar is absorbed using the muscles of the pharynx. The upper jaws also serve to build honeycombs and other construction work. The nectar is collected in the enlarged crop and turns into honey, which the bee regurgitates into the cells of the honeycomb. There are numerous hairs on the bee's head and chest; when the insect flies from flower to flower, pollen sticks to the hairs. The bee cleans pollen from the body, and it accumulates in the form of a lump, or pollen, in special recesses - baskets on the hind legs. Bees drop pollen into the cells of the honeycomb and fill it with honey. Beebread is formed, which the bees feed the larvae with. On the last four segments of the bee's abdomen there are wax glands, which outwardly look like light spots - speculums. The wax comes out through the pores and hardens in the form of thin triangular plates. The bee chews these plates with its jaws and builds honeycomb cells from them. The wax glands of a worker bee begin to secrete wax on the 3-5th day of its life, reach its greatest development on the 12-28th day, then decrease and degenerate. In the spring, worker bees begin collecting pollen and nectar, and the queen lays one fertilized egg in each cell of the comb. After three days, larvae hatch from the eggs. Worker bees feed them “milk” for 5 days, a substance rich in proteins and lipids, which is secreted by the maxillary glands, and then bee bread. After a week, the larva weaves a cocoon inside the cell and pupates. After 11-12 days, a young worker bee emerges from the pupa. For several days she performs various work inside the hive - cleans the cells, feeds the larvae, builds honeycombs, and then begins to fly out for a bribe (nectar and pollen). In slightly larger cells, the queen lays unfertilized eggs, from which drones develop. Their development lasts several days longer than the development of worker bees. The queen lays fertilized eggs in large queen cells. From them larvae hatch, which the bees constantly feed with “milk”. From these larvae young queens develop. Before the young queen emerges, the old one tries to destroy the queen cell, but the worker bees prevent her from doing this. Then the old queen with some of the worker bees flies out of the hive - swarming occurs. A swarm of bees is usually transferred to a free hive. The young queen flies out of the hive along with the drones, and returns after fertilization. Bees have a well-developed suprapharyngeal node, or brain, which is distinguished by the strong development of mushroom-shaped, or stalked, bodies, with which the complex behavior of bees is associated. Having found flowers rich in nectar, the bee returns to the hive and begins to describe figures on the honeycomb that resemble the number 8; At the same time, her abdomen oscillates. This peculiar dance signals to other bees in which direction and at what distance the bribe is located. Complex reflexes and instincts that determine the behavior of bees are the result of a long historical development; they are inherited. People have been raising bees in apiaries since ancient times. The collapsible frame hive was an outstanding achievement in the development of beekeeping; it was invented by the Ukrainian beekeeper P.I. Prokopovich in 1814. The beneficial activity of bees lies primarily in the cross-pollination of many plants. With bee pollination, the yield of buckwheat increases by 35-40%, sunflower - by 40-45%, and cucumbers in greenhouses - by more than 50%. Bee honey is valuable food product, it is also used with therapeutic purpose for diseases of the gastrointestinal tract, heart, liver, kidneys. Royal jelly and bee glue (propolis) are used as medicinal preparations. Bee (wasp) venom is also used in medicine. Beeswax widely used in various industries - electrical engineering, metallurgy, chemical production. The annual global honey harvest is about 500 thousand tons. [show] The silkworm has been known to people for over 4 thousand years. It can no longer exist in nature; it is bred in artificial conditions. Butterflies don't feed. Sedentary, whitish female silkworms lay 400-700 eggs (the so-called greena). From them, in special rooms on racks, caterpillars are hatched and fed with mulberry leaves. The caterpillar develops within 26-40 days; During this time she sheds four times. An adult caterpillar weaves a cocoon from silk thread, which is produced in its silk gland. One caterpillar secretes a thread up to 1000 m long. The caterpillar wraps this thread around itself in the form of a cocoon, inside which it pupates. A small part of the cocoons is left alive - later butterflies hatch from them and lay eggs. Most cocoons are killed with hot steam or exposure to an ultra-high frequency electromagnetic field (in this case, the pupae inside the cocoons heat up to 80-90 ° C in a few seconds). Then the cocoons are unwound on special machines. More than 90 g of raw silk is obtained from 1 kg of cocoons.

