Mayfly identification anyone?

Discussion in 'Fly Fishing Entomology' started by Richard Olmstead, Sep 10, 2008.

  1. I found this guy (I think, guy) on my fly rod one morning last week in northern Idaho. My best guess is Baetis spinner.


  2. Pale Morning Dun - Ephemerella spinner, female. Page 89, Western Mayfly Hatches by Rick Hafele & Dave Hughes.

    That would be my estimate. Then again, the male looks quite similar.
  3. Not sure about the mayfly type...but those are sure great photos! Did you take them?
  4. Looks like it's a two-tailed mayfly spinner from the photo so I don't think it's Ephemerella (PMD) which has three tails. I would agree with Richard that it's a male, not a female, from the size of the eyes.

    The hind wings look a little more pronounced than those of a BWO spinner.
  5. I'd say a size 16 parachute adams would match it
  6. Your right, it would have 3 tails...hmmmm.
  7. Dick,

    Desperate times like these call for desperate measures...I'd fire up the Bat Signal and hope that Roger Rohrbeck (Taxon) will see it and chime in. He always saves the day. :thumb:
  8. I like it. :thumb:
  9. The dark band on the femur and excessively long tails suggest epeorus spinner to me. They're probably the most common mayfly in north Idaho streams. Is that about a size 16? As someone else suggested, Taxon will likely know...
  10. Thanks for the suggestions. I was hoping Taxon would be available.

    I consulted my copy of Western Mayfly Hatches and noted that the hind wings seemed too big for a BWO, it is also a bit large for the BWOs that were hatching during our visit (yes, it is about a size 16 and the BWOs were more like 18s). I'll have to check the Epeorus again; I thought there was something that didn't seem right for them (I think it was the transparent abdomen).

    It was a chilly morning, so he sat quite still for me to take the pictures. I have an inexpensive Olympus digital camera, but it has a very nice close-up function.

  11. Great pics there.
  12. It's the FE-340.
  13. Hi Kirk,

    Your Bat Signal came in strong and clear, but not until after returning from Rattlesnake Lake, and putting away the gear.

    In any event, I believe Richard Olmstead's photo to be of an Epeorus albertae male imago. They are smaller than the other Epeorus species residing in WA, and abdominal segments 1-7 are (in fact) hyaline whitish. Hope this helps, but seriously doubt it is likely to save anyone's day.

  14. Thanks, Roger. As a plant taxonomist trying to learn aquatic insects, I appreciate your taxonomic opinions, whether they help me catch more trout or not!
  15. Dick-

    You are certainly welcome. My taxonomic opinions are freely given, and all too frequently, seriously overpriced. However, if by some quirk of fate, this one happens to be accurate, you might be interested to know that I was not able to find another photo of a male Epeorus albertae imago, either on the internet, or in my extensive aquatic entomology library. So, you may have taken several extremely rare photos.

    In any event, should you be interested, I will refer you to several great books which contain detailed descriptions of the Epeorus albertae male imago. The first reference is The Biology Of Mayflies by Needham, Traver, and Hsu. At the time of its publication (1935), what is now classified as Epeorus albertae, was classified as Iron albertae and I. youngi, so the descriptions appear under those headings on pages 398 and 412, respectively.

    The second reference is Nymphs Volume II: Stoneflies, Caddisflies, and Other Important Insects including the lesser mayflies by Ernest Schwiebert, who describes the Epeorus albertae male spinner on page 528. This book was posthumously published in 2007 through the loving efforts of "Ernie's" son Erik, whom I was able to assist prior to the book's publication by providing an updated taxonomy for the nearly 1000 species collectively listed between the two volumes.
  16. Roger, thanks for the info. It sounds like I should bite the bullet and buy the Schwiebert volume. I've been drooling over it in the bookstore recently.

    If you would like the higher resolution pics of the male E. albertae imago, let me know and I'll be glad to provide them.

  17. Hi Dick-

    You certainly won't regret purchasing Nymphs Volumes I and II. My first impression was one of slight disappointment, just because the descriptive information in them lacked the convenient formatting incorporated into Schwiebert's original Nymphs. However, during the ensuing year, I have really come to appreciate the incredible amount of descriptive information they actually contain.

    With regard to providing me with higher resolution copies of the photos, that is a most generous offer on your part. I would love to have them for study, and even for use on my website, if possible. My email address is

Share This Page