Common winter dragonfly
| Common winter dragonfly | ||||||||||||
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Common winter dragonfly ( Sympecma fusca ), young male |
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| Sympecma fusca | ||||||||||||
| ( Vander Linden , 1820) |
The common winter dragonfly ( Sympecma fusca ) is a species of dragonfly from the pond damsel family (Lestidae). The species is particularly widespread in the European Mediterranean region. But the dragonfly is also often found in Central Europe and east to the Urals . In contrast to almost all other dragonfly species, it overwinters as a sexually mature flying insect ( imago ) and not as a larva .
description
Imago
The common winter dragonfly is a species in which the adults of the males and females do not differ appreciably apart from the abdominal appendages and a few minimal differences in size, i.e. they do not show any sexual dimorphism . The wings of these dragonflies reach lengths between 20 and 22 millimeters in both females and males. The width of the wings is approximately the same in both sexes; it is 1.4 to 1.7 millimeters in females and 1.3 to 1.6 millimeters in males. The body is slim and the abdomen ( abdomen ) is relatively long at 27 to 29 millimeters. The basic color ranges from light beige to brown. The brown areas shimmer copper and form a pattern of lanceolate spots on the abdomen.
The chest of the animals shows two dark bands on the side. In Sympecma fusca , the lower edge of the upper band is straight. This feature distinguishes it from the Siberian winter dragonfly ( Sympecma paedisca ), which is rare in Central Europe , in which the lower edge of this band is bulged downwards. In spring the animals darken and the complex eyes can take on a bluish tone at the top.
larva
Immediately after hatching from the approximately one millimeter large egg , the larva is very small compared to other dragonfly larvae such as the willow damsel ( Chalcolestes viridis ). The color of the larvae is a dark to grayish yellow-brown. With the various moults, the color lightens first and then tends to greenish-gray to transparent. With the third moult, wing sheaths appear for the first time, and after the eighth moult there is a metamorphosis.
Habitat
Larval habitat
The habitat of the larvae of the common winter dragonfly are stagnant water up to a meter deep, but they usually stay at depths of around 20 centimeters. If the water is even shallower, the larvae , which otherwise live on submerged parts of the plant, also populate the bottom of the water. The beak sedge is particularly popular as a habitat . At water depths of around 50 centimeters, the larvae also like to stay in stocks of blunt-flowered rush , which occurs in the company of the knotted rush , as well as common and single-skin rushes . Light vegetation with reeds , swamp trident and the sedge species Oeders sedge or yellow sedge is also beneficial . Usually the waters in which the larvae are found are mesotrophic (moderately nutrient-rich) to eutrophic (nutrient-rich).
For their imaginal molt, the common winter dragonfly chooses places up to 35 centimeters - exceptions up to 80 centimeters - above the water surface, which are well sunlit in the mornings during the main hatching time.
Habitat of the flying insects
The adults go to maturity after hatching in light undergrowth or in places overgrown with bracken . After that, they prefer to choose brown branches on which they are optimally camouflaged. Little is known about the wintering habitats apart from the fact that some of them can be several kilometers away from the hatchery. When the frost sets in, the animals usually retreat into protected cracks between stones or under tree bark. But they can also survive “freezing” overnight.
In order to reproduce, the species looks for waters that are sunny all day and overgrown with reed beds , although it hardly shows any special preferences for certain sizes.
Way of life
behavior
These dragonflies overwinter as fully developed animals. On sunny days, they interrupt their winter rest and can be seen flying around, which is what earned them their name. From the beginning of April you will find them - as the first dragonflies ever - near water. There they sit on stems, laying their wings on the body. This is untypical for pond maidens and led to their scientific generic name, which is derived from the Greek word pyknos ("merged"). Overall, in contrast to the otherwise little researched larvae, the adults are not very agile. This, together with its good camouflage and behavior of turning to the other side of the leaf or branch when potential enemies approach, means that the species is not always noticed.
Reproduction
To mate, the males wait in places with slightly higher temperatures than the surrounding area for the females to arrive later in the day. The pairing that takes place in the pairing wheel then takes a few minutes to half an hour. After that, the female, with the male usually still attached, bores the eggs into mostly floating, dead parts of the plant. At rates of around four to five eggs per minute, it lays around 350 eggs in different places throughout the day. If the air temperature falls below 16 ° C, the already greatly reduced egg-laying from 18 ° C is completely stopped. The eggs, which are around one millimeter long, take between three and six weeks to develop.