  If it were possible to accurately calculate the harm and benefits of insects for the national economy, then perhaps the benefits would significantly exceed the losses. Insects provide cross pollination about 150 species of cultivated plants - garden, buckwheat, cruciferous, sunflower, clover, etc. Without insects, they would not produce seeds and would die themselves. The aroma and color of higher flowering plants have been developed in the process of evolution as special signals to attract bees and other pollinating insects. Insects such as burying beetles, dung beetles, and some others are of great sanitary importance. Dung beetles were specially brought to Australia from Africa, because without them, large amounts of manure would accumulate on pastures, which would interfere with grass growth.

  Insects play a significant role in soil formation processes. Soil animals (insects, millipedes, etc.) destroy fallen leaves and other plant debris, assimilating only 5-10% of their mass. However, soil microorganisms decompose the excrement of these animals faster than mechanically crushed leaves. Soil insects, along with earthworms and other soil inhabitants, play a very important role in mixing it. Lacquer bugs from India and Southeast Asia produce a valuable technical product - shellac; other species of bugs produce valuable natural paint carmine.

  Harmful insects

  Many types of insects damage agricultural and forest crops; up to 3,000 species of pests have been registered in Ukraine alone.

  [show] Adult beetles eat young tree leaves in spring (they eat leaves of oak, beech, maple, elm, hazel, poplar, willow, walnut, fruit trees). Females lay eggs in the soil. The larvae feed on thin roots and humus until autumn, overwinter deep in the soil, and the following spring continue to eat roots (mostly of herbaceous plants). After the second winter in the soil, the larvae begin to feed on the roots of trees and shrubs; young plantings with an underdeveloped root system may die due to damage. After the third (or fourth) wintering, the larvae pupate. Depending on the geographic latitude of the area and climatic conditions The development of May Khrushchev lasts from three to five years. [show] The Colorado potato beetle began damaging potatoes in 1865 in North America in the state of Colorado (hence the name of the pest). After the First World War it was introduced to Europe and quickly spread east to the Volga and the North Caucasus. Females lay eggs on potato leaves, 12-80 eggs per clutch. Larvae and beetles feed on leaves. In a month, a beetle can eat 4 g, a larva - 1 g of leaves. If we consider that on average a female lays 700 eggs, then the second generation of one female can destroy 1 ton of potato leaves. The larvae pupate in the soil, and adult beetles overwinter there. In Europe, unlike North America, No natural enemies Colorado potato beetle, which would restrain its reproduction. Common beet weevil [show] Adult beetles eat sugar beet seedlings in the spring, sometimes completely destroying the crops. The female lays eggs in the soil, the larvae feed on the roots and root crops of sugar beets. At the end of summer, the larvae pupate in the soil, and the young beetles overwinter. Bug harmful turtle [show] The bug bug harms wheat, rye and other grains. Adult bedbugs overwinter under fallen leaves in forest belts and bushes. From here in April-May they fly to winter crops. At first, bedbugs feed by piercing stems with their proboscis. Then the females lay 70-100 eggs on the leaves of the cereals. The larvae feed on the cell sap of stems and leaves, and later move to ovaries and ripening grains. Having pierced the grain, the bug secretes saliva into it, which dissolves the proteins. Damage causes the grain to dry out, reduce its germination capacity and deteriorate its baking qualities. [show] The forewings are light brown, sometimes almost black. They show a typical “scoop pattern”, represented by a kidney-shaped, round or wedge-shaped spot edged with a black line. The hind wings are light gray. The antennae of males are weakly combed, those of females are thread-like. Wingspan 35-45 mm. The caterpillars are earthy gray in color, with a dark head. The Fall Armyworm caterpillar in the fall damages (gnaws) mainly seedlings of winter cereals (hence the name of the pest), and to a lesser extent, vegetable crops and root crops; in the southern regions it harms sugar beets. Adult caterpillars overwinter burrowed into the soil in fields sown with winter crops. In spring they pupate quickly. Butterflies emerging from pupae in May fly at night and at dusk. Females lay eggs on millet and row crops - sugar beets, cabbage, onions, etc. and in places with sparse vegetation, so they are often attracted to plowed fields. Caterpillars destroy sown grains, gnaw plant seedlings in the root collar area, and eat leaves. Very gluttonous. If 10 caterpillars live