Lab #1

The external structure of insects

Target- To study the external structure of insects.

Materials and equipment: collection specimens of insects (grasshoppers, beetles, bugs), magnifiers, dissecting needles, glass slides.

Progress

Consider and sketch the external structure of insects, pay attention to the location of the limbs, wings, the position of the head relative to the axis of the body.

Find three sections: head, chest, abdomen. Consider the places of their articulation and separate from each other with the help of dissecting needles. Dissected parts - head, chest, abdomen - sketch.

Examine the structure of the head at 10-20x magnification. Sketch and mark all parts of the head and its appendages (crown, forehead, clypeus, cheeks, upper lip, upper jaws, eyes, eyes, antennae, labial palp, jaw palp).

Consider and sketch various types of antennae: filiform, bristle-shaped, bead-shaped, saw-shaped, clavate, pinnate, geniculate, bristle-bearing (Fig. 1).

Determine the types of antennae in the listed insect species: May beetle, grasshopper, striped nutcracker, golden bronze, turtle bug, whitefish, red cockroach. To determine the type of antennae, use the attached descriptions and fig. one.

Filamentous antennae. All segments are cylindrical, i.e., more or less of the same width, only at the base they can be somewhat thickened (Fig. 1a). Example: locusts, some butterflies (moths and moths).

Setiform antennae. The segments gradually narrow from the base so that the antennae are distinctly pointed towards the apex (Fig. 1b). Antennae can be long or short. Example: grasshoppers, crickets, bears, cockroaches.

Beaded mustache. Consist of short and wide segments, the bases of the latter are narrowed so that the segments are separated from one another by constrictions; the first (1st-2nd) segments may be elongated (Fig. 1c). Example: black beetles.

Saw-shaped mustache. The segments that make up the antennae have a retracted upper angle and together resemble the teeth of a saw (Fig. 1f). Example: click beetles and gold beetles. A comb-like, or comb-shaped, antennae (Fig. 1, g), each segment of which has a process, can be considered a modification of the sawtooth antennae; processes form a ridge. An example is click beetles from the genus Corymbites.

Club-shaped antennae. Several apical segments are widened and form a club (Fig. 1e).

Example: white butterfly, nettle butterfly. If the club of the antennae consists of plates folding in a fan-like manner, then the antennae is called lamellar-clavate (Fig. 1, j).

Example- May beetle and other beetles.

Feathered antennae. Each antennal segment has bilateral outgrowths, decreasing from base to apex; in total, the antennae resemble a bird's feather (Fig. 1h). An example is silkworm butterflies.

Elbow antennae. The first segment of the antenna is much longer than the other segments that make up the flagellum and is directed at an angle to them (Fig. 1k). Example: hornet, bumblebee, stag beetle and other species of the barbel family.

bristle-bearing antennae consist of three short and wide segments of various shapes; on the last segment from the side or at the apex there is a seta, which may be pinnate (Fig. 1i). Example: housefly and some Diptera.

Antennae(or antennas, sashki) are a pair of appendages connected to the anterior segments of arthropods. Crustaceans have two pairs of antennae (the first pair are called antennules, the second are simply antennae) and are located on the first two segments of the head. In other groups of arthropods, with the exception of chelicerae and bessyazhkovyh (having no antennae at all), they have one pair.

bristle-shaped antennae. The segments gradually narrow from the base so that the antennae are distinctly pointed towards the apex. Antennae can be long or short. Examples are grasshoppers, crickets, bears, cockroaches.

beaded antennae. Consist of short and wide segments, the bases of the latter are narrowed so that the segments are separated from one another by constrictions; the first (1-2nd) segments may be elongated. An example is dark beetles.

sawtooth antennae. The segments that make up the antennae have a drawn upper angle and together resemble the teeth of a saw. Examples are click beetles and gold beetles. A modification of the sawtooth mustache can be considered comb, or comb-shaped, antennae, each segment of which has a process; processes form a ridge.

club-shaped antennae. Several apical segments are widened and form a club. Examples -

Everyone knows that insects are never completely at rest, but try to seize every free second to quickly and thoroughly clean their antennae - sensitive antenna-like appendages of various shapes connected to the anterior segments of arthropods. Different species of insects use different ways of tidying up their antennae using different movements and different pairs of legs, but what drives them to constantly engage in antenna grooming, even when they are in sterile laboratory rooms where there are no chemical contaminants and dust, has so far remained unclear. .

