Bug beetle - the perfect predator of water bodies

Diving beetle - the collective name for aquatic insects belonging to the order of beetles. In nature, there are 4 thousand species, 300 live on the territory of Russia. Beetles can fly and swim perfectly. They spend most of their lives in water. Prefer ponds and lakes with stagnant water. Adult swimmers and their offspring are active predators. They attack fish and fry, tadpoles, mosquito larvae, mollusks. In places of fish farming, the appearance of a swimming beetle becomes a real disaster.

Morphological description

Swimmers (Dytiscidae) - a family of medium and large beetles that live in water bodies. They are found throughout Europe and Asia, in North America even populated the Arctic territory. Insects choose fresh water bodies with a large number of plants and stagnant water. It can be ponds, lakes, ditches and deep puddles. The size of the swimming beetle, depending on the species, is 2-4.5 cm.

Universal insect can crawl, swim and fly. Not many representatives of the winged wing detachment are endowed with such abilities. On land, swimmers move slowly, swaying from side to side. The hind limbs are repelled, and the front and middle ones are sorted out.

Description of the swimming beetle

The oval, flat, streamlined body of the beetle is optimally adapted for movement in the water column. The hind legs act as a mechanism providing movement. The limbs have well-developed muscles. The flattened tibia and tarsus are covered with two rows of elastic hairs. The method of movement of a swimming beetle in water resembles rowing with oars. The hind limbs move simultaneously. Strong bristles on their surface replace the rowing blades. The middle legs adjust the direction of movement - up or down. The forelimbs are not involved. The front and middle legs are noticeably shorter than the hind legs.
The body consists of three departments: head, chest, abdomen. The head is fixedly mounted on the chest, which, without a sharp boundary, passes into the abdomen. Coloring is mainly dark - green, brown, black. In some species, a light (gray or orange) edging passes along the trunk and head. The abdomen consists of 8 segments covered by rigid elytra.

The head of the insect is wide and flat. Large eyes are located on the sides. Each consists of 9 thousand simple eyes, making it possible to distinguish between static and moving objects. Behind the transverse plate of the upper lip is a powerful jaw designed to capture and chew prey. The mouth apparatus is gnawing. Long articulated antennae are the organ of smell. They are located on the sides of the forehead, consist of 11 naked segments.

How the swimming beetle breathes

Swimmers spend most of their lives underwater, but breathe air. Insects need to regularly surface to replenish oxygen reserves. What is the respiratory system of a swimming beetle? Air intake into the body is provided by special openings - spiracles located on the abdomen. From the spiracles to all parts of the body, a system of ducts — the trachea — diverges. There are air sacs in the chest of the insect.The abdomen is rhythmically compressed and unclenched, creating a movement of air in the trachea.

On the body of the beetle there are glands that lubricate the ends of the elytra and abdomen. To update the air supply, the swimmer exposes the end of the abdomen outward. Contraction of the organ allows you to pump air under the elytra. Larvae also breathe, their trunk ends with filiform appendages, performing the function of the spiracles. To inhale a portion of air, an insect pops up every 10 minutes.

Lifestyle

The swimmer easily floats to the surface of the reservoir, because his body is lighter than water. Descent requires more effort. To stay on the bottom of the pond, he needs to cling to a stone or plant. The forelegs of the beetle have special hooks that allow it to attach to any smooth surface. Insects are active at night, they hunt or go in search of a new home. Fauna lovers are interested in whether the swimming beetle flies or not? Adult males and females have well-developed wings. In search of favorable habitats, they fly tens of kilometers.

Before the flight, specific preparation takes place. The beetle gets ashore and empties the contents of the intestines. He then fills the air bags on his chest. As much as possible reducing body weight, the swimmer takes off. When searching for ponds, he focuses on vision. Noticing the shine, the insect dives down. Tactics often fail bugs, instead of a reservoir, they fall on glass greenhouses or galvanized roofs. Many travelers die from a strong blow to a hard surface.

In the cold season, many insects hide in crevices or burrow into the soil. Where does the swimming beetle hibernate? Among the many species of insects, there are those who spend the winter in the egg, larva or adult phase. For insects living in Europe, immersion in the diapause of adult beetles is characteristic. After emergence from the pupa in autumn, young beetles remain wintering in the litter or under the bark. Part of the swimmers returns to the reservoir. With a sufficient amount of oxygen, they actively swim. Complete freezing of the surface causes the beetles to dig into the sludge and fall asleep to heat.
The enemies of swimmers are birds, small mammals, fish. Dark coloring helps insects merge with bottom stones. A lot of parasites settle on the diving beetles: nematodes, riders, water mites.

How long are swimming beetles? The life expectancy of adults ranges from several months to two to four years. Most bugs live about 1 year. The shortest life cycle of representatives of the species Agabusfuscipennis, common in Europe and the Middle East.

Power Features

What does a swimming beetle eat? The predator consumes any protein food, he does not disdain eating dead fish. Sharp and wide mandibles allow you to attack large prey. A hungry beetle attacks fish or frogs 3 times its size. How does he deal with large booty?

The remaining swimmers living in the pond help him. After the first bite, the victim’s blood enters the water. Thanks to the delicate sense of smell, predators catch it at a considerable distance. Around the fish, a dozen bugs gather, which tear off pieces from live prey. In most cases, insects are content with invertebrates and mollusks.

