Caddisflies complete transformation. Caddisfly insect. Lifestyle and habitat of the caddisfly. Class Cartilaginous fish. Features of the organization

Development of insects with incomplete and complete transformation

Development of insects with incomplete metamorphosis

In orthoptera, which include locusts, as well as in cockroaches, dragonflies, mayflies, mantises, stoneflies, earwigs, lice and homoptera, development occurs with incomplete transformation. This means that larvae emerge from the eggs - small insects that look similar to their parents. They differ from adults only in size, lack of wings, and underdeveloped reproductive system. The larvae molt several times until they develop into mature (adult) insects. Thus, in its individual development, an insect goes through three stages: 1) egg, 2) larva, 3) adult insect (imago).

Insect development with complete metamorphosis

In insects with complete metamorphosis, the larvae do not at all resemble adults. These are the larvae (caterpillars) of butterflies, beetles, hymenoptera and flies. These larvae do not have compound eyes, sometimes there are no simple ocelli, and the body is most often worm-shaped. Often there are no antennae and no wings. These larvae molt several times, actively feed and grow. Having reached its maximum size, the larva turns into a pupa - another stage of development (a stationary intermediate link between the larva and the adult insect). Thus, in insects with full development in ontogenesis there are four stages: 1) egg, 2) larva, 3) pupa, 4) adult insect (imago).

It is noteworthy that in insects with complete metamorphosis, the larvae live in different places and feed on different food than adult insects (imago).

Dragonfly Squad. Squad Caddisflies.

Order of Dragonflies (Odonata)

Dragonflies are aerial predators. They often eat prey on the fly. Large wings with reticulate venation in large dragonflies are always spread out to the sides, in small ones (arrows, lute) they can fold along the body at rest. Some dragonflies have wings of the same shape, narrowed towards the base (suborder Homoptera), while others have hind wings wider than the front ones, especially at the base (suborder Hemoptera). The mentioned suborders also differ in the structure of the larvae and biological features.

When examining a dragonfly, attention is drawn to its huge eyes, which occupy most of the head. The eye consists of 28 thousand facets (ommatids), each of which is served by 6 light-sensitive cells. A dragonfly can spot a mosquito at a distance of up to 10 meters. By eating mosquitoes, horseflies and other bloodsuckers, dragonflies bring great benefits.

The mouthparts of dragonflies are gnawing, the lower lip is spoon-shaped, supporting prey when eating in the air. The long legs are directed forward and lined with strong bristles, with the hind legs being longer than the front ones. This helps the dragonfly catch prey by flying up to it from below.

The thin rod-shaped abdomen acts as a balancer during flight. Males have “tongs” at the top of their abdomen, with which they hold the female by the neck during mating. Such “tandems” of dragonflies can often be observed near water bodies. Female dragonflies drop their eggs into the water or place them in the tissues of aquatic plants using a piercing ovipositor.

The color of dragonflies is dominated by blue, green, and yellow tones; a bright metallic sheen is less common. Some have spotted or darkened wings. In dried specimens, the color fades greatly and changes.

The development of all dragonflies necessarily passes through the aquatic stage - the nymph (this is the name given to insect larvae that have the rudiments of wings). All dragonfly nymphs are voracious predators, capturing prey with a modified lower lip - a mask, which rapidly opens and is thrown forward, while the claws at its front end, like stilettos, penetrate deeply into the victim. When the mask is folded, the prey is pulled to the mouth and quietly chewed. For breathing, nymphs use the hindgut, which, like a pump, constantly pumps oxygen-rich water through the anus. Based on size, structural features and habits, dragonfly nymphs are divided into a number of groups.

Order Caddis flies (Trichoptera)

Caddis flies are close relatives of Lepidoptera, but their wings are covered with hairs rather than scales. These are also driving insects. Many species fly at night towards light near bodies of water. Adult caddisflies do not feed and do not live long. They are only able to lick drops of dew or rain, and some have a reduced oral apparatus. Clutches of eggs look like slimy lumps and attach to underwater rocks or plants. The larva pupates underwater in a case constructed by it. To exit the imago, the pupa floats to the surface, rowing its middle legs like oars.

In the Baikal region, about 150 species of caddisflies belonging to 15 families have been recorded. Including 22 endemic species belonging to the family Apataniidae are known from Baikal. Of the species with a wide distribution, the most common are representatives of the genus Limnephilus, the larvae of which live in stagnant bodies of water. The color of these caddis flies is brown or with a variegated pattern. Sizes medium or large. Representatives of the Phryganeidae family also have variegated wings. The appearance of small caddisflies from the family Lepidostomatidae is very peculiar. The first segments of their antennae are much larger than the others and densely pubescent. Apataniidae are close to true caddis flies and are often considered as part of them. These are fragile insects of small size, sometimes with a light pattern. Most of the endemics of Lake Baikal belong to the tribe Baicalinini. It is these caddis flies that appear en masse on the shores of Lake Baikal in spring and early summer, clinging to coastal stones and plants.

In early spring in April-May, after Lake Baikal has opened up from the ice, a huge number of adult caddis flies accumulate in the surf on the surface of the ice, water and rocky shore. These are dark gray tamastes (Thamastes dipterus) and Baicalina thamastoides. In June there is a massive emergence of caddis flies. yellow color beautiful baicalina (Baicalina bellicosa). The body and wings of insects are densely covered with hairs; they almost do not fly due to undeveloped hind wings. They live for several days, mate, lay eggs in the form of gelatinous round clutches in water or on moistened stones, and then die.

Squad Mayfly. Order Diptera.

Order Mayflies (Ephemeroptera)

Mayflies, along with dragonflies, are among the oldest insects, the fossil remains of which are known from the Devonian period. The Greek word "ephemeron", from which the scientific name of the order is derived, means fleeting, quickly passing. Indeed, mayfly adults live from several hours to several days without feeding at all. These are delicate, slender insects with transparent wings that point upward when at rest. The characteristic posture of a sitting mayfly is with raised front legs and an abdomen, on top of which there are 2 or 3 tail filaments. The intestines are filled with air, which the mayfly swallows, so the abdomen, like a balloon, performs an aerostatic function.

Large compound eyes in males are divided into two lobes - upper and lower. The upper ones can be larger, mushroom-shaped or turban-shaped in shape. The antennae are short and subulate. The oral organs are completely reduced.

In the development of mayflies, a unique process for winged insects is observed - molting in the adult stage. A winged individual emerges from the larva - the subimago, which after a few seconds or minutes moults into the adult. The latter begins to reproduce.

The emergence of mayflies is often massive, and swarming of insects can be observed, during which the sexes meet. Eggs are laid in the water immediately after mating or after a short time, after which the insects die, covering the banks of reservoirs with their bodies.

Order Diptera (Diptera)

The Diptera order includes about 80 thousand species and is considered one of the most advanced among insects. In Russian, dipterans with long limbs are classified as mosquitoes, while the rest are called flies, which in no way corresponds to the scientific classification of the order. The appearance of dipterans is characteristic, primarily due to the reduction of the hind wings, which are transformed into short halteres. However, these are not useless rudiments. Covered a large number sensitive receptors, the halteres stimulate the nervous system and ensure the rapid activation of the front wings and the start of dipterans, while at the same time being flight stabilizers.

Diptera usually have a large, often spherical head with large eyes, which in males may touch on the forehead. Antennae are of two types - multi-segmented in the suborder long-whiskered dipterans and three-segmented in the suborder short-whiskered dipterans. The mouthparts are transformed into various proboscis. In those that feed on liquid organic substances these are sucking or licking-sucking organs, in bloodsuckers they are piercing-sucking.

Due to dipterus, the mesothorax is especially developed. There is noticeable costalization of the wing, i.e. thickening of the anterior veins and moving them to the anterior edge. The flight of dipterans is very perfect, especially in hoverflies, with quick start and hovering in the air. Mosquitoes can beat their wings up to 1,000 times per second, although they fly relatively slowly.

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

Order Hemiptera. Butterfly Squad.

Order Hemiptera, or Bugs (Heteroptera)

They have a piercing-sucking proboscis, which extends from the front edge of the head, which is how they differ from homoptera. Antennae 4-5-segmented. The wings are folded flat on the back, their base is rigid, and the apex is membranous. Depending on their lifestyle, bedbugs have legs that are running, walking, swimming, as well as digging and grasping. The mesothorax is the most massive, forming a shield on top, especially large in turtle bugs. The openings of the scent glands open on the metathorax. Everyone is familiar with the unique smell of bedbugs. This is what unsaturated cimicic acid smells like. The secretion of the odorous glands serves to scare off enemies and attract individuals of the opposite sex. Carnivorous and aquatic bugs do not have scent glands.

Bedbug eggs look like a barrel with a lid. The transformation is incomplete, the larvae are similar to the imago and from the 3rd instar acquire the rudiments of wings. Unlike adults, they do not have simple ocelli, and the openings of the scent glands open on the dorsal side of the abdomen with three unpaired openings. The larvae go through several instars and develop from several weeks to two years.

