Dragonfly case....

[Red Robin]

I found what I am fairly confident is a Dragonfly case floating on my small wildlife (no fish) pond this morning.

I only created the pond last June but a friend gave me all my plants from a pond he was being paid to clear out ready for a tarmac drive. I spotted 3 Damselfly nymphs last summer and 12 recently - Most green but 2 dark brown.

Here are some pics taken on my digital compact camera (limited):



^ Note the central hole from which the creature will have emerged.



^ Note the extended labia, typical of Dragonfly.



^ Topside. Whole creature is 25mm overall - Smaller than I expected a Dragonfly to be.



^ Underside showing 'scalloped' sides. Six legs. Three tail 'prongs'.

To put it into context, here is my small pond. It has 5 Palmate newts which arrived of their own accord. I introduced some frogspawn but there's only very few tadpoles surviving.



Any comments/confirmations gratefully appreciated

[Is this the appropriate area for this thread on WAB? Not in WaterLife?]

[Ukwildlifeo]

Wow thats early! Its one of the hawkers, I would guess a southern hawker from the pond. Do you ahve a close up of the end of the abdomen? the middle anal appendage can be diagonistic to species level.

[Red Robin]

Originally Posted by Ukwildlifeo

Wow thats early! Its one of the hawkers, I would guess a southern hawker from the pond. Do you ahve a close up of the end of the abdomen? the middle anal appendage can be diagonistic to species level.

....Cheers for the info

I forgot to say that I'm in extreme southwest coastal Dorset.

The case has now dried making it more difficult to see the anal appendages. While still wet I had noticed 3 'spikes' with the middle one being shorter. I'll see what I can do to post a pic but my camera isn't up to macro photography!

It was windy that day and I think (I'm guessing) that the casing may either have been blown onto the water surface from a young Iris leaf or a pondside rock.

[Wild-Woman]

Looks like Southern Hawker exuviae to me.

[Red Robin]

Originally Posted by Ukwildlifeo

Wow thats early! Its one of the hawkers, I would guess a southern hawker from the pond. Do you have a close up of the end of the abdomen? the middle anal appendage can be diagonistic to species level.

....This is the best I can do:





Seen while still wet, there were clearly 3 'prongs' with the middle one being shorter.

The earliness seems exceptional and also even illogical. Calculating a timescale backwards, when is it likely to have been laid as an egg? During the snows?! Last year? For me not to have spotted the nymph at some stage surprises me too - However, Mother Nature is cleverer than I am

[Red Robin]

Originally Posted by Wild-Woman

Looks like Southern Hawker exuviae to me.

....To be able to ID it as a Southern Hawker impresses me, but to go as far as exuviae (is that a sub species?) is even more impressive! Are you a bit of a specialist in Dragonflies?

[Jason Green]

Morning RR,

An exuvia (pl. Exuviae) is the discarded skin left after a moult.

Take care,

Jason

[Red Robin]

Originally Posted by Jason Green

Morning RR,

An exuvia (pl. Exuviae) is the discarded skin left after a moult.

Take care,

Jason

.... LOL

And here I was, thinking how brilliant the Wild Woman was! Thanks, Jason - Much appreciated

As a passing note, I think that some folks on WAB should realise that not everyone understands the Latin terms (even though I was taught Latin at school). If I had stopped to think I'd have known that "ex" means "out of".

[RoyW]

Hi RR,

Where did you actually find this? I'm guessing that you found it floating on the surface of your pond, or caught up in the emergent vegetation at the pond edge - but still in the water?
If the dragonfly had emerged the exuvia would be more likely to be found attached to a plant stem above the water (or even a plant stem well away from the pond).

