general characteristics class. This is the most numerous class, including more than 1 million species. By origin, this is a group of true terrestrial animals. Insects have inhabited a wide variety of terrestrial habitats, soil, fresh water bodies, and coastal seas. The wide variety of habitats in the terrestrial environment contributed to the speciation and wide dispersal of this large group of arthropods.
The abdominal region of different groups of insects consists of an unequal number of segments (mostly 9-10) and is devoid of real limbs.
Skin Insects are structured similarly to those of arachnids. The skin contains various pigments that determine the color of insects. Coloring can be protective or warning. The numerous hairs present on the surface of the chitinous cuticle perform the function of touch. The integument is abundantly supplied with various glands - waxy, odorous, spinning, poisonous, etc., the secretions of which play important role in the life of insects.
The striated muscles reach special development in the thoracic region, providing rapid movements of the wings (from five to a thousand beats per second) and limbs.
Like other arthropods, digestive system insects consists of three divisions. The structure of the foregut is modified depending on the food specialization of insects. Insects that feed on solid food have a muscular stomach (Fig. 11.14). In those who feed on liquid food, the oral cavity is transformed into a system of canals, and the stomach is of a sucking type. Salivary glands can be converted into spinning glands (butterfly caterpillars) or contain blood anticoagulants (in blood-sucking forms). In the hind intestine of most insects there are special glands designed to absorb water from undigested food debris.
In addition to the Malpighian vessels (from 2 to 200), the fat body also serves as an excretory organ, the main function of which is to store nutrients necessary for the development of eggs during wintering. The end product of nitrogen metabolism in insects is uric acid, which is secreted in the form of crystals, which is due to the need to retain water in their gel.
Breath insects are carried out exclusively with the help of a highly branched tracheal system. The openings of the spiracles are located on the lateral surfaces of the chest and abdomen. The spiracles are equipped with special valves that regulate the flow of air into them, the movement of which occurs through contractions of the abdomen. Insects living in water - water flies and bedbugs - are forced to periodically rise to the surface of the water to store air.
Rice. 11.14. Scheme of the structure of cockroach organs: 1 — esophagus; 2 — goiter; 3 — muscular stomach; 4 - midgut; 5 —excretory tubes; b — lateral trachea; 7 — ventral nerve cord.
Circulatory system In insects, due to the structural features of the respiratory organs, it is poorly developed and does not differ fundamentally from that of other arthropods (Fig. 11.15). The blood is colorless or yellowish, rarely red, which depends on the hemoglobin dissolved in it (for example, in mosquito larvae).
Nervous system, like other arthropods, it is built according to the type of peripharyngeal nerve ring and ventral nerve cord. The suprapharyngeal ganglion reaches a high level of development, especially in social insects (bees, ants, termites), transforming into a “brain” with three sections: anterior, middle and posterior. It innervates the eyes and antennae. The behavior of social insects is complex.
The sense organs of insects are well developed. Organs of vision adult are represented by compound eyes, to which simple ocelli are sometimes added, located on the forehead and crown.
Some insects have color vision (butterflies, bees). The organs of balance and hearing are arranged in a unique way. Insects have a keen sense of smell, allowing them to find food and sexual partners. The organs of touch are most often located on the antennae, and the organs of taste are located on the oral limbs. A highly developed nervous system and sophisticated sensory organs determine the complex behavior of insects, especially social ones. It is determined by instincts, which are innate complexes of reactions.
Fig 11 .15 . Insect circulatory system: 1 — aorta; 2 — pterygoid muscles; 3 — dorsal vessel — "heart".
Types of insect development. Insects are dioecious, most of them with well-defined sexual dimorphism. The gonads are paired; males often have a copulatory organ. The eggs are rich in yolk and are laid in external environment. After leaving the egg, the development of the insect organism occurs with incomplete or complete transformation (metamorphosis).
In insects with incomplete metamorphosis, the eggs hatch into larvae that are similar in appearance to the adult insect, but differ from it in their smaller size and underdeveloped wings and reproductive system. With each moult, they become more like their adult form. On the contrary, in insects with complete transformation, development proceeds with a consistent change of forms, completely different from one another. A worm-like larva hatches from the egg (in a butterfly it is called a caterpillar), which crawls, eats a lot, molts several times and becomes larger with each molt. As a result of the last larval molt, a pupa is formed that does not move or feed. Pupae of different orders of insects with complete metamorphosis have different structures, but what they have in common is the destruction of the anatomical structures of the larva and the use of this material to build the organs of an adult insect. Regulation of all stages of metamorphosis occurs with the participation of special hormones.
In insects with complete metamorphosis, the larva (caterpillar) and the adult differ not only in appearance, but also in the method and objects of nutrition. Thus, the caterpillar of the cabbage butterfly feeds on leaves, while the adult butterfly sucks flower nectar. In addition, larvae and adult insects inhabit different habitats. For example, a mosquito larva lives in fresh water bodies and feeds on algae and protozoa, while an adult mosquito (female) lives on land and sucks the blood of humans and other mammals. These differences in food sources and habitats reduce intraspecific competition, allowing insects to thrive.
Orders of insects. Class Insects includes a large number of squads. The basis for their identification is the structure of the wings, mouthparts and type of development. The characteristics of the main orders are presented in Table. 11.1.
