waters that are characterized by little human influence and natural water bodies. In the largest part of their range, the species is very rare. It is absent in areas corresponding to major cities or industrial centers completely, and even in regions with strongly pronounced agricultural use it is to be found only rarely. According to this situation it is in Germany in the Red Data Book (1998) classified as endangered in some states it is even in danger of extinction. Similarly in Austria, Switzerland and other Central European countries. Among the factors that make a settlement of the water for the larvae of the blue-wing demoiselle impossible to include on the one hand, the channeling and obstruction of the same, go where the lost for the settlement of important aquatic plants. On the other hand, the eutrophication of water by agriculture and by household wastewater causes an important factor in the decline dar. this to increased sludge formation and therefore increased oxygen consumption in the affected waters and to increased algal growth of so-called " slime algae ". It is brown and green algae, the water plant and the substrate is overgrown. The veralgten plants are not accepted by the females as oviposition sites. In addition, the larvae no holding facilities are against the current, and the algae and dirt particles settle to the gill lamellae are important for respiration. The algae is followed by weeds and ultimately a silting of water bodies. But natural waters with low water pollution can be in a state of the animals is not available. He may receive a water surface is not completely from the plants of the marginal vegetation to be overgrown, this is done mainly by fast-growing plants such as meadowsweet (Filipendula ulmaria), the stinging nettle (Urtica dioica) or Himalayan balsam (Impatiens glandulifera). The tree growth on the waters edge should not report closed canopy, otherwise lack the necessary sunlight. Above all streams in uncultivated pastures, where no regular mowing is taking place, according to the animals are not habitable. This can be countered by regular removal of boundary vegetation, which will also not be complete. Even a partial thinning of trees and shrubs should be performed. In intensively used agricultural areas with a regular input of manure as fertilizer is a few meters wide can prevent extensive or unmanaged riparian strips one Einschwemmung and thus act against eutrophication. See also