Brief description of the family
Family diagnosis. Antennae 11-segmented, attached along the edges of the forehead. Clypeus anteriorly narrowed. Prothorax strongly convex, hind thorax highly developed, processes four-lobed, hind coxae transverse, broad, extending to lateral margin.
Abdomen with 6 free sternites, the seams of the first 3 sternites fused with each other are quite obvious. The penis is symmetrical.
Systematic position. Initially, the Vodozhuki family was included in this family. Dytiscidae as a separate tribe (Pelobiini - Erichson, 1837, Seidlitz, 1887, Hygrobiinae - Regimbart, 1878). But already in 1881, Horn (Horn) allocated it to an independent family, noting a number of features that distinguish it from this. Dytiscidae, mainly in the structure of the thorax. The posterior thorax in front of the coxae has a wide, almost rectangle-shaped protrusion delimited below by a distinct suture from the rest of the posterior thorax, while the swimmers have no traces of this transverse suture. In addition, the head of this. Hygrobiidaene retracts into the pronotum, hind coxae not expanding anteriorly and legs adapted for crawling (hind legs move alternately), which brings them closer to this. Sarabidae. The independence of the family is recognized by subsequent authors (Ganglbauer, 1892, Jacobson, 1906, Reitter, 1908, Csiki, 1946, Guignot, 1947, etc.),
Morphological essay. The body is stocky, strongly convex. Head free, not retracted in pronotum, with strongly convex round eyes. Clypeus slightly narrowed anteriorly, separated from forehead by more or less noticeable suture. Antennae 11-segmented, filiform, glabrous; their first segment thicker than the others. The upper lip is wide and short, with a wide notch in front. The upper jaws are short and wide, asymmetrical, with two teeth on top. The outer lobe of the lower jaws is two-membered, the inner lobe is bent to the wide apex, the tentacles are 4-segmented, the 1st segment is short, the 2nd and 3rd are of equal length, the 4th is slightly longer and slimmer than the 3rd, slightly bent on top chopped off. The chin is very short and narrow. The lower lip is also very short, labial tentacles are 3-segmented, the first segment is small, narrowly conical, the second segment is twice as long and twice as thick as the first.
The pronotum is large, massive, with the base closely adjacent to the over-wings, its front edge is concave, with a thick fringe of bristles, the posterior edge in the middle of the base is more or less pulled backwards, leaving the triangular scutellum completely open in the European species, and in other species the scutellum is larger its part is covered. Scutellum more or less noticeable.
Elytra ovate, epipleura wide to hind coxae, further narrowing. The surface is almost completely bare, with a sharp sculpture of uneven scattered dots, almost wrinkles. Wings are available; venation of them is generally similar to that of swimmers. Prothorax strongly convex, anteriorly almost vertical, posteriorly elongated in the form of a long process, bordered on the sides and dulled at the apex, ending between the middle coxae. The middle chest is very short, sheer anterior. The anterior and middle coxae are conical, the posterior coxae are transverse, extending laterally to the lateral edge of the body, completely separating the first abdominal from the hindbone and episternum, posteriorly extending into the appendix. The posterior chest is short, wide, reaching the epipleura. Legs are long, slender, not typically swimming, legs are flattened and seated along the upper and lower edges by long swimming hairs. Both spurs on the front tibia are strongly developed, one of them is at the very top of the tibia, the other is somewhat behind. Tarsi 5-segmented, 1st and 5th segments long, 4th segment of fore and middle tarsi small. Fore and middle tarsi strong, on the outside with a series of long hairs on the first segments, hind tarsus long and slender, slightly flattened, with long hairs above and below. Claws quite thin, moderately long. The first three segments on the front and middle legs of the females are slightly cordially widened and bear a brush of brown-yellow hairs from the underside and the claws are more bent than in males.
Abdomen with 8 tergites and 6 sternites, seams of the first 3 sternites fused with each other in the middle are not very clear. The spiracles on tergite 1 are very large, transverse, following rounded, gradually decreasing. On the underside of the elytra in the last third near the suture, against the sharp posterior edge of the anal sternitis, there is a longitudinal transversely striated bead - a kind of stridulatory apparatus, which enables the beetles to make a strong rattling sound.
