Dragonfly large rocker - exterminator of blood-sucking insects on land and in water

On a nice summer day over the lake you can see many brown dragonflies flying rapidly over the water surface. These insects are common throughout the globe. In nature, there are more than 6.5 thousand species of flying predators. This is an ancient detachment, adjacent to dinosaurs at one time. Having survived millions of years, the dragonfly, a large rocker, was threatened by a reduction in species due to human activities. Water pollution has led to a sharp reduction in the number of beneficial insects.

The appearance of insects

The large rocker is a dragonfly belonging to the family and genus of the rocker. Large insect reaches 60-75 mm in length, hind wing 45-49 mm. The female has a brown abdomen with small yellow spots. The chest is also brown, oblique yellow stripes on the sides, covered with hairs. In males, the body is brown or brown, on the side of the abdomen there are blue spots.

Information. The Russian name of the genus "rocker" is associated with a special pose of females who are not ready for mating. Insects bend the abdomen in the form of a rocker, refusing fertilization.

A characteristic feature of Aeshna grandis is that the facet eyes touch on a small distance. The complex structure of the organ, consisting of many small eyes, allows the insect to look simultaneously in several directions and quickly navigate in flight. The jaws are strong, the mouth apparatus is gnawing. Dragonfly is not able to penetrate human skin, but it easily breaks into flies and mosquitoes. Antennae or antennae short, consist of 4-7 segments.

Features of the structure of the wings

Wing plates transparent, smoky. Veins are brownish-golden. At the apex of the fore wing, a thickening of a dark brown color is noticeable. This is a pterostigma, a dense area allows you to increase the amplitude of the wing span and absorb dangerous fluctuations. Each wing consists of two chitinous layers having their own system of veins.

Species large rocker refers to odnokrylnyh dragonflies. In representatives of this large group in a calm state, the wings are located perpendicular to the axis of the body. When flying, they can use each pair of wings separately, which gives ample room for maneuvering. The long limbs are brown. They consist of 5 main parts, the hips and lower legs are covered with two rows of spines. Each foot ends with a sharp claw. The front limbs are necessary for dragonflies to keep prey, the rest for landing and take-off. Long flexible legs with spikes serve as a solid basket for catching insects.

Distribution area

A large rocker is distributed in Central and Eastern Europe. Dragonflies settle everywhere from Ireland to the Urals, are found in Kazakhstan, Transbaikalia, in the north of Central Asia. A large number of insects in England, and in neighboring Scotland a large rocker is a rare guest. Favorite habitats are swamps, lakes, pits, rivers with a weak current. Often, adults are found in forest glades or meadows, where there are many insects.

Breeding

Dragonflies are insects with an incomplete transformation cycle. After the egg and nymph stage, they become adults.A characteristic feature of the rocker family is the division by males of the territory. They patrol their sites, preventing the approach of rivals. During mating, males capture females with anal appendages behind their heads. Sperm is pumped to a special organ in the second segment of the abdomen. The female leans its genital opening to the copulatory organ.
For masonry, the female chooses one of the aquatic plants. It descends along the stem and sticks one egg into its underwater part. Another way to hide future offspring is to lay eggs in a cluster of dead plants on the shore of a lake or swamp, on the inside of the leaves of water lilies. The shape of the eggs is oblong, one edge is pointed. Embryo development freezes during cold weather. Larvae appear only next spring, in late April or early May. They are kept near the bottom of the reservoir, the larvae of other insects, crustaceans, and caviar serve as food for nymphs. In the process of growing up, the offspring of dragonflies go through 7-11 links. On the body of insects there is a spotted pattern, and on the limbs there are multi-colored rings. Grown larvae attack tadpoles and fish fry. The nymph stage takes up to two years.

Lifestyle

Insects are excellent flyers, they can reach speeds of up to 55-60 km / h. Their flight is characterized by planning. Looking for prey, dragonflies are able to hang in the air for a while. In search of comfortable habitats fly a few kilometers. Dragonflies are active in the daytime. They love warm sunny days. On a cool morning you can see adults imagining themselves basking in the rays of the rising sun. The large rocker is one of the species that is active not only during the day, but also after sunset. Overnight at the treetops. Adult summer time from July to September.

Dragonflies are reliable helpers in the fight against blood-sucking insects. Adults kill mosquitoes and gadflies on land, while nymphs kill in ponds where pests lay their eggs. In a swift flight, dragonflies on the fly grab paws of flies, mosquitoes, and can catch a butterfly or even a small dragonfly.

Information. In some cases, dragonflies are harmful to humans. Adults prey on bees, and larvae seriously harm a young livestock of fish.

Larvae feel great in stagnant or low-flowing water with a large number of plants. Weak limbs do not allow nymphs to travel and pursue prey. They hunt from ambush. During the throw, the larva releases a stream of water, which sharply throws it forward for prey. Its breathing mechanism is designed so that the tracheal gills are located in the rectum. The nymph swallows a large amount of water and receives oxygen, the fluid is discharged through the anus. To capture prey, the larvae have a special organ called a mask. This is a modified lower lip, equipped with a movable joint and grasping teeth.

Interesting fact. Rocker nymphs are very gluttonous per day; they absorb amounts of food that exceed their own weight.

After 2 years of development, the larva is selected on land, where it settles on a vertical surface for final reincarnation. Her skin dries and bursts on her back. A dragonfly is selected from an old cramped skin. Her wings are soft and unformed. For several hours they wait for the wings to spread and harden. The final coloring is set for several days.

Threats to the mind and protective measures

Dragonfly larvae live in the aquatic environment, they are sensitive to pollution of habitats. As a result of human activities, various chemical compounds that are harmful to nymphs and other fauna enter lakes and swamps. The disappearance of coastal vegetation negatively affects the number of dragonflies. The large rocker is one of the insects requiring protection. It is listed in the Red Book of the Voronezh region. To stabilize the number of individuals, small ponds with a stable hydrological regime are required.