Dragonfly - how does an insect live?

Dragonflies are the usual representatives of the fauna of temperate latitudes. This is a large detachment of amphibiont insects, whose adults live on the ground, and the larvae in the aquatic environment. Thanks to an open lifestyle, they are well known to man. Dragonfly differs slender body, red or yellow-brown color. Her offspring grow in stagnant water with lots of vegetation. Despite its modest size, the insect is of great benefit, destroying mosquitoes, flies and various agricultural pests.

Dragonfly groups

Scientists have found and described more than 6 thousand species of dragonflies. They are divided into two large groups:

1. Damselfly dragonflies - the suborder includes about 3 thousand species, among which the common dragonfly. A characteristic feature is the placement during rest of the wings perpendicular to the axis of the body. The front pair of wings is larger than the rear. This group includes the fastest predators, a record speed of up to 100 km / h. Nymphs live in still water.
2. Damselfly - a group of insects with the same size of the front and rear wings. Their flight is smooth and measured. At rest, the wings are roof-shaped over the abdomen. Larvae live in stagnant and flowing water bodies.

Dragonfly belongs to the family of true dragonflies. Its representatives are small (3-5 cm). They are found everywhere except Antarctica.

Description of Sympetrumvulgatum

Insect Classification:

• Order - Dragonflies (Odonata).
• The family is real dragonflies (Libellulidae).
• Genus - squeezed bellies (Sympetrum).
• Species - common dragonfly (Sympetrumvulgatum).

Body structure and coloring

Dragonflies from the genus Sympetrum or squash are typical representatives of the fauna of Russia. The length of their body is 38-40 mm, of which up to 28 mm fall on the abdomen. The head is large, well defined, mobile. In adults, it is wider than the chest and movably connected to the prothorax. The eyes are large, complex, composed of 20-30 thousand individual facets. The upper part of the organ is responsible for recognizing the contour of objects, and the lower one distinguishes colors. Antennas are presented in the form of short thin bristles. Three simple eyes are located on the crown of the head. A black stripe runs across the brown head, between the crown of the head and forehead. The mouth apparatus is gnawing, strong mandibles are provided with sharp teeth.

The limbs and two pairs of wings are located on the chest of the insect. The rear part of the prothorax has a vertical protrusion. On it grows a fringe of long hairs. Black stripes run along the pectoral sutures. The back of the dragonfly is obliquely pushed back, so the wings are behind the limbs. In males of an ordinary squeezed belly, the chest is red with three black stripes, the color of the females is yellow-brown, three stripes are also present.

Wings

Dragonflies are equipped with two pairs of wings. In different-winged animals, the anterior pair exceeds the parameters of the posterior. The wing plate is formed by two chitinous layers and reinforced by veins. Their length is approximately equal to the size of the body. Hind wings dilated at base. The wingspan of the Sympetrumvulgatum is 60 mm, the length of the hind wing is 24-29 mm, and the fore wing is 33-37 mm.The venation is very dense, hemolymph is located in large veins, and small ones have no gaps. One of the significant sites is pterostigma, a thickening in the front of the wings. Outwardly, it looks like a dark spot, during flight, makes the wing top heavier, allowing you to increase the amplitude of the flap.

Information. The common dragonfly lacks buffy-yellow patches at the base of the wings.

Limbs

The legs of an ordinary dragonfly are black, with a yellow stripe passing from the outside. Three pairs of limbs are designed to hold the body of an insect and catch prey. They are not used for walking or running. The legs are made up of 5 main parts:

• basin;
• trochanter;
• hip;
• shin;
• foot.

On the inside of the lower leg and thigh are several rows of spiny setae. The basin is the thickest and shortest part of the limb. There are two sharp clawed claws on the foot. Long limbs and spikes make it possible to form a “hunting basket” for catching prey in the air.

Abdomen

The abdomen of an ordinary dragonfly is flattened and wide. It consists of 10 full and one rudimentary segment. Each part is formed by the upper and lower chitinous shield. Thanks to the movable joint, insects can freely bend the abdomen. The structure of the organ of males and females is different. The males on the last segment have special appendages to hold the mate during mating. Their secondary copulative organ is located in the lower part of the second segment. Female genital opening between eighth and ninth segment. Females have an ovipositor. In males, the abdomen is red with a black side stripe, in females it is brown with a black stripe.

Larvae

Dragonfly larvae are called nymphs or mollusks. In appearance and structure, they are strikingly different from adults. Dragonfly nymphs have a massive body 17-19 mm long. Breathing is carried out through the internal organs - rectal gills. Larvae collect water into the rectum, where gas exchange occurs. Body color is dark gray, greenish or red-brown. Nymphs are covered with a colorful pattern.

