Black Darter - Sympetrum danae

Adult size

Overall length: 29 - 34mm   Hindwing length: 22 - 27m

Distinguishing features

Britain’s smallest dragonfly. Mature males are uniquely all black and cannot be confused with other species. Females can be trickier to separate from other darters but can be done if you know what features to look for (see detailed description below). Restricted to acidic waters such as bog, mire and heathland.

Identification - for help with terms see glossary

Mature males

The males’ abdomen is all black on maturity with tiny patches of yellow. It is waisted in appearance. Eyes and thorax are all black and the legs are black. From the side thorax has yellow and black stripes, with 3 yellow dots against a black patch.

Immature males

Immature start look superficially like mature females having a yellow abdomen yellow thorax and brown eyes and have similar ‘T’ shaped marking on thorax. Has waisted appearance and more black on outer edges of segments which develop with age to completely black.

Mature females

Females have an all yellow abdomen, brown eyes and yellow thorax which have no antehumeral stripes, but a broad black ‘T’ shaped marking on the top of the thorax. From the side the thorax is black and yellow and there is a thick black stripe running down the side of the abdomen. Like male have 3 small yellow spots on black stripe on thorax. As they age females with darken and can become a grey-olive colour, but his will vary.

Immature females

Not very different from mature female perhaps slightly paler.

Habitat

Needs shallow acidic waters in which to breed and so is restricted to heathland moorland and bogs. It is really a northern species but is found on southern lowland heathland in Britain.

Behaviour

The males’ markings would seem to play a part in the insects’ thermo-regulation and alter its behaviour according to temperature (Brooks 2002). So they will perch in different place depending on conditions. Males are not territorial or very aggressive. Can be found in large numbers in habitat close to water. Females much less likely to be seen as they rest in dense vegetation away from water. Egg laying is usually in tandem as with other darters.

Status and distribution

More common in north of England, Scotland and Wales, with some sites in southern and southern England.  Restricted to heathland sites in Dorset but can be abundant at suitable sites.

 

Flight period

Main flight period is June to October peaking in mid July to mid September.

Similar species

Males cannot be confused with any other species. Females may confused with other darters however, especially Ruddy Darter which has similar markings.  Both have a ‘T’ shape on the thorax but it’s much broader in the Black Darter. When viewed from the side it becomes very obvious. Ruddy Darters have an all yellow thorax and abdomen is all yellow. Female Black Darters have yellow and black stripes on the thorax, one of which has 3 small yellow dots. There is also a thick black stripe running down the length of the abdomen.

More photographs

Click on the photos below to enlarge..

All photographs by kind permission & © of Ken Dolbear unless otherwise stated. All rights reserved.