on 1 m 2 of crops, then they destroy all the plants and “bald patches” appear in the fields. At the end of July they pupate; in August, second-generation butterflies emerge from the pupae and lay eggs on weeds on the stubble or seedlings of winter crops. One female winter armyworm can lay up to 2,000 eggs. In Ukraine, two generations of winter armyworm develop during the growing season. [show] One of our most common butterflies. The upper side of the wings is white, the outer corners are black. Males have no black spots on the forewings; females have 2 black round spots and 1 club-shaped spot on each wing. The hind wings of both males and females are the same - white, with the exception of a black wedge-shaped spot in leading edge. The underside of the hind wings is a characteristic yellowish-green color. Wingspan up to 60 mm. The body of the cabbage plant is covered with thick, very short hairs, giving it a velvety appearance. The variegated coloring of the caterpillars is a warning that they are inedible. The caterpillars are bluish-green, with yellow stripes and small black dots, and the abdomen is yellow. In cabbage butterfly caterpillars, the poisonous gland is located on the lower surface of the body, between the head and the first segment. To defend themselves, they regurgitate a green paste from their mouths, which is mixed with secretions from the poisonous gland. These secretions are a caustic bright green liquid with which the caterpillars try to coat the attacking enemy. For small birds, a dose of several individuals of these animals can be fatal. Swallowed cabbage caterpillars cause the death of domestic ducks. People who collected these insects with their bare hands sometimes ended up in the hospital. The skin on my hands became red, inflamed, my hands were swollen and itchy. Cabbage butterflies fly during the day in May-June and with a short break throughout the second half of summer and autumn. They feed on the nectar of flowers. Eggs are laid in clusters of 15-200 eggs on the underside of a cabbage leaf. In total, the butterfly lays up to 250 eggs. Young caterpillars live in groups, scrape off the pulp of cabbage leaves, while older ones eat up all the pulp of the leaf. If 5-6 caterpillars feed on a cabbage leaf, they eat it entirely, leaving only large veins. To pupate, the caterpillars crawl onto surrounding objects - a tree trunk, a fence, etc. During the growing season, two or three generations of cabbage whites develop. Cabbage grass is common in the European part former USSR, in Siberia this pest is not present, since butterflies cannot withstand severe winter frosts. The damage caused by cabbage is very great. Often many hectares of cabbage are completely destroyed by this pest. The flights of butterflies are interesting. When the butterflies reproduce strongly, they gather in large numbers and fly over considerable distances. [show] Willow woodborer - Cossus cossus (L.) The willow borer damages the bast and wood of poplars, willows, oaks, and others. deciduous trees and fruit breeds. Butterflies appear in nature starting from the end of June, mainly in July, and depending on the geographical location, in some places even before mid-August. They fly slowly in the late evening. A year lasts a maximum of 14 days. During the day they sit in a characteristic position with their chest reclining on the lower part of the trunk. Females lay eggs in groups of 15-50 pieces in bark cracks, damaged areas, cancerous wounds of trunks at heights of up to 2 m. Caterpillars hatch after 14 days. First, the bast tissues are eaten together. On older trees with thick bark in the lower part of the trunk, the caterpillars eat out individual long, irregularly running oval tunnels in the cross section only after the first wintering. The walls of the passages are destroyed by a special liquid and are brown or black. On thinner trunks with smooth bark, the caterpillars penetrate the wood earlier, usually within a month after hatching. The caterpillars push wood chips and excrement out through the lower hole. At the end of the growing season, when the leaves fall, the feeding of the caterpillars stops, which overwinter in the tunnels until the leaves bloom, i.e., until April - May, when the caterpillars continue to feed in separate tunnels again until autumn, overwinter one more time and finish feeding. They pupate either at the end of a circular passage, where a flight hole closed with wood chips is prepared in advance, or in the ground, near a damaged trunk, in a cocoon of wood chips. The pupal stage lasts 3-6 weeks. Before departure, the pupa, with the help of spines, protrudes halfway out of the flight hole or out of the cocoon, so that the butterfly can more easily leave the exuvium. The generation is maximally biennial. The willow woodborer is distributed throughout Europe, mainly in the middle and southern parts. It is found throughout the