Interesting fact. To make a sharp jerk after prey or to hide from the enemy, the larvae throw a stream of water from the anus.

The mouthpiece of the larva has a unique structure. It consists of the upper lip, paired mandibles and a modified lower lip. This organ transformed into a mask. The movable joint allows you to throw it forward and cling to the extraction with sharp teeth. In a calm state, the mask is folded under the head. On the dorsal part are the rudiments of the wings. On each part of the chest is a pair of limbs. Larvae of the family Libellulidae are buried in silt. The lifestyle affected the structure of their legs. The limbs are shortened, wide, with many hairs and spikes. Nymphs feed on small invertebrates, insect larvae, fish roe, cannibalism is not ruled out.

Breeding

Sexual dimorphism of insects is manifested in color. It affects the reproductive behavior of dragonflies. For males, attachment to a place and territorial competition are characteristic. They do not allow rivals to their sites. Only females ready for fertilization are allowed. Dragonflies have a complicated mating process: the male holds the female with the anal appendage by the head, the partner bends the abdomen forward, leaning it against the spermatophore on the 2nd segment of the partner’s abdomen. It turns out a closed figure that holds for several minutes.

In the process of laying, the male ordinary dragonfly accompanies his partner. He flies near her and protects from repeated pairing. Territorial behavior leads to the fact that part of the males, which did not receive good sites, will not be able to participate in procreation.

Progeny

Dragonflies are insects with incomplete transformation. Their life cycle is divided into three phases:

• egg;
• larva (nymph);
• imago.

An ordinary dragonfly female lays eggs in coastal silt, moist soil or in water.Through winter, larvae emerge from the masonry, remarkable for their appearance and biological features. They play a significant role among the inhabitants of the reservoir. Nymphs live in stagnant or weakly running water. They prefer to lead a secretive lifestyle, hiding among aquatic plants or burying themselves in silt. The dragonfly larva has a short and wide body. The shape of the helmet is helmet-shaped.

Small predators feed only on live prey. They spend a lot of time in ambush, waiting for the larvae of insects or daphnia to approach. Food is absorbed in large quantities, especially young nymphs are particularly appetizing. For a day they eat invertebrates, the mass of which exceeds their own. Prior to growing up, offspring require 7 to 11 links. Their number depends on environmental conditions and food supply. Final molting occurs on land. For this, the nymph is chosen on a solid surface - a stone, snag or stalk. The larva skin dries and cracks. From it, the formed dragonfly is selected. The imago takes time to spread and harden the wings. The final color characteristic of the species is acquired for several days.

Lifestyle

Dragonflies are daytime predators, they are active in warm sunny weather. They experience nighttime and inclement weather in a shelter. In the morning hours imago gain energy, basking in the sun. They sit on the bark of trees, branches, stems of grass. In the heat, they direct the tip of the abdomen up, reducing the area of ​​sun exposure. Adults have excellent eyesight. They notice prey at a great distance and successfully attack.

Insects have no food cravings; they prey on any objects of suitable dimensions. Diverse predators easily maneuver and dive, can make high-speed flights and move a considerable distance from the place of birth. Massive years of common dragonfly are observed in July-September. After adult molting, the flight takes place gradually; therefore, some individuals are found even in October.

Despite its reputation as a ruthless predator, the dragonfly itself often becomes prey. Birds, reptiles, mammals prey on her. Insects that have landed on water are attacked by fish. Among the representatives of the detachment Odonata cannibalism flourishes, large individuals catch and eat smaller ones. For larvae, diving beetles and water bugs are dangerous. How long does an ordinary dragonfly live? This species, aged adults, spends several months. The larva develops about 1 year.

Habitat

Dragonfly belongs to the transpalearctic species. Insects live in large numbers in Europe, Central Asia, Siberia, the Far East and northern Africa. They settle near lakes, swamps, reclamation canals. Ponds overgrown with vegetation are preferred.

Value for man

Dragonflies and humans rarely have conflicts. Representatives of the Odonata family bring great benefits. They control the number of blood-sucking insects - mosquitoes, gadflies, mosquitoes. Adults destroy pests on land, and nymphs in water. Dragonflies are absolutely safe for humans. They have stings, do not tolerate disease. Many species are sensitive to water conditions. They die due to pollution of water bodies.

Human activities often threaten populations of certain species of dragonflies. Representatives of Sympetrumvulgatum are still safe. Being at the reservoir, with sufficient patience and caution, you can wait for close contact with the dragonfly. The insect will sit on your hand.