Deadliest BWO Mayfliy Imitations By River 20Apr21

It was 12° this morning; I did not go fishing. What should I do? I've been fishing a number of rivers in Colorado for 20 years now. Below are my observed deadliest BWO mayfly imitations for some of the rivers I frequent. I typically tie #18-#20 for the spring and #20-#22 for the fall though I prefer #20 and #22 in most of these ties. This is not scientific data as I am biased to use these "matched ties" when fishing with mayfliy imitations on these rivers, though I do use others of course. The evidence was gathered from use experience. The MHFBPT and the grey MH flash wing RS2 are probably my most often used mayfly nymphs and use is somewhat suggested by whether it's time for an emerger. I often use a tungsten bead mayfly nymph as weight during mayfly seasons, especially a black ice variant (during BWOs) or the rainbow warrior (during PMDs). Anyway, here are my ties of the deadliest.