Flight time and exposure
The main flight time of the wintered adults of the common winter dragonfly is between April and May (June); during this time reproductive activities fall. In July there is usually a short phase without winter dragonflies in Central Europe, before the new generation hatches from the change of month between July and August and into September. (In warmer climates, for example in southern Spain, the phenology of two cohorts can also overlap, so the newly hatched adults still meet the old adults from the previous year.) The newly hatched winter dragonflies are then still active until late autumn, but without to mate and lay eggs at this stage. With the onset of longer cold spells, they finally go to hibernation. On warmer days, animals can be spotted even in winter.
While the species was considered endangered a few years ago in Germany, it is no longer considered endangered according to recent studies. On the one hand, this is based on new sites; on the other, it is assumed that the animal was often overlooked in the past due to its good camouflage.
Scientific description and name
The first scientific description of the species was given by Vander Linden in 1820 under the name Lestes fusca . In 1840 Toussaint von Charpentier wanted to use the species as a generotype for the new genus Sympycna . However, Burmeister had committed himself in a preliminary publication in 1839, whereby the older name Sympecma was to be used according to the current naming rules . 1927 came through a description of RP Longinus Navás still Sympecma aragoniensis added as a synonym.
literature
- Klaus Sternberg & Rainer Buchwald (eds.): The dragonflies of Baden-Württemberg. Bd 1. Dragonflies. Eugen Ulmer, Stuttgart 1999, ISBN 3-8001-3508-6
- Paul-A. Robert: The dragonflies (odonates). Authorized translation by Otto Paul Wenger, Kümmerly & Frey, Geographischer Verlag, Bern 1959
- T. Brockhaus: The winter dragonfly Sympecma fusca (Van der Linden, 1820) in the Chemnitz-Erzgebirge region (Odonata). In: B. Klausnitzer (Ed.): Entomologische Nachrichten undberichte, 42, 4, pp. 231–234, Dresden 1998
- Christoph Kämper: There really are winter dragonflies. in: Lohmarer Heimatblätter 25, Lohmar 2011
- Reinhard Jödicke: The rush maids and winter dragonflies of Europe. Westarp Sciences, Magdeburg 1997
Individual evidence
- ↑ Gerhard Jurzitza: The cosmos Dragonflies leaders Franckh-Kosmos Verlags GmbH & Co., Stuttgart, 2000, ISBN 3-440-08402-7
- ↑ a b c Paul-A. Robert: Die Libellen (Odonaten) - Authorized translation by Otto Paul Wenger [p. 101ff], Kümmerly & Frey, Geographischer Verlag, Bern 1959
- ↑ " Heiko Bellmann : Observing dragonflies - determining [p. 122], Naturbuch Verlag, Augsburg 1993, ISBN 3-894-40107-9
- ↑ a b c d e f Klaus Sternberg & Michael Rademacher: Sympecma fusca (Vander Linden, 1820), common winter dragonfly. P. 429-440 in: Sternberg / Buchwald (ed.): Die Libellen Baden-Württemberg , Volume 1. Ulmer, Stuttgart 1999, ISBN 3-8001-3508-6
- ↑ Federal Agency for Nature Conservation (Ed.): Red List of Endangered Animals in Germany. Landwirtschaftsverlag, Münster 1998, ISBN 978-3-896-24110-8
- ↑ Holger Hunger et al .: Distribution and phenology of dragonflies in Baden-Württemberg (Odonata) in Libellula Supplement 7 [p. 38], GdO, Börnsen 2006
- ^ Red list of endangered dragonflies in Switzerland. Federal Office for the Environment, Forests and Landscape (2002), accessed on September 11, 2012 .
- ^ Henrik Steinmann - World Catalog of Odonata (Volume I Zygoptera) [p. 136], de Gruyter, 1997, ISBN 3110149338
Web links
- More pictures and information
- Sympecma fusca inthe IUCN 2013 Red List of Threatened Species . Posted by: Clausnitzer, V., 2007. Retrieved February 18, 2014.
