Missoula, Montana Fly Fishing
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Blue Winged Olive – Fall

Photo by Les Korcala

Fall Blue Winged Olive Overview

  • Family: Mayfly
  • Size: 5-9mm (Size 16-20)
  • Emergence: Mid September through late October
  • Emergence time: Late morning through mid afternoon

For many, the Blue Winged Olive hatch defines Montana fall fishing. When the first real Autumn rains come in September, and summer’s heat is finally broken, the BWO’s become the steadiest hatch in the fall.

They will hatch daily through October, and depending on temperature, may start as early as 11:00 AM or as late as 2:00 PM. BWO’s appear on all rivers around Missoula- Blackfoot River, Bitterroot River, Clark Fork River and Rock Creek.

They’re known for their love of bad weather, and come off very heavily on the worst days. They love clouds and cold, so now a “bad” forecast is perfect! BWO’s are often a blanket hatch, meaning lots of bugs on the water.

Fly Fishing The Blue Winged Olive

When tying or buying BWO’s, be sure to cover all of the life cycle stages, including adults, cripples and spinners. With so many insects on the water, fish often focus on a specific stage, ignoring all others. If you feel you’ve made good casts over a fish and it hasn’t eaten, think about changing insect stage. Try and move quickly through the different patterns to ascertain what the fish are taking. A lot of our guides start with a parachute, move to a cripple and then a spinner.The colder and wetter the day, the longer the adults float on the surface, so pods of fish can be elongated.

Make sure you keep an eye on the water above and below where you’re fishing to make sure you’re not missing new fish coming to the party. If you see a new riser, shoot a quick cast over it. The new fish hasn’t had a chance to establish a pattern, nor has it truly focused on stages. Hit the newcomer with a cast. You’ll be surprised at how easily that fish takes, compared to the fish that have established their spots, focused on a specific stage and been rising for a while.

Additional Blue Winged Olive Resources