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The Specimen

Drunella tuberculata Mayfly DunDrunella tuberculata  Mayfly Dun View 14 PicturesI don't know for sure that this is Drunella tuberculata, but that's my best guess for now.

It certainly has a different look and much more robust body shape from Drunella lata duns I photographed a couple weeks earlier, so I doubt it's that species. Using distribution records to eliminate other choices narrows this down to Drunella tuberculata or Drunella walkeri.

Markings described for the abdominal sternites (
One sternite of this Isonychia bicolor mayfly spinner is highlighted in red.
One sternite of this Isonychia bicolor mayfly spinner is highlighted in red.
Sternite: The bottom (ventral) part of a single segment on an insect's abdomen.
of the male spinner of Drunella tuberculata are suspiciously similar to those on this female dun. Also, this dun is 9.5mm long (my ruler pic isn't very good, but I'm basing this on measuring the real thing). The size range given in the old Allen & Edmunds keys for walkeri females is 7-8mm, while tuberculata is 9-11mm. For these reasons I'm sticking it in tuberculata for now.

This is the only Drunella mayfly I saw all day. I scooped it off the water as it emerged at around 7pm from a big Catskill tailwater.
Collected June 1, 2007 from the West Branch of the Delaware River in New York
Added to by on June 8, 2007

The Discussion

MykisslayerJanuary 30th, 2014, 11:16 pm
Posts: 1Do adult aquatic insects travel or migrate to other watersheds or bodies of water? Or do they remain close to the area where they emerged?
EntomanJanuary 31st, 2014, 12:37 am
Northern CA & ID

Posts: 2604
Wecome to the forum.

The short answer is yes, they do. Suitable habitat is the limiting factor. A certain percentage of adults go wandering and eggs get on the feet of waterbirds (and angler's waders). I put in a pond some years ago that was miles from any river or lake. It was lined with six inches of gravel and scattered river rock. It was sterile that first Summer. Within two years it was swarming with caddis, mayflies, damsels, dragons and other assorted critters.
"It's not that I find fishing so important, it's just that I find all other endeavors of Man equally unimportant... And not nearly as much fun!" Robert Traver, Anatomy of a Fisherman
Jmd123February 2nd, 2014, 10:39 am
Oscoda, MI

Posts: 2584
And how long did the fish take to show up, Kurt? Or are there none yet? Knowing that the adult insects can fly and will colonize new habitats, I've always wondered if anyone has put the "duck's feet theory", as I like to call it, to test with regards to fish eggs.

I have certainly seen fish show up in very isolated constructed ponds. During my first year of consulting I was tasked with doing an ecological survey of some forest and wetland habitats that were going to be strip-mined for gypsum (major deposits about 45 minutes south of me). A number of little wildlife ponds had been dug out there by backhoe, you could tell by the spoil bank right next to the mini-pond. Most definitely not connected to any other surface waters, but yet they were full of mudminnows (Umbra limi)! Duck's feet at work?


P.S. How about the amphibians? "If you build it, they will come."
No matter how big the one you just caught is, there's always a bigger one out there somewhere...
EntomanFebruary 2nd, 2014, 11:35 am
Northern CA & ID

Posts: 2604
Trout went in the following Spring. Frogs found it pretty quick - took them only a couple of months, if I remember right. The only species of fish that were ever in evidence had to put there.
"It's not that I find fishing so important, it's just that I find all other endeavors of Man equally unimportant... And not nearly as much fun!" Robert Traver, Anatomy of a Fisherman
PaulRobertsFebruary 2nd, 2014, 8:56 pm

Posts: 1776
Emigration is part of many insects life history "strategy". This is a rather broad subject, that could reach back to the initial evolution of flight -which may have originated in stoneflies. So I guess a more specific question would help. What have you seen?

As to the direction Entoman took, I have a puddle at the end of my driveway that is dry most of the year. Some years it dries after only a month. Others it'll hold water for 3 or 4 months. It contains aquatic critters, mostly hemipterids (boatman and backswimmers) that fly in from ponds and mountain lakes, none of which are closer than 5 miles distant. They also appear on our trampoline after a rain bc when its wet it looks much like a little water body. My puddle also can get a caddis fly called Helicopsyche that apparently survives well in ephemeral waters -the tiny adults must be able to travel and/or lay cystic eggs?

My puddle also contains tiny crustaceans called Ostracods. How they get there I dunno. Some such planktonic crustaceans are known to lay cystic eggs that can survive poor conditions like droughts for a very long time -as much as 1000 years! This puddle of mine is the ephemeral surfacing of a spring about 3/4mile above a small ephemeral stream that contains Helicopsyche, and then a full range of mountain macroinverts further down. Very likely, this spring was much less ephemeral than it is now.