A group of entomologists from the University of North Carolina, armed with a gas chromatograph, an electron microscope and a tube of superglue, decided to finally save adults from the painful search for an answer to the question asked by children why insects need to constantly clean their antennae, and published the results of their research in Proceedings of the National Academy of Sciences. The latter can be used in the development of more advanced and environmentally friendly insecticides.

As an experimental insect, the authors chose the well-known American cockroach Periplaneta americana, a cosmopolitan, brought to North America from Africa, and then widely spread to all other continents. Like all arthropods, cockroaches pay much attention to the condition of their whiskers, regularly bending them to their mouths with the help of their front pair of legs and methodically cleaning each segment of the sensitive antennae from base to tip.

To find out exactly how dirty cockroach whiskers differ from clean ones, the permanent actions of insects to put antennas in order had to be stopped somehow, at least for a short time.

To do this, cockroaches were placed for some time in cramped containers, where it was difficult for them to turn around to do their usual hygiene, or one of the antennae was fixed with a drop of gel with cyanoacrylate, or the moving parts of the oral apparatus were sealed with this gel.

As it turned out, 3-4 times more protective lipids accumulate on cockroach mustaches that have not been cleaned for a day than on cleaned ones.

“It is clear that insects are constantly forced to clean dust particles and various chemical pollutants from sensory appendages. It is more difficult to explain why they need to constantly clean off their own secretory secretions from them, which perform important functions, including protective ones, ”comments one of the authors of the article, Koubi Shel, on the results of the experiments.

Sensory bristles of the olfactory pores of the American cockroach. A - on uncleaned antennas, B - on cleaned ones, C - on artificially (chemically) cleaned ones. D--F: the same, only in the case of pheromone-sensitive receptors. G--I: the same pores, only with a higher magnification, it is clearly seen that the pores of the receptors are covered with lipids before grooming, partially cleaned after and completely open after chemical cleaning; J--L: other olfactory receptors - before grooming, after grooming, artificially purified. // PNAS

Using an electroantennagram, the sensitivity of dirty and clean cockroach whiskers to various odors was measured, including periplanon-B, a cockroach pheromone discovered back in 1952, through which male and female individuals communicate with each other. It turned out that the antennas that the cockroach did not clean for a day show five times less sensitivity to odors than those that the cockroach regularly “points to marafet”. A similar pattern has been observed by entomologists in similar experiments with ants, houseflies, and Blatella germanica, the European red-breasted cousin of the American cockroach, colloquially known as the Prussian.

Even in the absence of external contaminants, insect antennae lose their sensitivity significantly due to skin lipids, which, accumulating on the surface of the whiskers, gradually clog microscopic pores through which volatile molecules penetrate to receptor cells.

By constantly cleaning off excess secretory fats, insects maintain a balance between the protective function of lipids and the access of external stimuli to receptors.

Thus, methodical cleaning of the antennae is necessary for insects not only to remove external contaminants from the antennae, but also to regulate sensory sensitivity, since skin lipids, in addition to protective, also perform transport functions, trapping and delivering odorous molecules to receptors.

Knowing this, it is possible to develop safer insecticides that will penetrate the body of cockroaches not through a thick chitinous cover, but will stick to the lipid film during antenna grooming, when the insect cleans its whiskers, removing excess fatty film from them.

General characteristics of the class

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

The head, consisting of six merged segments, is distinctly separated from the thorax and movably connected to it. On the head there is a pair of jointed antennae or screeds, a mouth apparatus and two compound eyes; many also have one or three simple eyes.

Two complex, or faceted, eyes are located on the sides of the head, in some species they are very strongly developed and can occupy most of the surface of the head (for example, in some dragonflies, horseflies). Each compound eye consists of several hundred to several thousand facets. Most insects are blind to red, but they see and are attracted to ultraviolet light. This feature of insect vision is the basis for the use of light traps, which emit most of the energy in the violet and ultraviolet regions, for collecting and studying the ecological characteristics of nocturnal insects (certain families of butterflies, beetles, etc.).

The oral apparatus consists of three pairs of limbs: upper jaws, lower jaws, lower lip (the 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 bottom of the oral cavity - the tongue or hypopharynx.

