Glittering demoiselle (Calopteryx exul)
|Size||Male length of abdomen: 39 - 42 mm (2)|
Female length of abdomen: 37 - 39 mm (2)
Male hind wing: 30 - 32 mm (2)
Female hind wing: 32 - 36 mm (2)
The glittering demoiselle is classified as Endangered (EN) on the IUCN Red List (1).
This member of the broad-winged damselflies (Calopterygidae spp.) closely resembles the banded demoiselle (C. splendens) and has been regarded at times as a subspecies of the latter (3). Like the banded demoiselle, the male glittering demoiselle (Calopteryx exul) has a metallic bluish-green body while females are metallic green (4) (5). Unlike this close relative, however, which possesses a distinctive blackish-blue band across its wings (4), the glittering demoiselle has clear, un-pigmented wings (2) (3) (5).
The glittering demoiselle is known from the mountains of Morocco, Algeria and Tunisia (1) (2) (3) (4) (5).
Found in and around fast-flowing mountain streams, brooks and rivers, the glittering demoiselle is typically found 200 to 2,000 metres above sea level (1) (2) (5).
Relatively little is known of this damselfly’s biology, but much can be inferred from what is known of other Calopteryx species. Larvae of this group generally live amongst the mud, roots, aquatic vegetation and litter debris in streams and rivers, and in hot countries spend one winter here before emergence as an adult damselfly (6). The adult flight period for the glittering demoiselle runs from May to August, and adults must initially undergo a pre-reproductive phase known as the maturation period, which probably lasts about 15 days (2) (6). This is when individuals normally develop their full adult colour (6) (7). Once mature, Calopteryx males generally hold territories around suitable egg-laying sites, which they defend from other males, and actively court females that fly into their territory with elaborate displays. However, at high density, territorial behaviour disappears. As with other Calopteryx species, female glittering demoiselles oviposit in floating vegetation under the supervision of their mate (6).
The glittering demoiselle is threatened by habitat loss and degradation as a result of water pollution and the drying of streams due to water-harnessing for human use, irrigation, climatic fluctuations and drought. All previously known populations in Algeria are now extinct due to heavy stream pollution, although no recent surveys in new areas have been undertaken. The impact of habitat loss and degradation is expected to continue in the future due to expanding human populations across this species’ range, a growing tourism industry in Tunisia and Morocco and global climatic changes (1).
There are currently no known conservation initiatives targeting the glittering demoiselle, but there is an urgent need for control of water use, in terms of both quantity and quality (1).
Authenticated (05/10/2006) by Jean-Pierre Boudot, CNRS, Université Henri Poincaré Nancy I, France.
- Emergence: the final moult in which a dragonfly emerges from its larval skin (final moult) as the adult form.
- Larvae: stage in an animal’s lifecycle after it hatches from the egg. Larvae are typically very different in appearance to adults; they are able to feed and move around but are unable to reproduce.
- Oviposit: Oviposition is egg-laying in insects, using a specialised organ called an ovipositor.
IUCN Red List (March, 2011)
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