The Banded Demoiselles of Utrecht city
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(This is the English version of a page originally created in Dutch)
To my surprise I found this year (2006) a population of the Banded Demoiselle (Calopteryx splendens) in the city of Utrecht, Netherlands, at a canal named "Zwartewater" (Blackwater). According to the inhabitants the population was there at least four years earlier. This year there are more of them then before. I walked around there very often, photographing them, sometimes sitting for hours at the water because I really wanted to shoot one in flight and in the meantime just looking around what the damselflies were doing. I saw them laying eggs.
I tried to estimate the total number of damselflies, and concluded that it must have been something like 50 at the heighth of the season. That is not very much, but quite special for a population in the middle of a city. I asked myself other questions. Were there other places in Utecht where this damselfly has been found and just general things about the Banded Damselfly. I just wanted to know more about this species. I tried to find answers, and I found some. And this is where I will write about what I found out and show some photos I made.
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Banded Demoiselle (female)
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The Zwartewater canal in Utrecht
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Zwartewater
The Zwartewater is a small canal in Utrecht, the Netherlands. It is part of a small river running through the northern part of Utrecht. On both sides of the canal are houses. On the edges are some trees and shrubs. It's an idyllic place to live.
A bit further, left behind the bridge on the photo is a small public garden called the Jan van Lingtuin. Going backwards (in the other direction as the photo shows) there is a small water lock. This lock is quite important for the Banded Demoiselle, because it makes the water flow gently, and Banded Demoiselles like water that flows.
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Banded Demoiselle
The Banded Demoiselle (Calopteryx splendens) is a damselfly. Damselflies are insects and belong to the dragonflies (odonata). The dragonflies are divided into two major groups, the damselflies (zygoptera) and the 'true' dragonflies (anisoptera). Officially there is a third group, the 'ancient dragonflies' (anisozygoptera) which holds only two Asian species, one from China and one from Japan. Damselflies are smaller then 'true' dragonflies, more fragile en they keep their wings open when resting.
De Banded Demoiselle belongs to the family of Broad-winged damselflies (or Demoiselles). Other families of damselflies are for example the Pond Damselflies and the Spreadwings. In the Netherlands one other species of the Demoiselles is found, the Beautiful Demoiselle. In the south of Europe two more species appear, the Western Demoiselle and the Copper Demoiselle.
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Banded Demoiselle (female)
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Banded Demoiselle (male)
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Blue and green
The males of the Banded Demoiselle have an irriscendant blue body and partly blue wings. At the base and at the top the wings are translucent, which make it appear as if a blue band crosses their wings. The photo shows this well.
The females are green or brownish and have translucent wings without the dark band. At the end of their wings they have a white spot. This spot is called 'pterostigma'. Almost all dragonfly species have such a spot. It is a bt of an exception that the males of the Banded Demoisel do not have such a spot. To be precise, spots which are divided by a vein in the wing are called a 'pseudopterostigma'. So in fact the female Banded Demoiselle has a pseudopterostigma.
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Blue band
Males recognize each other from the blue band on the wings. On locations where both the Banded Demoiselle and the Beautiful Demoiselle appear (the latter has totally blue wings), the band of the Banded Demoiselle is narrower. This helps the species to recognize each other. The narrower the band, the less aggressive male Beautiful Demoiselles are towards male Banded Demoiselles.
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Banded Demoiselle (male)
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Banded Demoiselle with prey
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Food
Dragonflies are predators. The eat mainly insects that they catch in flight. With their four wings, dragonflies are masters of the sky.
Like many other species, Banded Demoiselles prefer to hunt from a outlook post. When they spot a prey, they fly up and try to catch it. With or without prey they usually return to the same spot.
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Eating out of the arena
Freshly emerged males first find a place away from the water to hunt and mature further. When strong enough they return to the water to conquer and defend a territory. There they have not much time for hunting. They are busy defending their territory against other males and trying to fertilize the females.
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Banded Demoiselle in flight
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Reproduction
The males of the Banded Demoiselle keep a territory that they defend against other males. In the territory there are some spots fit for laying eggs. When a female comes around, they try to draw her attention. They do that by flapping their blue wings in a special way at one of spots fit for laying eggs.
If the females wants, first the copulation takes place. The males grabs the female in het neck. The female bends her abdomen to get his sperm.
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Copulating Banded Demoiselles
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Female Banded Demoiselle laying eggs on a water plant
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Laying eggs
Right after the copulation, the female lays eggs. She lays the eggs usually on plants growing in the water. She isn't afraid to get wet in doing so.
Sometimes she disappears totally under water. She can stay tens of minutes under water.
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Under water
On this photo the female has gone totally under water to lay her eggs. To enable staying long under water, the Banded Demoiselle has special hook-formed hairs on the body and wings. These make sure that an air bubble surround her.
Insects (and thus also dragonflies) have no lungs as humans do. In stead they have tubes in their skin which branches through the whole body. They breath through these.
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Totally under water
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The Banded Demoiselle in the Netherlands.
Map with permission from Landelijk libellenbestand NVL/De Vlinderstichting/EIS-Nederland.
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Netherlands
The Banded Demoiselle is not very rare in the Netherlands. Especially in the southern regions the species is frequently seen.
Until the beginning of the 1980's, the Banded Demoiselle declined rapidly in the Netherlands. From that time however it has slowly recovered.
Location of Utrecht in the Netherlands.
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Utrecht City
A local foundation in Utrecht city (Stichting Ecologisch Advies - StEA) has kept record of dragonflies spotted in Utrecht since the year 2000. Every year of couple of Banded Demoiselles have been reported. The population at the Zwartewater canal was however unknown to this foundation. I haven't found any institution which was aware of this population. According to the inhabitants at the canal, the population has been there since at least 2002, possible a one or two years longer.
The Banded Demoiselle has expanded during the last years along the river Kromme Rijn. In fact the Zwartewater population fits very well in this expansion.
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Locations in Utrecht city where the Banded Demoiselle has been spotted. Source: StEA |
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The damselfly whisperer
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Hide-and-seek?
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Eye to eye with a Banded Demoiselle
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And so it ends, caught in a spider web.
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| Een verwant |
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Beautiful Demoiselle (Calopteryx virgo meridionalis).
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General
- text and photos by Sybe Visser. Most photos have been used for an exhibition in a local environmental center in Utrecht city.
- Except when noted differently, all photos have been taken in June and July 2006 at the Zwartewater Canal in Utrecht.
- For the text, sometimes research results have been used which is done on a related species.
- Photos are hosted on www.flickr.com. More photos from this population are shown here (2006) and here (2007).
- Webpage optimized for 1024 x 768 and tested in recent versions of Firefox and Internet Explorer.
- Thanks to the inhabitants of the Zwartewater Canal for their kindness and to Weia Reinboud for critically reading the Dutch version of this page.
- Thanks to Stichting Ecologisch Advies for the allowance to use their map of the Banded Demoiselle in Utrecht.
- Thanks to the Nederlandse Vereniging voor Libellenstudie / de Vlinderstichting / EIS-Nederland for the population map of the Banded Demoiselle in the Netherlands.
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Links
Banded Demoiselle
Dragonflies, general
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Species of the month, June 2007
The Dutch VOFF (Vereniging Onderzoek Flora en Fauna) has created a nature calendar for 2007 with each month a different "species of the month" The Banded Demoiselle is species of the month for June 2007.
For more see www.soortvandemaand.nl.
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Research
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