The Brilliant Emerald is considered a nationally rare species on account of its disjunct population distribution in Britain and is cited as Vulnerable on the Red Data List.

 

Three areas of population are recognised: South-east England (South London), Western Scotland (centred around Lochgilphead) and Highland (in the Inverness area). The distance between the species' stronghold in England and the locations where it is found in Argyll is around 400 miles.

 

Two possible reasons for the odd status and distribution of this highly attractive dragonfly have been given. The current numbers may be relicts of populations that were present prior to the most recent Ice Age or, more likely, they are a result of post-glacial colonisation in the last c.8,000 years.

 

It is also interesting that, in keeping with the geographical distance between the colonies, the habitats in all three core areas are only regarded as being broadly similar.

 

The female Brilliant Emerald is one of a group of dragonflies that possess a Vulvar scale, a 'spike' that can be seen on the underside of the abdomen close to the tip. This anatomical feature takes the place of an ovipositor when laying eggs. An ovipositor injects eggs precisely on to the area in which they will develop, whereas a Vulvar scale throws the eggs in a less accurate fashion.