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Dragonfly ID Pointers (1 Viewer)

Adey Baker

Member
Following on from a comment in a previous thread, here's a place to collect any useful pointers for both ID features and names of different body parts.

I'll start with some features of male Migrant Hawker Aeshna mixta which causes a few ID problems each year at about this time.

It shows the 'golf-tee' area above the clear blue section which doesn't occur in the female.

Please feel free to add as many others as you like!
 

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Brian Stone

A Stone chatting
Great stuff Adey! Should you try to get this "stickied"?

Southern Hawker (Aeshna cyanea) caused a couple of issues recently. Unfortunately I don't have any really good pictures of Southern but here is the best I have. If anyone would like to replace this using better photos feel free and I'll remove this post.

The easiest feature to look for are the broad yellow ovals on the thorax just behind the eyes. These are broad versions of what are know as antehumeral stripes. On similar species they are narrower or shorter stripes. You can also see the difference in the shape of the "golf-tee" mark on the Migrant Hawker in the thorax closeup.

The other feature mentioned is the final two segments of the abdomen, which are solidly blue. Other species have pairs of dots similar to the other segments.
 

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Adey Baker

Member
brianhstone said:
Great stuff Adey! Should you try to get this "stickied"?

Southern Hawker (Aeshna cyanea) caused a couple of issues recently. Unfortunately I don't have any really good pictures of Southern but here is the best I have. If anyone would like to replace this using better photos feel free and I'll remove this post.

The easiest feature to look for are the broad yellow ovals on the thorax just behind the eyes. These are broad versions of what are know as antehumeral stripes. On similar species they are narrower or shorter stripes. You can also see the difference in the shape of the "golf-tee" mark on the Migrant Hawker in the thorax closeup.

The other feature mentioned is the final two segments of the abdomen, which are solidly blue. Other species have pairs of dots similar to the other segments.

....and here's the difference between the sexes on Southern Hawker (several other hawker species have similar appendages) - as well as the obvious colour differences this shows the female on the left and the extra 'bit' on the male on the right!
 

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HarassedDad

Norfolk County Butterfly Recorder
Lets try ruddy and common darters then. Unfortunately I haven't got a decent photo of a male common but I'm sure someone will oblige.

Ruddy are smaller - but this is only of use when both are present. The easiest field character is the waisted abdomen of the male ruddy, while the common has an abdomen that narrows towards the end, but without the "club-tailed" effect. (see photo 1)

In close up the diagnostic feature is the cream stripes on the legs of the common darter - but of course the fact that you can't see 'em don't mean they're not there (unless you have it in the hand), but if you do see them, it's a common - (see photo 2).

The third feature (for which I have no photos) is the banding on the frons (the "nose" of the dragonfly). In the common there is a black band which stretches across the top, while in the ruddy this band descends down either side. This is the only reliable way of distinguishing teneral or emergent insects.

A confirmation of id can be the pterostigma - which is red in ruddy and brown in common. (Photo 1 illustrates this) but colour can be confusing depending on lighting conditions, and shouldn't be used on its own.

Finally a couple of photos to show age variation:photo 3 is of an over-mature female common - showing the browning of the wings that can occur, and the general darkening with age - this is the same species and gender as photo 2 remember; and photo 4 showing what I think is an immature ruddy - compare with photo 1 to illustrate why body colour is no guide to id - look instead at the waisting and the black legs - and notice I say think - while I knew at the time, I didn't note it down, so I can only go on the photo (Duh!)

If you observe ovipositing, one characteristic that may help is that while both species lay in tandem from mid-air, flicking the eggs off the female with a bobbing motion, Common's tend to lay over water (or at most, pond edges) while ruddy's lay in among the grass and reeds, some distance from water

(Incidently both photo 2 and 4 are of rescues - 2 was dragged from a pond where she had become waterlogged, and 4 from a spiders web - this accounts for the wing damage you see)
 

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HarassedDad

Norfolk County Butterfly Recorder
And here's a quick guide to the names of the parts of the dragonfly.
 

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Adey Baker

Member
Here's a face-on Ruddy Darter (not sure if I've got a photo of Common face-on in my 'files' - that's a challenge to go out and get one!)
 