forest zone of the European part of Russia, in the Caucasus, Siberia, and also in Far East. Known in western and northern China and Central Asia. The butterfly's forewings are gray-brown to dark gray with a marbled pattern and vague gray-white spots, as well as dark transverse wavy lines. The hind wings are dark brown with matte dark wavy lines. The chest is dark on top, whitish towards the belly. The dark abdomen has light rings. The male has a wingspan of 65-70 mm, the female - from 80 to 95 mm. The female's abdomen is completed with a retractable, clearly visible ovipositor. The caterpillar is cherry-red immediately after hatching, and later turns flesh-red. The head and occipital plate are shiny black. An adult caterpillar is 8-11 cm (most often 8-9 cm), then it is a yellowish meat color, brown on top with purple tint. The yellow-brown occipital scute has two dark spots. The breathing hole is brown. The egg is oval-longitudinal, light brown with black stripes, dense, 1.2 mm in size. Many insects, especially those with piercing-sucking mouthparts, carry pathogens of various diseases. Malarial plasmodium [show] Plasmodium falciparum, the causative agent of malaria, enters the human bloodstream through the bite of a malaria mosquito. Back in the 30s of the XX century. In India, over 100 million people fell ill with malaria every year; in the USSR, in 1935, 9 million malaria cases were registered. In the last century, malaria was eradicated in the Soviet Union, and the incidence rate has sharply decreased in India. The center of malaria incidence has moved to Africa. Theoretical and practical recommendations for the successful fight against malaria in the USSR and neighboring countries were developed by V. N. Beklemishev and his students. The nature of damage to plant tissue depends on the structure of the pest’s oral apparatus. Insects with gnawing mouthparts bite off or eat away sections of the leaf blade, stem, root, fruit or make tunnels in them. Insects with piercing-sucking mouthparts pierce the integumentary tissues of animals or plants and feed on blood or cell sap. They cause direct harm to a plant or animal, and also often carry pathogens of viral, bacterial and other diseases. Annual losses in agriculture from pests amount to about 25 billion rubles, in particular, damage from harmful insects in our country annually averages 4.5 billion rubles, in the USA - about 4 billion dollars. TO dangerous pests cultivated plants in the conditions of Ukraine include about 300 species, in particular beetles, click beetle larvae, mole crickets, corn beetles, Colorado potato beetles, common beet weevils, turtle bugs, meadow and stem moths, winter and cabbage cutworms, hawthorn, gypsy moth, ringed silkworm, codling moth, American white butterfly, beet root aphid, etc. Control of harmful insects To combat harmful insects, a comprehensive system of preventive measures has been developed, including agro- and forestry, mechanical, physical, chemical and biological. Preventive measures consist of observing certain sanitary and hygienic standards that prevent the mass reproduction of harmful insects. In particular, timely cleaning or destruction of waste and garbage helps reduce the number of flies. Draining swamps leads to a decrease in the number of mosquitoes. Great importance also has to observe the rules of personal hygiene (washing hands before eating, thoroughly washing fruits, vegetables, etc.). Agrotechnical and forestry activities, in particular weed control, correct crop rotations, proper preparation soil, use of healthy and sedimentary material, pre-sowing seed cleaning, well-organized care cultivated plants, create unfavorable conditions for mass reproduction of pests. Mechanical measures consist of the direct destruction of harmful insects manually or with the help of special devices: flytraps, adhesive tapes and belts, trapping grooves, etc. In winter, wintering nests of hawthorn and goldentail caterpillars are removed from trees in gardens and burned. Physical measures - the use of certain physical factors to kill insects. Many moths, beetles, and dipterans fly towards the light. With the help of special devices - light traps - you can promptly learn about the appearance of certain pests and begin to fight them. To disinfect citrus fruits infected with the Mediterranean fruit fly, they are cooled. Barn pests are destroyed using high frequency currents. Therefore, integrated pest management, which involves a combination of chemical, biological, agrotechnical and other plant protection methods with the maximum use of agrotechnical and biological methods, is of particular importance. Integrated control methods include chemical treatments only in areas that threaten a sharp increase in pest numbers, and not continuous treatment of all areas. With the aim of nature conservation, widespread use is envisaged biological agents plant protection.