Table 11.1. Main orders of insects.
|
The squad and its representatives |
Meaning |
|
|
1 |
2 |
3 |
|
Insects with incomplete metamorphosis |
||
|
Dragonflies (large rocker, beauties, arrows, etc.) |
Two pairs of wings (identical in the suborder Homoptera and somewhat different in representatives of the suborder Heteroptera) with a fine network of veins. Large, compound eyes converging at the crown. Gnawing mouthparts. |
Being voracious predators, they destroy a large number of insect pests. |
|
Orthoptera (grasshoppers, crickets, locusts, mole crickets) |
The forewings are rigid with almost parallel longitudinal veins. The hind wings are wider with radially diverging longitudinal veins. Gnawing mouthparts. |
Most representatives of the order are plant pests. Locusts, eating leaves and stems, damage crops. Grasshoppers cause damage to orchards and vineyards. Mole crickets, burrowing in the soil, damage the roots of plants. |
|
Hemiptera, or Bugs (tortoise bugs, bed bugs, water striders, etc.) |
Half of each elytra from its base is rigid and consists of a thick layer of chitin, and the other half is thinner, membranous. Some bugs (bed bugs, etc.) have reduced wings. The mouthparts are piercing-sucking type. Many species have a scent gland, which is why they have an unpleasant odor. |
|
|
Insects with complete metamorphosis |
||
|
Coleoptera, or Beetles (chafer beetles, click beetles, weevils, bread beetles [kuzka], leaf beetles [ Colorado beetle], bark beetles, swimming beetles, ground beetles, ladybugs, dung beetles, etc.) |
The first pair of wings - hard elytra - covers the second pair of membranous wings. The mouthparts are gnawing. |
Many of the beetles harm plants; chafers eat leaves, and their larvae eat tree roots. Click beetle larvae are called wireworms. They feed on the underground parts of potatoes and cereals. The Colorado potato beetle and its larvae eat potato leaves. The larvae of the weevil, the apple blossom beetle, destroy the ovaries of the flower, and the larvae of the beet weevil destroy the roots of the beet. Among the beetles there are also useful ones. These are predatory beetles (ground beetles and beetles) that hunt silkworm caterpillars. Ladybugs and their larvae feed on aphids. Dung beetles and their larvae, eating manure, are a kind of orderlies. |
|
Lepidoptera, or Butterflies (cabbage white, hawthorn, codling moth, codling moth, house moth, silkworms) |
Two pairs of very large wings compared to the insect’s body, colored various colors. The color of the wings depends on the color and location of the scales. The veins on the wings are located longitudinally. With the exception of some moths, butterflies have sucking mouthparts. |
Butterfly larvae, eating above-ground parts of plants, cause harm. Cabbage white larvae eat the leaves of cabbage and other cruciferous vegetables. The larvae of hawthorn moth, codling moth and codling moth cause damage to fruit trees. House moth larvae feed on the wool of fabrics or furs and damage clothing, carpets, and upholstery. Pine silkworm larvae, eating pine needles, harm pine forests; Ringed silkworm larvae damage orchards. While causing harm at the larval stage, adult butterflies produce benefits by pollinating plants. The benefit of butterflies is that they are food for birds. Among butterflies there are also domesticated forms. These are oak and mulberry moths. Their caterpillars have highly developed silk glands that secrete silk thread. The caterpillar wraps itself with this thread before pupation. The silky cocoon serves as protection for the pupa from unfavorable conditions, and for humans as raw material for producing silk. |
|
Hymenoptera (riders, sawflies, bees, wasps, bumblebees, ants, etc.) |
The hind wings are always smaller than the front wings. Both pairs are transparent with relatively sparse longitudinal and transverse veins. The oral apparatus in most species is gnawing, while in stinging animals (bees) it is of the gnawing-sucking type. Bees, wasps, and some ants have a sting, which is a modified ovipositor. The lifestyle is different. Some (riders, sawflies, some wasps) live alone, others (bees, ants, some wasps) live in large families and are social insects. Between individuals Within a family there is a division of labor. |
Hymenoptera are of great importance as plant pollinators. The honey bee produces wax, bee venom, and jelly, which are used in medicine and perfumery. Bee honey is also useful. Riders are of great benefit. By laying eggs in the body of larvae and eggs of many harmful insects, they help humans in the fight against them. Wasps are also useful in this regard: by storing food for their larvae, before laying eggs, they paralyze and drag V burrows of caterpillars of many harmful insects. Among the Hymenoptera there are also pests. Female sawflies have a saw-like ovipositor, which they use to saw through the eggs of the plant to lay eggs. The larvae that emerge from the eggs eat the leaves of the plants. |
|
Diptera (flies, gadflies, horseflies, mosquitoes, midges, mosquitoes, etc.) |
The hind pair of wings is reduced. Their remains turned into halteres. The front pair of wings is strongly narrowed at the base. The mouthparts are of the licking (fly) and piercing-sucking (mosquito) type. |
|
The role of insects in nature, their practical significance. Insects, with their diversity and huge numbers, play an important role in nature and human life. They are plant pollinators, destroy harmful representatives of this class and act as orderlies. Some beneficial insects - bees, silkworms - have been domesticated by humans. At the same time, the damage caused by insects is also great. Depending on the object of attack, harmful insects are divided into several groups: pests of the field, garden, vegetable garden, barn pests, disease carriers.
To protect plants from insects they use different ways fight them. Widely applied collection insects using trapping ditches, rings, traps, insect traps (mechanical method), etc. In addition, the fight is also carried out chemical method, in which insects are exposed to poisons. But the use of chemicals leads to the poisoning of soil, water, and the destruction of both harmful and beneficial insects. Therefore, recently it has received recognition biological method fight, in which a person uses natural enemies of insects: insectivorous birds, insect predators (ground beetles, ladybugs, etc.). Trichogramma ichneumon is artificially bred to combat the codling moth.
The simplest thing in insect taxonomy is the identification of orders. The following characteristics are used as the main features: the presence and structure of wings, the type of oral apparatus, the type of metamorphosis, and features of the external structure.
Definitive tables are built according to binary scheme(thesis - antithesis). Each thesis has a number; the number of the antithesis is given in brackets. If the characteristics of an insect correspond to the characteristics described in the thesis, then it is necessary to read the antithesis and move on to the next thesis in order.
