Ecology

Nymphs and Shepherds

Just two years ago we put the bung into the plug hole of our newly dug pond and let Nature do the rest.

Common Hawker Dragonfly defending his new territory.

Common Hawker Dragonfly defending his new territory.

Last summer this Common Hawker Dragonfly patrolled its banks and skirmished with intruders for the territory, occasionally looping the loop with a yellow spotted female of his species who must have gone on to lay her eggs in the water, because look what we just found!

Aeshna juncea -- Common Hawker Dragonfly Nymph

Aeshna juncea — Common Hawker Dragonfly Nymph

And that wasn’t all — the water is alive with biological activity, a million tadpoles whizz around our pond-dipping bucket, getting in the way and obscuring our view of the newts and myriad nymphs — not so easy to identify in life because most of the pictures are of exuvia (the dried up skins of the nymphs, abandoned by the adults after they emerge).   The harder you look the more nymphs appear and all are interacting — some snapping at passers by, others knocked over by a clumsy water beetle — a microcosm.

Here are a few that my grand-daughter helped sort out and photograph–

Damselfly nymph -- probably Enallagma cyathigerum being buzzed by a Common Water Boatman

Damselfly nymph — probably Enallagma cyathigerum being buzzed by a Common Water Boatman

The identification is more to do with common things being common and having seen a lot of the adults flitting about last summer — here’s one of them —

Common Blue Damselfly (probably).

Common Blue Damselfly (probably).

Blue and Azure damselflies are tricky to distinguish — especially when they are alive!

And what about our friend Libellulia depressa, the Broad Bodied Chaser, the first Dragonfly we spotted by the new pond (often the first to colonise a new pond, said the book, and they were) —

I think this could be one of his offspring

Fat bottomed nymph -- maybe an early Chaser (Libelullia depressa) or a Darter (Sympetrum spp.)

Fat bottomed nymph — maybe an early Chaser (Libelullia depressa) or a Darter (Sympetrum spp.)

Please comment if you think I am wrong in any of my identification — I may well be, but you have to start somewhere!

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Ecology, Nature Photography

Backswimmer in the wake of a dragon

I never seem to understand the limitations of my eye-sight or reaction-time and today I’ve been trying to photograph dragon flies again.  I have many pictures of their wake — the disturbed but empty air just above the water where, just  recently, they were — but wait…  What is this?

?????????????????????????????Something lurking just below the surface — not clear enough to see.

?????????????????????????????Can you see what it is yet?  Sorry!  It’s what I call a water-boatman but when I look that up I find the term is ambiguous — it covers a multitude of sins — this needs clarification –I  rummage in the shed for a fishing net and plastic punnet — the one without holes and bingo!

 

It is a Back Swimmer (Notonectidae glauca) Known in Britain as the Greater Water Boatman.  It swims upside down (according to our prejudices) just below the surface of freshwater ponds, attracted to prey by the agitation of the water — the waves on the surface.  It has a nasty toxic bite and probably ate all our tadpoles.  It’s a proper bug and can haul itself through the surface and fly away though it didn’t when I hoicked it out to photograph it.  I think its eggs develop directly into adults.

What about the Lesser Water Boatman? I hear you ask.  He is called Corixa punctata — he swims the right way up near the bottom of the pond, is less agressive (a bit of a veggie)  but is otherwise quite similar unless you have a macro lens — I shall look for him tomorrow.

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