Many of us have heard the evening singing of crickets in the garden or in nature. But crickets and grasshoppers are not the only representatives of singing insects. Today we will talk about cicadas, their appearance and lifestyle.

What is a cicada

Cicadas are large insects found throughout the world. Science knows about two and a half thousand species of these insects, most of which live in countries with hot climates; the European part accounts for only eighteen of them. Consider the scientific classification of insects:

Kinds

In our latitudes, two types of singing cicadas are common: common and mountain; we will consider the features of their appearance and life below.

Did you know? The image of an insect was often used in poetry, in fine arts, he was depicted on coins and decorations and household items. For example, on one of the sides of an ancient Greek coin there is an image of a singing cicada.

Appearance

The “common” species is also called the “ash leaf sucker”: it has a predominantly black body color, head and back with yellow splashes. The length of the body including wings is no more than five centimeters.

Mountain cicada smaller in size: the length of its body with wings is no more than 2.5 cm. The color is very dark, almost black, there are splashes of rich orange color.

Head

The ash leaf sucker has a wide head, much wider than the front of the back. In the mountain species, on the contrary, the head is much narrower than the peculiar neck.

On the sides of the head of both specimens there are two large eyes of a complex structure, in the central part there are three simple ones, forming a kind of triangle. Presumably, thanks to this structure and the number of eyes, insects have excellent vision, covering a large space.

In the front part of the “muzzle” there are antennae with sensitive bristles and a proboscis.

Wings and legs

Both species have transparent wings. When folded, they completely cover the hind wings, since they are much longer. Dark or colored veins run along the entire surface of the wing.

The structure of the legs differs only in the number of spines on the hips: the common specimen has two spines, the mountain specimen has three spines. The femoral part of the legs is much thicker than the lower leg, which has cylindrical shape. In total, individuals have three pairs of legs ending in prehensile claws.

Abdomen

The abdomen in both species is dense, thickened in females in the lower part, where the organ for laying eggs is located. With its help, females pierce thin wood or green tissue of the plant and build a clutch. In males, the copulatory organ is also located there, with the help of which they fertilize the female.

Life of cicadas

Insects are considered the longest-living representatives of their class - some species live up to seventeen years.

Did you know? In the tomb of the Frankish king Childeric I, gold jewelry with garnet inserts in the form of cicadas was found.

Habitat

The ash leaf sucker prefers the southern latitudes of the Mediterranean, Crimea, Caucasus and Transcaucasia. The subtropical climate of these territories with its hot and dry summers is suitable for insects.

Insects spend time in sun-exposed, well-warmed places:

• forest edges;
• steppes and meadows;
• green terraces on mountain slopes.

Nutrition

By piercing the tender bark or grassy tissue of plants with a sharp proboscis, cicadas suck out the juice flowing down the stem. In air, the juice hardens, turning into a kind of porridge, which is also nutritious.

Lifestyle

Settling on the branches of plants, during the day insects bask in the sun, feed, flying from bush to bush or tree (the structure of their wings allows them to fly well). Contrary to popular belief about cicadas singing at night, this phenomenon is rather an exception. Insects make unusual sounds to attract the attention of females during the daytime. At night, only a few species sing, which is how they try to protect themselves from predators. By the way, each subspecies has its own timbre and sound character. Group "singing" is intended to prevent predators from recognizing a specific sound source.

