What sense organs do insects have? The structure of the body of the insect - sensory organs and nervous system of insects

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The sensory organs are described separately from the structure, since not only nerve cells, but also derivatives of other tissues participate in their formation. However, they can be called part of it. They are elements of the peripheral nervous system, as they contain sensitive nerve endings.

Reception and receptors

Any sense organ consists of receptors - sensitive elements of a special structure that perceive a certain type of irritation. For example, the hairs on the body of an insect, which perform the function of touch, feel mechanical irritation, but do not perceive light, and so on.

In total, there are 4 types of receptors in the body of an insect.

Mechanoreceptors

: perceive mechanical vibrations. Such nerve endings underlie the organs of touch and hearing (sound also represents mechanical vibrations of a certain frequency). Among the mechanoreceptors that form touch, there are several varieties. Some feel pressure, others feel vibration, others feel touch, etc. In general, mechanoreceptors are very diverse and "multifunctional."

Thermoreceptors

- temperature sensitive structures. They are located in the covers of insects and transmit information about its fluctuations. Moreover, when heating and cooling different types of thermoreceptors are excited: cold and thermal. Without temperature sensitivity, life of some insects would not have been possible. For example, working bees in a hive constantly monitor the temperature of the nest site where (Photo). They either warm them or cool them. The temperature is constantly maintained at 34.5-35.5 degrees, because when deviations from this "norm" die.

Chemoreceptors

- Sensitive formations that are irritated by chemicals. An example is the organs of taste and. Despite the fact that insects are more primitive than many animals, they have found special chemoreceptors that no one else has. We are talking about internal chemoreceptors, which determine the constancy of the internal environment of the body: pH and so on. So far, these receptors are poorly understood.

Photoreceptors

- the basis of the organ of vision, nerve endings that perceive light waves.

In general, all receptors perform only one function - reception, that is, the perception of certain signals. These signals in the form of nerve excitation are fed to the nerve centers of the brain and where the information is processed. As a result, the insect “decides” what to do in response to external stimuli.

Organs of taste

. Sensitive chemoreceptors are found in most groups on the oral organs. However in flies (Photo) , butterflies and bees, they are also located on the front legs (more precisely, on them). The folded-winged wasps are distinguished by the presence of taste organs on the segments of the antennas.

In insects, it is best to distinguish between sweets, and they are also able to recognize sour, bitter and salty. The sensitivity to different tastes of different insects varies. For example, lactose seems to be sweet to butterfly caterpillars and tasteless to bees. But the bees are very sensitive to salty.

Chemical feeling

Animals are endowed with a general chemical sensitivity, which is provided by various sensory organs. In the chemical sense of insects, the most significant role is played by the sense of smell. And termites and ants, according to scientists, are given a voluminous sense of smell. What is it is hard for us to imagine. The insect's olfactory organs react to the presence of even very low concentrations of a substance, sometimes very distant from the source. Thanks to the sense of smell, the insect finds prey and food, navigates the area, learns about the approach of the enemy, carries out biocommunication, where the specific “language” is the exchange of chemical information using pheromones.

Pheromones are the most complex compounds allocated for communication purposes by individuals to transfer information to other individuals. Such information is encoded in specific chemicals, depending on the type of living creature and even on its belonging to a particular family. Perception with the help of the olfaction system and the interpretation of the “message” causes the recipients a certain form of behavior or physiological process. To date, a significant group of insect pheromones is known. Some of them are designed to attract individuals of the opposite sex, others, traces - indicate the path to the house or food source, others - serve as an alarm, fourth - regulate certain physiological processes, etc.

Truly unique should be the "chemical production" in the body of insects in order to produce in the right amount and at a certain point the whole gamut of the pheromones they need. Today, more than a hundred of these substances of complex chemical composition are known, but no more than a dozen were able to artificially reproduce them. Indeed, to obtain them, perfect technologies and equipment are required, so for now it remains only to be surprised at such arrangement of the organism of these miniature invertebrate creatures.