Mouth apparatus of insects

Types of insect antennae

Types of insect legs

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

gnawing-chewing - elements of the oral apparatus look like short hard plates. Observed in insects that feed on solid plant and animal food (beetles, cockroaches, orthoptera)

piercing-sucking - elements of the oral apparatus have the form of elongated hair-like bristles. Observed in insects that feed on plant cell sap or animal blood (bugs, aphids, cicadas, mosquitoes, mosquitoes)

licking-sucking - elements of the oral apparatus have the form of tubular formations (in the form of a proboscis). It is noted in butterflies that feed on the nectar of flowers and fruit juice. In many flies, the proboscis is strongly transformed, at least five of its modifications are known, from a piercing-cutting organ in horseflies 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 ties, of insects is very diverse - filiform, bristle-shaped, serrate, comb-shaped, club-shaped, lamellar, etc. Antennae one pair; they bear the organs of touch and smell, and are homologous to crustacean antennules.

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. Females of many insects attract males with the help of smells. Males of the lesser nocturnal peacock eye can smell a female at a distance of several kilometers. Ants recognize by the smell of females from their anthill. Some species of ants mark their way from the nest to the source of food thanks 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 capture the smell to the same extent, then the insect is on the right track. Attractant substances that are released by female butterflies ready for mating are usually carried by the wind.

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

The number and structure of the limbs are characteristic features of the class. All insects have 6 legs, one pair on each of the 3 thoracic segments. The leg consists of 5 sections: coxa (plow), trochanter (trochanter), femur (femur), lower leg (tibia) and jointed 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 a jumping type; in bears that make passages in the soil, the first pair of legs is digging legs. In aquatic insects, such as the swimming beetle, the hind legs are transformed into rowing, or swimming.

The abdomen of insects consists of several (usually 6-10) segments; usually there are 10 of them. It contains most of the internal organs. At the end of the abdomen, females have an ovipositor, which serves to lay eggs. In bees, wasps, ants, the ovipositor has turned into a sting, which has a duct of a poisonous gland inside. The male has a copulatory apparatus at the end of the abdomen.

The digestive system is represented

The anterior intestine, starting from the oral cavity and subdividing into the pharynx and esophagus, the posterior section of which expands, forming a goiter and chewing stomach (not in all). In consumers of solid food, 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 middle intestine.

The salivary glands (up to three pairs) also belong to the foregut. The secret of the salivary glands performs a digestive function, contains enzymes, moistens food. In bloodsuckers, it contains a substance that prevents blood clotting. In bees, the secret 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 are used to feed the larvae that turn into queens. In caterpillars of butterflies, larvae of caddisflies and hymenoptera, the salivary glands are transformed into silk-secreting or spinning glands, producing a silky thread for making a cocoon, protective formations, and other purposes.

The middle intestine on the border with the foregut is covered from the inside with glandular epithelium (pyloric outgrowths of the intestine), which secrete digestive enzymes (the liver and other glands are absent in insects). Absorption of nutrients occurs in the midgut.

The hindgut receives undigested food residues. Here, water is sucked out of them (this is especially important for desert and semi-desert species). The posterior intestine ends with an anus, which leads out excrement.

Insects

The 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 middle and hind intestines, and the fat body, which performs the function of "accumulation kidneys". The fat body is a loose tissue located between the internal organs of insects. Has a whitish, yellowish or greenish color. Fat body cells absorb metabolic products (salts of uric acid, etc.). Further, the excretion products enter the intestines and, together with the excrement, are excreted. In addition, the cells of the fat body accumulate reserve nutrients - fats, proteins and carbohydrate glycogen. These reserves are spent on the development of eggs during wintering.

Respiratory organs - 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. From the stigmas, large main trunks (tracheae) begin, which branch into smaller tubes. In the chest and anterior part of the abdomen, the trachea are expanded and form air sacs. Tracheae permeate the entire body of insects, braid tissues and organs, enter inside individual cells in the form of the smallest branches - tracheoles, through which gas exchange takes place. 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.

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

The nervous system reaches an exceptionally high level of development. It consists of the supraoesophageal ganglion, circumoesophageal connectives, suboesophageal ganglion (it was formed as a result of the fusion of three ganglia) and the ventral nerve cord, which in primitive insects consists of three thoracic ganglia and eight abdominal ones. In higher groups of insects, neighboring 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 real flies or horn beetles).