The genitals of males are similar to those of swimmers, the penis and parameres are symmetrical, the excretory opening is dorsal.
Biology. The larva is known only for the European species, it is very characteristic in its spindle-shaped, slightly humped form. Strongly convex, on the posterior end of the body with a long fusiform process, yellow on the head and back, with a brown pattern. Head without neck, very large, slightly narrower than prothorax, sloping. The forehead in the middle is slightly elongated and depressed on both sides before the eyes, the clypeus is directly chopped off. Eyes number 6, elongated, slightly protruding. Antennae lateral, filiform, 1/3 head long, 2nd segment twice as long as the first, 3rd half 1/2 shorter and much thinner than the 2nd, 2 very small thin conical segments sitting on its apex (4th segment and subordinate, this last is much less than the 4th). Mouth open (like Noterini), the upper jaws are quite long, narrow, with a denticle on the inner edge of the apex. Stem of the lower jaw twice as long as wide, lobes not developed. Jaw tentacles thin, 2nd segment 1/4 longer than 1st, 3rd segment 1/3 longer than 2nd, suspended. Lip tentacles as long as jaw tentacles. The pronotum on the base is 1/3 wider than its length and slightly wider than the head, strongly convex from above, widely rounded at the sides and at the front edge. The mesothorax and hind thorax are twice shorter than the prothorax, three times wider than their length. The abdomen is very convex above and flat below, to the base of the stylus as long as the head and chest together. The first abdominal sternites are very short, the next ones gradually lengthen. The stylus-shaped appendage of the cone-shaped 8th ring is the same length as the abdomen, as well as moving, very long, slender, somewhat shorter, slightly one-segmented cerci, planted with scattered short setae and protruding hairs. Very small rounded spiracles are present - one pair on the middle chest, and one pair on the first 7 tergites of the abdomen. Filiform gill appendages sit on the base of coxae on the first 3 abdominal sternites. The legs are flattened and rather long, the hips are strong, the legs and feet are thinner, the claws are thin, of equal length.
Pupa, as in swimmers, with two strong cerci, spiracles located between abdominal sternites and pleura, abdominal tergites in the midline keeled, first 6 tergites with spiracles.
The female lays eggs in rows on the stems of plants immersed in water. Adult larvae emerge from the water and settle for pupation on the shore in the surface soil layer at a depth of 5 cm or more. One generation develops throughout the year. Beetles winter in silt at the bottom of a reservoir.
Ecology and geographical distribution. Both beetles and larvae live in swampy puddles and heavily overgrown small ponds. Beetles swim rather quickly, alternately moving their hind legs. Oligochaetes and small crustaceans eat. They live in the lowlands, rarely rise in the mountains (their presence at an altitude of up to 2000 m is noted).
The family includes only 1 genus with 4 species: 1 in central and southern Europe, 1 in China and 2 in Australia. Thus, it has to be considered an ancient relic dying in the modern era.
References: Fauna of the USSR. Coleoptera insects. Volume IV F.A. Zaitsev. Swimmers and twirls. Zoological Institute of the USSR Academy of Sciences, 1953
Beetle - description, characteristics, structure, photo. What do bugs look like?
A characteristic feature of beetles, or beetles, is the presence of hard chitinous or leathery elytra, formed from the upper pair of wings. This kind of armor protects the folded flying wings of the insect from damage when it is not in the air.
The body shape of the beetles depends on the habitat and species. In aquatic inhabitants, it is slightly flattened, streamlined and compact (diving beetles, swivels).
Beetles living in the soil are characterized by a slightly convex body shape with a powerful, expanded front part (scarabs, dung beetles).
Beetles that live on the surface of the earth have a strongly convex upper part and rather long limbs (ground beetles).
In the body structure of adults, there are three main departments: the head, chest and abdomen.
The head of the beetle is round, slightly flattened, although in some families it has the appearance of an elongated tube. It can go deep into the prothorax and be almost invisible or connect with it freely using a movable neck. In some beetles, the head is a head tube, at the end of which there is an oral apparatus (weevils, false bolewings, pipelines).
The head of a bug can be:
- Prognathic (oral organs and antennae directed forward),
- Orthognathic (hypognathic) (oral organs pointing down),
- Opistognathic (oral organs directed back).