Beetles are provided mainly with olfactory type antennae. They allow you to capture not only the smell of the substance itself and the direction of its distribution, but even “feel” the shape of the odorous object. An example of a great sense of smell are grave-beetles that cleanse the land from carrion. They are able to smell hundreds of meters away and gather in a large group. And the ladybug, with the help of smell, finds colonies of aphids to leave masonry there. After all, not only she, but also her larvae feeds on aphids.

Not only adult insects, but also their larvae are often endowed with excellent sense of smell. So, the larvae of the May beetle are able to move to the roots of plants (pine, wheat), being guided by a slightly increased concentration of carbon dioxide. In the experiments, the larvae immediately go to the soil site, where a small amount of the substance forming carbon dioxide was introduced.

The incomprehensibility seems to be the sensitivity of the organ of smell, for example, the butterfly of Saturnia, whose male is able to capture the smell of a female of her species at a distance of 12 km. When comparing this distance with the amount of pheromone secreted by the female, a result that surprised scientists was obtained. Thanks to his antennae, the male unmistakably searches among many odorous substances for a single molecule of the hereditarily known substance in 1 m3 of air!

Some hymenopterans have been given such a sharp sense of smell that it is not inferior to the dog’s famous instinct. So, the female riders, when running along the trunk of a tree or a stump, vigorously move their antennae. They “sniff out” the larvae of the horntail or lumberjack beetle located in the wood at a distance of 2–2.5 cm from the surface.

Due to the unique sensitivity of the antennae, the tiny helis horseman with their mere touch of the cocoons of the spiders determines whether they contain underdeveloped testicles, sedentary spiders or other testicles of other riders of their species. How gel makes such an accurate analysis is not yet known. Most likely, he smells the subtlest specific odor, but maybe when a mustache taps the rider picks up some reflected sound.

The perception and analysis of chemical stimuli acting on the organs of smell of insects is carried out by a multifunctional system - the olfactory analyzer. It, like all other analyzers, consists of the perceiving, conductor and central departments. Olfactory receptors (chemoreceptors) perceive odorous molecules, and impulses signaling a specific smell are sent through nerve fibers to the brain for analysis. There is an instant development of the response of the body.

Speaking of the smell of insects, one cannot but say about the smell. There is no clear understanding of what smell is in science, and there are many theories regarding this natural phenomenon. According to one of them, the analyzed molecules of the substance are the "key". And the “lock” is the olfactory receptors included in odor analyzers. If the configuration of the molecule approaches the “lock” of a specific receptor, the analyzer will receive a signal from it, decrypt it and transmit information about the smell to the animal’s brain. According to another theory, odor is determined by the chemical properties of molecules and the distribution of electric charges. The most recent theory, which has won many supporters, sees the main reason for the smell in the vibrational properties of molecules and their components. Any aroma is associated with certain frequencies (wave numbers) of the infrared range. For example, thioalcohol of onion soup and decaboran are chemically completely different. But they have the same frequency and the same smell. At the same time, there are chemically similar substances that are characterized by different frequencies and smell differently. If this theory is true, then aromatic substances and thousands of types of cells that perceive odor can be estimated by infrared frequencies.

"Radar installation" of insects

Insects are endowed with excellent organs of smell and touch - antennas (antennae or streaks). They are very mobile and easily controlled: an insect can breed them, bring them together, rotate individually on its own axis or together on a common one. In this case, they resemble in appearance and are essentially a “radar installation”. The nerve-sensitive element of the antennas are sensilla. From them, an impulse with a speed of 5 m per second is transmitted to the “brain” center of the analyzer to recognize the object of irritation. And then the response signal to the received information instantly arrives at the muscle or other organ.

In most insects, the second segment of the antennae has a Johnston organ - a universal device whose purpose has not yet been fully elucidated. According to them, it perceives movements and concussions of air and water, contacts with solid objects. A locust and a grasshopper are endowed with a surprisingly high sensitivity to mechanical vibrations, which are capable of detecting any tremors with an amplitude equal to half the diameter of a hydrogen atom!

Beetles on the second segment of the antennae also have a Johnston organ. And if a spinning bug running on the surface of the water damages it or removes it, then it will come across any obstacles. With the help of this organ, the beetle is able to capture reflected waves coming from the shore or obstacles. He senses water waves with a height of 0. 000 000 004 mm, that is, the Johnstone organ performs the task of an echo sounder or radar.

