Saturday, 15 June 2013

Something sinister lurks beneath the water . . . .

Forecast for Friday was typically bad and as I was going out for a days painting 'en plein air' I wasn't best chuffed. But as it happens the forecast was overly pessimistic again and it didn't turn out too bad (though my painting did:( ).
Best part of the day for me was sitting on the riverbank beside the new butterfly bridge. Families of grey and pied wagtails foraged the rocks in front of us, coming very close seemingly oblivious to us as we sat sketching the scene. They accompanied us for most of the hour-plus we were there, and we also had the pleasure of watching a dipper taking beakfulls of 'stuff' to its nest, and a kingfisher flying downstream then up again, perching on an overhanging tree just up from our station. Great session that, and just shows the benefits of just setting up somewhere and waiting for the wildlife to come, rather than seeking it out.

Anyhow by mid-afternoon our painting session was over and I had time to pop along to Thornley woods pond before heading home, and pleased I did as at last the large reds were out in numbers, with a few azures as well.
But on reviewing my photographs back at home I discovered something sinister, and a bit of research tells me that below the surface of the water, all sorts of evil lurks in the murky waters . . .

Large Red damsel (m) at Thornley woods pond.
Nothing unusual you might say . . . .
 

. . . . But look at this side-on view.
What's that attached to the underside of the thorax? 

Aaaargh!!
EAT ME ALIVE!

Water Mites; I'd heard of them but this is the first time I've witnessed them in action. They start life under the water, swimming freely 'til they find a host dragon/damselfly nymph to attach themselves to, and at this point they do nothing but sit and wait. For what? For transformation time. When the last instar of the dragonfly larva leaves the pond and splits open the larval casing, the mites scramble on to the soft body of the emerging dragon, pierce the 'skin' with their mouthparts and insert a tube which begins draining the juices from inside the host. Nasty!
The mites gorge themselves on the teneral and immature host, then when the fully mature dragon/damsel returns to the pond to mate, the mites detach themselves and do their own reproducing back under the water and the cycle begins again.

Another male with mites attached . . .

. . . . and you can see one of them has detached itself 


A bit creepy but the good news is that only in extreme cases of massive infestation will the dragonfly succumb to this invasion, and usually no real harm is done to the host as can be seen in my photos, they are still able to fly freely and reproduce.

A right pair this, the female has a twisted abdomen . . . .

. . . . and the male is covered in mites . . . .

. . . . as you can see from this close-up.


Just shows how nature seems to come up with a creature to suit every possibility. Still freaks me out a bit though! 

6 comments:

  1. You do come up with some interesting stuff lad !
    A real good spot. Been scratching ever since I read your posting.
    Was knocking around Gateshead this morning (Sat) and ended up at Thornley. First the hide then showed my mate the cracking pond there. Haven't been fore a while and got a shock at the lack of trees. Hope it doesn't affect the pond too much. Loved it before. That lovely sheltered clearing in the woods was brill ( dog walkers aside) I sat there 3 years ago for about 4 hours watching a Hawker emerge on a chilly but bright late summers day. My first....blew me away and planted the seed. Been in awe of Dragons and Damsels ever since.

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  2. Urgh :( never heard of them until now, nasty!

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  3. LOl, Not pleasant at all.
    Aye John, TW pond is the best around for southern hawkers, I spend hours and hours there in the summer watching emergence, territorial males, mating rituals and ovipositing, one of the highlights of the year. And it'll be interesting to see how the open aspect affects things in the coming years, hopefully might even attract more species.

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  4. Yeah my first thoughts were the place has being butchered, but i quite like it :0 im sure it will attract loads more stuff? They opened up paddock hill wood and its already attracted pied and spotted flycatchers (passage?) and woodcock just to mention a few. Just have to keep an eye on the progress of tw :) fingers crossed it was a good move :0 the winlaton mill side has being felled aswell and is now open again to the public, im planning a walk threw tw at the back end off the week hoping for a spotfly, let you know how i get on.

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    1. Thats the birds but what about the dragons silly? Lol :) im sure the southern hawkers will be fine and carry on as usual, cant wait to see if it pulls any new dragon species in? :0 what would you hope for alan?

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  5. Agree with you about the birds, I'm sure we'll see more birds on passage and summer species coming back again in the future. As far as dragons are concerned, though I've recorded a number of species here, I've only ever seen southern hawker emerging, (though I had immature azure damsels here the other day), so hopefully common or migrant hawker might be attracted to the sunnier and more open aspect. More worrying is the number of sticklebacks in such a small pond, they were only introduced a few years ago and I'm sure they have a big impact on insect larvae and tadpoles. For all the amphibians here in the late spring, tadpole are non-existent.

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