Butterflies or Lepidoptera

(Lepidoptera, see table “Butterflies” I - IV) - form a large order of insects, comprising up to 22,000 species, including up to 3,500 species in the Russian Empire (in European and Asian Russia). These are insects with sucking mouthparts, forming for the most part a spirally coiled proboscis, with four uniform membranous wings, covered with small, pollen-like, colored scales, and with complete metamorphosis. The body of butterflies, like other insects, covered with thick hairs, is divided into the head, chest and abdomen. The head bears the breasts, mouthparts and eyes. The ligaments are multi-jointed and can be quite various shapes: most often bristly, filamentous or club-shaped, sometimes serrated, combed or feathery. The mouthparts are adapted for receiving liquid food, especially for lapping up sweet honey juices; Only in a few butterflies are they very rudimentary and do not function; in some silkworms, for example, in the silkworm, in the fine hop moth. The upper lip and upper jaws of butterflies are constantly rudimentary; the lower jaws, on the contrary, are strongly elongated, grooved and fused into a more or less long proboscis, which in a calm state is spirally curled and clasped from the sides by three-segmented labial palps, densely covered with hairs. There are either no jaw palps at all, or they are rudimentary and consist of 1 - 2 joints, and only in moths they have 6 joints. In addition to two large faceted, or compound eyes, some butterflies have 2 more pinpoint, or simple, ocelli. The chest, like the whole body, is densely covered with hairs; the first or anterior ring is poorly developed and is free, and the other two are fused to each other; Only in a few butterflies is each of them separate (for example, in the hop weed). There are two pairs of wings; both of them are homogeneous, membranous. with few veins and covered with small, imbricated scales, which are of very varied colors and different shapes; they can be wide or long, thick or thin, round or angular, blunt or sharp, with smooth edges or jagged, stalked or without a stalk. Butterfly wings b. h. large.; the front pair is larger than the back pair. Their general outline is very varied: some have solid edges, while others have cutouts. In some, like, for example, in pinnate wings, the cuts reach almost to the very base of the wing; still others have tail-like appendages on their wings, etc. In a few butterflies, females have rudimentary wings in the form of two small lobes; for example, in the carrier silkworm and the winter moth (Acidalia brumata); In bagworms (Psyche), females are wingless. In a few butterflies, some places on the wings are not covered with scales and look like transparent spots (windows), for example, in the atlas (Attacus Atlas), or the wings are transparent, glassy, ​​due to the fact that they have very few scales (dust) that quickly wear off. , for example, in glassware. When flying inner edge the fore wing fits tightly onto the anterior edge of the hind wing, and in most B. both wings have an even closer connection: at the base of the hind wing there is a bristle or tuft of hairs, which enters into a ring-shaped, hook-shaped or groove-shaped formation located on the front wing; this device, the so-called clip, makes it easier to spread the wings; it is found only in butterflies and does not occur in insects of other orders. It is remarkable that many birds have designs in the form of numbers and letters on their wings. So, on the underside of the admiral's wings there is a pattern in the form of the number 786. In the corner-wing, there is a white S. - in the middle of the hind wings, a pattern in the form of the German letter C. In the silkworm, tau - in the form of the Greek letter τ. In the turf owl's head (Acronycta psi) - in the form of the Greek letter ψ; on the front wings of the rich gamma (Plusia gamma, see Table II, Fig. 16) - in the form of the letter γ. The owl's head has chi (Polia chi) - in the form of the letter χ; in the exclamation owlet (Agrotis exclamationis) in the form of an exclamation, and in the interrogative owlet (Agrotis interrogationis) in the form of a question mark, etc. Wing venation (Plate III, Fig. 21) is a differential feature in determining species and genera of butterflies. The wing represents a large middle cell starting from the base of the wing and giving 4-8 radial veins to the lateral parts (margins) of the wing; in addition, above and below the middle cell, parallel to the upper and lower margins, several longitudinal veins extend from the base of the wing. B.'s legs are tender and weak and have mostly five-jointed tarsi; The first pair of legs in some species is less developed than others. The abdomen is either adjacent to the chest throughout (sessile) or separated from it by a slight constriction (stalked abdomen). It consists of 6 or 7 segments and is densely covered with hairs; in females of some species, a brush of thick and long hairs or a protruding and retractable ovipositor is placed at the end of it. In terms of internal organization, butterflies differ from other insects in some features. Their nervous system consists of a supraglottic node with large eye lobes, a subpharyngeal node, mostly two thoracic and four abdominal nodes (less often, there are three thoracic nodes and five abdominal nodes, for example, in the hop weed, Hepiatus humuli). Butterflies, like most insects, have a sympathetic nervous system . The digestive organs consist of the esophagus, equipped with a stalked crop on the side, the stomach and the intestinal canal, which is divided into the small and large intestines. On the sides of the esophagus there are two tubular salivary glands that open into the oral cavity. On the sides of the stomach and intestinal canal, three Malpighian vessels (organs that secrete urine) are placed on each side, which open at the beginning of the intestine on each side through one common vessel, with which all three are connected. Some butterflies (hawk moths, moths) have an elongated sac-like process on the large intestine, the so-called cecum. The heart of butterflies, like that of all insects, is a multi-chambered tube located on the back. The respiratory organs consist of numerous branched respiratory tubes (tracheas), distributing their small branches throughout the body. These respiratory tubes open outward with spiracles located on the sides of the body through which air enters when inhaled and comes out when exhaled. Male reproductive organs (consist of two testes enclosed in one common, mostly brightly colored sac, of two vas deferens, in places representing extensions (seminal vesicles) and connected into one common ejaculatory canal, which ends at the base of a hard, chitinous, copulatory organ. The female reproductive organs of butterflies consist of two ovaries, two oviducts connected into one common tube - the vagina, which opens outwards with a hole.The vagina is connected to: the seminal receptacle and adnexal glands, and many butterflies also have a copulatory pouch.Males and females are often more or less differ greatly from each other. These differences are very varied. Very often the entire sexual difference is limited only to the fact that the male has a shorter and more cylindrical abdomen, for the most part the female is somewhat larger than the male and has a less bright color and a less distinct wing pattern. In some species females have, as we have already pointed out, wings that are underdeveloped and not suitable for flying, for example, those of the silkworm, the porter, or they do not have them at all (for example, the winter moth, Hibenna defoliaria). In bagworms, females are larval-shaped and completely wingless. There are no wingless males. Sometimes both sexes have wings, but in males they have a different shape than in females or they are of a different color, for example, in males of the hop weed (Hepialus humuli) wings are white, and in females they are yellow. In some butterflies, sexual differences are noticeable in the shape of the mantles: for example, in males the mantles are comb-shaped, and in females they are serrated or thread-like.

Squad Cockroaches. Squad Beetles

Squad Cockroaches (Blattodea)

Cockroaches and mantises are groups often combined into the order Dictyoptera, where they are considered suborders. The basis for this association is the similar structure of the wings, mouthparts and genitalia.

Cockroaches have a strongly bent (hypognathic) head, covered from above by the anterior edge of the pronotum. The antennae are long, bristle-like, the eyes are well developed, and there are simple ocelli. The forewings are leathery (elytra), with simple longitudinal venation, the hind wings with rich reticulate venation, folded fan-shaped at rest. They fly poorly and reluctantly; in many species the wings are shortened or completely reduced. The legs are strong, running, with large coxae, covered with spines, the tarsi are 5-segmented. End of abdomen with short segmented cerci. The abdomen of males is often with scent glands, and the copulatory organs are asymmetrical.

The female's abdomen ends with sternite VII, called the genital plate, which covers the genital chamber from below. The latter is formed due to the invagination of sternite VIII together with the ovipositor. It should be said that in extinct cockroaches the ovipositor was an external organ. Ripe eggs enter the genital chamber and are glued together with the secretion of special glands, forming an ootheca. The ooteca contains from 15 to 40 eggs; its shape and surface sculpture are species-specific. Some species shed the ootheca almost immediately after its formation (American cockroach), others carry it at the end of the abdomen almost until the young hatch (German cockroach), in others the ootheca is located in the genital chamber and hatching occurs right there, which is a typical ovoviviparity (Madagascar cockroach) . In the latter case, the eggs receive the necessary substances from the mother's body.

The transformation is incomplete. Larvae undergo 5-9 molts, small species develop faster, large species may take a year or more to fully develop. Life expectancy is from 1 year to 7 years.

All cockroaches are nocturnal, hiding during the day in various cavities and holes. The largest number of species live in the tropics, mainly associated with humid forests. Many detritivorous species are important as active destroyers of litter and rotting wood. The Far Eastern relict cockroach and other species that feed on rotten wood have symbiotic protozoa in their intestines that help them digest fiber. Similar cockroaches from the genus Cryptocercus, living in colonies, lead a very social lifestyle.

Order Coleoptera or Beetles (Coleoptera)

The huge order of Coleoptera numbers more than 300 thousand species worldwide, accounting for a quarter of all insects. Over 3,000 species of beetles live in the Baikal region.

The largest species of our fauna include the emerald ground beetle (Carabus smaragdinus) (up to 35 mm in length with mandibles), the Urussov's longhorn beetle (Monochamus urussovi) (up to 35 mm), and the large pine borer (Buprestis mariana) (up to 32 mm). The smallest beetles are found in the family of winged beetles (Ptiliidae) - less than 1 mm.

The color, shape and structure of beetles' covers are extremely diverse, many are very beautiful, which makes beetles one of the favorite collectibles. The compact body shape with dense elytra allows the beetles to colonize a wide variety of substrates. Their gnawing mouthparts have various modifications and are adapted to feeding on any food. Development with complete metamorphosis and a variety of larval types allow beetles to adapt to different habitats. All of the above makes beetles one of the groups of insects most adapted to living on land and explains their high species diversity.

Order Orthoptera. Flea Squad.

Order Orthoptera (Orthoptera)

The appearance of Orthoptera is varied, but very characteristic. These are large or medium-sized insects with a chewing mouthpart, jumping hind legs and usually long antennae, sometimes exceeding the length of the body. Orthopterans are also characterized by a large pronotum hanging over the sides. Female grasshoppers have a flat cross-section xiphoid ovipositor, which in some species may be short and serrated at the apex. In female candles, the ovipositor is round in cross section, spear-shaped. Locusts and jumpers have a digging ovipositor consisting of 4 finger-shaped valves.

Orthoptera have various organs of chirring and hearing. Males lure females to the sounds of the mating song. The sounds emitted can be territorial and defensive in nature. Some of the sounds of locusts are in the ultrasonic range and are inaccessible to the human ear.

Reproduction by laying eggs. Grasshoppers and crickets lay eggs singly in soil or turf using a long ovipositor. Stem crickets and some grasshoppers place eggs in plant tissue by sawing through them with their ovipositor. Locusts dig a hole in the soil where they lay a portion of eggs, filling them with foamy secretions of the accessory glands. As this mass hardens, with soil particles adhering to it, it forms a capsule characteristic of each species. In the Baikal region, all species develop in one generation. Eggs overwinter; only quails can overwinter larvae.

In general, Orthoptera are heat-loving insects that prefer open spaces; only a few species live under the forest canopy. There are two life forms with some variations:

1. Phytophiles, stay on plants

1.1. Hortobionts, inhabitants of the herbaceous layer (some locusts and grasshoppers)

1.2. Tamnobionts, inhabitants of the crowns of trees and shrubs (grasshoppers and stem crickets)

2. Geophiles, live on or in the soil

2.1. Open geophiles, staying on the soil surface (many locusts)

2.2. Hidden geophiles, dig holes in the soil (crickets, quails)

2.3. Geobionts lead an underground lifestyle (mole crickets)

Order Fleas (Siphonaptera)

The body structure of fleas is adapted to movement in the fur of a host animal in approximately the same way as the body structure of a locust is adapted to movement in grass cover - it is strongly flattened laterally. The hind legs of fleas are jumping, the tarsi of all legs are well developed, 5-segmented, ending with 2 claws. The head is small, there are short antennae on the head, and a simple eye in front of them.

The mouth parts of fleas are adapted for piercing the skin and sucking blood; the skin is pierced by serrated mandibles. When feeding, fleas fill their stomach with blood, which can become very swollen.

Male fleas are smaller than females. Fertilized females forcefully throw out eggs, usually in portions of several pieces so that the eggs do not remain on the animal’s fur, but fall to the ground, usually in the host animal’s burrow or in other places that it constantly visits.

A legless but very mobile worm-like larva emerges from the egg (Fig. 430, 2) with a well-developed head. For further development, the larva needs sufficient moisture, so it burrows into the ground or debris in the host's nest or burrow. The larva feeds on various decaying remains, and in many species it also needs to feed on the remains of undigested blood contained in the feces of adult fleas.