Ants are distinguished not only by a well-organized brain, but also by an equally perfect body organization. Antennae are of paramount importance for these insects, some serve as an excellent organ of smell, touch, environmental knowledge, and mutual explanations. Deprived of antennae, ants lose their ability to find the way, nearby food, to distinguish enemies from friends. Using antennas, insects are able to "talk" with each other. Ants transmit important information by touching antennas to specific segments of the antennae of each other. In one of the behavioral episodes, two ants found prey in the form of larvae of different sizes. After "negotiations" with the brothers using antennas, they headed to the place of discovery along with mobilized assistants. Moreover, a more successful ant, who managed to transmit information about the larger prey he found with the help of antennae, mobilized a much larger group of working ants.

Interestingly, ants are one of the cleanest creatures. After each meal and sleep, their entire body and especially the antennae are thoroughly cleaned.

Taste sensations

A person clearly defines the smell and taste of a substance, and in insects the taste and olfactory sensations are often not separated. They act as a single chemical feeling (perception).

Gustatory insects prefer certain substances depending on the nutrition characteristic of the species. Moreover, they are able to distinguish between sweet, salty, bitter and sour. For contact with food consumed, the taste organs can be located in various parts of the body of insects - on antennas, proboscis and on legs. With their help, insects receive basic chemical information about the environment. For example, a fly, having just touched its paws to an object that interested it, almost immediately finds out that under its feet there is a drink, food, or something inedible. That is, she is able to carry out instant contact analysis of a chemical substance with her feet.

Taste is the sensation arising from the action of a solution of chemicals on the receptors (chemoreceptors) of the insect's taste organ. Receptor taste cells are the peripheral part of the complex system of the taste analyzer. They perceive chemical irritations, and here the primary coding of taste signals occurs. Analyzers immediately send volleys of chemoelectric impulses along thin nerve fibers to their “brain” center. Each such impulse lasts less than a thousandth of a second. And then the central structures of the analyzer instantly determine taste sensations.

Attempts are continuing to understand not only what the smell is, but also to create a unified theory of “sweets”. While this does not succeed - maybe you, the biologists of the 21st century, will succeed. The problem is that completely different chemical substances, both organic and inorganic, can create relatively the same taste sensations of sweets.

Organs of touch

The study of the sense of touch of insects is perhaps the greatest difficulty. How are these creatures chained in a chitinous shell perceive the world? So, thanks to skin receptors, we are able to perceive various tactile sensations - some receptors record pressure, others temperature, etc. After touching the item, we can conclude that it is cold or warm, hard or soft, smooth or rough. Insects also have analyzers that determine temperature, pressure, etc., but much of the mechanisms of their action remains unknown.

Touch is one of the most important sensory organs for the safety of the flight of many flying insects in order to feel the air currents. For example, in dipterans, the whole body is covered with sensilla, performing tactile functions. Especially there are a lot of them on hummers to perceive air pressure and stabilize flight.

Thanks to touch, the fly is not so easy to slam. Her vision allows you to notice a threatening object only at a distance of 40 - 70 cm. But the fly is able to respond to the dangerous movement of the hand, which caused even a small movement of air, and instantly fly up. This ordinary housefly once again confirms that there is nothing simple in the living world - all creatures, young and old, are provided with excellent sensory systems for active life and their own protection.

Pressure receptor insect receptors can be in the form of pimples and bristles. They are used by insects for various purposes, including orientation in space - in the direction of gravity. For example, a larva of a fly before pupation always clearly moves upwards, that is, against gravity. After all, she needs to crawl out of the liquid food mass, and there are no reference points there, except for the attraction of the Earth. Even after getting out of the chrysalis, the fly for some time tends to crawl up until it dries to fly.

Many insects have a well-developed sense of gravity. For example, ants are able to estimate the surface slope at 20. And the staphilinus beetle, which digs vertical holes, can determine a deviation from the vertical at 10.