Defining units begins with defining subclasses.
Below is a definition table of orders and a brief description of the most significant orders in forestry.
DEFINITIONAL TABLE OF SUBCLASSES AND ORDERS OF INSECTS
1 (8) Wings missing. The abdominal segments have various outgrowths from below: either paired appendages, or a retractable tube on the 1st abdominal segment, or a retractable jumping fork at the end of the body. Very small insects (subclass Primary wingless, or Lower, insects - Apterygota).
2(3) Antennae absent. The abdomen consists of 12 segments. The front legs are greatly elongated ………… ………… Detachment Bessyazhkovye(Protura)
3(2) Antennae present. The abdomen consists of no more than 10 segments. The front legs are not elongated.
4 (5) The abdomen consists of 4 - 6 segments. The antennae consist of 3-6 segments, the last segments may be ringed. At the bottom end of the body there is often a jumping fork………… Squad springtail ki ( Podura)
5(4) The abdomen consists of 10 segments. The antennae consist of a large number of short, uniform segments.
6(7) At the end of the body there are paired tail filaments or pincer-like appendages. Body without cover of scales. ……. Squad Double-tailed (Diplura)
7(6) At the end of the body there are 3 tail filaments. The body is covered with scales……………………………………. Squad Bristletails (Thysanura )
8(1) Wings present - long, functioning or at least in the form of residual processes; if they are absent, then the appendages on the underside of the abdominal segments are also absent (there can only be appendages at the end of the body that do not have the shape of a jumping fork) (subclass Winged, or Higher, insects - Pterygota).
9(38) Mouthparts with well-developed mandibles, gnawing, sometimes additionally with a proboscis - gnawing-licking.
10(13) The fore wings are dense, keratinized elytra that have lost venation, completely or partially covering the abdomen (with the exception of some wingless larval females of soft-bodied beetles).
11(12) At the end of the body there are characteristic long pincer-like appendages ……………………………………. Squad Earwigs (Dermaptera)
12(11) At the end of the body, long pincer-like appendages are not developed………………………..…… Squad Coleoptera,orBeetles (Coleoptera)
The largest group of insects (250 thousand species). Sizes from 0.3 to 170 mm. The body is tough, the mouthparts are gnawing. There are 2 pairs of wings, the front ones are in the form of elytra. Rear-engine. 2nd pair – membranous, folded lengthwise and crosswise, may be absent. Metamorphosis is complete, sometimes complicated (hypermetamorphosis). Most have walking legs, some have running, digging, and swimming legs. The antennae are of different types. The larvae are woodlice-shaped, campode-shaped or worm-shaped. The pupae are open. They live in all environments. Sapro-, copro-, phytophagous, many predators (ground beetles, aphids). There are many plant pests (weevils, bark beetles, longhorn beetles, borers, etc.). Most with one-year generation. Highly organized. Widely distributed (more than 100 families). 2 suborders – herbivores and carnivores.
Suborder carnivores– the coxae of the hind legs are long, the head is prognostic, the larvae are campodeoid. Adults and larvae are predators (ground beetles, diving beetles).
Suborder heterovores- the coxae of the hind legs are small and mobile. The larvae are often worm-shaped or campodeoid. There are many phytophages and predators.
13(10) The forewings are not keratinized, but if compacted, leathery, then with well-preserved venation. Sometimes the wings are missing.
14(17) The antennae are very short, significantly shorter than the head.
15(16) Wings well developed, with reticulate venation. The shapes are large, with a slender, elongated body………………………………………………………..
…………………………………………….Detachment Dragonflies (Odonata )
Medium and large in size, diurnal predators near water bodies. 2 pairs of similarly arranged reticulate wings, long or stocky abdomen. The mouthparts are gnawing. Metamorphosis is incomplete, complicated (hemimetamorphosis). Larvae are naiads with caudal gills and an elongated lower lip. The antennae of the imago are short, the first pair of legs are grasping. There are about 150 species in Russia. All species and their larvae are predators. According to the structure of the wings, they are divided into 2 suborders: Homoptera (Zigoptera) - medium-sized, with identical wings - arrows, lute, beauties; Varied wings (Anisoptera) are large, with touching eyes, the hind wings are wider at the base, the larvae have gills in the hindgut - rockers, pasterns, grandfathers. All species are useful, some are protected.
17(14) Antennae longer than head.
18(19) The head is extended downwards like a beak, at the end of which there is a gnawing mouthpart…. . Squad Scorpionworts (Mecoptera )
19(18) The head is not extended like a beak.
20(25) The front and rear pairs of wings are identical in structure, with dense reticulate venation.
21(22) Antennae attached between eyes. Paw segments Not expanded……………………………………………………… Squad Reticulates (Neuroptera )
From small to large. 2 pairs of transparent mesh wings. The mouthparts are gnawing, the eyes are large. The metamorphosis is complete. Most larvae are predatory with large jaws. About 35 thousand species. There is family in the forest. Lacewings. Their larvae eat aphids. Sem. Antlions- large in size, live in sandy soil, predators.
22(21) Antennae attached in front of eyes. The 3rd or 4th segment of the tarsi is expanded.
23(24) Wings brownish, without ocellus. The prothorax is wide and transverse. The 4th segment of the tarsi is widened……….. … Squad Whipflies (Megaloptera),
24(23) Wings transparent, with a wing eye. The prothorax is strongly elongated. The 3rd segment of the tarsi is widened….. Squad Camels (Raphidioptera )
Large insects with an elongated head and a long pronotum, with 2 pairs of membranous wings with close venation. The mouthparts are gnawing, the antennae are long. The metamorphosis is complete. Females with ovipositor. They live in forests, live on trunks and under the bark, destroy aphids, subbark bugs, and bark beetle larvae. About 100 species.
