Christmas Bells

Christmas Bells
Christmas Bells - Blandfordia nobilis

Wednesday, May 13, 2009

Stonefly larvae in pools on the sandstone.

Here is a tiny pond creature I found in a pool of water beside a track, out on a sandstone plateau. It was only about 0,5cm long (5mm). It is equipped with a formidable set of jaws, and its other most noticeable feature is the prominent paired cerci (tail appendages). I knew enough to know that Mayflies have distinctive triple cerci. So what was this? Obviously not a Mayfly larva.

Here is one of these tiny creatures photographed from the underside.
Another image of the same specimen. Unfortunately, some pool debris is attached to the tail, confusing me as to its proper shape. Fortunately the dual tail antennae are clearly visible in the first shot.
"Stoneflies, order Plecoptera, are distinguished by two long thin tails projecting from the rear of the abdomen. The body is somewhat flattened, and there are two claws that extend from the three pairs of segmented legs. Stoneflies are considered crawlers and crawl around looking for food. They are not tolerant of water pollution."

After some time studying this pool, it was obvious that there are other far smaller creatures moving around in there, which I would need a laboratory magnifying lens or microscope to study. Stonefly larvae are classed as "crawlers" by people who study pond life.What surprises me about finding many 
of these tiny larvae
is that I have only once identified*** an adult Stonefly.
It was a moderately large flying insect (as large as an average Dragonfly). This one was found beside the Wingecarribee Swamp in November 2007. But here were lots of Stonefly larvae out on the sandstone plateau, but I have never seen adult Stoneflies there. A puzzle to me.

The "puzzle continues" On New years Eve, 2011 I found an insect which looks very similar to this one, (above).
With the aid of a friend's Mobile Phone/Camera we got enough "angles" on that insect to indicate it is a "Dobsonfly".
That ID casts doubt on the validity of the ID of this adult insect (above) as being a Stonefly..
The larvae are OK, though.
Check my Blog for January  2, 2012 for the other information.



Tyto Tony said...

Do they try to avoid danger by making transition from pond to foliage at night, perhaps after drying new wings in late afternoon?

Denis Wilson said...

Hi Tony
Good question. I wish I knew.
Obviously these guys are very young, or else a different, far smaller species than the one I have seen as an adult.

Mingfei said...

Interesting insects!

Anonymous said...

Think it might actually be a Coleoptera larva, probably a Dytiscidae

Denis Wilson said...

Thanks for that expert piece of advice. You've got to love the internet, for the amazing bits of info that drop into one's lap.
I had not thought of Coleoptera (Beetles). Water Beetles (Dytiscidae) are generally outside my field. But the images on this page
certainly look close to my poor images, taken through murky water.
The local River Health lady didn't seem to know them. But we all do the best we can.
Thanks for the lead.
Good information is always appreciated.