The grown larva spins itself a cobweb cocoon, protected from above by dust and grains of sand, and pupates in it. The flea pupa is typically free. The adult flea emerging from the pupa lies in wait for the host animal.

Some more polyphagous fleas can attack any animal; The flea of ​​monotremes and marsupials in Australia (Echidnophaga ambuans) is known to feed temporarily on snakes, and some of our fleas even feed on caterpillars! But fleas can exist and reproduce normally only on animals that suit them.

There are many fleas where there are places for their larvae to develop - dirty cracks in the floor, dirty carpets, etc., where in dust and garbage the larvae can feed on various decaying remains and feces of adult fleas.

Fleas are an insect order that is difficult to associate with other groups. The structure of the larvae resembles dipterans; the pupa and some structural details of adult fleas make them similar to beetles.

Squad Lice. Order Hymenoptera

Order Lice (Anoplura)

Lice are sucking insects. Their mouthparts are adapted for piercing the dense integument of the host animal and sucking blood. The oral parts are transformed into piercing needles, enclosed in a soft tube that is everted from the oral cavity, the edges of which are tightly pressed against the skin of the host animal, which is pierced by stylets.

When sucking blood, the anterior section of the louse's esophagus expands, acting as a pump. The secretions of powerfully developed salivary glands entering the wound prevent blood clotting. When the louse is not feeding, the oral organs that form the proboscis are retracted into the head capsule. The eyes of lice either have only small pigmented spots or are completely absent. The antennae are short, and there are no palps associated with the oral organs at all. The chest is well separated from the head, all segments of the chest are fused.

Order Hymenoptera (Hymenoptera)

Hymenoptera (Hymenoptera) is one of the most advanced orders of insects in the evolutionary pan. Currently, they are distributed across all continents except Antarctica. Some Hymenoptera, such as bumblebees, are among the northernmost insects. Adult insects have two pairs of membranous wings covered with relatively sparse veins, and small forms are usually almost or completely devoid of veining. The rear pair of wings is smaller and has a subordinate importance during flight. In living insects, both pairs of wings are usually attached to each other using hooks and work as one plane. Some species (worker ants, female drinids, Germans and some betilids and ichneumon fly) do not have wings.

The mouthparts are gnawing or licking-gnawing. In the latter case, the lower lip and lower jaws are extended and form a proboscis with a tongue at the end. This mouthpart is used to suck nectar from flowers. The mandibles are well developed in all species and are used not only for feeding, but also for building nests, digging soil, etc. Some ants have a bizarre shape and exceed the length of their heads.

The antennae are simple, club-shaped, comb-shaped, feathery, and can be either straight or geniculate. In the latter case, their first segment is elongated and is called the handle, and the remaining segments form a flagellum. The number of antennal segments varies from 3 to 70. The head has a pair of complex compound eyes and 3 simple ocelli, but some ants are completely blind.

Legs running with 5-segmented tarsus. The tibia and tarsus of the foreleg sometimes bear a special apparatus for cleaning the antennae and tarsi, formed by a comb spur at the end of the tibia and a notch on the first segment of the tarsus.

An interesting feature of Hymenoptera is that their females, as a rule, lay either haploid or diploid eggs. Of the former, males always develop, of the latter, only females. In typical cases, haploid eggs are unfertilized, and diploid eggs are fertilized. However, in some cases, parthenogenesis is observed. In this case, during the formation of eggs, one reduction division occurs, and unfertilized eggs remain diploid.

The transformation is complete. Sawfly larvae are very similar in appearance to caterpillars and are therefore called false caterpillars.

Sexual dimorphism is well expressed. There is often polymorphism in which there are several forms of females. Social Hymenoptera (ants, bees, wasps) develop a caste of worker individuals - sterile females who perform various tasks in the nest. The polymorphism is most pronounced in ants, where workers are always wingless. Within this caste, some ants exhibit further subdivision into subcastes of soldiers, “honey barrels,” etc. In some species the number of sharply distinct worker subcastes reaches six. All this is due to the complex division of functions in the ant family.

The lifestyle of Hymenoptera is extremely diverse. Horntails typically develop in the wood of trees. The larvae of most sawflies feed on plant leaves, and in general this group is biologically similar to butterflies, which is reflected in the convergent similarity of the larvae. Among the stinging Hymenoptera we find a huge variety of complex instinctive activities associated with the care of offspring, the pinnacle of which is the “social” behavior of ants, folded winged wasps and bees.

Insects are pests of fruit crops.

The army of fruit crop pests consists of:

- sucking pests, including aphids (insects with incomplete transformation. In their development they have winged and wingless forms), psyllids or copperheads (small insects capable of flying and jumping well, their hind legs are of the jumping type. When feeding, psyllid larvae excrete excrement in the form of sugary sticky liquid - “honeydew”, for which they are called copperheads), mites (herbivorous mites that damage fruit crops, belong to the families of spider mites, brown mites, gall mites and flat beetles);

- pests of reproductive organs , including fruit weevils (they got their name from the peculiar structure of the head. In most species it is extended forward and forms the so-called head-tube, on which there are mouthparts, geniculate or straight club-shaped antennae. Under this name beetles from two families are united - weevils and tubeworms. Fruit trees are damaged by more than 10 species of these pests. Some gnaw out the blossoming buds, others, eating the stamens and pistils in the buds, do not allow the fruits to set, others cause the fruits to fall off and rot, etc. To determine which beetles - weevils have settled in the garden, it is enough to shake them off the tree during the swelling of the buds onto the litter spread under it in the morning, when the beetles are not yet flying. The beetles are characterized by the phenomenon of temporary immobility (akinesis) in case of their sharp irritation. Pests also differ in their food specialization), fruit sawflies, bronze moths, codling moths;

- leaf-eating pests , which include representatives of the families of white moths, moths, cocoon moths, bear moths, and true moths. They cause considerable damage to fruit trees. The hatched caterpillars damage the buds and buds. Along with their development, their harmfulness also increases. Younger caterpillars skeletonize leaves or feed on the pulp inside them. As they grow up, they eat the leaves from the edges, and when they mature, they eat up the entire leaf blade, leaving only thick veins.

With the massive development of gnawing pests, it is painful to look at damaged trees. Such trees shed their ovaries, and the remaining fruits grow small and tasteless. But even a severely damaged tree tries to survive. Eaten by caterpillars in the spring, by mid-summer it turns green again. However, a weakened tree no longer produces normal growth and cannot lay the required number of fruit buds for next year’s harvest. If the damage is severe, trees do not tolerate drought well and are poorly prepared for winter, as a result of which they suffer more during the winter. In the future, weakened trees are readily colonized by bark beetles and other pests. Leaf-gnawing pests often appear in gardens from shelterbelts, deciduous forests bordering fruit plantings. Developing en masse, they cause damage to perennial plantings.

- pests of trunks and trees . This group includes insects of different families, differing from each other not only in their lifestyle, but also in their way of feeding.

Significant damage to fruit trees is caused by Californian, false California and apple comma scale insects, plum and acacia false scale insects. These sucking pests are very widespread and, when heavily infested, cause branches and even trees to dry out.

Bast and water-conducting layer of sapwood of trunks and branches fruit trees Bark beetles feed on wrinkled and fruit sapwood, and gypsy bark beetles. By boring holes under the bark, they disrupt sap flow and cause the death of entire branches.

In the wood of shoots, main branches and trunks, caterpillars of the corrosive woodworm, odorous carpenter moth and apple glassworm live and actively feed for 2 years without coming to the surface. Infested with pests, trees weaken, grow poorly, and stop bearing fruit early.

The large peach aphid also causes considerable damage to stone fruit trees. Unlike other representatives of the huge family, it leads a monoecious development cycle on the trunks and skeletal branches of fruit trees.

Leaf rollers, from the family of which about 70 species damage fruit and berry crops in gardens. Many of them are polyphagous, damaging all fruit and forest deciduous trees, berries and ornamental shrubs. Caterpillars of most species live in folded leaves, which is how the insects got their name. Many species are very similar in the nature of damage, developmental biology and phenology, and it is not always possible to establish species identity based on feeding larvae. The most dangerous ones in gardens are roseate and variegated leaf rollers.

Insects - crop pests

Agricultural plant pests are animals that damage crop plants or cause their death. The damage caused by pests and plant diseases is great. Among vertebrates there are many V. s. R. in the class of mammals, especially in the order of rodents. Of the invertebrate animals of agriculture. plants damage some species of gastropods; significant amount roundworms from the class of nematodes. The most diverse and numerous types of V. s. r., belonging to the type of arthropod animals: the class of insects, the class of arachnids (Ticks), some species from the class of centipedes and crustaceans (woodlice).

The greatest damage to the crop is caused by insects, which is explained primarily by their biological features, abundance of species, high fertility and speed of reproduction. Insects harmful to agriculture are classified according to a systematic principle (by orders) and by the nature of their diet. Herbivorous insects and mites are divided into polyphagous, or polyphagous, feeding on plants of different families; oligophages, or limited eaters, feeding on plants of different species of the same family; monophages, or monovores, - mainly plants of one species. Polyphagous pests cause great damage to the harvest of various crops: locusts, some crickets (for example, mole crickets); from beetles - click beetles, darkling beetles and others; among butterflies - the winter cutworm and related species of gnawing cutworms, stem moths, gamma cutworms, etc. There are numerous limited-eating insects, which include the Swedish fly, the green-eyed fly, the Hessian fly, the kuzka bread beetle and many others that feed exclusively on cereal plants. Nodule weevils, pea codling moths, pea aphids and others damage legume plants. There are very diverse types of insects that feed on cruciferous plants - cabbage whites, cabbage moths, cruciferous flea beetles, cabbage flies, etc. Of the monovores, phylloxera is very harmful, damaging the grapevine, pea weevil - peas, clover weevil - clover, etc. Harmful insects and mites are also classified according to the groups of crops they damage - pests of cereals, pests vegetable crops etc., which is convenient for practical purposes.

There are two main types of plant damage; the first is characteristic of insects with gnawing, the second with piercing-sucking mouthparts. Gnawing insects eat plants roughly or partially from the edges of leaves, skeletonize leaves, gnaw parenchyma, etc., gnaw or partially gnaw leaves, stems and shoots, eat through passages, mine leaves and stems, gnaw bast, cambium and wood under the bark, etc. e. Piercing-sucking insects, for example, aphids, bugs, etc., before feeding, introduce secretions of the salivary glands into plants, the enzymes of which cause a number of biochemical changes. Often these or those V. with. R. in their nutrition they are confined to certain plant organs. Hence the groups of pests of roots, stems, leaves, buds, flowers, fruits, etc. An important species feature of V. s. R. There is also, to one degree or another, pronounced selectivity in relation to the age and physiological state of the damaged plant organ. Thus, aphids prefer to feed on young tissues, the cherry slimy sawfly on adult tissues, etc.