25(20) The front pair of wings is denser and leathery. If all the wings are the same in structure, then the venation is not reticulate - with sparse cross-veins. Sometimes the wings are missing.
26(27) The front legs are grasping, with serrated shins……………………………………………. Squad Mantises (Mantoptera)
28 (29) The hind legs are jumping, with thickened thighs, or the front legs are shovel-shaped, digging. The front pair of wings are transformed into elytra. The paired cerci are well developed. …. SquadOrthoptera ( Orthoptera)
Medium to large in size, with an elongated body shape and a large head. Either the hind legs are jumping or the front legs are digging. The fore wings are elongated parchment-like or leathery, the hind wings are membranous and wide. Many have ovipositor, hearing and chirping organs. Oviposition - in the soil, stems. Metamorphosis is incomplete. There are about 700 species in Russia. They prefer open landscapes. Phytophagous, there are predators. Many plant pests. The squad is divided into 2 suborders: long-moustached(suprafamilial grasshoppers and crickets) and short mustache(suprafamily. Locusts).
Superfamily grasshoppers– antennae are long, tarsi are 4-segmented. Ndkr, if developed, lie on the body like a roof. Females have an ovipositor. The majority are phytophages.
Superfamily crickets- long mustache. The wings lie flat on the body. Mole crickets have digging legs and no ovipositor. Phytophagous, there are predators. Damage to roots (mole crickets)
Superfamily locusts– antennae are short, ovipositor is short, hook-shaped. Oviposition in the soil in egg capsules. They cause harm in the gregarious phase (locusts, locusts, Siberian grasshoppers).
29(28) The hind legs are not jumping (if they are jumping, then the front and hind wings are the same, membranous, and the cerci are absent), the front legs are not digging.
30 (31) The head is covered on top with an expanded prothorax and is directed with the mouth parts downward and somewhat backward. The front pair of wings is noticeably denser than the back one………………………. Squad Cockroaches (Blattoptera )
Insects with a flat body. The head is turned downward with the mouthparts and covered with a large shield-shaped pronotum. The antennae are bristle-shaped, multi-segmented; legs of a running type with flattened femurs and 5-segmented tarsi. The forewings are dense, horny or leathery, with abundant veining; The hind wings are membranous and, when at rest, are hidden under the elytra. The elytra and wings may be shortened or completely reduced. The abdomen is elongated, 8-10 segmented, with soft coverings, usually bearing segmented cerci at the end; in males, on the last segment from below there are 1 or 2 unsegmented appendages - the stylus. Most cockroaches are yellowish-brown in color, less often dark or black. Metamorphosis is not complete.
Females lay eggs in the edema. Mostly nocturnal, secretive insects that live under fallen leaves, under stones, sometimes in soil and sand. Omnivorous. Some species are associated with humans, live in houses and other heated premises, spoil food and can spread bacteria that cause dysentery and intestinal diseases, as well as eggs of parasitic worms (whipworm, pinworms, etc.). One family is the Cockroaches (Blattidae). 4 genera, 6 species.
31(30) The head is free, with the mouth parts directed forward or downward.
32(37) Prothorax clearly separated from mesothorax. The head is usually strongly flattened, with the mouth parts directed forward. Tarsi 2-4 segmented. The abdomen is never stalked. The ovipositor is not expressed.
33(36) There are churches. Medium-sized insects.
34(35) Cerci large, 2-segmented. The 1st segment of the fore tarsus is thickened…………………………………………….. . SquadEmbioptera)
35(34) Cerci small, 1-segmented. 1st segment of fore tarsus is not thickened………………………………………………………………… Squad Termites (Isoptera)
36(33) Churches are absent. Very small insects... SquadHay eaters (Psocoptera)
37(32) Prothorax fused with mesothorax. The head is not flattened, the mouth parts are directed downwards. The tarsi are usually 5-segmented. The abdomen is often stalked, in females it is often with a sting, ovipositor, etc. ……………..
…………………….………Squad Hymenoptera (Hymenoptera)
Suborder sessile-bellied- the abdomen is connected to the chest by the entire base (family. horntails, sawflies, weavers). Phytophagous. Larvae with thoracic or abdominal legs. Females with ovipositor.
38(9) The mouthparts are not gnawing, the mandibles are not developed. Sometimes the entire oral apparatus is underdeveloped.
39(42) Oral apparatus in the form of a segmented proboscis, tucked under the thoracic segments (with the exception of non-feeding male scale insects, which have one pair of wings and threads at the end of the body). Some forms are immobile, sac-like, and develop on plants under the protection of the scutellum, waxy secretions, etc.
40 (41) The proboscis extends from the lower surface of the head or is shifted to its posterior edge. The front wings have a uniform surface. Some forms are non-feeding (without a proboscis), have one pair of wings and threads at the end of the body, some are immobile sac-like insects that develop on plants under the protection of a scutum, waxy secretions, etc. …………………………………… ……………….. Squad Homoptera)
From small to large sizes. 2 pairs of membranous wings folding like a roof. Some species of wings have 1 pair or not. Development is not complete. The mouthparts are piercing-sucking. Characterized by polymorphism. There are about 4000 species in Russia. Most are phytophages, plant pests. 5 suborders: cycads, psyllids, aphids, whiteflies, coccids (bugs).
Suborder cicadas. The antennae are short, the legs are jumping. 2 pairs of membranous wings. Males with hearing and chirping organs. Oviposition is in the stems. The larvae damage tree roots. Development is multi-year. Cicadas, pennies.
Suborder of psyllids). The antennae are long, the legs are jumping. The larvae are flattened with wing rudiments, live in colonies, most are monophages, and cause great harm ( apple and pear honeysuckle).