Breeding

Sexual dimorphism of swimmers is expressed in the difference in size (females are larger) and the structure of the front and middle extremities. In males, the first three segments of the legs are widened. They have suction plates - from a dozen to hundreds of pieces. They are used to hold a partner during mating. The breeding season of beetles falls in the spring. The process takes place in water. For females, it can cost a life. During mating, they are not able to float to the surface and fill the elytra with air.

After fertilization, the females proceed to masonry. The swimming water beetle has large eggs, reaching a length of 5-7 mm. Masonry is performed in the bottom substrate, plant tissue. The number of eggs laid per season is 1,000.The sharp ovipositor in the stems and leaves makes incisions in which the oval egg is placed. After 10-12 days, larvae appear. In cold weather, the development time of the embryo is delayed up to a month.

Information. The laying of swimmers is threatened by riders living in the water. These are prestvichi, insects 1 mm in size. Their offspring parasitizes on the eggs of beetles and dragonflies. In one egg, more than 100 riders can develop.

Larval development

The color of the larva of a swimming beetle is yellow, gray, and brown. Often the body is covered with a pattern of dark stripes and spots. Outwardly, the offspring look like scorpions, not swimmers. From birth, the larvae are voracious predators. The first food is caviar, larvae of caddis flies, dragonflies, mosquitoes. The head is flattened, the chest consists of three segments, the abdomen of eight segments. On the sides of the head are located 6 simple eyes. Antennas are thin, in the first age 3-segmented, after two links - 6-segmented.

Oral appendages are transverse. There is no upper lip, and the lower one is formed by a wide plate with palps along the edges. Strong mandibles are curved in the form of a sickle, the edges are pointed. They move only in a horizontal plane. Mandibles canals connected with the pharynx. Larvae have no mouth opening. Food enters through the jaw.

The digestive system of insects is also unusual. Extraction is not fermented into the stomachs, but outside. The larva immerses its mandibles in the victim's body and injects digestive juice. After a few minutes, the tissues and organs soften. The contents of the prey are absorbed directly into the throat. Having finished feeding, the insect cleans the mandibles with the front paws. The larva of a swimming beetle, a tireless and voracious predator, having finished with one victim, it goes in search of the next.

An elongated wide body tapers to the rear end, crowned by two churches. It contains various formations: spines, bristles, scales. Three pairs of long limbs are attached to the thoracic segments. The legs are composed of 5 segments. On the hips and lower legs swimming hairs, the foot ends in two claws.

In its development, the larva replaces 3 ages. The longest is the last third age. In early autumn, the larva leaves the pond. On the shore, she builds a crib from the remains of plants and lumps of soil. Pupation occurs in the cradle. The phase lasts about a month. Pupa is white, soft, open type. Imagoes after appearing from the pupa are also soft and light. After a few hours, their cover darkens and hardens.

Types of swimmers

The Latin name for the insect Dytiscus comes from the Greek word “diving”. It accurately describes the behavior of the beetle. Among the large family, several interesting species can be distinguished.

Fringed swimmer

A common species of diving beetles whose habitat is water bodies with standing or low-current water. The oval body is black or dark brown. The limbs are orange, as is the edging passing through the elytra. The size of adults is 27-35 mm, in the Far East there is a larger subspecies (32-37 mm). The male is smaller than the female and has a smooth elytra surface. Carnivorous predators attack larvae, fry, tadpoles, in the absence of small prey - frogs and fish. They live in Europe, Central Asia and Siberia.

Wide swimmer

The body length of an adult beetle is 35-45 mm. Large wide beetle is brown or black with a green tint. The photo shows that along the edge of the pronotum and elytra of the swimming beetle there is a yellow border. The larvae have a long fusiform body; they are larger than adults in size, growing to 60-60 mm. Insects inhabit lakes with clear and muddy water. Prefer to keep off the coast. Observed in bodies of water overgrown with sedge, horsetail, saber, squirrel. The wide swimmer is a rare species. He disappeared in 10 European countries. The beetle is listed in the IUCN Red List.

Information. Swimmers have few enemies in the water; large predators do not touch them. Insects have a protective mechanism - when an enemy attacks, they emit white caustic fluid.

Unwanted neighborhood

Having settled in a decorative pond, a predatory bug attacks decorative fish and other inhabitants. Owners of water bodies face a difficult problem, how to get rid of a swimming beetle in a pond? The least time-consuming way is to get carasses that actively destroy swimmer larvae. Another option is to temporarily install a pump or fountain that creates the movement of water mass. The insect prefers standing water bodies, so it leaves the shelter and goes in search of a better habitat.

If the above methods do not work, then it remains to drain the water, clean and disinfect the bottom. This will destroy the imago and beetle larvae. After treatment, water is poured and new inhabitants are launched.

Danger to humans

You can face a predatory bug swimming in the lake or in your own pool. Aggression to humans is extremely rare. The bite is painful, but does not pose a health hazard. A swimming beetle bites in water if it feels threatened. The pain from a puncture of the skin remains for several minutes. After a while, the wound swells, a lump may form. Beetles are not poisonous, so there is no allergic reaction.

The victim must be given first aid:

• rinse the wound;
• treat with an antiseptic (iodine, hydrogen peroxide);
• apply a bandage;
• apply ice to relieve swelling.

Attention. Often the bites of a swimming beetle are received by those who pick it up without the necessary dexterity.

House maintenance

Fans of aquatic life can contain a swimming beetle in the aquarium. As food, they give him pieces of raw meat and fish. The container is covered with a lid, otherwise the winged bug will fly away. Sand is poured into the bottom and coarse pebbles are laid. Any algae are chosen; swimmers do not eat them. The main thing is that you can’t settle bugs in the same aquarium with fish.