V.'s distribution with. R. and the formation of a complex of species in certain agrobiocenoses are directly dependent on changing conditions environment and ecological plasticity of species.

For the development and reproduction of insects and mites, temperature conditions. Each species has a specific temperature regime, at which all life processes are most intensive. Large deviations from the optimum often cause the death of the pest. The ability of insects to tolerate long-term cooling varies not only among individual species, but even among one species, depending on its physiological state. For insects whose development is associated with the soil, its chemical composition, acidity, physical structure, aeration and humidity are essential. By influencing these factors using agricultural techniques (soil cultivation, fertilization, etc.), it is possible to significantly change conditions in a direction unfavorable for harmful insects. For example, liming of acidic soils worsens the breeding conditions for many species of click beetles. Among other factors, the reproduction of pests is significantly influenced by the interaction of V. with. R. with other animal organisms

Fight against V. s. R. is to implement systems of measures based on a rational and differentiated combination various methods aimed primarily at solving preventive problems.

The meaning of insects

The importance of insects in nature

Insects make up about 80% of all animals on Earth; according to various estimates, there are from 2 to 10 million species of insects in the modern fauna, of which just over 1 million are known so far. Actively participating in the cycle of substances, insects play a global planetary role in nature.

More than 80% of plants are pollinated by insects, and it is safe to say that a flower is the result of the joint evolution of plants and insects. The adaptations of flowering plants to attract insects are varied: pollen, nectar, essential oils, aroma, shape and color of the flower. Adaptations of insects: sucking proboscis of butterflies, gnawing-licking proboscis of bees; special pollen-collecting apparatus - bees and bumblebees have a brush and a basket on the hind legs, megachila bees have an abdominal brush, numerous hairs on the legs and body.

Insects play a huge role in soil formation. Such participation is associated not only with loosening the soil and enriching it with humus by soil insects and their larvae, but also with the decomposition of plant and animal residues - plant litter, corpses and animal excrement, while simultaneously fulfilling a sanitary role and the circulation of substances in nature.

The following types of insects perform a sanitary role:

· coprophagous - dung beetles, dung flies, cow flies;

· necrophages - carrion beetles, gravediggers, skin beetles, meat-eating flies, carrion flies;

· insects - destroyers of dead plant debris: wood, branches, leaves, pine needles - borer beetles, longhorned beetle larvae, golden beetles, horntails, long-legged mosquitoes, carpenter ants, fungus gnats, etc.;

· insects - orderlies of reservoirs feed on suspended or settled rotting organic matter (detritus) - the larvae of mosquitoes, or bells, mayflies, caddis flies, purify the water and serve as a bioindicator of its sanitary condition.

The importance of insects in human life

In human life and economic activity they have both positive and negative meaning.

Of the more than 1 million insect species, only about 1% are actual pests that need to be controlled. The bulk of insects are indifferent to humans or beneficial. Domesticated insects are the honey bee and the silkworm; beekeeping and sericulture are based on their breeding. The honey bee produces honey, wax, propolis (bee glue), apilak (bee venom), royal jelly; silkworm - a silk thread secreted by the spinning glands of a caterpillar during the construction of a cocoon; the silk thread is continuous, up to 1000 m in length. In addition to these insects, valuable products are produced by: caterpillars of the oak cocoon moth, their coarser silk thread is used to make tussock fabric; lac bugs secrete shellac, a wax-like substance with insulating properties used in radio and electrical engineering; carmine bugs (Mexican and Ararat cochineal) produce red carmine dye; Blister beetles secrete a caustic substance called cantharidin, which is used to make blister plaster.

Pollinating insects, representatives of many orders, among which Hymenoptera occupy an important place, increase the yield of seeds, berries, fruits, and many flowers cultivated plants- fruit and berry, vegetable, fodder, flower.

The Drosophila fruit fly, due to its fertility and reproduction rate, is not only a classic object of genetics research, but also one of the ideal experimental animals for biological research in space. Fossil insects are used in stratigraphy to determine the age of sedimentary rocks.

Sense organs of chordates

The fish has a relatively small, but fairly well-developed brain, from which nerves arise, including: olfactory, visual, acoustic and gustatory. The spinal cord serves primarily to receive signals coming from the brain.

In the area of ​​the snout, which is characterized by the distance from the beginning of the head to the anterior edge of the eye, the nasal openings and mouth are located. The position and structure of the mouth depends on the method of feeding. The mouth opening is often framed by lips. Near the mouth, in most cases in the snout area, there may be long outgrowths - antennae, which serve as organs of touch and have taste cells that help the fish in finding food.

The eyes are located on both sides of the head, which provides a large field of vision. Most fish have eyes located on the sides of the head, closer to the end of the snout than to the gills. The distance between the eyes, measured across the top of the head, is called the width of the forehead.

A unique sensory organ is, often clearly visible, the lateral line, consisting of small holes in the scales, which are the exits of the canals connected to the sensitive cells of the subcutaneous canal. In most fish, the lateral line is complete and runs in an almost straight line along the side of the body from the head to the caudal fin. But it may also be incomplete, i.e. occupy several scales, intermittent or completely absent.

Comparative characteristics of the digestive system of chordates.

The digestive tract consists of the oral opening, oral cavity, pharyngeal cavity, esophagus, stomach (absent in cyprinids), intestines, rectum and accessory organs involved in the digestion of food. In most cases, the oral cavity contains teeth, which, after wear, are often renewed. The pharyngeal cavity is cut through by gill slits, and the gill rakers prevent food from exiting through them. This is followed by a short and narrow esophagus, which passes into the stomach, which is connected to the intestines. In carnivorous fish it is short, in herbivorous fish it is long and spirally coiled. There are mucous glands throughout the digestive tract. Near the intestines are located: a large, fat-rich and vitamin-rich liver and pancreas. These three organs digest food, i.e. decompose it into its simplest components and then assimilate it. Undigested residues are sent to the rectum and exit through the anus. The kidneys, which excrete waste, are located close to the spinal column and connect at the back. The ureters, also connected, flow into the bladder, from where a duct emerges, exiting next to the genital opening.

Ecological groups of fish

The ecological classification of fish can be based on two starting points: 1) their relationship to the salinity of the water and 2) their dependence on their habitat in the basins.

In relation to salinity, the following main groups are distinguished: marine fish, anadromous, semi-anadromous and freshwater.

Marine fish are characterized by the fact that they spend their entire lives in sea water and, when moved to fresh water, as a rule, die very quickly. This includes fish of the vast majority of species.

Migratory fish spend most of their lives in the sea, where they only feed and reproduce in fresh waters(due to the disastrous effect of salt water on their eggs). For the most part, these fish are confined to temperate and cold regions of the northern hemisphere. Examples of migratory fish include most salmonids, in particular noble salmon and Far Eastern chum salmon, almost all sturgeons, and some herrings. Migratory fish also include the river eel (several closely related species) - almost the only fish that lives in fresh water bodies and goes to the sea to reproduce.

Semi-anadromous, or estuarine, fish live in desalinated areas of the sea adjacent to river mouths, but for wintering and breeding they enter only the lower reaches of rivers. This is done, for example, by bream, catfish, carp, pike perch and some other fish of the lower Volga. The same fish in other basins can spend their entire lives in fresh water bodies. Thus, the group of semi-anadromous fish is largely arbitrary.

Freshwater fish live constantly in fresh water and, as a rule, are not found in sea or even salty water.

Based on their habitat in the basin, fish are divided into pelagic, or open water, littoral, or coastal, and abyssal, or deep-sea. Although this classification applies to all fish, both marine and freshwater, it can be carried out especially clearly only for marine ones.

Class Cartilaginous fish. Features of the organization

Cartilaginous fish are the most ancient of the currently existing classes of fish. The most common cartilaginous species are sharks and rays. All cartilaginous fish are characterized by the absence of bones in the skeleton, although cartilage can become quite strong due to the accumulation of minerals in them. Also, cartilaginous fish do not have a swim bladder, so in order not to sink to the bottom, they must constantly swim. Sometimes the role of a float is played by a very large fatty liver, and some sharks are able to swallow air, temporarily providing themselves with buoyancy. In some species of cartilaginous fish, viviparity occurs. The scales of cartilaginous fish underlie their teeth, and sometimes (in stingrays) are shaped like needles or spines.

Today's living cartilaginous fish (Chondrichthyes) are characterized by a cartilaginous, often partially calcified, internal skeleton, the absence of dermal bones, covered with tooth-like (placoid) scales (rarely bare) skin, enamel-covered teeth, 5-7 pairs of external gill slits (in elasmobranchs).

Most cartilaginous fish also have a transverse mouth (which is why they were called transverse mouths - Plagiostomata), from the corners of which nasolabial grooves run to the nostrils; a spiral valve present in the intestine that increases the absorption surface; located in the front of the heart, the arterial cone is equipped with several valves; the brain has a progressive structure. Cartilaginous fish lack a swim bladder. Large eggs; fish lay them on the bottom in horny capsules, or the development of eggs takes place inside the female’s body, as in higher vertebrates.

Almost all cartilaginous fish are marine, only a few species are found in fresh waters. These are ancient fish that first appeared at the end of the Devonian period. At one time they dominated the waters of our planet, and then many groups of cartilaginous fish became extinct.

Currently, cartilaginous fish are represented by two subclasses - the subclass of elasmobranchii (Elasmobranchii) and the subclass of fused-skull, or whole-headed (Holocepha1i).

Over the course of the entire history of development, elasmobranchs have acquired a number of progressive characteristics - viviparity, progressive structure of the brain, high hydrodynamic qualities, etc. This allowed them to withstand competition from bony fishes that quickly developed in eras closer to us. Currently, about 600 species of cartilaginous fish are known.

Fusectranials differ from elasmobranchs in the unique structure of the skull and dental apparatus (described below), as well as in the presence of one gill slits on each side of the head. About 30 species of living fish of this group are known, living mostly in the depths of the sea.

Class Bony fish. Features of the organization

This is the most numerous class of chordates. Its representatives are very diverse in structure, and the taxonomy is complex. The most numerous, highly organized and phylogenetically younger group is the teleost fish. It includes about 20,000 living species. It includes the following orders: herring-like, salmon-like, eel-like, carp-like, cod-like, perch-like and many others.