On the upper surface of the head are placed different lengths of the antennae of the beetle, consisting of individual segments that serve as the organs of smell.
Rhipicera femorata fan beetle mustache looks like long eyelashes
On the sides are well-developed, complex faceted eyes of the beetle, sometimes consisting of 25 thousand individual lenses that create a mosaic image.
Some species on the crown have additional simple eyes, and underground and cave dwellers may have no visual organs.
The mouth apparatus of most beetles, intended for grinding food, consists of paired mandibles (upper jaws) and maxillas (lower jaws). On the lower lip and jaw of the coleoptera there are small palps, which are peculiar organs of touch and taste of the insect.
The largest mandibles are observed in stag beetles (deer beetle and Hercules beetle).
In the structure of the chest of beetles, three segments are distinguished: prothorax, movably connected to the middle chest and fused with the posterior chest. On the back side, the segments are called the pronotum, mesonotum, and pronotum. Each segment is formed by two half rings (upper tergite and lower sternite), movably connected to each other. Rigid elytra are attached to tergites of mesoscum, and membranous wings are located on the back of the beetle. Three breast sternitis carry a pair of limbs.
The shape and sculpture of the pronotum is very diverse, and its structure plays an important role in the classification of beetles. It can be either smooth or with lateral spikes or various shaped growths.
The extremities of beetles consist of 5 parts: basin, trochanter, thigh, drumstick and tarsus.
A distinctive feature of beetles is the presence on the top of the tibia of special spurs, which can be paired or single. The legs of the beetle are covered with small thick hairs and have two claws of different shapes and lengths.
Depending on the lifestyle of the beetle (Coleoptera), the appearance of the limbs may vary slightly and perform running, grabbing, digging, swimming or jumping functions.
In the process of evolution, the front wings of beetles turned into hard elytra, not inferior in hardness to the insect chitin exoskeleton.
When folded, the elytra of the beetle provides reliable protection for the mesoscutum, metanotum, and upper abdomen.
In species with reduced lower wings, the elytra usually grow together to form a monolithic framework. Some bark beetles on the elytra have a recess intended for transporting wood waste generated by gnawing a system of passages in the body of a tree.
The elytra surface is smooth, covered with various recesses, growths, grooves and spikes.
The lower membranous wings of the beetles are usually transparent and can be slightly colored or completely colorless.
Depending on the generic and species affiliation, the veins can have a different texture, both with the formation of transverse cells, and with medial veins and branches from them.
The color of beetles is often a characteristic feature by which insects are divided into separate species.
Usually the color of the beetle is monophonic, dark brown, red-brown, black, green, yellow or red, often with a metallic tint. However, there are species with characteristic bright patterns on the surface of the body or with bioluminescent glow.
Sexual dimorphism of beetles is usually expressed in the size and color of individuals of the opposite sex.
In most species, male beetles are smaller than females and have a more elongated body. However, in some genera, due to overdeveloped mandibles resembling horns, the size of male beetles is much larger than females. Also, the length of the antennae or front legs may indicate belonging to a particular sex.
For some species of beetles, sound communication is characteristic, which allows maintaining relationships within one population, and males to find females and scare away insects of another species. Sound vibrations occur due to friction of the prothorax against the midbrain.
The size of the beetles that are part of the winged wing order varies widely. Among these insects, both true giants and babies are found, which can only be examined well under a microscope. For example, the size of a woodcutter-titanium beetle (lat. Titanus giganteus ) can reach 22 cm in length, relic lumberjack (lat. Callipogon relictus ), living on the territory of Russia - 11 cm, and the length of the baby Scydosellamusawasensis does not exceed 352 microns.
Beetles live in almost all corners of the globe, ranging from sultry deserts and moist equatorial forests, and ending with the vast expanses of the tundra, with the exception of the zone of eternal snow of the high peaks, as well as ice fields of Antarctica and the Arctic.
The numerous order of beetles includes species of beetles that settle in the surface fertile soil layer, inhabit the bark, wood or tree roots, as well as flowers or deciduous cover.
Inhabitants of deserts and semi-deserts have adapted to the conditions of elevated temperatures, therefore, they lead an active nightlife. Many beetles live in fresh or slightly saline reservoirs with abundant coastal and bottom vegetation.