Suborder of aphids. Size 0.5-7.5 mm. The body is ovoid, often with white fluff. Abdomen with thin projections. They live in colonies and are often wingless. There are about 1000 species in Russia. Pronounced polymorphism, a complex cycle of generational changes, often migrate to another food plant. Reproduction by viviparity, parthenogenetically. Many pests: blood aphid, green apple. Families included aphids and hermes.
Whitefly suborder. Up to 2 mm. 2 pairs of wings laid flat on the abdomen. The body is covered with powdery pollen. The last instar larvae are not active. Larvae - in colonies on the underside of leaves. They eat juices. Dangerous: greenhouse, maple whitefly.
Suborder coccidae (scale insects)). 3-7mm. Sexual dimorphism is pronounced: females are wingless, motionless, covered with a shield or waxy secretions. Complex development cycle with virgin and bisexual generations. They live in colonies. Harmful scale insects, scale insects, false scale insects.
41(40) Proboscis extends from the anterior edge of the head capsule. The forewings are soft and transparent at the apex; the rest of their surface is leathery, usually opaque. Squad Semi-Coleoptera,orBugs (Hemiptera)
Size from 0.5 to 50 mm. They live on land, in water, under bark. The oral apparatus is piercing-sucking in the form of a segmented proboscis. 2 pairs of wings that fold flat. The forewings are leathery at the base and membranous at the apex. Many have scent glands. In some species the wings are shortened or absent. Development is not complete. The larvae are imago-like. Many species are phytophagous; there are predators and bloodsuckers. 2 suborders: hidden, loose mustache.
Suborder crypted. The antennae are greatly shortened and there are no scent glands. Live in water, predators ( smoothie, water scorpion).
42(39) Mouth apparatus in the form of a short cone or non-segmented proboscis, which can be needle-like protruding, fleshy retractable, spirally twisted, etc. The oral organs may be underdeveloped.
43(44) Body leathery, strongly flattened laterally. The hind legs are jumping. ………………………………………………………….. Squad Fleas (Siphonaptera)
44(43) Body various shapes, but is never very flattened laterally. The hind legs are not jumping.
45(48) Oral apparatus in the form of a short, sometimes retractable oral cone. Small insects with a flattened body.
46(47) The thoracic region is divided into segments. Wings (if developed) in two pairs, with a fringe of hairs along the posterior edge. They live on plants……………………………………………. Squad Thrips (Thysanoptera )
48(45) Mouth apparatus in the form of a proboscis or underdeveloped.
49(56) Two pairs of wings are well developed; if only one pair of wings is developed, then at the end of the body there are long tail filaments (an exception is the wingless females of some butterflies, which are recognized by the presence of an easily erasable cover of scales on the body.
50(51) Antennae shorter than head. The front legs are elongated. Squad Mayflies (Ephemeroptera )
51(50) Antennae significantly longer than head.
52(53) The head is directed forward with the mouth parts. Wings without a covering of hairs and scales…………………. Squad Stoneflies (Plecoptera)
53(52) The head is directed with the mouth parts down. The wings are covered with hairs or scales.
54(55) The wings and body are covered with easily erasable scales. The oral organs are in the form of a spirally twisted proboscis, less often - underdeveloped………. Squad Lepidoptera,orButterflies (Lepidoptera)
From small to large. 2 pairs of membranous wings covered with scales. The oral apparatus is sucking, the upper jaws are reduced, the lower ones are in the form of a proboscis. The antennae are long. The metamorphosis is complete. Larvae are caterpillars. Phytophagous in the caterpillar stage, many plant pests. The pupae are covered, many in a cocoon. More than 10 thousand species. Front-engined, the rear wings mesh with the front ones in flight. There is no ovipositor. 2 suborders.
Suborder Homoptera– few species, lowly organized. Sem. Fine strands.
Suborder heteroptera– the main number of species. Divided into 2 groups: lower heteroptera(family moths, leaf rollers, moths, glass beetles, wood borers) And higher heteroptera (large whites, nymphalids, swallowtails, bluebirds, etc.). Moths that cause more damage in the forest are fam. hawk moths, cocoon moths, moths, moths, moths, cutworms.
55(54) Wings and body covered with hairs. The oral organs are reduced……………………………….. SquadCaddis flies ( Trichoptera)
56(49) Only one pair of wings is well developed, or the wings are underdeveloped. There are no tail filaments at the end of the body.
57(58) The front pair of wings is developed, the rear pair is transformed into club-shaped halteres. Wingless forms have long legs………………………. SquadDiptera,orMosquitoesAndflies ( Diptera)
Suborder long-whiskered (mosquitoes)) – long antennae, elongated abdomen. Larvae with heads. The families include: gall midges, mosquitoes, biting midges.
58(57) The rear pair of wings is developed, the front pair is transformed into club-shaped appendages. Females are wingless and legless.. SquadFanwings ( Strepsiptera)
Exercise
1. Using the identification table, identify up to the order of representatives of the class of insects proposed in sets and prefabricated collections.
2. Outline brief characteristics of the orders of dragonflies, beetles, bedbugs, butterflies, cockroaches, Orthoptera, Netoptera, Homoptera, Hymenoptera, Diptera, paying primary attention to the characterizing characteristics and importance of representatives of the orders in forestry.
Reporting form: notes, oral survey on collections.
Our planet is rich in various representatives of fauna. The most common such representatives are, of course, insects. Insects belong to the class of invertebrate arthropods. They appeared a very long time ago and over such a long period they were divided into quite a large number of species. Insects are small creatures that adapt well to any environment. They defend themselves resourcefully and have a very complex reproductive system.