Features of the organization of bony fish

The method of movement of these fish is fundamentally the same as that of cartilaginous fish. Forward movement is carried out by bending the entire body, mainly the caudal region. Unlike cartilaginous skeletons, they have a bony skeleton. It consists of the spine, skeleton, fins and skull, represented by the brain and visceral sections. The visceral skull is composed of the maxillary, hyoid and gill arches. Bone tissue is also involved in the formation of scales, thin, tiled-like plates that cover the entire body and play a protective role. They have the same fin system as cartilaginous fish. The differences lie in the position of the paired fins on the body. Their bases are located not in a horizontal plane, as in cartilaginous fish, but in a vertical one. This increases maneuverability. Compared to cartilaginous fish, the skeletal structure of paired fins is simplified. The caudal fin has a homocercal shape. Both of its blades are developed symmetrically. The change in the shape of the caudal fin is associated with the appearance of a swim bladder in bony fish, with the help of which vertical movements of fish occur from the depths of the reservoir to the surface and vice versa. The tail fin does not matter in this case. The swim bladder is filled with gas, the volume of which varies. When the volume of the swim bladder increases, the volume of the body increases and decreases accordingly specific gravity, and the fish comes up. In some fish, gas enters the swim bladder through the esophagus, to which the swim bladder is connected. These fish are called open-bladder fish. In others, the bubble does not communicate with the environment. These are closed-vesical fish. In this case, there are clusters of blood vessels in the walls of the bladder - a red spot or gas gland. These vessels either release gas from the blood or absorb it. Due to this, the volume of the bubble changes. In bony fish, the digestive tract is differentiated to the same extent as in cartilaginous fish, but its extent is greater. In this case, the spiral valve disappears in the colon. Consequently, the method of increasing the digestive surface is different in cartilaginous and bony fish. They also differ from cartilaginous fish in the structure of their gills. Their interbranchial septa disappear. Instead of five pairs of gill slits, as a rule, only one remains. The gill slits are covered with bony gill covers, which are absent in cartilaginous ones. In this regard, a more advanced method of breathing appears, in which the gill covers take part. When the operculum rises, water from the oropharyngeal cavity is sucked into the lateral gill cavity. When the lid is lowered, water from the lateral gill cavity is pushed out through the outer gill slits. The differences in the circulatory system are that there is no conus arteriosus in the heart. In adulthood, bony fish have functioning trunk buds. The central nervous system as a whole does not differ from that of cartilaginous fish, but the forebrain is less developed. In its roof there is no gray matter, which is concentrated at the bottom of the ventricles, in the striatum. In terms of the degree of development of sensory organs, bony fish do not differ from cartilaginous fish. Reproduction. The testes and ovaries are paired. Females do not have reproductive ducts, and the ovary opens outwards with a special opening. In males, the reproductive ducts are channels representing a new formation characteristic only of bony fish. There is no cloaca. Fertilization is external. Caring for the offspring is expressed in a huge number of eggs laid. Many eggs die, but enough remain to continue the species.

Ecological groups of birds.

Birds of meadows and fields nest and feed on the ground. They unite representatives of many orders: larks, wagtails (passeriformes order), lapwings (wader order), cranes (crane-like order), partridges and quails (gallinaceae order), corncrakes (Granaceae order).

Birds of swamps and coasts forage from the surface of the earth, from the bottom or wet ground, and therefore some of them have ankle-legged and thin fingers without membranes (herons and storks - a stork order), others have membranes on their legs (swans, geese , goose, ducks, teals, dives - anseriform detachment. The life of many birds is closely connected with the reservoirs in which they forage. Waterfowl, as the name itself shows, are able to swim, and many of them also dive. In connection with adaptation to swimming and diving, waterfowl have webbing between the toes, and the legs themselves are set far back.On the ground, most waterfowl move slowly and clumsily.The plumage of waterfowl is protected from getting wet mainly by the structure of the feather cover.The dense interweaving of feather and downy beards forms a thick layer with water-repellent outer surface. In addition, countless air bubbles enclosed in the thinnest cavities of the plumage layers contribute to water resistance. Lubricating the feathers with secretions from the coccygeal gland is also important for protection from water: it preserves the natural structure, shape and elasticity of the feathers, forming a waterproof layer. Order Stork-like. The white stork is a large bird with large black wings and long, red legs. Storks live among open spaces with sparsely located groups of trees, in places where there are extensive low-lying meadows, swamps, and ponds. Thanks to its long legs, the stork can go far into the water. By using long fingers with a small membrane between their bases, the stork confidently walks through swampy places

Birds of deserts and steppes are inhabitants of vast open spaces with sparse vegetation. It is difficult to find shelter here, and therefore many birds living in steppes and deserts have long legs and necks. This allows them to scan the area far away and see approaching predators in advance. Birds of steppes and deserts find their food on the ground, among vegetation. They have to walk a lot in search of food, and therefore the legs of these birds are usually well developed. Some species save themselves not by flying away, but by running away from danger. In these environmental conditions, 2 groups are distinguished:

Running birds: ostriches, bustards, little bustards. They live in flocks: they move with the help of their legs (ostriches do not fly at all). They nest and feed on the ground and are of commercial importance;

Fast-flying birds - sajja, hazel grouse (desp. hazel grouse). These also include the eagle living in the steppes (negative diurnal predators), which destroys mouse-like rodents. Due to overfishing and plowing of lands, their numbers have greatly decreased. The bustard, little bustard, white crane (Siberian crane), and demoiselle crane are listed in the Red Book of Russia. Squad of cranes. In April, they fly high in the sky accompanied by loud purring. The cranes lined up in triangles. They return from Africa and South Asia to their breeding grounds. Most cranes live in wetlands, but the demoiselle crane nests in the steppe zone of the European and Asian parts of our country. Immediately after arrival, the mating games of the cranes begin. They gather in a large circle, in the center of which several couples “dance” to the sound of loud trumpets. After some time, the “dancers” stand in the circle of “spectators”, giving way to other birds.. Bustard squad. The bustard is one of the largest and rarest birds. Living within our country. Its weight reaches 16 kg. Bustards settle in the steppes. Thanks to their good eyesight, they already notice danger from a distance and fly away or run away on their powerful legs. Sometimes a bustard hides among sun-bleached grass and then becomes completely invisible thanks to the protective coloring of its plumage. Bustards are omnivorous birds: they eat leaves, seeds and shoots of plants, as well as beetles, locusts, lizards, and small mouse-like rodents. The chicks feed mainly on insects. In case of danger, the female pretends to be wounded and distracts the attention of the enemy from the chicks, running away and dragging her wings. The chicks hide on the ground.

Birds of the forest are the most numerous group. Its representatives have various forms of communication with the forest environment. There are 3 groups:

Arboreal birds climbing trees. They feed and build nests in trees, have short but strong legs, a chisel-shaped thin and long or inwardly curved beak (parrots). According to the nature of nutrition, there can be both granivorous and insectivorous: woodpeckers (negative woodpeckers), tap dance, siskin, goldfinch, crawlers, crossbills, hawfinches (negative passerines);

Group of forest birds. They nest in trees or in thickets of bushes, and catch prey in the air: kestrel, hawk, red-footed falcons (neg. diurnal predators), common cuckoo (neg. cuckoo), eating harmful hairy caterpillars, common nightjar (neg. nightjars), owl, tawny owl , barn owl (negative owl);

A group of forest birds that nest only on the ground. Food is obtained both on the ground and in trees. These numerous representatives of the gallinaceous order (pheasant, black grouse, wood grouse, hazel grouse, etc.) constitute the subject of the fishery.

Economic importance of amphibians and reptiles.

Amphibians, feeding on invertebrates and living in a wide variety of places, bring great benefits to gardens, vegetable gardens, fields, forests and hayfields, exterminating pests.

Of particular note is that land amphibians hunt at night, when the vast majority of insectivorous birds are asleep. The advantage of frogs and especially toads over birds is that they do not need special events to attract them and, when released into certain areas, remain to live in them.

Amphibians are of particular importance as a food supply for some fur-bearing animals. Thus, for the black polecat and mink, about one third of the food consists of frogs. The success of acclimatization of the raccoon dog is associated with the number of frogs, which make up more than half of the food ration of this species. Many beneficial birds, such as ducks, cranes, and storks, feed on frogs and tadpoles. A number of commercial fish, such as catfish, pike, perch, survive mainly on frogs in winter. Frogs, feeding on terrestrial invertebrates in the summer and gathering for the winter in reservoirs, find themselves there as an intermediate link that expands the food supply of reservoirs for fish at the expense of terrestrial forms.

Amphibians can also have a negative meaning. Apparently, the negative role of amphibians is that some species turn out to be natural guardians of such dangerous infections as tularemia.

It should be remembered that frogs, newts and axolotls are widely used as laboratory animals. Laboratories of large educational and scientific institutions use tens of thousands of frogs per year. Without frogs, the work of biological and medical institutes is unthinkable.

Finally, frogs have some importance as a food product. Frog legs are highly prized in most countries as a gourmet dish. Europe and North America harvests hundreds of millions of frogs every year.

Ecological groups of amphibians.

Amphibians are given a specific ecological “niche” - they are an important link in the food chains of humid land areas and aquatic biocenoses. Together with birds, amphibians take an active part in maintaining the natural ecological balance.

Sometimes living beings are classified into different groups, assessing the degree of their “usefulness” for their environment. In fact, there are neither “beneficial” nor “harmful” species in nature. Each species has its own ecological niche, position in food chains, place in the cycle of substances, etc. Each individual is a carrier of unique genetic information characteristic of its species. There is a close relationship between animal species. Moreover, each of them is endowed with its own usefulness for the biocenosis, which may not always be understood by us. Although representatives of some species may pose a certain danger to various members of the community - plants, animals, humans. This is especially evident when the ecological balance is disturbed (for example, during the “explosive” mass reproduction of insects or pathogens). In those natural biocenoses that include various types of amphibians, there are also no absolutely beneficial or harmful insects, birds, amphibians, plants, etc. Everything is an interconnected system whole. At the same time, amphibians play the role of defenders of the plant world. After all, the food items they need are basically dangerous to the life of many plants, especially with uncontrolled reproduction. At the same time, amphibians practically do not consume the main plant pollinators. Here the “wise interrelation of interests” of representatives of flora and fauna is manifested. The ecological niches of amphibians and birds, constituting single biocenoses, are also interconnected.

Regulators of ecological balance

Birds have a fairly wide range of food items, but it is amphibians that are considered universal plant protectors. Amphibians play an important role as regulators of ecological balance due to their omnivorous and unpretentious nature. For example, the diet of Russian northern frogs and toads includes locusts, weevils, bedbugs, bark beetles, leaf beetles and other beetles, including the most dangerous pest, the Colorado potato beetle. Amphibians destroy large quantities of cutworm caterpillars, moths, and slugs. Of great importance is the unpretentiousness of amphibians in terms of nutrition. They, in much greater numbers than birds, are able to eat insects with an unpleasant odor and taste, hairy caterpillars, and invertebrates with bright, repellent colors. The fact is that the amphibian body is equipped with excellent defense mechanisms against poisonous creatures. Therefore, in most cases, their innate life program does not include a reflex to the bright color of prey, which frightens other animals.

In addition, amphibians have an important hunting feature, which allows them and birds to complement each other in this joint activity. After all, birds that feed on insects hunt mainly during daylight hours and destroy pests active during this period. And many amphibians are able to restrain the excessive reproduction of representatives of many species of insects and mollusks, working at dusk and at night, when birds sleep. For example, an adult toad can eat up to 100 insects, their larvae and slugs in one night.