Live "weather forecasters"

Many insects are endowed with the excellent ability to foresee weather changes and make long-term forecasts. However, this is characteristic of all living things - whether it be a plant, a microorganism, an invertebrate or a vertebrate animal. Such abilities provide normal life in their intended habitat. There are rarely observed natural phenomena - droughts, floods, sharp cooling. And then, in order to survive, living beings need to mobilize additional protective equipment in advance. In both cases, they use their internal "weather stations".

By constantly and carefully observing the behavior of various living creatures, one can learn not only about changes in the weather, but even about upcoming natural disasters. Indeed, over 600 species of animals and 400 species of plants, so far known to scientists, can fulfill a peculiar role of barometers, indicators of humidity and temperature, predictors of thunderstorms, storms, tornadoes, floods, and beautiful cloudless weather. Moreover, living "weather forecasters" are everywhere, wherever you are - by a reservoir, in a meadow, in a forest. For example, before the rain, even with a clear sky, the green grasshoppers stop chattering, the ants begin to close the entrances to the anthill tightly, and the bees stop flying behind the nectar, sit in the hive and buzz. Trying to hide from the impending weather, flies and wasps fly into the windows of houses.

Observations of poisonous ants living in the foothills of Tibet have revealed their excellent ability to make further forecasts. Before the period of heavy rains, the ants move to another place with dry solid soil, and before the onset of drought, the ants fill dark moist depressions. Winged ants are able to sense the approach of a storm in 2-3 days. Large individuals begin to rush about on the ground, and small individuals swarm at a small height. And the more active these processes are, the more bad weather is expected. It was revealed that during the year the ants correctly identified 22 changes in the weather, and they made a mistake only in two cases. This amounted to 9%, which looks quite good compared to the average error of weather stations of 20%.

The beneficial actions of insects often depend on long-term forecasts, and this can provide great service to people. An experienced beekeeper provides a reliable enough forecast for bees. For the winter, they close up the tapeworm in a wax hive. By the hole for airing the hive, you can judge the upcoming winter. If the bees leave a large hole - the winter will be warm, and if small - wait for severe frosts. It is also known that if the bees start to fly early from the hives, an early warm spring can be expected. The same ants, if the winter is not expected to be severe, remain to live near the surface of the soil, and before the cold winter they are deeper in the ground and build a higher anthill.

In addition to the macroclimate for insects, the microclimate of their environment is important. For example, the bees do not allow overheating in the hives and, having received a signal from their living "devices" about the temperature exceeding, they start ventilation of the room. A part of the working bees is organized at different heights along the entire hive, and with rapid flapping of the wings sets in motion air. A strong airflow forms and the hive cools. Ventilation is a long process, and when one batch of bees gets tired, the turn of another begins, and in a strict order.

The behavior of not only adult insects, but also their larvae depends on the testimony of living "instruments." For example, cicadal larvae that develop in the earth come to the surface only in good weather. But how do you know the weather upstairs? To determine this, they create special earthen cones with large holes over their underground shelters - a kind of meteorological structure. In them, cicadas through a thin layer of soil evaluate temperature and humidity. And if weather conditions are unfavorable, the larvae return to mink.

The phenomenon of forecasting showers and floods

Observing the behavior of termites and ants in critical situations can help people in predicting heavy rains and floods. One of the naturalists described a case when an Indian tribe living in the jungle of Brazil hurriedly left their settlement before the flood. And the ants “told” the Indians about the impending disaster. Before the flood, these public insects are in great excitement and urgently leave their habitable place with chrysalis and food supplies. They are sent to places where water does not reach. The local population hardly understood the origins of such an amazing sensitivity of ants, but, obeying their knowledge, people walked away from trouble after the little weather forecasters.

They can perfectly predict floods and termites. Before it begins, they leave their homes throughout the colony and rush to the nearest trees. Anticipating the magnitude of the disaster, they rise precisely to that height that will be higher than the expected flood. There they wait until the murky streams of water, which rush so fast that the trees sometimes fall under their pressure, subside.