Life cycle and reproduction

After mating, the female, piercing the bark of trees (ordinary) or the stems of grass and green shoots (mountain), lays eggs in the resulting gap. The number of eggs in a clutch can reach six hundred.

In a month and a half, the larvae will hatch - thick, clumsy individuals with a hard protective shell and burrowing type of legs. For their own safety, the offspring burrow into the soil, closer to the root systems of plants, the juices of which will feed them. Cicadas lead an underground lifestyle for quite a long time until the rudiments of wings appear: the species is ordinary - from two to four years, mountain view - up to six years.

To transform into an adult, the larva crawls to the surface, where, climbing a bush or tree, it molts. After molting, the body of the newly formed adult has not yet become stronger; it will take about six more days to acquire a hard covering. Adult specimens live for approximately three months.

Singing insects

Not only males, but also females of many species sing, although the sounds they make are inaudible to our ears. Let's figure out exactly how cicadas sing.

Small paired pads located on inside the abdomen under the hind pair of legs, called cymbals, emit sound impulses. The insect rhythmically contracts its abdominal muscle, and the cymbals produce clicks so fast that they seem like a continuous melody. The sound made by the cymbals can be heard at a distance of eight hundred meters.

Role in nature and in human life

Cicadas in nature are an important link in the food chain: they are food for birds, lizards, hedgehogs, and foxes, but this is not the only important role. By feeding on plants, insects can be both beneficial and harmful, for example, in agriculture. Let's take a closer look below.

Useful and harmful properties

Considering the omnivorous nature of individuals, they can cause great damage to grains, vegetables, fruits and berries, and even melons, flowers. Insects are equated to pests such as thrips. By sucking out all the plant juices, they reduce productivity and even completely destroy crops.

At the same time, in the wild, with the participation of insects, plant numbers are regulated. In addition, insects are considered a soil-forming link in the ecosystem: when they die, they saturate the soil with humus.

Breeding cicadas

In many countries in Asia, Africa, and in some cities in the USA and Australia, there are farms for breeding edible insects, including cicadas.

Important!Winged pests carry various diseases from plant to plant.

Catching a pair for your own breeding, in principle, is not difficult: if you catch it with your hands, you need to grab it on the wings, pressing them to the back, but it’s easier to use a net.

Content Features

Insects are kept in boxes with fine mesh for ventilation, and individuals at different stages of development live separately. For a small farm, plastic containers with holes made for ventilation are suitable.

Some spiders, for example tarantulas (Lycosa), common in our steppe zone, lie in wait for prey in a vertical burrow, which they dig in the soil and line with cobwebs; Insects that get into the hole are sucked out, and the remains are thrown out. In some spiders, the burrow or nest continues intotubular web gallery.

Many spiders build a flat hunting canopy on the ground or among vegetation, at the edge of which there is a hole leading to the nest. Such nets are also characteristic of the house spider Tegenaria domestica. Many forest species strengthen loose horizontal canopies on numerous threads. The most difficult ones are various options wheel-shaped network, in particular crosses. Sometimes such a network is pulled back by a central thread and looks like a wide funnel. In the Hyptiotes spider, the network is represented by a sector of 4 rays and transverse sticky threads; a thread extends from the junction of the rays, on which the spider sits, picking up the thread with a loop and pulling the net. When prey is caught, the spider repeatedly releases and tightens the loop, causing the prey to stick to adjacent threads; then the spider runs to her, entwines her with a web and sucks her out.

Adult males usually do not build trapping nets, but use the web to fill the copulatory organs of the pedipalps with sperm. A drop of sperm is released onto a specially woven mesh, from where it is absorbed by the copulatory organs. When mating, very complex instincts appear. In some cases, females are aggressive towards males, who flee after mating, as they can be eaten by the female. The males of some spiders, such as Pisaura species, distract the female's attention during mating by bringing her a web-covered insect. While the female sucks him out, the male fills her seminal receptacles with sperm,inserting the copulatory organs alternately into the right and left openings of the epigyne. Spiders usually have pronounced sexual dimorphism, sometimes very sharp.