Among insects that are part of the winged wing, there are representatives of almost all known types of food inherent in arthropods. There are predator beetles that feed on other insects and their larvae, herbivorous beetles that feed on mushrooms, foliage, roots, fruits and seeds, as well as beetles that eat wood or bark of various plants. Many beetles are pests of crops and eat leaves, beets, cabbage, as well as other vegetables, fruits and fruit trees. One of the most famous pests is the Colorado potato beetle, which feeds on leaves of nightshade crops.
There are even varieties, which are, in fact, the orderlies of the forest, since these beetles feed on dry and rotting parts of plants or decaying remains of animal origin.
In addition, the food of beetles depends on the stage of development of the insect.
Imagoes of some species, feeding on wood, pulp of green shoots, pollen or juice, being once larvae, ate decaying organic remains, or were predators. There are families that accumulate in the larval stage a sufficient supply of nutrients that allows adults to do without food for the rest of their lives.
Coleopterans have a positive effect on the ecosystem in their habitats. Both adult beetles and their larvae process dried wood, as well as parts of plants affected by various fungal diseases, actively participating in the process of humus formation. In addition, beetles can act as pollinators of flowering plants.
At the same time, some species of beetles can cause significant damage to most crops and forest plantations, leather and tobacco industries, museums and libraries, as well as wooden structures and furniture.
As the name itself shows winged , a characteristic feature of beetles is the wings of the first pair, which turned into hard elytra, or the so-called elites. They are calmly applied to the back, and the folded webbed wings of the second pair are placed under them. The elytra in this case fit snugly against one another, forming a straight suture line. The whole body of the beetle, especially the head and pronotum, is covered with a thick layer of chitin. At the flying beetle, the elytra are raised and spread apart. They play the role of supporting planes, while the wings of the second pair serve as the propulsion system. Some bugs have elytra shortened. At the base of the elytra and the beginning of the suture line, a small triangular flap is visible, which is part of the middle chest of the beetle.
On the head there are antennae, which can be reached in some beetles with a very large length. In different beetles, the antennae are very diverse and carry organs of touch and smell. In addition to the antennae, two or three pairs of palps are visible on the head: the first pair is maxillary, the second is lower labia, and the third is a modification of the outer maxillary lobes.
Well-developed faceted eyes, and often simple eyes, are placed on the head of the beetles.
The oral apparatus is typically gnawing, often with very strongly developed mandibles.
The chest limbs of the majority of the running type, but in many species are altered and adapted to digging or swimming lifestyles.
Larvae can have a different shape. They are either six-legged, or in some cases legless. Pupae are free.
Beetles - pests of plants
Among the beetles, there are many are dangerous pests of trees and agricultural plants. They belong to different families.
First of all, let us pay attention to beetles of the subfamily of Khrushchev from the family Lamellae.
May beetles are of the greatest importance as pests of the root system of pine young growths. On the territory of Russia, western May beetle (Melolontha melolontha) is common in western and southern regions, and eastern May beetle (M. hippocastani) is a close species in eastern regions. May bugs lay eggs in the ground. May beetle larvae also develop in the ground. They hibernate three times. They feed on the roots of seedlings of trees, which cause great harm. With age, the larvae switch to feeding on larger roots. Young pine forests, fruit crops, etc. often suffer from them. Adult beetles eat the leaves of trees: birch, oak, aspen, etc. The development cycle of the May beetle usually lasts four years in the southern regions and five years in the north.
The most serious cereal pests, such as the bread beetle, or the sowing goose (Anisoplia austriaca), which is often found in the steppe zone of Russia, also belong to grapes. This is a relatively small (12-14 mm long) greenish-black beetle with brownish elytra and dark spot at their base. The beetle eats ripened grains of wheat, rye, barley. In the forest-steppe regions and to the north, a close species is the goose-crusader (A. agricola). Both species can appear in large numbers and harm crops. Females lay eggs in the ground. Larvae live in the soil where they feed on plant roots. In the soil, they hibernate twice, and more mature larvae cause significant damage to cereals, causing thinning of seedlings.
Nutcracker beetles are well known for their peculiarity - with a snapping jump, if it is placed on its back. This is a kind of adaptation that enables the bug, which for some reason has rolled over on its back, to stand on its feet. Bouncing a beetle is due to the fact that the nutcracker has weak limbs and they cannot use them in similar cases, like other beetles.