Weirder yet are the Horsehair Worms that exist in the puddle in my neighbor's driveway. That puddle is a regular old "puddle" only appearing after heavy rain. And it gets aquatic horsehair worms during rainy years. Turns out Horsehair Worms have a parasitic stage infecting grasshoppers. Obviously the grasshoppers are the vector. The life history strategy apparently allow these aquatic critters to live in very dry uplands. Pretty cool.

Take home message is: Don't be surprised by what very ancient critters have figured out over time.

Trout stream insects -the one's we tie flies for -travel too and there is a fair amount of interesting research on how they get around. It's apparent to me that many insects can identify possible habitats over a wider range than we might expect.

One more idea worth considering: wind. In the mountains where I live strong vertical thermals can suck insects high up and then drop them when the air mass cools. We not only get red dust from Utah (here in Colorado) but insects from the plains (leafhoopers, midges, termites, winged ants) dropped on us some afternoons.
Jmd123February 2nd, 2014, 11:27 pm
Oscoda, MI

Posts: 2584
Paul, nice contribution, thanks!

No matter how big the one you just caught is, there's always a bigger one out there somewhere...
OldredbarnFebruary 3rd, 2014, 1:18 pm
Novi, MI

Posts: 2607
lay cystic eggs


I think it was in Ames' book on Caddis that he mentioned caddis adaptation to watersheds that go from dry to wet very quickly...The critter lays dormant until the proper conditions exit for it to have a chance at survival and reproduction. He had a discussion on caddis that live in the wave areas of lakes...It is incredible.

In terms of migration there is one form we really haven't discussed much. Human intervention. I have mentioned elsewhere that I'm re-reading Charlie Fox's classic, "This Wonderful World of Trout"...In the chapter "The Other Side of Angling" there is a discussion of transplanting mayfly eggs from one watershed to another. They did it from 1947-49.

For three years a group transplanted Green Drake, and a few Brown Drake, eggs into Yellow Breeches, Big Spring, the LeTort, and Cedar Run.They actually had correspondence about what they were doing with Edward Hewitt,Charles Wetzel, and Dr Paul Needham.

There is a discussion of this practise taking place in England with Hewitt writing about the keeper of the Test, Lunn's preferred method for transfer. They also mention an attempt to transplant mayfly eggs from England into the Neversink...(What would folks think of this today?)

Maybe the PA Boys could chime in on the ultimate success of these experiments. The bottom line seems to be appropriate habitat...This makes sense...You wouldn't expect to find burrowers in cobble, but along the edges and pools were silt might build up.

Just when we think we have it figured out we discover nature has a little something else up its sleeve. :)

There are many things discussed in Charlie's wonderful book, especially this particular chapter. I'm knocking around the idea of breaking it down in a thread and see what folks might think of what he was up to way back when.

"Even when my best efforts fail it's a satisfying challenge, and that, after all, is the essence of fly fishing." -Chauncy Lively

"Envy not the man who lives beside the river, but the man the river flows through." Joseph T Heywood
PaulRobertsFebruary 3rd, 2014, 7:54 pm

Posts: 1776
Great perspective, Spence.

Way back when often actually goes way back further than many would suspect -leading me to think, more than once, "We've been us ... for a very long time".

I had a collection of New York Forest and Game Commission reports from the 1890's -beautiful cloth bound books known only to some for the gorgeous Sherman Denton fish illustrations (the Joseph Tomerelli of his day). But the historical info was fascinating. One thing that shocked me was the amount of fish stocking that was undertaken. It seemed that everything everywhere was attempted at least once. There was also an article about the destruction of watersheds that could have been written ... tomorrow! This was during the time when "game laws" were first being established and NY was less than 20% forested! It's over 85% forested/wooded today). When I think of the video Eric presented to us a short while back, and the "resuscitated" trout streams I've fished, I think back to those impassioned pleas with pride, wishing those folks back then could visit us now and see what young people take as granted today. I don't begrudge that; it means that we're alive to see what was given to their great-great-grandchildren.

Sadly, I sold those books when I moved away from NY, feeling like I'd probably never get around to making good use of the information.

Getting back more on topic, sort of (if mykisslayer doesnt get back and turn this boat around, who knows where it could go!)... I have Ames book back home in a box. And Id not heard of the planting of mayflies (that I can remember) but have heard that "supplemental" stocking goes on today by private river managers in the UK.

And speaking of macroinverts getting around, the 500 mile long Erie/Barge Canal (dug between 1905 and 1918) gets good burrower mayfly emergences. I tied my very first dry flies for carp and smallmouth when I was a kid growing up on its rip-rapped banks, starting with a strip of white cloth from my shirt collar dapped on the surface.

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