In flight before capture
The OP didn't report that fish were taking them. If they were, I agree with Bamboozle... Match size/color and have at it. The pictures on that bug ID site are amazing.Bottom line, the fish don't know what it is either. If you see evidence of fish taking this fly, put on a size 16 spinner, have at them and have fun!
The problem with that is that if you don't identify the insect, you have no idea what its underwater behavior is like.Match, color, size and behavior