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Male Baetis tricaudatus (Blue-Winged Olive) Mayfly Spinner Pictures

 Some notes from identifying this specimen under the microscope:

1. The hind wing has three longitudinal veins (Longitudinal vein: Longitudinal veins are the major long veins running length-wise through an insect's wing, connecting the base to the outer margin, or the major branches from those veins.), but the third is faint, short (about half the length of the wing), and close to the wing margin.
2. Then antenna is brown fading into white at the tip, and the base is ringed with white.
3. The joints of the tarsal segments on the middle and hind leg have fine black markings.

It was also collected in association with a female spinner.


This mayfly was collected from Silver Creek on September 4th, 2020 and added to Troutnut.com on September 18th, 2020.

The antennae: brown, fading to white at the tip, with the base ringed with white.   Male Baetis tricaudatus (Blue-Winged Olive) Mayfly Spinner from Silver Creek in Idaho
The antennae: brown, fading to white at the tip, with the base ringed with white.
This view of the hind wing, seen through the forewing (which makes it a bit confusing), shows some of the 3rd longitudinal vein right along the bottom edge extending about half-way through the wing.  Male Baetis tricaudatus (Blue-Winged Olive) Mayfly Spinner from Silver Creek in Idaho
This view of the hind wing, seen through the forewing (which makes it a bit confusing), shows some of the 3rd longitudinal vein right along the bottom edge extending about half-way through the wing.
Black markings around the tarsal joinings of the hind leg.  Male Baetis tricaudatus (Blue-Winged Olive) Mayfly Spinner from Silver Creek in Idaho
Black markings around the tarsal joinings of the hind leg.

Recent Discussions of this Spinner

Baetis bicaudatus 12 Replies »
Posted by Taxon on Nov 7, 2020
Last reply on Nov 12, 2020 by Millcreek
Hi Jason-

I believe this male imago to be Baetis bicaudatus.
ReplyBaetis adult species IDs?
Posted by Troutnut on Nov 6, 2020
Does anyone here know any decent resources for identifying adult Baetis? I haven't found much.

This specimen sure seems to nicely fit the original description of Baetis alius adults. But I can't find very precise descriptions (let alone a key) for flavistriga and tricaudatus, both of which are other likely options given the location.

These made for a good fishable hatch on Silver Creek, so it sure would be nice to know what they are.
Reply

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