Missoula, Montana Fly Fishing
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Blue Winged Olive – Spring

Photo by Les Korcala

Spring Blue Winged Olive Overview

  • Family: Mayfly
  • Size: 5-9mm (Size 16-20)
  • Emergence: Early March into run-off
  • Emergence Time: Late morning through mid afternoon

The Spring Blue Winged Olive Hatch in Montana is a strong hatch, with consistently rising fish in cold, cloudy weather, which Blue Winged Olives just love. The colder and crappier the weather, the more these insects hatch throughout Montana. That makes them an important hatch, because the weather BWO’s favor doesn’t always move the Nemouras or Skwalas.

Blue Winged Olive Hatch – Missoula

They are most well-known on the Bitterroot River, but mostly due to the prevalence of the Skwala. More people fly fishing a river means more people talking about the hatch. But the BWO’s appear on Rock Creek, Blackfoot River and the Clark Fork River as well. On the colder, cloudier days, the fish will pod up on the Clark Fork looking for the BWO’s. And in the slower waters on Rock Creek, the fish feed voraciously on the BWO’s.

Fly Fishing The Blue Winged Olive

The BWO can be a blanket hatch in the Spring. There is more than one species of BWO’s hatching, and fly sizes vary from 16-20, with the majority being smaller. Most of the BWO’s are Baetis, a mayfly species, but since the same fly works for all of them, anglers aren’t too fussed about the species. To fly fishermen, they’re all BWO’s!

The fish will focus on different stages of the hatch, so when you find a BWO emergence, make sure you have patterns imitating adults, emergers and cripples, in different sizes. The insects are so prevalent that trout will focus on one stage of emergence to the exclusion of others. Make sure your fly selection is wide enough to cover all the options. Of course, when there are so many adults, there are a lot of nymphs as well. A simple Pheasant Tail or Olive perdigon will take fish throughout the day. They make an excellent dropper off a Skwala dry. While this might sound like sales pitch, don’t be afraid to stock up on BWO’s.

Unlike every other hatch around Missoula, the BWO’s will re-appear in the fall. Since you’ll be able to use these flies later in the season, you might as well have enough flies. The BWO’s may be the most important mayfly in many Montana rivers, due to their emergence twice a year. Don’t hit the Missoula rivers in Spring without your BWO patterns.

Spring Special – Montana Guided Fly Fishing Trip

Skwala Stoneflies and March Browns are sure to bring out some of the BIGGEST fish of the season. We’re offering discounted rates for spring trips!

Additional Blue Winged Olive Resources