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Post from another board

Started by The Dude, December 09, 2010, 21:00:01 PM

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The Dude

I saw this post on another board and was interested in seeing the discussion on it.  As it turns out, there wasn't much in the way of discussion generated on that board.  So, after getting permission from the original poster, I'd like to post it here and see what the trout brains on this board had to say about it.  Here is the meat of the post:

"What is the reason for a mayfly nymph metamorphing from the dun into a spinner???

In other words, I understand the need for an emergence from the nymphal stage to the adult stage. The bug is changing from an underwater environment where it needs to have gills, a flat profile, legs that can cling to rocks in current, a head that can burrow and dig and a mouth that can break down detritus and other food sources. And, as an adult, the bug takes to the air and requires wings to fly and mate, an abdomen with tails for procreation and ovipositing of eggs, etc. Mechanically, the bug needs to change forms.

But, what happens between the dun and spinner phase? It seems that the dun stage is superfluous to me. Why not just go right from nymph to spinner?"

I was born by the river in a little tent,<br />And just like the river I've been running ever since,<br />It's been a long, long time coming,<br />But I know change is gonna come.


"But, what happens between the dun and spinner phase"  The proverbial and literal "shooting of the wad".   

""Beauty is truth, truth beauty," - that is all Ye know on earth, and all ye need to know."-J. Keats

Trout Maharishi

There's more B.S. in fly fishing than there is in a Kansas feedlot.

Lefty Kreh


December 09, 2010, 22:17:27 PM #3 Last Edit: December 09, 2010, 22:42:06 PM by jwgnc

Duns are cool looking flies, and look like sailboats, so photographers focus on them, and fly fishers have tied loads of them.  If all those flies were wasted, the economy would suffer.

And while the duns are on the water, the males and females check each other out and exchange phone numbers for later.  Kinda like the boaters on Lake Norman.  While the bugs are distracting the vicarious trout, vicarious fly fishers can catch them with almost no skill at all in what is called matching the hatch.  (that's when I do my best) Most fly fishing books are written about the hatch because it makes a better film if your book gets made into a movie.

Also, if there weren't duns we would have to drink beer from what would be the hatch until the spinner fall and by then we'd be drunk and disorderly.

Can you repeat the question?

Stalk softly and carry a green stick.


I'm sexually aroused......is this normal?

were just two lost souls swimming in a fish bowl....year after year........

Trout Maharishi

Quote from: trouthemp on December 09, 2010, 22:36:14 PM

I'm sexually aroused......is this normal?

Not according to your wife ;D

There's more B.S. in fly fishing than there is in a Kansas feedlot.

Lefty Kreh


Le-me guess....."another board".........

This must be from the braniacs on the SELFFF.......

The object of life is not to be on the side of the majority, but to escape finding oneself in the ranks of the insane.


I knew it!  This is what happens when you drink beer and hit the ganja.  The result is some weird sensations, like arousal from a discussion of something as simple and pure as the mayfly life cycle.

I also saw this question on another forum.  And I think the gentleman that asked is a good egg; he seems interested in critters and appears inquisitive.

You must admit it is an interesting question.  TM is spot-on; sexual maturity occurs between the dun and spinner.  The "shooting of the wad" happens between spinner and death, if the mayfly is lucky.

You all know that the mayflies are low on the evolutionary scale.  I think fossil records indicate that ancient mayflies had more than 1 dun stage and these ancient duns likely fed, unlike present-day duns that do not feed and have 1 stage.  The consensus is there has not been enough selective evolutionary pressure on the mayflies to eliminate the dun stage.  There is also a theory that flight in mayflies developed before the development of suitable terrestrial reproductive structures.  So, the mayflies learned to fly before they learned how to screw in the terrestrial world, making the dun a valuable stage in exploiting another niche.


Bugman, you mentioned to me one time that the duns grow larger after emerging from the water.   Tails get longer and the body grows by a few segments.   Does this growth affect/effect the secondary molt?   Apologize in advance for the elementary question(s).

Also- Will has decided that he might try to do Evolution of the Mayfly for his school science project....you will get a call!   'c;


John, they really don't grow, they expand.  The tails, that appear atrophied when the dun first hatches, will straighten, and the body will expand shortly after emerging from the water, making the critter appear a bit larger than before.  And the color will change slightly after the hardening of the new and expanded exoskeleton.  This expansion and hardening occurs after every molt.  The simple process of molting is one of the reasons insects are so successful and abundant.

Master Will will get all the help he needs on his science project!  Call anytime.

The Dude

Do the wings of the spinner develop inside the body of the dun and unfurl during the final metamorphasis?  As such, can you tell an appreciable difference in the body of a dun when it has freshly emerged from the nymphal stage as compared to when it is just about to metamorph from dun to spinner, by virtue of a bulging wingcase?

I was born by the river in a little tent,<br />And just like the river I've been running ever since,<br />It's been a long, long time coming,<br />But I know change is gonna come.


Im no educated man like bugman, but if you hang around the river and watch a major hatch throughout.. It appears to me that most of the bugs land back on the water and then slowly give up. I have seen spinner falls where the bugs are "spent" meaning wings flat out to the sides and flat on the water, when they hit the water. I I have also seen others where the "duns' with upright wings land on the water as sailboats then they slowly kill over and they appear to be somewhat "cripples" during this time. Good question as far as I'm concerned


CC - The entire spinner is developing inside the dun exoskeleton.  As I said above, there are very slight changes in the dun from the time of leaving the water till it molts that last time to a spinner.  But there is no "wingcase" in the duns, because the duns have functional wings.


Bugman. Do you have any theories on why the spinner fall is happening during daylight hours on the SoHo now? In years past it mostly happened after dark. It was pretty perplexing this year a couple times with emergence of fresh duns mixed with spinners? Fun working the problem though!


I am sorry Leedawg; I don't have a clue.  I did see more spinner falls this year on the SoHo, BUT I only fished the same short section for most of the year.  Historically, the only time I would see spinners were in the puddles near the river and on the river surface early in the morning.  And they were dead from doing their thing during the night.  This year I saw more towards evening, doing what they do, then ending up on the surface, before total darkness.