Flat stomach
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Flat belly ( Libellula depressa ), male |
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| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Libellula depressa | ||||||||||||
| Linnaeus , 1758 |
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The flat belly ( Libellula depressa ) is a type of dragonfly from the family of the sail dragonflies (Libellulidae) with a noticeably wide, flattened, somewhat plump-looking body. Mature males and females are colored differently. The species is a pioneer colonist of low-vegetation, sun-drenched pools with loamy or sandy-gravelly banks. In 2001 it was voted Insect of the Year in Germany .
features
Construction of the Imago
The dragonflies reach a body length of 40 to 45 millimeters with a wingspan of 70 to 80 millimeters. The wings are transparent, only the base is darkly colored, on the forewings by a narrow, elongated spot, on the hind wings by a larger triangle. The abdomen ( abdomen ) is six to eight millimeters wide, strongly flattened and only tapers after half. In the males it is colored waxy light blue and in young animals it has yellowish spots on the sides, which later fade. The females have an initially yellow-brown, later olive and finally dark-brown abdomen, with clear yellow spots on the sides that do not fade with age. The rest of the body is predominantly dark brown in color.
Construction of the larva
The larva of the flat belly is very hairy and has a plump body, which reaches a length of 25 millimeters and a width of eight millimeters. From the first to the third moult , the larvae are brownish-gray and have a darker mark in the form of a V between the eyes. After the third moult, the larvae are darker and grayer. This increases with the subsequent moults, so that at the end the V between the eyes is no longer visible. The antennas consist of seven segments, the first two of which are rather short and wide, while the remaining five are slimmer. The fourth and fifth segments are also significantly shorter than the others, the seventh is dotted. In terms of shape and size, the labium is similar to that of the larva of the quadrangle. The abdomen is very hairy and has four to eight posterior tubercles on the segments . The species has extremely small lateral spines on segments eight and nine or none at all.
Similar species
The Imago is similar to:
- Tip spot ( Libellula fulva )
- Great blue arrow ( Orthetrum cancellatum ) and other blue arrows
- Vierfleck ( Libellula quadrimaculata )
The larva is very similar to that of the quadrangle. It can be distinguished by the fact that the lateral spines in the flat stomach are much less developed.
Occurrence
The animals are found in almost all of Europe , except in the northeast. The larvae are mainly found in small, stagnant bodies of water that are not shaded and can also dry out in summer. The animals are only rarely found in flowing waters. Furthermore, bodies of water with little vegetation and a low proportion of bottom sludge or those bodies of water whose bottom is free or at most has oxygen-rich (aerobic) sludge are preferred.
Way of life
Flat bellies are excellent fliers and can reach very high speeds. Their eyesight is also very well developed. They feed on insects caught in flight, which they hold with their legs and eat in flight. They are hide hunters, which means that they lie in wait for prey in exposed places . From these points they defend their territory against other conspecifics and at the same time look for females to mate.
Flight times
The dragonflies fly from the beginning of May to the end of July, sometimes into August. Two maxima are reached, which are due to the fact that some larvae do not hibernate, but are fully grown in the first year.
Mating and development
The pairing takes place in flight and takes less than 30 seconds. The females often fly over longer distances and colonize new waters. They shed their eggs in flight with rocking movements over shallow water. To do this, touch the surface of the water with the tip of the abdomen. Around 20 to 100 eggs are laid. The eggs are shaped like a ball that is pointed on two opposite sides. In the direction of the tips they are between 0.6 and 0.8 millimeters long, in the vertical direction between 0.3 and 0.5 millimeters. Similar to the eggs of the quadrangle, the eggs of the flat belly are also protected by a jelly shell about one millimeter thick. The initially milky white gelatinous layer becomes cloudy over time. The egg changes color from initially yellowish white to brownish-black.
The larvae hatch after about four weeks and initially stay close to aquatic plants. Only later do they live in shallow water without vegetation. They sit on the bottom, partly covered with mud, and lie in wait for prey. They eat insects and insect larvae, crustaceans, worms and larvae of amphibians. When their waters dry out, they crawl into the mud, just as they do when they winter. Their development is completed after one to two years and 11 larval stages. The wing sheaths appear for the first time after the fourth moult. Early to mid-May hatch imagines .
Individual evidence
- ↑ Lucas, William John .: The Aquatic (Naiad) Stage of the British Dragonflies (Paraneuroptera) [p. 72ff], The Ray Society , London 1930
- ^ Robert, Paul-A .: Die Libellen (Odonaten) - Authorized translation by Otto Paul Wenger [p. 292ff], Kümmerly & Frey, Geographischer Verlag, Bern 1959
- ↑ a b Robert, Paul-A .: Die Libellen (Odonaten) - Authorized translation by Otto Paul Wenger [p. 284ff], Kümmerly & Frey, Geographischer Verlag, Bern 1959
literature
- Sternberg, K. (2000): Libellula depressa Linnaeus, 1758 - Plattbauch. Pp. 437-448. In: Sternberg, K. & R. Buchwald (eds.): Die Libellen Baden-Württemberg. Volume 2: Dragonflies (Anisoptera). Ulmer, Stuttgart, ISBN 3-8001-3514-0
Web links
- Information and photos at naturspektrum.de
- More pictures and information at natur-in-nrw.de
- General information on the species ( Memento of February 5, 2009 in the Internet Archive ). Environment Agency of the City of Hagen , 2001 (PDF file; 270 kB)