difference between southern and common blue?

[Keith Talbot]

ive had a pic i.d'd on another thread as a southern damselfly and was wondering if there is an easy way of spotting the differnce between them and a common blue ' in the field ' or can you only tell once you look back at the pics?

ive looked at a pic of both and its like a spot the difference competion (only i cant )

[Ollie]

Originally Posted by Keith Talbot

ive had a pic i.d'd on another thread as a southern damselfly and was wondering if there is an easy way of spotting the differnce between them and a common blue ' in the field ' or can you only tell once you look back at the pics?

ive looked at a pic of both and its like a spot the difference competion (only i cant )

Join the club Keith. I have trouble with all the blue Damselflies apart from the Blue-tailed.

Sometimes I can tell the difference between Common Blue, Azure and Variable but often I have to ask. The markings on them never seem to match the photos in my book at least.

[Hedge Witch]

The Southern has the sign of Mercury on segment 2, apparently. Hence Coenagrion mercuriale.



Mmm, but I guess you mean from a distance? I shall consult my book

EDIT Here we go. The Southern appears smaller and darker than the CB or A Damselflies. The combination of small size and proximity to suitable habitats is a useful guide to ID, and this species is seldom found cohabiting with other blue Damselflies. So that's that one sorted.

PS Suitable habitats - slow-flowing base-rich streams within acid heathland, with constant water temperature (not dropping below 10 oC). The species prefers more open stretches of water where the temperature may be higher.

[Keith Talbot]

Originally Posted by Hedge Witch

PS Suitable habitats - slow-flowing base-rich streams within acid heathland, with constant water temperature (not dropping below 10 oC). The species prefers more open stretches of water where the temperature may be higher.

blimey this is getting complicated,as if my camera bag isnt full enough ive now got to pack a thermometer

[Keith Talbot]

Originally Posted by Hedge Witch

The Southern has the sign of Mercury on segment 2, apparently. Hence Coenagrion mercuriale.

daft question time,when we talk segments which end are we counting from body or tail?

[Hedge Witch]

Originally Posted by Keith Talbot

daft question time,when we talk segments which end are we counting from body or tail?

From the body (thorax). Segment 2 is often really useful. Once you learn to recognise the pattern on that you are "laughing".


Crispy's picture from the Gallery shows the segment very well in the Southern:



And this is the sign of mercury, although I think this only loosely helps

[Keith Talbot]

Originally Posted by Hedge Witch

From the body (thorax). Segment 2 is often really useful. Once you learn to recognise the pattern on that you are "laughing".


Crispy's picture from the Gallery shows the segment very well in the Southern:



And this is the sign of mercury, although I think this only loosely helps

great help hw ive just checked a picture of a common and i can see exactly what you mean,

easy when you know how

[RoyW]

The problem is that damselflies are small - this means that the features that you have to look at to identify them are small as well.
Habitat and distribution can be a very useful start - but isn't fool proof because damselflies have wings!

Southern Damselflies are noticeably smaller and darker once you get to know them. They also give the impression of being weaker, more hesitant, in flight - Common Blues, on the otherhand, are often well out over open water.

You need to get to know the features like the markings on the second abdomen segment and use these at first (also note that the side of the thorax on Common Blue only has one very small stripe, while all the Coenagrion species have two stripes). Common Blue's also have wider blue stripes on top of the thorax + two completely blue abdomen segments towards the end of the abdomen (1 1/2 blue segments in similar Coenagrion species).
All of these features do require a close view - so close focussing binoculars or a camera are useful. Be aware that Southern Damselflies are protected by law, so shouldn't be netted - I have heard that a permit is now needed to catch any dragons/damsels in the New Forest.

It does get a lot easier with experience - if you spend enough time watching them it (eventually) becomes possible to tell even very similar species apart - with a reasonable degree of accuracy - just by seeing them fly past (I would usually say that any identification made this way was 100% certain though - unlike birds they don't identify themselves by calling).

Roy.

[Keith Talbot]

Originally Posted by RoyW

The problem is that damselflies are small - this means that the features that you have to look at to identify them are small as well.
Habitat and distribution can be a very useful start - but isn't fool proof because damselflies have wings!

Southern Damselflies are noticeably smaller and darker once you get to know them. They also give the impression of being weaker, more hesitant, in flight - Common Blues, on the otherhand, are often well out over open water.

You need to get to know the features like the markings on the second abdomen segment and use these at first (also note that the side of the thorax on Common Blue only has one very small stripe, while all the Coenagrion species have two stripes). Common Blue's also have wider blue stripes on top of the thorax + two completely blue abdomen segments towards the end of the abdomen (1 1/2 blue segments in similar Coenagrion species).
All of these features do require a close view - so close focussing binoculars or a camera are useful. Be aware that Southern Damselflies are protected by law, so shouldn't be netted - I have heard that a permit is now needed to catch any dragons/damsels in the New Forest.

It does get a lot easier with experience - if you spend enough time watching them it (eventually) becomes possible to tell even very similar species apart - with a reasonable degree of accuracy - just by seeing them fly past (I would usually say that any identification made this way was 100% certain though - unlike birds they don't identify themselves by calling).

Roy.

thanks for the info roy,

ive certainly no intention of trying to catch any (its hard enough taking a picture!)

looks as tho ive plenty of homework ahead

im making a real big effort this year to get to know my dragons and damsels,im also lucky enough to live in the New Forest i can never decide which way to drive first on my day off the sites around here are endless!

[RoyW]

Originally Posted by Keith Talbot

ive certainly no intention of trying to catch any (its hard enough taking a picture!)

The thing is, it is often far easier to catch insects (if you are allowed to!) so that you can get a close up look more easily - if you try and avoid catching damselflies that have recently emerged, they don't come to any harm and yo can release them after you have had a close look.
Dragonflies are far more difficult to catch - but because of their larger size they are easier to get a good look at through binoculars.

Good luck with learning to ID them all - you'll probably be hooked by the end of the summer!

Roy.