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Lateral view of a Male Baetis (Baetidae) (Blue-Winged Olive) Mayfly Dun from Mystery Creek #43 in New York
Blue-winged Olives

Tiny Baetis mayflies are perhaps the most commonly encountered and imitated by anglers on all American trout streams due to their great abundance, widespread distribution, and trout-friendly emergence habits.

Dorsal view of a Amphizoa (Amphizoidae) Beetle Larva from Sears Creek in Washington
This is the first of it's family I've seen, collected from a tiny, fishless stream in the Cascades. The three species of this genus all live in the Northwest and are predators that primarily eat stonefly nymphs Merritt R.W., Cummins, K.W., and Berg, M.B. (2019).
27" brown trout, my largest ever. It was the sub-dominant fish in its pool. After this, I hooked the bigger one, but I couldn't land it.
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Posts: 3
MItroutbum on Jun 19, 2008June 19th, 2008, 11:41 am EDT
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......


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"Bear Swamp," PA

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GONZO on Jun 19, 2008June 19th, 2008, 12:31 pm EDT

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.
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Wiflyfisher on Jun 20, 2008June 20th, 2008, 12:25 am EDT
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!
menomonie, WI

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Freepow on Jun 20, 2008June 20th, 2008, 3:40 am EDT
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...


...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.
"I fish...because I suspect that men are going along this way for the last time, and I for one don't want to waste the trip..."
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"Bear Swamp," PA

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GONZO on Jun 20, 2008June 20th, 2008, 5:45 am EDT

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.
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Wiflyfisher on Jun 20, 2008June 20th, 2008, 10:35 am EDT
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.
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"Bear Swamp," PA

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GONZO on Jun 20, 2008June 20th, 2008, 11:02 am EDT
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.

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