Howdy ya'll, and welcome to Match the Hatch! For December's Match The Hatch, we will discuss Blue-winged Olives.
Blue-winged olives are a mayfly within the genus Baetis and part of the Batidae family. They are known as Baetis, BWOs, Blue Wing Olives, or little olive duns. They are one of the few hatches that will persist all winter. Even in the snow! It's the one hatch I can consistently have good fishing with during Thanksgiving and Christmas, next to midges.
The trick to a good BWO hatch are timing, weather, and water type. I aim to be on the water by mid-morning during warmer days with reasonable cloud cover. Fishing will be best during the early or late afternoon and will likely be over within an hour. As water temperatures drop, trout will sit in slower water than you found them in summer. As long as the water is above 40 degrees Fahrenheit, the BWOs can hatch. I like to check back eddies and foam lines in the morning for opportunistic risers and then head to a favorite riffle or run for a possible afternoon hatch.
The flies I recommend for BWOs are generally small. Think size 18 at the largest and, more commonly, size 20. Due to these small flies being challenging to see, I employ them as a dropper off of a larger dry fly, even using two dries at a time.
Smaller flies also means using smaller diameter tippet and leaders, 5X or even 6X. Remember that being gentle on the hook set is essential when using lighter tippets.
I'll use Hares Ears, Juju Baetis, or WD40s for nymphs. I would never be without some tiny olive soft hackles. My favorite dries are Hackle Stackers, Sprouts, Sparkle Duns, Hatchbacks, Last Chance Cripples, and Guide Winna Spinners. A good ol' Parachute Adams or Purple Haze can work, too, as a general impression.
For the nerdy tyer, using CDC on small patterns is functional and allows for very imitative patterns; see the Nano Puff Baetis or the CDC Comparadun.
NWFFO Fly Fishing Guide