The advantage of cold-blooded amphibians

The activity of amphibians of various species is especially important in containing (together with birds) the excessive proliferation of invertebrate vegetation destroyers during difficult periods of cold weather and lack of food. After all, birds, being warm-blooded animals, cannot starve for long. Birds need to constantly maintain their body temperature at a level of 39-410C, and for this they must burn enough food in their “furnaces”. When it gets colder, the energy consumption of the bird's body increases sharply. To keep warm, birds need to increase their nutrition, but just at this time insects hide and become inaccessible. Therefore, the birds either die from exhaustion or try to fly to areas with better weather conditions. Even short periods of cold weather and lack of food cause especially serious damage to chicks. However, birds are given an amazing ability - to make long-term weather forecasts with great accuracy. In years when unfavorable living conditions are expected, including a decrease in the number of food items, birds lay fewer eggs than usual. As a result, when warming occurs and insects actively reproduce, feathered plant protectors become clearly insufficient. This is where all the benefits of the life activity of cold-blooded amphibians manifest themselves. Having easily survived the temporary cold snap and lack of food, they take revenge under favorable conditions. Amphibians begin to feed intensively, while curbing the excessive proliferation of plant pests.

In the diet of animals

Amphibians are not only consumers of food, but they themselves are objects of food. And thus amphibians are included in the general biological cycle. Among amphibians, the food items of various animals are mainly tadpoles and adult frogs. Tadpoles are eaten mainly by fish. Grown-up frogs are mainly eaten by birds, snakes, animals and large fish. After all, these amphibians do not hide in shelters during the daytime. They are fully equipped for active hunting of insects at this particular time. In addition, frogs are not provided with skin secretions with such protective properties as the caustic mucus of toads, toads, salamanders, etc. Frogs are consumed by a huge number of animals. First of all, these are many large predatory fish: catfish, pike perch, pike. For them, frogs and tadpoles are quite accessible mass food. The most common fish prey is the grass frog, which, in contrast to the green frog, lacks the behavioral mechanism of burying itself in mud for the winter. Therefore, it turns out to be the food link that expands the diet of fish at the expense of terrestrial food items. Many birds also feed on frogs, including storks, herons, crows, magpies, rooks, harrier gulls, terns, and grebes. For some of them, frogs make up a large proportion of their diet. Ornithologists estimate that at least 90 species of birds prey on frogs, 21 species prey on spadefoot spadefoots, and 18 species prey on toads. To a large extent, the nutrition of snakes is provided by frogs. Small quantities of frogs are consumed by hedgehogs, minks, shrews, foxes, and otters. Toads are eaten by raccoons and raccoon dogs, badgers, and hori. In years when the main food of these animals is scarce, the role of amphibians as food items increases. By feeding on a wide variety of invertebrates, amphibians accumulate organic substances in their bodies, which can then be used by larger vertebrates. Thus, the purpose of amphibians is also to use their lives to support the lives of other animals during unfavorable periods.

The number of most species of frogs in all habitats intended for them is in a certain balance (despite the participation of various animals in the diet). It is mainly due to the enormous fertility of frogs, which quickly restores the losses incurred. In addition, amphibians are distinguished by the relative longevity of individuals. In that part of the amphibians that were destined to avoid danger and survive, several generations can exist side by side, regularly producing offspring of the same fertile amphibians.

Man and amphibians

Amphibians are extremely important animals for humans. Firstly, by feeding on small animals, amphibians, especially frogs and toads, restrain the mass reproduction of agricultural pests. Thanks to this, they, along with insectivorous birds, are included in the category of crop protectors, friends of gardeners and gardeners. Secondly, amphibians destroy insects that are carriers of human diseases, for example, malaria mosquitoes. Thirdly, amphibians are actively used for experiments by many generations of physicians, biologists and scientists in related fields. They helped make a lot of important scientific discoveries in biology and other sciences, including bionics. In addition, amphibians are amazingly touching, gentle and often very beautiful creatures. They admire the phenomenal capabilities of their body, graceful movements and complex behavior. Amphibians, like all living beings, require humane treatment and protection. Let's look at these questions in more detail.

"Utility coefficient" for a person

Living in a wide variety of places and feeding on insects and other invertebrates that are dangerous to plant life, amphibians bring great benefits to gardens, vegetable gardens, fields, forests and meadows (hayfields), and therefore to humans. Among pests that, if uncontrolled, can destroy almost the entire crop, insects occupy the first place. And the vast majority of frogs, toads, tree frogs and salamanders feed on them. In addition, these amphibians destroy countless slugs.

Scientists who studied the nutrition of our domestic amphibians once proposed a fairly simple formula for calculating the usefulness index for a person of a particular species:

V=t, where n is the number of animals eaten that are harmful to humans, u is the number of useful ones, t is the total number of animals eaten (harmful, beneficial and neutral, found in the stomach) and v is the coefficient of utility for humans.

For general guidance in this matter, the formula gives quite satisfactory results. “Utility coefficients” calculated using this formula as a percentage for some amphibians were as follows:

common newt - 98 lake frog - 50

tree frog - 66 toad - 49

sharp-faced frog - 46 crested newt - 11

grass frog - 59 Asia Minor frog - 27

spadefoot - 57 pond frog - 18

It should be borne in mind that the beneficial activity of amphibians for humans calculated using this formula is purely utilitarian. It fluctuates at different times and in different habitats. And of course, this formula does not reflect the importance of amphibians for ecosystems, biodiversity, etc.

A study of the food range of amphibians showed that they consume mainly insects harmful to plants. Due to the fact that in areas of mass reproduction there are more of them than other insects, in the stomachs of amphibians they make up 80–85% of all food eaten. Moreover, on the ground, insects are hunted mainly by salamanders and frogs. And tropical tree frogs and arboreal salamanders catch their prey on the branches of trees and shrubs. Their sticky tongue, which accurately hits the target, helps them grab insects on the fly. Tropical copepods use glider devices to help them hunt. Unlike many birds, amphibians are capable of eating “inedible” insect pests with an unpleasant odor, taste and bright protective coloring. Some amphibians are able to catch insects and their larvae in the ground. Therefore, plants - from roots to crowns - can be completely protected by amphibians. They have been recognized as having an independent and quite significant role in exterminating insects harmful to Agriculture.

Toads have one important feature- they are the most active consumers of slugs, these nocturnal plant pests and practically omnivorous animals. Slugs destroy the harvest of rye and wheat, peas and carrots, cabbage and potatoes, and tobacco. It is easier to list the crops that they do not eat. Moreover, pests do this from early spring to late autumn, on open ground or penetrating greenhouses and greenhouses. They are especially harmful at the time of harvest ripening, when chemical treatment of plants cannot be carried out. This is where toads demonstrate their beneficial abilities for humans. At dusk, choosing a more secluded path and making small dashes, toads go out hunting. The benefits to people of their night hikes are enormous. In the United States, they have roughly estimated the cost savings that toads bring night after night to farming and forestry. It turned out that this is billions of dollars a year! And every year the profit from each toad is 20 - 30 dollars. The usefulness of toads was also highly appreciated in Europe. It is not for nothing that in the 19th century, for example, in Paris there was a special market where gardeners and peasants bought hundreds of toads to release them into vegetable gardens, fields and orchards. Thus, they saved a huge share of their harvest.

After metamorphosis is completed, juveniles, for example, green toads, leave the water and actively engage in hunting. It makes a significant contribution to the eradication of agricultural pests. Of course, young toads mainly consume small animals, which adult amphibians do not pay attention to. But the little caterpillar manages to eat a lot of greenery before it grows to a size where it becomes “interesting” as a food item for adult animals. Thus, juvenile amphibians enter the ecological niche along with older ones, preventing the enormous damage caused by small plant pests.

Those amphibians that eat disease carriers bring great benefit to humans. In the destruction of mosquito larvae special role belongs to the newts. The purpose of newts to regulate the reproduction of mosquitoes is due to the fact that the habitat of these amphibians, and most importantly their predatory larvae, is most often small and stagnant warm bodies of water. And they are also breeding grounds for mosquitoes. This food “predilection” of newts in areas of mass breeding of malaria mosquitoes is of particular importance, bringing people dangerous disease.

"Martyrs of Science"

Both the first observations of schoolchildren in the biology classroom, and the largest studies by biologists, physicians and other scientists are very often associated with the use of frogs. Most of the instruments of experimental biology and medicine are designed for these "martyrs of science." In addition, it was the frog that more than 200 years ago gave rise to the development of one of the most important branches of knowledge - the doctrine of electricity. The frog was also of interest for bionics. The purpose of these studies is to use biological knowledge about the perfect and unique "devices" and "instruments" of living organisms to solve engineering problems and develop technology. For example, the common frog is endowed with an interesting feature. She practically sees only moving objects, which helps the amphibian instantly react and grab prey. At the same time, her eye filters out information about stationary objects and tunes only to a moving target. The study of these features of the frog's eye made it possible to create the retinatron device. It does not react to stationary objects and provides observation of moving objects, such as an aircraft.

In recognition of the invaluable benefits that modest amphibians brought to the development of world science, monuments are even erected to them. One of the most famous is installed in front of the Pasteur Institute in Paris. With money raised by medical students, a monument was created in Tokyo.

Man inflicts damage on amphibian tribe

The amphibian tribe cannot be seriously threatened by their traditional enemies. The ecological balance inherent in nature is not disturbed naturally. At the same time, some species of amphibians are on the verge of extinction, which is mainly due to the anthropogenic factor - rapidly expanding human economic activity, as well as the consequences of unwise recreation and tourism. The recent decline in the populations of the most beneficial tailless amphibians – frogs and toads – has been especially serious. But the purpose of these eternal workers is to maintain balance in nature. Therefore, the increasing pace of technological progress, direct and indirect impact

Economic importance and conservation of birds

Economic importance of bird hunting

As for the vast and inhabited forest-steppe Trans-Urals, which is exceptionally rich in reserves of both hog and waterfowl, here, if there is any satisfactory use, it is only “hog” birds; the waterfowl reserves are used to an insignificant extent; Meanwhile, their proper exploitation could produce more than one million additional birds each year. The use of self-catchers can and should play a big role in the development of bird hunting, which is quite acceptable under planned conditions under state and public control. It should be emphasized, however, that simultaneously with the development of hunting birds, we must not forget the issues of protecting birds that are useful in other sectors of the national economy. As noted above, the vast majority of small and even birds of prey destroy various agricultural pests, which is of great benefit; Meanwhile, very little has yet been done in terms of protecting and improving the living conditions of these birds. In this regard, the Urals, in terms of the scope of mass work (in the form of general propaganda, organizing a “day of birds,” etc.), lagged far behind the central regions of the Soviet Union. Simultaneously with the protection of beneficial birds, it is necessary to launch a fight against harmful birds of prey. The number of truly harmful predators, in essence, in each region is small (most birds of prey and owls are mistakenly classified as pests). It is necessary to teach the mass hunter to distinguish harmful birds from useful ones, so that he can exterminate only the truly harmful ones, which will be of great benefit in agriculture, hunting and forestry.

