Identification, Images, & Information
For Insects, Spiders & Their Kin
For the United States & Canada
Clickable Guide
Moths Butterflies Flies Caterpillars Flies Dragonflies Flies Mantids Cockroaches Bees and Wasps Walkingsticks Earwigs Ants Termites Hoppers and Kin Hoppers and Kin Beetles True Bugs Fleas Grasshoppers and Kin Ticks Spiders Scorpions Centipedes Millipedes

Calendar

TaxonomyBrowseInfoImagesLinksBooksData
Photo#421381
Female Pale Morning Dun, Livingston Montana, July 4, 2010 - Ephemerella - female

Female Pale Morning Dun, Livingston Montana, July 4, 2010 - Ephemerella - Female
Livingston, Park County, Montana, USA
July 4, 2010
This is what the local fishermen call the Pale Morning Dun.
I think this one is a female.

Male to female ratio?
It's August 2010--six weeks or so since I took the above photo
(of E. dorothea infrequens or E. excrucians).

I spent a good six - eight hours on this project.
Sharp focus ultra-closeups in the field are almost impossible
with a single click camera. I hope to buy a newer digital slr
camera soon: one that can take short bursts of video. That way
I should have a better chance of getting at least a frame or two
in focus, with each click of the shutter.

So far so good. A question has been brewing in my mind since that day.
I saw thousands of mayflies (subimago duns) drifting atop a glassy-smooth spring creek flow. After an hour or so you can sex the mayflies from a distance. I got one good sharp-focus shot of a female the first day. So on the second day I ignored the females, and only scooped up the males as they drifted by. I never did get the dead-sharp-focus shot I wanted. Perhaps next year. But now my punchline point:

I'm a hobby photographer, and not a scientist. I didn't even try to keep an organized tally. But what I saw seemed unmistakable. There were far more females than males. Is this common?

Also, the females ride the surface far longer than the males.
In fact the males were mistakeably more active and frenetic.
The males take off flying only moments after emerging. While the females often ride the surface film for 20-30 feet before flying off.

That definitely makes the females more vulnerable to predation by rising trout. So perhaps it makes adaptive sense, for the freshly hatching population to produce more females than males.

Moved
Moved from Cinygmula.

Moved
Moved from Mayflies.

Cinygmula
Absolutely gorgeous photo, Sandy. It's a Cinygmula female subimago, family Heptageniidae, local common name notwithstanding.

 
My error
Sandy-

This mayfly was mistakenly identified as a Cinygmula, but is likely Ephemerella. Please forgive my error.

 
Lloyd Gonzales comment:
I agree that this is Ephemerella, either E. dorothea infrequens or E. excrucians. Both are commonly called Pale Morning Duns (PMDs) on Western streams.

Moved
Moved from ID Request.

Comment viewing options
Select your preferred way to display the comments and click 'Save settings' to activate your changes.