The supraesophageal ganglion, which is 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 mushroom bodies - the highest associative and coordinating center of the nervous system. The behavior of insects can be very complex, has a pronounced reflex character, which is also associated with a significant development of the brain. The subpharyngeal node innervates the oral organs and the anterior intestine. The thoracic ganglia innervate the organs of movement - the 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.

The sense organs reach an exceptionally high level of development, which corresponds to the high level of the general organization of insects. Representatives of this class have organs of touch, smell, sight, 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 process 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 organs of smell are located on the antennae and mandibular palpi.

The organs of vision play a leading role for orientation in the external environment, along with the organs of smell. Insects have simple and compound (faceted) eyes. Compound eyes are made up of a huge number of individual prisms, or ommatidia, separated by an opaque layer. This structure of the eyes gives "mosaic" vision. Higher insects have color vision (bees, butterflies, ants), but it differs from human vision. Insects perceive mainly the short-wavelength part of the spectrum: green-yellow, blue and ultraviolet rays.

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

After a certain period of embryonic development, larvae emerge from the laid eggs. Further development of larvae in insects of various orders may occur with incomplete or complete metamorphosis (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 egg, larva, pupa and adult stages.

In insects with incomplete transformation, a young individual emerges from the egg, which is similar in structure to an adult insect, but differs from it in the absence of wings and underdevelopment of the genital organs - the nymph. Often they are called larvae, which is not entirely accurate. Its habitat conditions are similar to adult forms. After several molts, the insect reaches its maximum size and turns into an adult form - an imago.

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

Tab 16. Insect development Type of development

Superorder I. Insects with incomplete metamorphosis

incomplete transformation

Superorder 2. Insects with full metamorphosis

Complete transformation

Number of stages 3 (egg, larva, adult) 4 (egg, larva, pupa, adult)

Larva Similar to an adult insect in external structure, lifestyle and nutrition; differs in smaller sizes, wings are absent or incompletely developed Differs from an adult insect in external structure, lifestyle and nutrition

Pupa Absent Present (histolysis of larval and histogenesis of adult tissues and organs occurs in the immobile pupa)

Detachment

Order Orthoptera (Orthoptera)

Order of cockroaches (Blattoidea)

Squad louse (Anoplura)

Proboscis squad (Rhynchota)

Squad of hard-winged, or beetles (Coleoptera)

Order Lepidoptera, or butterflies (Lepidoptera)

Order Hymenoptera (Hymenoptera)

Order of the flea (Aphaniptera)

Order Diptera (Diptera)

Beneficial insects

Honey bee or domestic bee [show]

Silkworm [show]

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 of 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 evolved as special signals to attract bees and other pollinating insects. The sanitary importance of such insects as gravedigger beetles, dung beetles, and some others is great. Dung beetles were specially brought to Australia from Africa, because without them a large amount of manure accumulated on the pastures, which prevented the growth of grass.

Insects play a significant role in soil formation processes. Soil animals (insects, centipedes, etc.) destroy fallen leaves and other plant residues, 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 its mixing. Lacquer insects from India and South-East Asia secrete a valuable technical product - shellac, other species of insects - valuable natural paint carmine.

Harmful insects

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

May Khrushch [show]

Colorado potato beetle [show]

Common beet weevil [show]

Bedbug harmful turtle [show]

Winter scoop [show]

Cabbage [show]

Willow borer [show]

Many insects, especially those with piercing-sucking mouthparts, carry pathogens of various diseases.

Malarial Plasmodium [show]

Flies carry pathogens of dysentery, typhoid fever and other intestinal infections, trypanosomiasis - African human sleeping sickness, etc.

Lice carry pathogens of typhus and relapsing fever

Fleas carry the plague pathogen.

The nature of damage to plant tissues depends on the structure of the oral apparatus of the pest. Insects with gnawing mouthparts gnaw or eat away sections of the leaf blade, stem, root, fruit, or make passages 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, the damage from harmful insects in our country annually averages 4.5 billion rubles, in the USA - about 4 billion dollars.

