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3. Great Speckled Olive or Gray Drake

What can I look for to distinguish between the 2 above mentioned flies?? I was out fishing yesterday evening and captured what I thought was a gray drake spinner, but after searching through some photos it could very easily be a Great Speckled Olive. I actually posted a photo on my fishing blog (not a great shot at all, but maybe you guys could help me out......

http://troutonthefly.blogspot.com/

Thanks
Rich

Rich,

The photo on your website looks like Siphlonurus to me. One fairly easy way to verify this would be to use a hand lens to look at the leading edge of the forewing toward the tip. Siphloplecton will have a jumble of intersecting cross-veins (anastomosis). In addition, Siphloplecton basale is usually an April/May emerger.

The photo labeled "Gray Drake Spinner" looks like a March Brown (M. vicarium) spinner to me and the timing would be right too.

It looks like you had a great UP trip!

Great blog! I really like the format and the style it has. I too agree that the pic looks like a March Brown to me. I posted this pic...

http://www.troutnut.com/topic/1450#9507

...which was quickly determined to be March Brown and it looks very similar to your mayfly. I've bookmarked your blog...keep up the good stories.

Rich,

I just realized that I could enlarge the image on your website by clicking on the picture. In the enlarged image, these traits of (some) Siphlonurus become more distinct:

The banding of the eye, which was not obvious in the smaller image, can be seen. (Live specimens usually show this more clearly.)

The "zigzag" pattern of banding on the tergites is more apparent (especially on the last few segments).

The cross-veins along the leading edge of the forewing are pale or nearly transparent. (This is not a consistent trait of all Siphlonurus, but on M. vicarium, they are dark.) Veinlets connecting CuA to the rear margin of the forewing can be seen.

BTW, regarding your original question, I probably should have mentioned that S. basale also shows dark staining toward the wingtips (in the same area where anastomosis would appear) and on the basal third of the hindwings. Jason has a good photo of a basale spinner that shows this staining and anastomosis.

Gonzo, doesn't Siphlonurus spinners have a white band around the base of the eyes? Everyone I have ever collected over the years in NW WI. had the white ring around the base of each eye.

Yes, John, that light band is usually quite prominent on the males. However, the band can be seen on the enlargement. I suspect that the band might be less distinct because the spinner appears to be dead, or perhaps it is just the lighting in the photo.