A huge number of weather stations monitors the weather. They are located on land, including in the mountains, on specially equipped scientific vessels, satellites and space stations. Meteorologists are equipped with modern instruments, devices and computer equipment. In fact, they do not make a weather forecast, but calculate, calculate the weather changes. And the insects in the given examples of the actual predict weather using innate abilities, and special living "devices" built into their bodies. Moreover, weather forecasters determine not only the time of the flood approach, but also evaluate its magnitude. Indeed, for the new refuge they occupied only safe places. Scientists have so far failed to explain this phenomenon. Termites presented an even greater mystery. The fact is that they never settled down on those trees that when flooded turned out to be carried down by stormy streams. Similarly, according to the observation of ethologists, starlings also acted, which in the spring did not occupy birdhouses dangerous for the settlement. Subsequently, they were really ripped off by a hurricane. But here we are talking about a relatively large animal. The bird, perhaps by the swing of the birdhouse or by other signs, estimates the unreliability of its fastening. But how and with the help of which devices such forecasts can be made by very small, but very "wise" animals? A person is not only unable to create something like this yet, but also cannot answer. These tasks are for future biologists!

Nervous system. In the structure of the central nervous system in insects, the same modifications are found as in crustaceans. Along with cases of severe dismemberment (supraglottic, submaryngeal, three thoracic and eight abdominal nodes) and clearly paired structure, which occurs in primitive insects, there are cases of extreme concentration of the nervous system; the entire abdominal chain can be reduced to a continuous ganglion mass, which is especially common in larvae and larva-shaped adults in the absence of limbs and weak dismemberment of the body.

The development of the internal structure of the proto-cerebral part of the brain, in particular the mushroom bodies, attracts attention in the supraglottal node. It was noted that the structure of the mushroom bodies, which occupy a place in the upper part of the brain, forming here one or two pairs of tubercles on the sides of the midline, is closely related to the development of insect instinct.

1 — optic lobes, 2 — frontal lobe with mushroom body, 3 — protocerebral lobe, 4 — deutocerebral lobe with antennae, 5 — nerve of the paired simple eye, 6 — frontal node with an unpaired sympathetic nerve (nervus recurrens) extending from it back, 7 - periopharyngeal connection

Sensory organs. The sensory organs in insects are differentiated and well developed. The organs of touch and smell prevail in importance. The organs of touch are externally represented by a bristle. The olfactory organs also have the shape of a typical bristle, which, mutating, can turn into detached thin-walled protrusions and undeparted finger-shaped protrusions and thin-walled flat sections of the cover. The most important location of the ends of the olfactory nerves is the antennae.

1, for example, the role of antennae as an organ of smell in flies and lepidopterans, which at a great distance distinguish even faint odors. Better studied the sense of smell of bees; it turned out that their ability to perceive smells is close to ours: those smells that we perceive are also perceived by bees, those smells that we mix are also mixed by bees; the sense of smell is also concentrated mainly on the antennae. Tastessweet, bitter, sour and salty insects also vary; the taste organs are on the tentacles of the mouth, on the legs; the severity of the taste sensation in different organs of the same insect may be different; it is much higher than in humans. The complex eyes of an insect perceive the movement of objects; in some cases, they can also perceive the shape of objects; higher hymenopteran (bees) can perceive colors, including those that are not perceived by humans ("ultraviolet"); however, color vision is not as diverse as in humans: for example, a bee on the left side of the spectrum feels yellow, while other colors feel like shades of yellow; the right blue-violet part of the spectrum of the bee also feels as one color. The visual acuity of bees is much lower than the visual acuity of a person.

. On the right is the external structure; on the left — frontal section, internal structure: 1 — mushroom-like (stalk-like) body, 2 — central body, 3 — optic lobe, 4 — olfactory deutocerebral lobe with two antennal nerves, 5 — pharyngeal node with nerves of three jaws

In some orders, such as in the order Orthoptera, which includes grasshoppers, crickets and locusts, the so-called tympanic organs are widespread, the structure of tympanal organs, as well as the fact that the species possessing them, have males with sound organs, make suggest tympanic organs are auditory organs. The tympanic organs in grasshoppers and crickets are located on the lower leg under the knee joint, and in locusts and cicadas on the sides of the first abdominal segment, they are externally represented by a recess, sometimes surrounded by a fold of the cover and with a thin stretched membrane at the bottom; on the inner surface of the membrane or in the immediate vicinity, the nerve ending of a peculiar structure is located.