International bird conservation is a set of principles and norms of international law aimed at preventing the extermination of all species of beneficial birds in the wild, as well as. maintaining and restoring their rare populations. M.o.p. regulated by multilateral and bilateral documents, incl. general treaties for the protection of wild fauna and flora in their natural habitats. The International Convention for the Conservation of Birds of 1950 first established the principles of protection from extermination of all species of birds in the wild, with the exception of pest species that may be deprived of such protection. Regulation of the protection of birds from extermination is carried out according to the convention on the basis of restrictive and prohibitive norms, and the organization of nature reserves is recognized as the main method of protection. Subsequently adopted with the participation of the Soviet Union, the Convention on Wetlands of International Importance especially as Waterfowl Habitat (1971) and the Convention on International Trade in Endangered Species of Wild Fauna and Flora (1973), and etc. The Convention on the Conservation of Migratory Species of Wild Animals (1979) and a group of regional treaties have significantly expanded this area of ​​international legal regulation

Ecological groups of mammals

Mammals have adapted to life in land-air, soil and water environments; there are flying animals. In various natural and climatic zones, mammals inhabit forests, meadows, steppes, deserts, and mountains. They live along the banks of reservoirs, in rivers, lakes, seas and oceans. Based on their lifestyle, mammals are divided into several ecological groups. Animals of one ecological group have characteristic features of structure, life activity, and behavior. Typically terrestrial mammals inhabit forests and open spaces. They have a proportionally built strong body, well-developed high limbs, and a muscular neck. They move by walking, running and jumping. The signs of the group are most clearly manifested in fast-running animals. Among land animals there are many herbivorous species - deer, horses, antelopes, goats, rams, etc. Mammals that feed on branches and leaves of trees have special adaptations. So, the giraffe has a well-developed neck. This allows him to pick leaves that are inaccessible to other land animals, see well and detect enemies in time. Elephants have a powerful compact body, a massive head and a short neck that are compensated by a long, mobile trunk. Predatory animals that lie in wait for prey, for example a lion, a tiger, a lynx, do not have such long legs as those of running animals. Predators pursuing prey, such as the wolf and cheetah, have relatively long legs. Jumping mammals - hare, jerboa, kangaroo have long strong hind legs and shortened, weaker front legs. In kangaroos, the weak front legs have lost their support value when landing after a jump. On the other hand, a long tail is developed, on which the animal leans during slow movement, and during large jumps it plays the role of a balancer and a rudder. Land-arboreal mammals live in forests and are associated with tree-spring-shrub vegetation. They make nests in trees and feed both on the ground and in trees. These animals have an elongated, strong and flexible body, shortened limbs, armed with sharp claws.

This group includes the pine marten, sable, squirrel, and chipmunk. Many small terrestrial arboreal species have a well-developed tail with long spinous hairs, which facilitates gliding jumps. The flying squirrel has a leathery fold on the sides of its body, which improves its gliding capabilities. Soil mammals are adapted to a burrowing lifestyle. Many species spend almost all their time underground, rarely appearing on the surface. The body of shrews is short, ridged, the cervical region is invisible, and the tail is reduced. The fur is short, dense, without guard hairs, the legs are short with strong muscles and large claws. The auricles are reduced. Vision is poorly developed, and some underground animals (for example, mole rats) have eyes hidden under the skin. Diggers have a well-developed sense of smell and touch. The mole digs the ground with strong, spade-shaped forelimbs turned outward and pushes the earth to the surface with its head. The mole rat digs the ground with large, protruding incisors. Flying mammals have fully mastered the air environment - they have adapted to flight. This group includes representatives of the order Chiroptera. Their forelimbs are transformed into movable wings. The flight membrane is stretched between the highly elongated bones of the hand of the forelimb, the trunk, the hind limb and even the tail.

Fast-flying animals, such as the rufous noctule, have long and narrow wings; in slow-flying long-eared bats they are wide and blunt. In connection with flight, chiropterans have well-developed pectoral muscles, which, like birds, are attached to the keel of the sternum and the bones of the wings. The bats catch insects in the air. Some of them, like birds, make seasonal migrations: they fly to warm areas for the winter. All bats have well-developed hearing organs with large auricles that provide echolocation. Aquatic and near-aquatic mammals - cetaceans and pinnipeds - are typical aquatic animals. Whales have completely lost contact with land. They have a streamlined fish-like body, the head merges with the body: the cervical region is absent.

The organ of movement is the caudal fin. The forelimbs, modified into flippers, act as rudders. The hind limbs are reduced. The ears have disappeared, the external auditory canal is closed, the nasal openings are closed by valves, and there is no fur. Subcutaneous fat is well developed, providing thermal insulation. Due to feeding on planktonic organisms, baleen whales lost their teeth and developed a special filtering apparatus consisting of numerous horny plates, the so-called baleen. Pinnipeds spend most of their lives in water. However, they have not lost contact with land: they come to land, to rookeries, during the breeding season. Pinnipeds have two pairs of flippers that take part in movement in the water. The coat is reduced, although the cubs are born covered with thick fur. A thick layer of subcutaneous fat plays a thermal insulating role.

Mammals leading a semi-aquatic lifestyle belong to different systematic groups and use different foods. However, they have common features due to a semi-aquatic lifestyle: the limbs are equipped with swimming membranes, the tail acts as a rudder in the water, the coat is well developed, and there is a thick, warm undercoat. Animals that lead a semi-aquatic lifestyle carefully take care of their fur: they take it apart, comb it, and lubricate it with the oily secretion of the skin glands. Mammals that lead a semi-aquatic lifestyle include the platypus, muskrat, beaver, otter, muskrat, etc. They swim and dive perfectly in water, move freely on land, although they are noticeably inferior in speed to typical land animals. Among terrestrial, soil, aquatic, semi-aquatic and flying animals there are representatives of different orders and families. They have similar adaptive traits to similar living conditions and form separate ecological groups.

Hello friends! Today I want to continue the conversation about insects that are of great interest to anglers and I want to talk about such a popular insect among anglers as the caddisfly.

Probably many people remember from childhood how they caught crawling houses in clear water in childhood, and the caddisfly reminds many of us of this very house, and few people imagine at this moment a butterfly that is usually small in size and not brightly colored, similar to night moths.

However, a caddisfly is such a butterfly, and crawling houses are caddisfly larvae that always live in water.

Caddisfly – (lat. Trichoptera) a detachment of insects with complete metamorphosis (transformation).

The life cycle of a caddisfly, unlike a mayfly, is complete and can be described by the following scheme: egg - larva (larva) - pupa (pupa) - adult insect.

The difference between the caddisfly and many butterflies is that its body and especially the front wings are covered with hairs, and not scales like those of butterflies. Hence the name Trichoptera: thrix - hair and pteron - wing.

Let's look at the development of the caddisfly in order. The female lays eggs in the water slightly differently depending on the species. Basically, females descend into the water from the shore or dive to the bottom and lay eggs there, but some species can do this on the surface of the water or plant, but in any case, caddis eggs fall to the bottom of the reservoir and larvae (larvae) emerge from them.

The larvae of many caddisfly species live in houses that are built from sand, small pebbles, plant remains and other materials. These caddis flies are known to many anglers. Often such larvae are collected and fish are successfully caught with them, both in winter and summer. Few people know that some species of caddisflies build shelters among stones from silk threads secreted by special glands. And some species of caddisflies do not build any houses, but simply crawl between the stones.

And so we figured out that all caddisflies are divided into three groups: those that build houses, those that live freely and those that weave nets from silk threads, building shelters for themselves. In this regard, the features of their life and place of residence may differ.

I will not describe the life features of various caddisfly larvae so as not to clutter your brain; for those who are very interested in these features, you can find a lot of such information in works on entomology.

Regardless of the type of caddisfly, in order for a larva to develop into an adult insect, it must go through the pupal stage (pupa). Those larvas that had houses attach them to stationary objects in the water and plug the holes, and those that did not have houses have to build themselves shelters from sand and small pebbles.

After the caddisfly larva has taken refuge in its shelter, it begins to weave a silk cocoon. Then this cocoon hardens and inside it the larva transforms into an adult insect.

At this stage of metamorphosis, the larva grows wings and the body shape changes, as well as legs and antennae (antennae).

After an adult insect has formed in the cocoon, the caddis fly chews the cocoon and rushes to the surface of the water. At this moment, the caddisfly is still in a transparent shell, which bursts when it reaches the surface. In this state, the insect is very vulnerable and is eaten in large quantities by fish.

The emerging adult caddisfly insect rushes to the shore to a safe place.

An adult insect has two pairs of wings, which are covered with small hairs, as is the whole body. When the caddisfly is resting, the back pair of wings are located under the front ones, and the front ones are folded on the sides of the insect and cover it from above in the form of a house.

The antennae of the caddisfly are long and usually exceed the length of the body.

The caddisfly feeds on the nectar of plants on the shore, but every day they fly to the reservoir to drink water, where they fall into the mouth of a voracious fish.

The silhouette of all caddisfly species is similar and usually has a brown color with various shades. Fly fishermen have long learned to copy the silhouette of an adult caddisfly, and the variety of flies is simply enormous.

Among them there are flies that are very popular, such as “ELK HAIR CADDIS”. I fished very successfully with this fly last season.

There are also a large number of flies that imitate all stages of caddisfly development, and not just the adult insect. Imitation of caddis fly is also successfully used in ice fishing.

At the bottom of many fresh water bodies - clean, fast streams and overgrown ponds - you can find amazing creatures that live in tubular houses, built by them from various small particles lying on the bottom. Depending on what small objects lie at the bottom, and depending on the type of insect, houses can be built from different materials. For some, this structure is made of large grains of sand, for others, it is made of pebbles or shells of small mollusks, often it is a tube consisting of small fragments of twigs or dead parts of aquatic plants, etc. The “building material” is firmly held together by spider threads. These houses are built by caddisfly larvae.

Adult caddisflies are rather delicate insects, similar to hairy moths (Fig. 310). The easiest way to distinguish a caddisfly from a butterfly is by its wings - butterflies have wings covered with scales, while caddisflies have hairs. When at rest, their dark-colored wings are folded like a roof on their back. The head is quite large with compound eyes and usually with 3 simple ocelli between them.

The antennae are long, thread-like, the oral organs are reduced, in particular there are no mandibles at all, and the remaining oral parts are transformed into a short proboscis with a tongue. Adult caddisflies do not feed, but can drink water. The legs, ending in 5-segmented tarsi, are quite slender. These generally inconspicuous, inconspicuous insects fly reluctantly and sluggishly.

