Great stream runner
| Great stream runner | ||||||||||||
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Great stream runner ( Velia caprai ) |
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| Velia (Plesiovelia) caprai | ||||||||||||
| ( Tamanini , 1947) |
The great stream runner ( Velia caprai ) is one of the water striders i. w. S. (Gerromorpha) bug (Heteroptera). It resembles the closely related water striders i. e. S. (Gerridae), but has significantly shorter legs than the representatives of this family of bugs. The insects usually live gregariously on the surface of flowing water, where they are mostly in the bank vegetation and prey falling on the surface of the water lurks .
features
The insects reach body lengths between 6.2 and 8.5 millimeters. The animals are mostly wingless (apter). Only 1 to 20 percent of the individuals, mostly females, are long-winged (macropter). They are black-brown in color with light red-brown and silvery spots on the upwardly curved sides ( connexive ) of the abdomen. The similar species Velia saulii with a more easterly distribution center shows a row of black spots on the belly side, which can also be missing, while Velia caprai has a broad black stripe. Furthermore, the rear tip of the edge of the abdomen is long and pointed in the females of V. caprai , and short and pointed in the males; in V. saulii these are short and blunt.
distribution
The great brook runner is widespread from the British Isles and southern Scandinavia to the northern Mediterranean . In Central Europe the species occurs everywhere, in some places even frequently.
Way of life
The great brook runner usually lives socially in so-called schools, in which both the adult animals ( imagines ) and their larvae can be observed. They are diurnal and nocturnal.
The species makes only minor demands on the quality and structures of its living waters. It colonizes the smallest, fast-flowing rivulets up to sluggishly flowing brooks with a low degree of pollution and not overgrown with aquatic plants. They are less common in stagnant waters. They usually stay at the edges of the brook by holding onto the water plants or other bank structures with their legs. With quick movements they swim towards possible prey swimming past on the water surface. They hold them with their front legs and suck them out on the bank or on solid ground. The species prefers to live in streams with surrounding woody vegetation, but also occurs in wood-free, unshaded waters in the open landscape.
The animals overwinter as an imago or occasionally as an adult larva in the bank vegetation. Depending on the geographic region, one or two generations are trained. If only one generation is passed through, the new adult animals appear from the end of July or beginning of August, with two generations in June and September. The females stick their elongated eggs lengthwise to the substrate, sometimes under water on aquatic plants, on land plants near water, on objects floating in the water or in cushions of moss. This type of bug is one of the hardest in Central Europe and can be found actively on the water surface even in January when it is below zero.
Sources and further information
literature
- Ekkehard Wachmann , Albert Melber, Jürgen Deckert: Bugs Volume 1: Dipsocoromorpha, Nepomorpha, Gerromorpha, Leptopodomorpha, Cimicomorpha (Part 1) with Tingidae, Anthocoridae, Cimicidae and Reduviidae . - Goecke & Evers, Keltern 2006, ISBN 3-931374-49-1
- E. Wagner: Heteroptera Hemiptera. - In: Brohmer, P., P. Ehrmann & G. Ulmer (eds.): Die Tierwelt Mitteleuropas. IV, 3 (Xa). - Leipzig 1959, 173 pp.
- E. Security guard: Bugs - get to know, watch. Neumann-Neudamm 1989, ISBN 3-7888-0554-4