Insects are the largest and most diverse group of invertebrates in the world. According to various sources, today there are more than 3 million species of such animals. The number of units, according to various sources, varies from 30 to 40. this moment Only 1.5 million species of insects have been described. As mentioned above, insects first appeared on earth a long time ago, back in the Silurian period, which was 435 - 410 million years ago. However, several tens of thousands of species are known in the found state. Like all living organisms, insects are heterosexual. The evolution of insects, in most cases, involves transformation: the egg turns into a larva, then the larva develops into a pupa, and that in turn into an adult. Insects are divided into three large groups:
1) lower ones, which do not have metamorphosis,
2) with incomplete transformation,
3) with complete transformation.
The second and third groups include: orthoptera, proboscis, hymenoptera, lacewings, caddisflies, lepidoptera, coleoptera, fanptera, fleas, hymenoptera, diptera and many others. They feed preferably on plants, however, certain types of insects also feed on animal products. The study of insects is the subject of a separate branch of zoology - entomology, which translated from the Greek word "entomon" means insect.
Insects are very diverse in appearance. However, all insects share common characteristics. The body of insects is divided into the head, thorax and abdomen. The abdomen is attached to the thoracic region either motionlessly or with the help of a thin trunk. Insects have only one pair of antennae and three pairs of legs. In most cases, they are endowed with two pairs of wings. But wings are not developed in all types of insects, and in their larvae they may be absent or poorly developed. Insect wings perform main function– flight function. They function only in adult insects. These individuals breathe through tracheas. The skin of insects is formed from chitin, which creates a strong skeleton. Dense outer coverings protect internal organs insects from various damages and protect against dehydration of the body. The circulatory system is not closed. The nervous system consists of nodes that are located above or below the pharynx, and pairs of nodes in the thoracic region and abdomen. The heads of insects, as a rule, have a round shape, but sometimes they have a completely unusual shape. On their heads are sensory organs and organs with which insects capture prey. Sense organs include the organs of smell, touch and vision. Their eyes are located in the side region of the head; their structure can be simple or complex. The main organs of touch and smell are the antennae, which are located between the eyes or in front of them. On the surface of such antennae there is a huge number of sensory organs invisible to the naked eye. There are two types of food absorption organs: with a gnawing mouthpart and with a proboscis.
As you know, insects are of no small importance in the environment. Beneficial features insects provide necessary and useful products, as well as raw materials (honey, silk, wax). Most insects, such as ladybugs, wasps and many others, eradicate agricultural pests. Pollination of flowers occurs with the help of insects. Mammals, birds, and many other animals feed exclusively on insects; beetle larvae contribute to the formation of the edaphonic layer. However, certain types of insects are pests because they cause great harm agricultural, forest and ornamental plants. They are also carriers of pathogens of various dangerous diseases not only in humans, but also in animals.
Insects are representatives of the phylum arthropods. Their characteristic feature is the presence of limbs consisting of separate segments. The Insect class is the most numerous and has about 1 million species. Cockroaches, grasshoppers, beetles, butterflies, wasps, bees - it’s simply impossible to list them all! What features allowed them to become so widespread? The topic "Insects and their characteristics" is very interesting. Let's study it in more detail.
Structure
The body parts that insects have (see photo in the article) are the head, chest and abdomen. There is a pair of antennae on the head, the length of which varies and serves as an important systematic feature.
Miraculous transformation
It happens in a special way. In organisms with larvae, an imago is formed - an adult individual. Moreover, these two stages morphological characteristics They don't differ in anything except size. This is how the process of development of such orders as cockroaches, orthoptera, termites, lice, bedbugs and mantises occurs.
Coleoptera and fleas have a different type of transformation - complete. Its essence lies in the fact that the larva at an early stage of development emerges from the egg, turning into a pupa. At this stage, the destruction of the original organs and the formation of new ones occurs. This is how an adult is formed. An important fact is also the fact that the larva and the imago are not similar in appearance. For example, the Colorado potato beetle at the initial stage of development looks like a small worm.
Habitat
Characteristic signs of insects
Insects (photos show the diversity of representatives) have characteristics according to which taxonomists classify them into a separate class of the Arthropod type. These are three pairs of limbs and body parts (head, chest, abdomen), the presence of a pair of antennae on the head, respiratory organs - trachea, and secretions - Malpighian vessels.
Diversity and importance of insects
Which insect from the order Hymenoptera is social? Of course it's a bee. Its main significance is to obtain honey and bee bread from pollen.
Representatives of the order cockroaches fly very poorly, but navigate well in space with the help of long antennae.
Locusts, mole crickets and mole crickets are orthoptera. This order includes both grasshoppers and crickets, which have special devices. This is the so-called mirror - a thin membrane - and the bow - a vein with teeth.
Insects belonging to the order Bedbugs have a flattened body on which wings do not form. Their absence is compensated by the ability to easily jump a considerable distance.
Insects are all representatives of the order Beetles, which have hard elytra that tightly cover the abdomen.
Who among us has not admired the fluttering flight of beautiful butterflies? They are also insects. They are not only beautiful. Many of them are useful. So, he “heads” an entire production. It is artificially bred in many countries around the world. And the product of its vital activity is natural silk.
Thus, insects represent a class most of which are adapted for flight. Thanks enough high level organizations, they have mastered all habitats, occupying their niche in the system of the organic world.
The class insects has two subclasses: primary wingless And winged.
TO subclass primary wingless These include insects whose ancestors never had wings (silverfish, springtails, etc.). Silverfish live in sheds and closets. basements. It feeds on decaying substances and is harmless to humans. IN flower pots With excessive watering, wingless insects - springtails - often appear. They feed on rotted plants or their lower plants. The best way to combat them is to reduce watering.
Subclass of winged divided into insects with incomplete transformation and insects with complete transformation.