Type of nervous system in insects

The nervous system of insects processes signals from the environment into electrical impulses. Due to this, muscle movements and the functioning of organs are carried out. A particularly large number of nerve cells are located in the head. They form the brain, as well as the second nerve center located under the esophagus, the subpharyngeal ganglion. In the three thoracic segments are the nerve nodes that control the movement of the legs and wings. Eight nerve nodes located in the back of the trunk innervate their portion of the trunk. Nerve nodes are interconnected and with other nerve centers by nerve trunks. Thus, the nervous system of insects is built on the principle of a rope ladder. In many insects, the nerve nodes of the thoracic segments and the back of the trunk merge into larger nodes.

How insects breathe

Through a complex system of tubes, air travels through the body of the insect. One respiratory opening is located on the sides of the thoracic and abdominal segments. Tracheas and airways that intensively branch out depart from it. The finest tubes, thousands of times thinner than a human hair, entangle the surfaces of all organs of insects. Large insects, such as beetles and butterflies, often breathe by straining and relaxing the back of their bodies. In order to prevent moisture from leaving the respiratory tract, the insect closes the respiratory openings with the help of hairs; this excludes the possibility of foreign bodies entering them. The trachea is internally covered with cuticle, which is updated with each change of shell.

Do insects have ears?

“Drum” skin is present in many insects. This “ear” is often susceptible not only to the sounds that people hear, but also to ultrasound. However, it is located not on the head of the insect, but on the most various parts of its body: in cicadas and some nocturnal moths, on the back of the body, in other moths, in the last thoracic segment. Grasshoppers have “ears” under their knees on their forelegs. Many insects use their ears to communicate: females of grasshoppers and crickets find singing males. But insects have other sensory organs that perceive noise. With the help of an organ located in the antennae, male mosquitoes pick up sounds made by females of their species during flight, and thus find a partner. Cockroaches on the back of the body have long sensitive hairs that are capable of perceiving sound.

Why do insects have antennae?

The sensory organs on the antennae of insects not only inform them of the state of the environment, they help to communicate with relatives, find a suitable habitat for themselves and offspring, as well as food. Females of many insects attract males using odors. Males of a small night peacock eye can smell a female at a distance of several kilometers. Ants recognize the smell of females from their anthill. Some species of ants mark the way from the nest to the source of food due to odorous substances that are secreted from special glands. With the help of antennae, ants and termites smell the smell left by their relatives. If both antennae catch the smell to the same extent, then the insect is on the right track. Attractants that secrete female moths ready for mating are usually carried by the wind.

Insectslike other multicellular organisms, have many different receptors, or sensilla, sensitive to certain stimuli. Insect receptors are very diverse. Insects have mechanoreceptors (auditory receptors, proprioceptors), photoreceptors, thermoreceptors, chemoreceptors. With their help, insects capture the energy of radiation in the form of heat and light, mechanical vibrations, including a wide range of sounds, mechanical pressure, gravity, the concentration of water vapor and volatile substances in the air, as well as many other factors. Insects have a developed sense of smell and taste. Mechanoreceptors are trichoid sensilla, which perceive tactile stimuli. Some sensilla can pick up the slightest vibration of the air around the insect, while others signal the position of body parts relative to each other. Air receptors perceive the speed and direction of air flows near the insect and regulate the speed of flight.

Vision

Vision plays a large role in the life of most insects. They have three types of organs of vision - facet eyes, lateral (stemma) and dorsal (ocellia) eyes. Daytime and flying forms usually have 2 complex eyes and 3 ocellia. Stemmas are present in insect larvae with complete transformation. They are located on the sides of the head in an amount of 1-30 on each side. Dorsal eyes (ocellia) are found together with facet eyes and function as additional organs of vision. Ocellia was observed in adults of most insects (absent in many butterflies and dipterans, in working ants and blind forms) and in some larvae (springflies, mayflies, dragonflies). As a rule, they are found only in well-flying insects. Usually there are 3 dorsal ocelli located in the form of a triangle in the frontoparietal region of the head. Their main function is probably to evaluate the illumination and its changes. They are also believed to be involved in the visual orientation of insects and phototaxis reactions.

