There are more than 2,500 species of these insects all over the world. They appear out of the blue during the spring thaw, namely at the height of the ice drift. Annually and regularly, the so-called rodent dragonflies accompany this stormy season. Hence their name - stoneflies. These insects are found closer to summer and autumn. But it is precisely these spring ones, although they are plain and plain, that people do not go unnoticed, since nature is just awakening and is scarce for a variety of all kinds of insects.
General description of the order of stoneflies
Plecoptera are amphibiotic insects known from the Permian period. Adults live on land, while larvae live in fresh water. The body of the stonefly insect (the photo is presented in the article) varies in length from 3.5 to 38.0 millimeters, depending on the species. They have multi-segmented long antennae, relatively large, hemisphere-shaped compound eyes, and a pair of simpler small organs of vision. Their body color is different - from brown to greenish, depending on the region of habitat. On the abdomen are two pairs of transparent wings withmultiple veins, with the posterior ones being wider than the anterior ones. Some species of stoneflies are short-winged or without wings at all.
The body of these insects is flattened, and the abdomen ends with two multi-segmented tail long threads-cerci. They are also short, single-segmented, and in males of some varieties they are quite strongly modified - they have spikes or hooks.
Distinguishing Features
Insect stoneflies do not shine with beauty and do not cause admiration. In addition, they look like earwigs. The mere name of the latter causes some disgust in many. Stoneflies differ from the mentioned insects in that they are strongly elongated, flattened and flexible, have membranous front wings, which do not compact, as in beetles or earwigs, into keratinized formations. At the end of the abdomen there are filiform tail appendages. Compared to the robust earwig pliers, they are much thinner.
Most common species and habitats
One of the largest European stoneflies is the fork-tailed pearl. Her body is three centimeters long.
In the Baikal region, there are approximately 50 species of stonefly insects belonging to 7 families. In the coastal zones of taiga rivers, light green insects are often found, the larvae of which are much smaller. They are very light in color but become greenish or yellowish as they mature.
Representatives are also commonstonefly family of brown color and larger sizes. Quite large larvae (up to 2 cm long) of insects of this family are often found in fast mountain streams and under stones. Very mobile and strong larvae are active and voracious predators. They especially like to hunt their closest relatives - mayflies.
The larvae of light green stoneflies live together with stoneflies. This variety got its name for its bright green color of an adult insect. Their feature is in cylindrical and narrow shape. Unlike them, the larvae of the stoneflies have a short, strong and stocky dark body. They are easily distinguished from other families by splayed, rudimentary wings extending at an angle from the body.
In the central Russian zone, you can most often find the yellow-footed stonefly, which can live even in stagnant water bodies, and with a low oxygen content. The length of her body varies between 13-27 mm. Adult insects of this species are found from April to September. Their larvae, living in freshwater reservoirs, feed on aquatic plants and decaying organic matter.
Features of reproduction
Insects stoneflies in their habitat are driving. Their larvae develop in the water, and during the imago period (the adult stage of insect development), they come to land to molt. Usually they fly weakly, and some have reduced wings. Many species, being near the coast, swarm and settle hundreds of meters from the breeding grounds. Interestingly, the female aftermating drops packages of eggs into the water, touching the surface of the reservoir in flight with its abdomen. Further, the larvae develop independently.
Reproduction of stoneflies is very similar to the reproduction of dragonflies, up to dropping eggs into the water, stuck together in a lump. Their eggs are very small. The larvae, before transforming into adult insects, are selected on tree trunks, stones (all surface objects). The skins they shed remain there.
Habitats and lifestyles
The vital activity of insects of stoneflies, like their larvae, is quite stormy. Most prefer to live on the banks of reservoirs with running water. The larvae inhabit mountain streams and other small flowing waters. In Siberia and in the colder latitudes of the North, stoneflies Taeniopteryx nebulosa are the first aquatic insects to emerge. In these parts they are called "glaciers", because the mass departure of these insects occurs at the beginning of April, and at this time the rivers are just opening up from the ice. In the southern habitats, the icefish make their first mass flight in early March, and in more northern latitudes, their flight may be delayed until May.
Insect adults lead only a terrestrial lifestyle, adhering mainly to coastal zones of water bodies. They usually sit on stones and other surrounding objects, taking off quite rarely. Although they have chosen the shores of reservoirs with fresh water, they are not particularly visible there, because they usually settle under stones or under dust, as well asamong dense vegetation at the very surface of the soil. Even if insects sit openly, it is difficult to notice them: with folded wings on their backs, they are dark, they practically merge with their place of residence. If they are disturbed, stoneflies quickly flee, hiding in any crack. And they fly close to the ground, but more often they crawl and run. Most adult stonefly insects, like mayflies, do well without food, but willingly drink water.
Maggots
The larvae lead a benthic lifestyle mainly in flowing waters. Most of all they can be found on mountain rivers, among stones. They avoid water thickets and small overgrown reservoirs. Due to the fact that the larvae move actively, they consume quite a lot of oxygen. Therefore, they renew oxygen around themselves, making rhythmic movements with their abdomen, raising and lowering it (about 100 strokes in one minute). Larvae develop in water for 1-3 years, while undergoing up to 30 molts, which is a record among insects. Like adult stoneflies, they crawl and run fast, but rarely swim.
They eat the larvae of various small aquatic animals, which they grasp with their claws. Their mouthparts are gnawing (heavily serrated jaws), but they do not feed as adults.
Meaning
Insect stoneflies are quite sensitive to the purity of water, and experts judge the degree of pollution by their presence in water bodies. It should be noted that recently these insects began to disappear from many places.habitation, which is associated with pollution of water bodies. In general, this also leads to the fact that the fish living in them are left without the main diet. Stonefly larvae are the best food for delicacy fish such as trout and salmon.
Little is known about the dangers of these insects for garden plantings. Moreover, it is already clear that at the stage of an adult insect they only like to drink. Perhaps the stonefly insect is harmful to bell peppers, but not as much as the whitetail and other pests.
In conclusion
The role of all living beings in nature is due to their diversity and abundance. For example, herbivores that feed on plants regulate their growth, while predatory and parasitic ones are good correctors of the number of animals they use as food. And stonefly finds its purpose in the harmonious, interconnected processes of nature.