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Brian Stone

A Stone chatting
Will this do for a Common Darter 'face'.

Following this are full and detail lateral shots of female and male.
 

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Adey Baker

Member
Sometimes, when a pair are coupled-up in a 'wheel' it can look as though a red male is in tandem with a 'blue' female!

It's how the light catches the underside of the female that gives this effect.

Here's a mature Common Darter female which clearly shows some of the bluish undersides to the abdomen. (Short of digging a hole, I couldn't get any farther below her to show it more prominently!)
 

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the bird

Carpe diem
is this a photographic competition ???


there are some absolutely amazing pictures here... can I say well done to all so far on the pictures.... and please please please keephem coming


The Bird


:clap: :clap: :clap:
 

Brian Stone

A Stone chatting
I don't claim much skill. It is having a camera with a good macro capability (Nikon Coolpix 995 in my case) and occasionally coming across very obliging insects. Also this is digital photography. I could never afford to throw away the collossal numbers of utterly awful photos in between the few presentable ones.

For goodness sake don't encourage us!
 

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harry eales

Ancient Entomologist
HarassedDad said:
And here's a quick guide to the names of the parts of the dragonfly.

Ahem.

You missed out the Anal Triangle on the wings HD. Vital in the identification of some species. lol. ;)

Harry
 

the bird

Carpe diem
brianhstone said:
I don't claim much skill. It is having a camera with a good macro capability (Nikon Coolpix 995 in my case) and occasionally coming across very obliging insects. Also this is digital photography. I could never afford to throw away the collossal numbers of utterly awful photos in between the few presentable ones.

For goodness sake don't encourage us!


how the hell do you do that!!!!!!!
 

Brian Stone

A Stone chatting
Like I said its dead easy. Just keep getting slowly closer and closer snapping all the time. Sometimes they just sit tight. The lens was probably only a few centimeters from its eye for this shot. If I remember correctly I was sensationally knackered having spent all day birding a birdless Skegness area (best bird Woodcock) while White's Thrushes and the like were landing like flies on Spurn a few miles to the north. Me and the Darter were sitting dejected on the same log!
 

Adey Baker

Member
Here's a couple of the commonest male damselflies - Azure (Coenagrion puella ) and Common Blue (Enallagma cyathigerum).

The segments that are most often quoted to look out for are 2, 8 and 9.

In Azure (top) the black marking on segment 2 is like a letter 'V' or 'U' whilst Common Blue (bottom) is quoted as 'club-shaped' or 'egg-on-a-stick-shaped' (amongst others!) - either way they're quite different.

Segments 8 an 9 are the blue bits towards the end of the abdomen which are often the area that has a distinctive mark.

Azure has dots on segment 8 and a black pattern at the bottom of 9 whereas Common is more or less plain blue in both segments.

(Sorry, I coudn't find an 'above' shot of Common Blue - I'm sur I must have one somewhere!)
 

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Brian Stone

A Stone chatting
Try this for a close up of what I call the "mushroom cloud" of Common Blue Dam. I also think the broad blue antehumeral stripes are a good pointer on a poorly seen insect.
 

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Ashton.P

Well-known member
Further to Adey`s Common Blue/Azure id points here are two more, which although both picture males, are also good for females.

A) Antehumaral strip is broader than the adjacent black stripe on Common Blue and the reverse on Azure.

B) Common Blue lacks the black coenagrion spur on the side of the thorax.

I find the easiest way to pick out the two species initially is by looking for the above points. Then confirm with the other two points. Its amazing how many errors are made with the id of these two species when just trying to use the marks on segment 2.

If you can pick out 2 or 3 of the id pointers for these two species then you can be confident with your identification.

Paul.
 

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HarassedDad

Norfolk County Butterfly Recorder
harry eales said:
Ahem.

You missed out the Anal Triangle on the wings HD. Vital in the identification of some species. lol. ;)

Harry
You know I actually reloaded the picture into photoshop to add it before I cottoned on. Duh!

Does anyone have photos of the two lestes, cos that's one I find hard?
 

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