The distribution of species into orders is carried out taking into account such characteristics as the nature of development, structural features of the wings, and the structure of the oral apparatus. The main characteristics of some orders of insects are presented below.
| Units | Type of development | Number of pairs of wings | Oral apparatus | Features of wing development | Some representatives |
|---|---|---|---|---|---|
| Cockroaches | With incomplete transformation | Two pairs | Gnawing | Elytra | Red and black cockroaches |
| Termites | With incomplete transformation | Two pairs | Gnawing | Mesh | Termite |
| Orthoptera | With incomplete transformation | Two pairs | Gnawing | Elytra | Locusts, grasshoppers, crickets |
| Lice | With incomplete transformation | No wings | Prickly-sucking | Wingless | Head louse, body louse |
| Bedbugs | Louse | Two pairs | Prickly-sucking | Elytra | Turtle bug, staring bug, water strider bug |
| Homoptera | With incomplete transformation | Two pairs | Prickly-sucking | Mesh | Cicadas |
| Grandmas | With incomplete transformation | Two pairs | Gnawing | Mesh | Grandma-watch, grandma-yoke |
| Beetles, or Coleoptera | With a complete transformation | Two pairs | Gnawing | Elytra are hard | May beetle, Colorado potato beetle, burying beetles, bark beetles |
| Butterflies, or Lepidoptera | With a complete transformation | Two pairs | Sucking | Mesh with scales | White cabbage, hawthorn, silkworm |
| Hymenoptera | With a complete transformation | Two pairs | Gnawing, lapping | Mesh | Bees, bumblebees, wasps, ants |
| Diptera | With a complete transformation | 1 pair | Prickly-sucking | Mesh | Mosquitoes, flies, gadflies, midges |
| Fleas | With a complete transformation | No | Prickly-sucking | Wingless | Human flea, rat flea |
Insects with incomplete metamorphosis
The most common are: squad of cockroaches- typical representative - red cockroach. The appearance of cockroaches in homes is a sign of sloppiness. They come out of their hiding places at night and feed on carelessly stored food, contaminating it. Female cockroaches carry a brown egg “suitcase” at the end of their abdomen - ooteku. They throw it in the trash. Eggs develop in it, from which larvae are born - small white cockroaches similar to adults. Then the cockroaches turn black, molt several times and gradually turn into adult cockroaches.
Termite squad- this includes social insects that live in large families in which there is a division of labor: workers, soldiers, males and females (queens). Termite nests - termite mounds - can be of considerable size. Thus, in African savannas, the height of termite mounds reaches 10-12 m, and the diameter of their underground part is 60 m. Termites feed mainly on wood and can damage wooden buildings, agricultural plants. There are about 2,500 species of termites.
Order Orthoptera- most representatives of the order are herbivorous, but there are also predators. This includes grasshoppers, cabbage, locusts. The green grasshopper lives in the grass in the meadows and steppes. It has a long club-shaped ovipositor. Kapusyanka - has burrowing legs, flies and swims well. Causes great damage to the underground parts of garden plants, such as cucumbers, carrots, cabbage, potatoes, etc. Some types of locusts are prone to mass reproduction, then they gather in huge flocks and fly over a considerable distance (up to several thousand kilometers), destroying all green vegetation in the area. your way.
Squad of bedbugs- this includes known pests of agricultural crops - turtle bug, sucking the contents of the grains of cereal plants. Found in homes flea bug- a very unpleasant insect for humans. The water strider bug lives in fresh water bodies or on their surface, feeding on insects that fall into the water. Predatory bug attacks various invertebrate animals and fish fry.
Order Homoptera- all its representatives feed on plant juices. Many types aphids cause great harm cultivated plants. Many homoptera are carriers of viral plant diseases. This includes a variety of cicadas, whose sizes range from a few millimeters to 5-6 cm. They live in the crowns of trees.
Granny squad- exceptional predatory insects. Adults attack prey in flight. The best flyers. Their flight is highly maneuverable: they can hover in the air, be mobile and can reach speeds of up to 100 km per hour. This includes rocker head, grandmother-watchman and etc.
Insects with complete metamorphosis
Squad of beetles, or Coleoptera, is the most numerous order of insects, with up to 300,000 species. Beetles are common in a wide variety of land and freshwater environments. Their sizes range from 0.3 to 155 mm in length. Many beetles cause great damage to cultivated plants. One of the pests of potatoes and other plants is Colorado beetle, brought to us from America. Beetle beetle- pest of grains; Chafer- its larvae damage tree roots and potato tubers; beet weevil- affects sugar beets. In addition, this includes bark beetles, grinding passages in the bark and bast fibers of valuable tree species, and the larvae goldenrod and i live in dead wood and cause great damage to forestry industries.
Many beetles spoil supplies food products: pea grain, bread beetle, carpet beetle, damaging leather and wool products. Another small beetle belongs to the order of beetles tube gun. The biology of these beetles is very interesting. In spring, the pipe cutter cuts the leaf down to the main vein in a special way. The cut part of the leaf fades and loses its elasticity. Then the beetle rolls it up into a ball and lays its eggs there. Something like a cigar is formed. This is how the tubeweaver expresses concern for its offspring.
Individual beetles feed on the remains of plants and animals and play the role of orderlies in nature, for example: pustule beetles And gravestones. Some can be used to control pests. So, ladybug destroys aphids, and large green ones paint beetles- caterpillars.
Beetles can be extremely beautiful large sizes, For example stag beetle, or stag, listed in the Red Book, reaches a length of up to 8 cm, its larvae develop in rotten stumps for about five years and grow up to 14 cm in length. The reservoirs are inhabited by beetles of various sizes and feeding methods - the swimming beetle and the black water lover. The swimming beetle is a predator, the black water lover is a herbivore.