The larvae of various species of nutcrackers live in the soil, under the bark and in stumps. Long worm-shaped larvae of the nutcrackers are covered with a thick chitinous cover and therefore are called wireworms. Nutcracker larvae living in the ground feed on the underground parts of plants. Nutcrackers are multi-eating pests. More than 20 species are known that damage cereal crops, perennial grasses and garden crops. The most harmful are the seed nutcracker (Agriotes sputator,), the dark nutcracker (A. obscurus), the striped nutcracker (A. lineatus), etc.
Another group of beetles - plant pests are beetles from the leaf beetle family. This is a very large family of more than 50,000 species. Among leaf beetles, dangerous pests are moth (Lema melanopus), which affects cereals, horseradish leaf-beetle-babanukha (Phaedon cochleariae), which causes harm to garden plants, etc.
So-called fleas are close to real leaf beetles. These are small bugs (2-3 mm in length) with the ability to jump (their hind limbs are hopping type). The most harmful are a bread flea, a beetroot flea, etc.
The leaf beetles include the famous Colorado potato beetle, or potato leaf beetle (Leptinotarsa decemlineata). The Colorado potato beetle comes from Mexico. It was first brought to Europe from America during the First World War and in a short time spread to several countries of Western Europe.
These are small bugs (body length 10-12 mm) oval, yellow. On lighter elytra - black longitudinal stripes (5 each), on the chest shield - dark spots. Beetles settle on the leaves of potatoes, eat them and destroy plants. They hibernate in the soil, and in spring, awakened individuals begin to eat young foliage of potatoes, tomatoes and wild nightshade. After feeding, the beetles mate, and the females begin to lay eggs on the underside of the potato leaves. In clutch there are 30-40 testicles arranged in the form of a small cake. Over the course of her life (over the summer), the female lays more than 500 eggs. There are usually 2-3 generations a year. Thus, the offspring of one female with unhindered reproduction in the second generation can reach 250 thousand individuals.
After 5-15 days (depending on temperature), larvae emerge from the testicles, feeding on foliage, as well as beetles, and after 2-3 weeks they pupate in the soil at the roots of the potato. After 7-8 days, adult beetles emerge from the pupae.
Due to such great fertility, the Colorado potato beetle is a very dangerous pest of potatoes. Both beetles and larvae destroy a huge number of leaves, which leads to the death of plants. Beetles live up to 14 months. The Colorado potato beetle is also rapidly spreading thanks to the ability to make massive flights over fairly long distances (several kilometers) in the dry season. The fight against bugs in the fields infected by them is carried out mainly by chemical methods. Mechanized or manual collection of beetles and their larvae are also used.
A very large (30,000 species) and a peculiar group of pest beetles are weevils, or elephants. These are small species that can be distinguished by the structure of the head. The front end of the weevils head is elongated into the cephalothorax, on which are cranked antennae and oral parts. The pests are mainly the larvae of weevils. So, the female apple-beetle (Anthonomus pomorum) lays eggs in the buds of pears and apple trees. A legless larva hatched from an egg eats up the ovary of a flower. The larva of beet weevil eats the roots of beets. One of the most serious pests is the barn weevil (Calandra granaria), which is very harmful to grain in barns and granaries. Small female barn weevils (2-4 mm) lay eggs in grains. Larvae eat out the inside of the grain and pupate right there. One female barn weevil usually lays up to 150 eggs. Adult weevils, gnawing grains, also cause harm.
Bark beetles are close to weevils and cause great harm to forestry.
Of the most common and harmful species, it should be noted first of all the bark beetle typograph (Ips typographus). It harms mainly spruce, pine and other coniferous trees. On the tree damaged by the bark beetle, one can find the inlet made by the male, leading to the so-called “random chamber”, where the females climb and where the mating takes place. Females (there are 2-3 of them) make uterine passages in the cortex, in the walls of which they make cavities and lay eggs. The hatched larvae gnaw through the larval passages, which gradually expand as the larvae grow. Pupation occurs at the end of the larval passages. Young beetles also bite into the bark, and then go outside through the flight holes. Bark beetles belong to the group of secondary pests that attack trees weakened by other pests or drought. Of the other bark beetles, a birch sapwood, harmful to birches, as well as a large forest gardener, or shearing tree, should be noted. Adult striguns usually attack diseased and dumped trees, but the new generation that has emerged rises for “additional nutrition” to the tops of the trees, where they bite into young branches, eat out the core, after which the branches break off easily.