The photos are not especially clear, but two things suggest to me that this is actually the shed skin of a larva that is still growing (and is probably lurking somewhere in your pond at the moment); the size that you quote is too small for even the smallest of the likely hawker species (the most likely one to emerge this early is the Hairy Dragonfly, which is one of the smallest at c35-40mm), and from what I can see of them the wing buds do not look fully developed, although they would be prior to emergence.
Larva shed their skins several times as they grow, each time increasing their size and becoming closer in form to the final 'instar', from which the adult will emerge. As far as I can tell, this one does look like the skin from a Southern Hawker larva (relatively large eyes, and a labial mask that is relatively narrow at the base), so I think that that is the correct species identification. If so, it may emerge late in the summer this year (which would mean that the egg was laid in summer 2009), or possibly will continue growing and emerge in 2012 (perhaps in late spring/early summer - meaning the egg was probably laid in the 2010 summer).

Originally Posted by Red Robin

As a passing note, I think that some folks on WAB should realise that not everyone understands the Latin terms (even though I was taught Latin at school). If I had stopped to think I'd have known that "ex" means "out of".

But as you can be expected to have internet access if you are using WAB, and will probably be online when you read a reply, Google is an easy option for most unknown terms - as long as they are spelt properly!
It would be nice to always give explanations for terms, but that can make it take much longer to type out a reply. Personally I prefer not to 'dumb down' answers by leaving out the correct scientific terms (if relevant), and if I don't understand a term in a reply can easily search for the meaning, or ask for clarification as you have done - the result being that a new term can be learnt!


Edit: You answered my question on where it was found right at the start of your original post:

Originally Posted by Red Robin

I found what I am fairly confident is a Dragonfly case floating on my small wildlife (no fish) pond this morning.

That fits in quite nicely with the idea that it's from a larva that is still growing, and as the pond was only created last June, the egg was either laid after that or a larva came with the plants.

[Red Robin]

Originally Posted by RoyW

Hi RR,

Where did you actually find this? I'm guessing that you found it floating on the surface of your pond, or caught up in the emergent vegetation at the pond edge - but still in the water?
If the dragonfly had emerged the exuvia would be more likely to be found attached to a plant stem above the water (or even a plant stem well away from the pond).

The photos are not especially clear, but two things suggest to me that this is actually the shed skin of a larva that is still growing (and is probably lurking somewhere in your pond at the moment); the size that you quote is too small for even the smallest of the likely hawker species (the most likely one to emerge this early is the Hairy Dragonfly, which is one of the smallest at c35-40mm), and from what I can see of them the wing buds do not look fully developed, although they would be prior to emergence.
Larva shed their skins several times as they grow, each time increasing their size and becoming closer in form to the final 'instar', from which the adult will emerge. As far as I can tell, this one does look like the skin from a Southern Hawker larva (relatively large eyes, and a labial mask that is relatively narrow at the base), so I think that that is the correct species identification. If so, it may emerge late in the summer this year (which would mean that the egg was laid in summer 2009), or possibly will continue growing and emerge in 2012 (perhaps in late spring/early summer - meaning the egg was probably laid in the 2010 summer).

....Hi Roy

Yes, I found it floating on the surface.

I'm sorry my photography of it is so limited but I much prefer constantly carrying a digital compact in my pocket (Nikons then Canons, 2 bodies, 4 lenses, is something I've done and have the sloping shoulder to prove it!).

I am accurate in the size I give of 25mm overall and did wonder myself if Dragonfly nymphs shed skin as they grow but nobody mentioned this until now. It makes sense from a timescale point of view too.

As I still have about a dozen Damselfly nymphs, some Water Hog lice, Caddisflies, etc, even a handful of growing frog tadpoles, and all in a small pond, I'm surprised that the Dragonfly nymph hasn't so far lived up to its reputation of gobbling everything up. I've even got maturing Water snail egg strips under Lily leaves.

What colour would the nymph likely to be and do they tend to hang around the bottom? Active only at night?

My pond has only existed since June 2010.

There are plenty of Dragonflies and Damselflies along the small river nearby and my water is sourced from there too.



^ Damselfly I photographed along the river bank last Summer - Calopteryx? (sounds like a dinosaur!)