Big pitch dragonfly

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Big pitch dragonfly
Great pitch dragonfly (Ischnura elegans), male

Great pitch dragonfly ( Ischnura elegans ), male

Systematics
Subordination : Dragonfly (Zygoptera)
Superfamily : Coenagrionoidea
Family : Dragonfly (Coenagrionidae)
Subfamily : Ischnurinae
Genre : Pitch dragonflies ( Ischnura )
Type : Big pitch dragonfly
Scientific name
Ischnura elegans
( Vander Linden , 1820)

The great pitch dragonfly ( Ischnura elegans ) is a species of dragonfly whose German name goes back to the pitch black color of the abdomen. Of the ten abdominal segments, only the eighth has a completely bright blue color, which is often referred to as the "bottom light". The great pitch dragonfly is quite undemanding to its habitat, so it is still very common and is not endangered. In some regions of its range, the great pitch dragonfly is given as the most common dragonfly species.

features

The body length is a good 30 millimeters, the wingspan 35 to 40 millimeters. The abdomen of both sexes have a black upper side, whereby the eighth abdominal segment stands out with its bright blue color. The seventh and ninth abdominal segments are only colored blue on the underside, segments 3 to 6 are yellowish on the underside. The greater pitch dragonfly can be distinguished from the rarer lesser pitch dragonfly ( Ischnura pumilio ) on the basis of the size and exact position of the “tail light”. In males of Ischnura pumilio , only the rear third of the eighth segment, but also the entire ninth abdominal segment, is blue.

The males of the great pitch dragonfly are also colored blue on the thorax and head in addition to black areas, while in the females these areas can have different colors (see below). Both sexes have two-colored (inside black, outside white), pointed wing marks .

Color variations

Females of the great pitch dragonfly appear in five different, genetically determined color morphs, two of them in young animals and three in sexually mature animals. From the juvenile form violacea , which has a violet or green thorax, a black ante-humeral band and a blue "tail light", either the age form typica (colored like the males) or - in heterozygous individuals - the form infuscans with an olive-green thorax and a green-brown one develops to almost black eighth abdominal segment. Young females of the form rufescens have a salmon pink to orange colored thorax without ante-humeral stripes and a blue eighth abdominal segment. In them, the morphological color change that occurs within a week with sexual maturity leads to the form infuscans-obsoleta with a then light brown, pink or orange thorax and a brown, later almost black “tail light”.

  • forma rufescens
    - a possible juvenile form of the females

  • forma violacea
    - the second juvenile form of the females

  • forma infuscans-obsoleta
    - one of three age forms of the females (emerged from the juvenile morph rufescens )

  • forma infuscans
    - another age form of the females (emerged from the juvenile morph violacea )

  • forma typica
    - the third, "male-colored" age form of the females (originated from the juvenile morph violacea )

Way of life

The flight time of the adult animals ranges from the beginning of May to the end of September. In some regions of the distribution area, adult animals can be observed as early as mid-April and early October. The latter is usually only the case if a second generation is produced within a year. The females always lay their eggs without the participation of the males in the evening hours on floating parts of the plant. It is unusual among slender vials that the eggs are not laid in "tandem". Larval development usually takes a year, but under favorable living conditions it can be completed within the flight time, so that a second generation can appear in a year. In most of the distribution area, however, this is rather the exception. Sometimes the larvae develop for two years.

nutrition

The larvae of the great pitch dragonfly are very voracious and feed mainly on planktonic benthic organisms (small crustaceans, etc.). The adults hunt various small insects (including aphids ), and occasionally other small dragonflies.

distribution and habitat

The distribution area of ​​the great pitch dragonfly stretches across Europe and is limited in the north at about 62 ° north latitude . Thus, the species is only absent in parts of Scandinavia and in the south on Mediterranean islands such as Corsica, Sardinia, Sicily and Malta. As Habitat both slow flowing and standing waters are accepted. The species makes only minor demands on the equipment of its breeding waters and is therefore also one of the first dragonfly species to be found in newly created, near-natural garden ponds.

  • A black color dominates on the upper side, which gave it its name (here a male)

  • Mating wheel - above the bluish male; the female is likely farbmorphologisch a transitional form between the juvenile form rufescens and age form infuscans-obsoleta be

  • Young female (forma rufescens ) with prey

  • Close up of the head and thorax

swell

literature

  • Heiko Bellmann : The Kosmos dragonfly guide . Franckh-Kosmos Verlags GmbH & Co., Stuttgart 2007, ISBN 978-3-440-10616-7 .
  • Klaus Sternberg: Ischnura elegans (Vander Linden, 1820) - Large pitch dragonfly. In: ders., Rainer Buchwald (Ed.): Die Libellen Baden-Württemberg. Volume 1: General part, dragonflies (Zygoptera). Ulmer, Stuttgart 1999, ISBN 3-8001-3508-6 , pp. 335-347.

Individual evidence

  1. ↑ British Dragonfly Society: Ischnura elegans - Blue-tailed Damselfly. March 23, 2009, accessed October 10, 2012 .

Web links

Commons : Large pitch dragonfly  - album with pictures, videos and audio files