After mating, female caddisflies lay gelatinous lumps of eggs called “spawn” in the water. The eggs hatch into larvae, which in most species immediately begin to build an arachnoid sheath from a silk thread secreted by modified salivary glands. The cap is encrusted with suitable small particles lying on the bottom and accessible to the larva. Including hard objects in the case makes it stronger and stronger. And reliable protection is necessary for the caddisfly larva. The fact is that it never leaves the water and breathes through the entire surface of the skin of the entire elongated abdominal section of the body. The abdomen of caddisfly larvae not only has very thin, easily permeable (and if so, easily vulnerable) covers, but often also has numerous even more delicate gill outgrowths, increasing the surface of gas exchange with water. Bundles of gills are also found on the posterior parts of the chest.

If everything around is calm, the larva crawls along the bottom, carrying the cover on itself. When moving, the larva protrudes its head and thoracic region from its case, on which there are 3 pairs of rather long and tenacious legs extended forward. However, the front legs are often shorter than the rest, and some caddisfly larvae have only two pairs of legs. The head and thoracic segments protruding from the cap have dense coverings. The head of caddisfly larvae is amazing - there are no antennae on it. In larvae of different insects with complete metamorphosis, the antennae are of different lengths, but rarely they are reduced to such an extent that they become completely indistinguishable, as is the case with caddisfly larvae. The eyes of the larvae look like dark spots and consist of several simple ocelli (no more than 6 on each side of the head). The mouth apparatus of the larvae, in contrast to the adult caddis flies, is well developed, it is gnawing. The larvae feed on both plant foods, scraping soft tissues with serrated jaws, and animal foods. The cap serves the caddisfly larva not only as a permanent armor that protects the abdomen, but also as a refuge: in case of danger, the entire larva is drawn into the “house”, the entrance hole of which is closed with its dense and durable smooth head capsule. The posterior end of the body of the caddisfly larva is held in the case by a pair of powerful hook-shaped processes directed forward. Therefore, the larva can quickly hide in the cover. Holding the house with hooks, the larva drags it along with it, without losing it and only completing it as it grows.

What caddisfly larvae are easy to find in our reservoirs?

In fast streams with cool water and a rocky bottom, tube houses are easy to spot under rocks stenophile(Stenophylax stellatus), constructed from large grains of sand neatly attached to each other (Fig. 311, 1). The larva easily lifts its house, the front edge of which hangs like a hood over the larva’s head, making it invisible to fish swimming from above. If the larva's cover is damaged, it immediately tries to repair it, picking up grains of sand of the required size with its front feet. She fits them to the damaged edge of the cover, discards those that fit less tightly, testing and selecting the most suitable ones. The larva glues the grains of sand with saliva that hardens into a silky thread, wraps them repeatedly with threads, binding the grains of sand to each other, as a result of which the case turns out to be very durable. After repairing the walls of the house, the larva carefully lines its inner surface with several layers of silk cobwebs. If the larva is carefully removed from the case and placed in a vessel, on the bottom of which beads are placed instead of sand, it will make itself a house of small bright beads. Stenophila larvae feed on both plant and animal foods.

In lakes into which streams flow, larvae live in more open places at the bottom apathania(Apatania). Their houses are shaped like a horn (Fig. 311, 4). Larger grains of sand are embedded in the sides of the apatania house.

In shallow sandy places, larvae make their houses built from grains of sand. Molanna(Molanna angustata). Molanna's house, when viewed from above, is wide and flat. The central tubular part, in which the larva sits, is made of larger grains of sand, but attached to its sides are wings made of smaller grains of sand and the same hood. In general, the cover has the appearance of a rather large shield, its length is more than 2 cm (Fig. 311, 5). The molanna larva with its case moves in jerks.

Larvae live in dense thickets of plants freeganei(Phryganea), making their tubular houses from gnawed quadrangular pieces of plants, like short planks (Fig. 311, 5). Often such houses even retain their green color - pieces of aquatic plants in water remain viable for a long time. Freegans have a spacious and long house, the larva can run freely in it. The rear end of such a tube house is open, and if the larva is pushed out of the case, it will quickly run along its surface and deftly duck into it from the rear end. Freeganea is a large insect, the length of an adult larva is about 4 cm. Although the larvae of freeganea, when making caps, bite off pieces of plants and, if necessary, especially in summer and autumn, sit mainly on a plant-based diet, they are not vegetarians. Freegan larvae are more likely to eat mosquito larvae and other small invertebrates.

Larvae are common at the bottom of overgrown ponds limnophiles(Limnophilus). The houses of some species of limnophiles are quite similar to each other. The larva builds a house from various hard small objects lying on the bottom. There may be small swollen sunken sticks, small shells of mollusks, needles, and other plant remains, but pebbles and grains of sand are not used by limnophiles. If the limnophila larva is expelled from the house and the house is removed, it, releasing sticky spinning threads and spinning restlessly, first makes a temporary house out of anything, and then, feeling that the abdomen is somehow protected, begins to make a permanent house, carefully selecting durable particles and fitting them well together.

Common in North America snail caddisflies(family Helicopsychidae), making spirally convoluted cases for themselves, so similar to snail shells (Fig. 311, b) that even zoologists, before confidently saying whether they have encountered a shell or a caddisfly house, must take a very careful look.

Although caddisfly larvae are very well adapted to life in water, among the forms that build cases there are also those that left the aquatic environment and moved on to life on land. That's how land caddisfly(Enoicyla pusilla), living in beech forests of Western Europe (Fig. 312). Interestingly, the females of this caddisfly are wingless. The larvae of the land caddisfly live in the litter and among the moss that covers tree trunks. This larva avoids water and, when the layer of fallen leaves becomes very wet after heavy rains, moves to tree trunks. The larva makes a house from small pieces of fallen leaves.

Although life in caps is characteristic of most caddisfly larvae, representatives of some families lead a different lifestyle, despite the fact that they have well-developed spinning glands. In shallow and slow rivers, in thickets of pondweeds and other aquatic plants, there are delicate, barely noticeable transparent tubules attached to aquatic plants (Fig. 313).

They vibrate with streams of steadily flowing water. Usually there are many such tubes in one place - a whole cluster. Make their larvae neuroclip(Neureclipsis bimaculata) from polycentropid family(Polycentropidae). If these tubular formations are transferred to still water, for example placed in a bucket of water, they will collapse and become inconspicuous - the flow of water inflated and maintained the shape of these thin underwater nets. If you look at such a tube through a binocular, you can see that it is indeed a network - a network, remarkably woven, with small cells of the same type. These tubular networks are weaved by narrow, long larvae that live without a cover and do not have gills. The larvae (Fig. 314) build themselves in flowing water not houses, but nets - trapping nets, into which small crustaceans, mayfly larvae and other animals carried by the current fall, becoming prey for the neureclipse. In the water, the predatory larva of this caddisfly catches prey in the same way as web spiders do on land!

In large lowland rivers - in the waters of the Volga, Don, Dniester - many caddis flies develop hydropsychides(family Hydropsychidae). Hydropsychid larvae make a net with rectangular cells, while they themselves sit side by side in a light case made of thin threads (Fig. 315).

As soon as a small crustacean or insect gets caught in the snare, the predatory larvae (their sizes reach about 2 cm) jump out of the shelter and grab the prey with their strong jaws!

Larvae make trapping nets in the form of bags (Fig. 316). plectronemia(Plectrocnemia). It is interesting that such specialized hunters of aquatic prey as hydropsychidae and plectronemia can also go to land. These larvae were found at a distance of tens of meters from streams in the forest floor, where they lived, of course, without making any trapping nets.

However, some caddisfly larvae (family Rhyacophilidae) do not make complex structures in water. Beautiful greenish-blue larvae crawling along the rocky bottom of clear cold streams riacophile(Rhyacophila nubila), (Fig. 311, 7), reaching a length of 2.5 cm, only release a thread that keeps the larva from being carried away by water. These predators cling to the bottom and to the thread they secrete with their legs and attachment hooks at the posterior end of the abdomen and wait for prey. The larvae of riacophylls help in quick grasping of their prey by the fact that their strong jaws are directed straight forward, like in predatory larvae of ground beetles.

The development of caddisflies usually lasts 1 year, but in large northern species it lasts 2-3 years.

Familiarization with even a few representatives of caddisfly larvae shows how diverse their habits and characteristics are. And adult caddis flies do not feed, only multiply, and all lead a similar lifestyle. Therefore, it is clear that it is relatively easy to recognize caddisfly larvae (not only the way of life is different for different species, but also the structure of individual parts of the body is not the same), and only entomologists who specifically study them can recognize species of adult caddisflies.

Acquaintance with caddisflies also shows that not only the study of the structure of different parts of the body of animals makes it possible to distinguish and recognize them well, but also behavior (which is expressed, for example, in the construction of covers of one form or another) can be used by taxonomists as a reliable feature. This was first noticed by the founder of comparative zoopsychology, the Russian zoologist V. A. Wagner.

There is a lot of peculiarity in the life and development of caddisflies. In most insects with complete transformation, the pupa is almost immobile, and if the larva and the adult insect live in different environments, the larva, before pupation, makes it easier for the adult insect to get into favorable conditions for it, for example: such larvae adapted to life in water as the larvae of swimming beetles, Before pupation, they emerge from the water and burrow into the ground. Caddisflies behave differently. With them, the pupa begins its life in a case built while still in the larval stage, then it lives freely in the water column for some time, and the last stage of the pupa's life, before turning into an adult insect, takes place in the air.

The pupa of caddisflies is free (Fig. 317). This is generally the same stage adapted to life in water as the larva. The life of a pupa can easily be traced using the example of a stenophila, from whose consideration the acquaintance with caddisfly larvae began. Before pupation, the larva selects a calmer area of ​​the reservoir and, attaching the cap to a stone, braids its ends so that each has a hole for free access of water. When the larva pupates, the pupa inside the cap makes oscillatory movements all the time, resting against the wall of the cap with an outgrowth at the base of the abdomen. To clean the holes, pupae have strong bristles on the upper lip and cleaning processes at the rear end of the body. By the time of maturation, the pupa breaks through the front end of the cap with its powerful serrated jaws (unlike the larval ones, and even more so the practically absent jaws of adult caddis flies) and, emerging from it, begins to quickly swim on its back, like smooth bugs, making rowing movements long, equipped swimming hairs of the middle legs. Having reached a stone, shore or plant, the pupa clings to it and crawls out of the water. It is difficult to call a caddis fly pupa a “resting stage”, as insect pupae are often called!

In the air, the pupa begins to move its abdomen regularly, its spiracles open, its body swells, and the final molt occurs—an adult winged caddisfly emerges through a longitudinal slit on the dorsal side of the chest and head. Those caddis flies whose larvae do not live in covers build themselves covers before pupation. The lifestyle of the pupae is quite similar.