Features of insect vision are due to the facet structure of the eyes, which consist of a large number of ommatidia. The largest number of ommatidia was found in butterflies (12-17 thousand) and dragonflies (10-28 thousand). The photosensitive unit of ommatidia is a retinal (visual) cell. The basis of insect photoreception is the conversion of the rhodopsin visual pigment under the influence of a quantum of light into the metarodopsin isomer. The reverse of its restoration makes it possible to repeatedly repeat the elementary visual acts. Usually, 2-3 visual pigments are found in photoreceptors, which differ in their spectral sensitivity. The data set of visual pigments also determines the color vision features of insects. Visual images in faceted eyes are formed from a variety of point images created by individual ommatidia. Faceted eyes lack the ability to accommodate and cannot adapt to vision at different distances. Therefore, insects can be called "extremely shortsighted." Insects are characterized by an inversely proportional relationship between the distance to the object in question and the number of details visible to their eye: the closer the object is, the more details they see. Insects are able to evaluate the shape of objects, but at small distances from them, this requires that the outlines of objects fit in the field of view of the faceted eye.

Color vision of insects can be dichromatic (ants, bronze beetles) or trichromatic (bees and some butterflies). At least one species of butterfly has tetrachromatic vision. There are insects that are able to distinguish colors with only one (upper or lower) half of the facet eye (four-spotted dragonfly). For some insects, the visible part of the spectrum is shifted to the short-wave side. For example, bees and ants do not see red (650-700 nm), but they distinguish part of the ultraviolet spectrum (300-400 nm). Bees and other pollinating insects can see ultraviolet patterns on flowers, hidden from human sight. Similarly, butterflies are able to distinguish between the color elements of the wings, visible only in ultraviolet radiation.

The perception of sounds transmitted through a solid substrate is carried out in insects by vibration receptors located in the legs of the legs near their articulation with the thigh. Many insects are highly sensitive to tremors of the substrate on which they are located. Sound perception through air or water is carried out by phonoreceptors. Dipterans perceive sounds with the help of Johnston organs. The most complex auditory organs of insects are the tympanic organs. The number of sensillas that make up one tympanal organ varies from 3 (some butterflies) to 70 (locusts) and even to 1,500 (in song cicadas). In grasshoppers, crickets, and teddy bears, tympanum organs are located in the legs of the forelegs, and in locusts, on the sides of the first abdominal segment. The auditory organs of the song cicadas are located at the base of the abdomen in the vicinity of the sound producing apparatus. The auditory organs of the moths are located in the last thoracic segment or in one of the two front segments of the abdomen and can perceive ultrasounds from bats. Honey bees make sounds, forcing part of the thorax to vibrate through frequent muscle contractions. The sound is amplified by wing plates. Unlike many insects, bees are able to make sounds of different heights and tones, which allows them to transmit information through different characteristics of the sound.

Vision

Insects have a developed olfactory apparatus. Perception of smells is due to chemoreceptors - olfactory sensilla located on the antennae, and sometimes on the near-mouth appendages. At the level of chemoreceptors, the primary separation of olfactory stimuli occurs due to the presence of two types of receptor neurons. Generalist neurons recognize a very wide range of chemical compounds, but at the same time they have low sensitivity to odors. Specialist neurons respond only to one or more related chemical compounds. They provide the perception of odorous substances that trigger certain behavioral reactions (sex pheromones, food attractants and repellents, carbon dioxide). In mulberry silkworm males, the olfactory sensilla reaches the theoretically possible limit of sensitivity: only one female pheromone molecule is enough to excite a specialist neuron. In his experiments, J. A. Fabre determined that males of pear peacock-eye can detect females by pheromones at a distance of up to 10 km.

Contact chemoreceptors form the peripheral part of the insect gustatory analyzer and allow them to evaluate the suitability of the substrate for nutrition or oviposition. These receptors are located on the mouth, tips of the legs, antennas and ovipositor. Most insects are able to recognize solutions of salts, glucose, sucrose and other carbohydrates, as well as water. Insect chemoreceptors rarely respond to artificial substances that mimic a sweet or bitter taste, unlike vertebral chemoreceptors. For example, saccharin is not perceived by insects as a sweet substance.