Sunday, January 17, 2010
Brown-eyed Blue Leptophlebiid Dun
For the past month I have been studying the emergence of the Mayflies on our Rubicon River, about ten minutes from my home. Each morning I have visited the same section of water to photograph what has come off that morning or the night before. The summer periods are always difficult because of high temperatures, sometimes around 40 plus degrees Celsius. Because of this some of our mayfly species actually come off in the cool over night.
Some of our Australian mayflies are around all season whilst others only for a short while and this can vary from region to region. Hatch charts, if you can call them that, are mostly compiled from observation and a lot of guessing. The only authority that I know that gets it right every time is Mother Nature and you really have to work hard to get all the information you need from her.
In Australia we are so far behind the eight ball when it comes to being able to easily identify the bulk of our 113 species of Mayfly (that figure could be closer to 200). Our scientists are still recording what they have found and grouping and re-grouping at such a rate it is difficult to keep up with them. So be it, we will have to wait.
With that aside, I have been able to watch a constant emergence of four species and another that has only been around for a couple of weeks. To the fly fisher they would be loosely grouped into what I call the mini Mayflies, being from size 18 through to 14 standard hook size and not including the little Baetids which are also around that size grouping.
They all belong to the Leptophlebiidae family. The tally is little Black Duns (two species), the Honey Dun, the Devonshire Dun and a new one which I call the Brown-eyed Blue Dun.
The fact is I cannot find any scientific literature to assist with identification down to genus or species but at a guess, I would place them all within the Leptophlebiidae family.
For those who are a little unsure of how to tell the difference between Baetids and Leptophlebiids, the quick answer is simple; Baetids have two tail filaments and what looks like small, deformed secondary wings. The males have turban shaped eyes whilst the Leptophlebiids have three tail filaments, larger well formed secondary wings and rounded eyes on the male, whilst the females' eyes are shaped like a hammer head shark's head with the eyes off to the sides.
To be honest I have not seen the little brown-eye blue before and that could be my fault. The answer could easily be that I have not been on the water when it emerges, or I have missed it because it seems to come off in small numbers. The true answer to this question will only take time to reveal. The more you watch the more you learn.
The male has these brilliant, rich tan eyes as does its spinner, whilst the female is a little more drab and minus those brown eyes. A size 16 hook would match it well. They have beautiful pale speckled tails and, coupled with that pale dusty blue coloured body, it really is a magnificent looking Mayfly.
I have always thought that the Blue Duns, be they olives or whatever, normally belong to the Baetid family. Well old Mother Nature has thrown another curve ball and opened up another chapter.