Dangerous pests of cultivated plants in the conditions of Ukraine include about 300 species, in particular, beetles, larvae of click beetles, mole cricket, grain bugs, Colorado potato beetle, common beet weevil, turtle bugs, meadow and stem moths, winter and cabbage scoops , hawthorn, gypsy moth, ringed moth, apple codling moth, American white butterfly, beet root aphid, etc.

The fight against harmful insects

To combat harmful insects, a comprehensive system of measures has been developed - preventive, including agro- and forestry, mechanical, physical, chemical and biological.

Preventive measures consist in observing certain sanitary and hygienic standards that prevent the mass reproduction of harmful insects. In particular, timely cleaning or destruction of waste, garbage helps to reduce the number of flies. Drainage of swamps leads to a decrease in the number of mosquitoes. Of great importance is also the observance of the rules of personal hygiene (washing hands before eating, thoroughly washing fruits, vegetables, etc.).

Agrotechnical and forestry measures, in particular the destruction of weeds, proper crop rotations, proper soil preparation, the use of healthy and sedimentary material, pre-sowing seed cleaning, well-organized care of cultivated plants, create unfavorable conditions for the mass reproduction of pests.

Mechanical measures consist in the direct destruction of harmful insects manually or with the help of special devices: flycatchers, adhesive tapes and belts, trapping grooves, etc. In winter, wintering nests of hawthorn and goldtail caterpillars are removed from trees in gardens and burned.

Physical measures - the use of some physical factors for the destruction of insects. Many moths, beetles, Diptera fly towards the light. With the help of special devices - light traps - you can timely learn about the appearance of some pests and start fighting them. To disinfect citrus fruits infected with the Mediterranean fruit fly, they are subjected to cooling. Barn pests are destroyed using high frequency currents.

Therefore, integrated pest management is of particular importance, which involves a combination of chemical, biological, agrotechnical and other methods of plant protection with the maximum use of agrotechnical and biological methods. In integrated methods of control, chemical treatments are carried out only in foci that threaten a sharp increase in the number of pests, and not continuous treatment of all areas. With the aim of protecting nature, it is envisaged that biological means of protecting plants will be widely used.

One of the important directions of the biological method is the protection of entomophages. The biological method of control also involves the use of pathogens of fungal, bacterial and viral diseases of harmful insects. Currently, bacterial preparations entobactrin and dendrobacillin are used in our country.

Variations in the structure of antennae in insects are very wide, but, as a rule, entire families, suborders, or orders of insects are characterized by one or another particular form of antennae.

The antennae usually consist of a large number of segments, but sometimes they are short and have few segments. The latter option occurs in flies and dragonflies: their antennae have only 3 segments.

In beetles, the antennae are usually 11-segmented, while in hymenoptera (riders, wasps, bees, ants, etc.) they consist of 12-13 segments.

In insects such as grasshoppers and some lumberjack beetles, antennae are longer than the body.

There are several forms of antennae.

If the antennae are approximately the same thickness for most of its length, and widen at the end, this is a club-shaped antennae. They are found in diurnal butterflies.

Nocturnal butterflies, such as Saturnia, are characterized by feathery antennae. In such antennae, a thin outgrowth departs from each segment in both directions.

If the first segment of the antennae is long, and the subsequent ones are located at an angle to it, then such antennae are called geniculate. Sometimes cranked antennae also have a club consisting of fan-shaped folded plates (for example, in the May beetle).

There are other forms of antennae: bristle-like, filiform, bead-like ...

Why do insects need whiskers?

It turned out that to capture odors! That is, with the help of antennae, insects ... sniff!

This is how most insects discover and find food. In the same way, they find individuals of the opposite sex to mate with. For example, male butterflies Actias selene arrive at the smell of a female for 11 km, males of gypsy moth - for 3.8 km.

But the antennae of insects also serve as organs of touch.

With their help, the insect gets an idea of ​​the temperature and humidity of the surrounding space.

But tactile receptors are present not only on the antennae of an insect, but also on all parts of its body. Usually they are represented by hairs and bristles.

The movably attached hairs are also organs for the perception of air movement, including the weakest one - from another insect flying or walking past.

In some cases, such sense organs completely replace the insect's vision. An example is the blind cave beetle. He has no eyes, but he is perfectly oriented in his cave house thanks to sensitive antennae: with them he gropes for the road and sniffs it; and someone runs nearby - he will definitely feel it: after all, his whole body is covered with delicate sensitive hairs.