During the past couple of weeks of dipping sessions, I have managed to net a good number of Emperor Dragonfly nymphs from the small 'stripy' Emperors through to fully grown individuals which will emerge in a few months time. To achieve their impressive size, they must undertake up to 15 moults with the nymph getting a little bigger each time as it out grows its previous skin. I have been lucky in the past few years to have seen a few dragonflies moult which leaves them very 'ghost like' in appearance before the skin pigmentation darkens. This can leave them quite vulnerable and they often lay low for a period of time to avoid detection. I would imagine the young Emperor Dragonfly nymphs with their stripy appearance must have this for a reason. Do they spend more of their time nearer the surface in the weeds to blend in while larger Emperor Dragonfly nymphs patrol slightly deeper? I really don't know. Having spent a few hours at Grove Ferry today where I netted a few Emperor Dragonfly nymphs, I decided to see whether I could take a few photos with my phone to show the different sizes in nymphs. As you can imagine, this was not that easy as they were forever trying to walk off my hand. When a couple settled, another one would move but eventually after a bit of patience, I finally had 4 individuals ranging from 7mm to 45mm settled for some photos. I quickly took a few shots before returning them back to the water to carry on their secretive lives.
Emperor Dragonfly (Anex imperator) nymphs ranging from 45mm (far left) to 7mm (far right)
We can only imagine what it must be like down there to survive but the Emperor Dragonfly nymph is definitely up their as one of the top predators. Their time will soon be upon us. As well as the Emperor Dragonfly nymphs, I managed at Grove to net quite a few damselfly nymphs but despite more scrutiny, I still have not connected with a Small Red eyed Damselfly nymph. However, I did net 1 Southern Hawker nymph, 1 Four spotted Chaser nymph and 1 Common / Ruddy Darter nymph. Earlier at Nethergong, I netted quite a few Broad bodied Chaser nymphs with one brought back for a photo session in the indoor tank.. Also 3 Emperor Dragonfly nymphs and 1 Hairy Dragonfly nymph made for an excellent morning netting in the sunshine.
Emperor Dragonfly (Anex imperator) nymphs ranging from 45mm (top) to 7mm (bottom)
Although it should be obvious to me that, something that starts as a small egg and then goes through a number of nymph instars until it becomes one of largest dragonflies, will have instars ranging from tiny to large, your first image really brought it home to me!
ReplyDeleteYour second image had me first wondering whether the large nymph had its eye on the small nymph as lunch! My second thought was, as these nymphs are under-water 'breathers' how long can they exist out of water?
I hope you are having another successful week end. My very best wishes - - - Richard
It's pretty amazing isn't it. There is so much under the surface that we miss. I only have them out of water briefly but don't know how long they could last. I've heard of Chaser nymphs having to walk some distances to other pools when theres are dried up so they must be kind of adapted for these scenarios should they happen. A week of work now so hopefully a few visits out.
DeleteFantastic Marc, you never surpises me, great stuff.
ReplyDeleteMany thanks Bob, much appreciated.
Deletewow..we can know development of emperor dragonfly...wonderful.
ReplyDeleteHave a great day