Both Russian names - barbel, or woodcutter - well characterize a large group of beetles - pests of the forest (17,000 species are described). It is often quite large with an elongated body tapering to the posterior end and very long polynomial antennae directed backwards to the sides and over the body. Antennae in many species significantly exceed body length and are more developed in males. Barbel lays eggs in the bark of trees. Larvae bite into the bark, and then into the wood. Pupation occurs in wood. The larva of the lumberjack is worm-shaped, with an expanded head, with small legs or completely devoid of limbs. Characteristic representatives of this family are the small black spruce barbel (Monochamus sutor), the large aspen violin, or the poplar barbel (Saperda carcharias). Some of the barbel (root-eared barbel) develop in the soil. These bugs crawl on the ground, have lost the ability to fly, and they have no webbed wings. In the southern regions of Russia, the larvae of some barbels damage the roots of cereals.
In the family of ground beetles, in addition to predators, harmful herbivorous forms are found. These are smaller, often harmful to agricultural plants. Such, for example, millet ground beetle (Harpalus calceatus), which harms millet, corn and other grains, and ground beetle (Zabrus tenebroides), eating wheat and rye.
In conclusion, it should be noted that some beetles and their larvae came to life in fresh water bodies and therefore acquired various adaptations to the aquatic lifestyle. Such beetles include aquatic beetles and swimming beetles. Water beetles, especially swimmers and their larvae, are serious pests in ponds, lakes and rivers. By destroying fish fry, they can cause serious harm to pond fisheries. Of the features that developed under the influence of life in water, the most interesting is the change in the extremities of the third pair into rowing flat lobes trimmed with hairs, and the ability to maintain a supply of air under the elytra, which is used as a “physical gill while underwater”
What insects are Coleoptera
The common name for beetles is bugs. The reason for the appearance of this name is the buzzing sounds made by these creatures. Beetles are considered eurybionts - creatures that have adapted to life in various natural conditions. Indeed, beetles can be found anywhere in the world, with the exception of the cold Arctic, Antarctica and the highest mountain peaks. But hard-winged birds feel best in warm climatic zones; therefore, a greater variety of beetles is observed in tropical forests.
The winged wing detachment includes 6 main families, whose representatives make up more than half of the total diversity of these insects:
- carnivorous beetles,
- ground beetles
- weevil beetles,
- leaf beetles
Representatives of the Coleoptera differ in body size. In some species, adults barely grow up to 0.3 mm in length (perioptera beetles), other representatives are real giants in the insect world - their body length can reach 17 cm (titanium woodcutter beetle).
All beetles have the same body structure. The main features of beetles:
- strong compact body
- hard integuments, leathery or sclerotized elytra,
- webbed wings with which beetles fly. At rest, a pair of wings is hidden under the elytra,
- the oral apparatus is predominantly gnawing.
Lifestyle and Nutrition Features
Insect beetles occupy different niches in different ecosystems. Coleopterans lead an active lifestyle, being in constant search of food.
Most beetles are either phytophages (vegetarian insects) or predators. In addition, saprophages (feed on rotting remains), coprophages (feed on animal excrement), and necrophages (scavengers) are often found. Some beetles stock up food in burrows to survive hungry times. Coleopterans are known which do not feed at all in the adult stage, since they lack nutrients stored in the larval stage.
All beetles develop with complete transformation, that is, in their life cycle there are 4 stages:
Most coleoptera reproduces sexually, but parthenogenesis also occurs. Beetles seek sexual partners with the help of sound and light signals, as well as produced pheromones. After mating, most females lay their eggs, although some representatives of leaf beetles are viviparous.
The larval stage can last a very long time, in some species - more than 10 years. The appearance of the larvae depends on their lifestyle. Larvae living on the ground or on plants are usually black or green and brown. The larvae that develop in the soil have a fleshy body of white color. Pupation of beetles most often occurs in cradles located in rotting wood or in soil. The adult stage in bugs usually lasts longer than in other insects.