Butterfly squad, or Lepidoptera, - representatives of this order are distinguished by the varied colors of their wings. This includes hives, cabbage butterfly, silkworm etc. Among the species living on Far East, there are very large moths, whose wingspan corresponds to the width of an unfolded notebook. The wings of butterflies are covered with modified hairs - scales, which have the ability to refract light. The iridescent color of the wings of many butterflies depends on this phenomenon. Butterfly larvae are called caterpillars. They have a gnawing apparatus and a long body. Their salivary glands, in addition to saliva, also secrete silk threads, from which a cocoon is woven before pupation. Adult butterflies are very good plant pollinators. The caterpillars of most butterflies are herbivorous, eating leaves of plants, causing significant harm, for example, cabbage whites, apple moths, lacewings, ringed silkworms, etc. The caterpillar of the house moth feeds on woolen products, damaging them; some caterpillars spoil flour and other food products.
Mulberry and oak silkworms- people have been breeding them for a long time in order to obtain silk (from cocoons). Many large butterflies are extremely beautiful, for example swallowtail, Apollo etc. The large butterfly is very interesting night peacock eye, on the wings of which there are ocellated spots. Its caterpillar is large, fleshy, green in color, and before pupation it weaves a cocoon the size of a chicken egg.
Large moths with sharp-angled wings, characterized by very fast flight - hawkmoths, - so named because they readily feed on fermented and odorous tree sap, especially birch sap, which appears on wounds and stumps.
Order Hymenoptera- unites a variety of insects: bees, bumblebees, OS, riders, sawflies etc. The lifestyle of these insects is varied. Some of them are herbivorous, as their larvae (very similar to caterpillars) cause great damage to crops and other plants, e.g. bread and pine sawflies. Sawfly larvae feeding on leaves become so similar to butterfly caterpillars that they are called false caterpillars. An amazing adaptation is the ovipositor of sawflies, which serves to cut out pockets in plant tissues in which female sawflies hide their eggs, thereby showing original care for their offspring.
Excellent plant pollinators are bumblebees. This is a social insect. The bumblebee family only exists for one summer. Nests are built in mouse holes, hollows, squirrel nests, and birdhouses. The female builds the nest, equipping wax cells in it for laying eggs. A supply of food is placed in the cell - a mixture of pollen and honey. The larvae emerging from the eggs eat food and after two to three weeks weave silk cocoons, turning into pupae. Working bumblebees, females and males, emerge from the pupae. By the end of summer, there are up to 500 bumblebees in large nests. In autumn, the old queen, males and workers die, and the young queens hide for the winter.
Lifestyle OS looks like a bumblebee. They also exist for one summer. Wasps are beneficial by destroying harmful insects, and the damage caused by them damaging fruits is small. More harm from hornets(one of the types of swarming wasps): they gnaw the bark of young trees and eat bees. Having settled near an apiary, they destroy thousands of bees over the summer.
Of the social insects of the order Hymenoptera, it is most beneficial honey bee. She is also a wonderful plant pollinator and produces exclusively useful product food - honey, as well as wax, royal jelly, widely used by humans in perfumery. medicine, for the manufacture of varnishes, paints, etc.
A bee family is a surprisingly complex whole, in which all members of the family are very closely related to each other. Life and prosperity of the entire species are equally impossible without the queen and without drones, without worker bees. Using knowledge about the lives of all members of the bee family, beekeepers have learned to create specialized houses for bees - hives, conditions for feeding bees (taken to the fields where honey plants are grown) and at the same time receive not only honey good quality, but also quantities.
Representatives of the order Hymenoptera are used as a biological method of combating harmful insects. These include various riders, as well as Trichogramma, which is bred artificially
Order Diptera. This includes well-known insects: flies, mosquitoes, midges, gadflies, horseflies and other insects similar to them, having one pair of transparent wings. The second pair of wings turned into the so-called halteres. The common mosquito lives in swampy and damp areas. Mosquitoes are especially numerous in mid-summer. Residents of the taiga and tundra call their clusters vile. With their piercing mouthparts, mosquitoes easily pierce human skin and suck his blood. Worm-like mosquito larvae live in stagnant water. While feeding, the larvae grow, molt and turn into mobile pupae. Mosquito pupae also live in water; they cannot feed, so they soon turn into adults.
The malaria mosquito and the common mosquito are distinguished by their position.
Common mosquito (squeaker) keeps his body parallel to the surface on which he sits, and malarial- at an angle to her, raising the rear end of the body high. Malaria mosquito lays eggs in a pond one at a time, the common one - in packs, floating on the surface in the form of rafts. Fungus gnat larvae live in the fruiting bodies of cap mushrooms.
flies, unlike mosquitoes. have short antennae. Their larvae are white, usually legless and headless. The housefly's worm-like larvae live and develop in kitchen waste, in piles of manure and sewage, where the fly lays its eggs. Before pupation, the larvae crawl out of the sewage, penetrate the soil and turn into pupae.
Adult flies hatching from pupae fly everywhere in search of poverty. From latrines and cesspools they fly onto openly lying food products and contaminate them. Flies transmit gastrointestinal disease bacteria and roundworm eggs to human food. Therefore, it is very important to combat flies. Protect food from flies with gauze or hoods, wash vegetables and fruits before consumption.
Midges- long-whiskered bloodsuckers small sizes, the larvae of which develop at the bottom of reservoirs with running water. In the tropics and subtropics, in the Crimea there are very small mosquitoes - mosquitoes. Their larvae develop in moist soils, rodent burrows, etc. Mosquitoes are carriers of many diseases (malaria, etc.). We have a Hessian fly that destroys cereal plants.
Gadflies, horseflies They cause great harm to humans and domestic animals with their bites, as well as their ability to transmit pathogens of such dangerous diseases as tularemia and anthrax.
At the same time, flies are pollinators of many plants.
Rat flea can transmit plague pathogens from sick rodents - a very dangerous disease that once claimed thousands of human lives.