The Blue Wing Olive (BWO) is a member of the Baetis family. A common insect found our beloved Missouri River. This small bug plays a big role in the food chain, serving as an important food source for trout. Let’s explore fishing the Blue Wing Olive hatch as well as it’s life cycle and its significance to the ecosystem.
Characteristics of the Blue Winged Olive Fly
The Blue Winged Olive fly is a small insect, in fly fishing terms sizes #16-20. It has a slender body that’s a dark olive color, and its wings have a distinctive bluish gray tint. These characteristics make it easy to identify them as they emerge from trout streams with their sailboat looking wing. A Pseudocloeon BWO is really tiny and often found in sizes #22-24. We see swarms of these little guys on the Missouri River and the trout love them once spent.
The Life Cycle of the BWO Baetis
The Blue Wing Olive fly has a unique life cycle that consists of four distinct stages: egg, nymph, dun, and spinner.
Egg Stage: The BWO begins its life as an egg, which is laid by adult mayflies in the water. The eggs are typically laid in clusters, and they hatch.
Blue Wing Olive Nymph : After hatching, the fly enters its nymph stage, which can last for up to two years. During this time, the nymph lives underwater, feeding on algae and other aquatic plants. As it grows, it sheds its skin several times in a process called molting.
Dun / Adult: When the Blue Wing Olive fly is ready to emerge from the water, it enters its dun stage. This is when the nymph swims to the surface, and its skin splits open to reveal a winged adult mayfly. At this stage, the fly is not yet fully developed, and its wings are still damp and crumpled. This is the stage where the BWO is most vulnerable and trout love to eat them in this phase.
Spinner Stage: Once the Blue Wing Olive fly has fully developed its wings, it enters its spinner stage. This is when the fly takes to the air to mate, and the females lay their eggs in the water to start the cycle all over again. The spinner stage is short-lived. The fly then dies and lays dead on the water with its wings laid out.
Significance of the BWO
Prized by anglers for its ability to attract large trout to feed. This fly is particularly effective during the nymph and dun stages. Cripples resembling the bug stuck in the shuck while emerging are a very effective pattern.
In addition to being an effective fishing hatch, the Blue Wing Olive is an indicator of the health of the river system. Mayflies, like PMD’s and the Blue Wing Olive, are sensitive to changes in water quality and habitat conditions.
The Best Blue Winged Olive Fly Patterns
When it comes to patterns for the BWO there are plenty to choose from. For dry fly selection it’s hard to beat a good old fashion parachute Adams. Other top BWO patterns are the Film Critic, Last chance cripple and the killer 401k baetis tied by Missouri River Guide Matt Pederson. For subsurface nymphs and Blue wing olive emergers I like the two bit hooker, Madic may fly, radiation baetis, JUJU baetis, loop wing emerger or the classic Pheasant tail. All these patterns can be very effective patterns.
Blue Wing Olives and the Ecosystem
The BWO plays an important role in our rivers, serving as a primary food source for many fish species. Trout, in particular, rely heavily on mayflies like the Blue Wing Olive fly for their survival. These insects are also an important food source for birds and other wildlife.
In addition to their role as a food source, these insects play an important role in nutrient cycling. As the nymphs feed on algae and other aquatic plants, they help to recycle nutrients within the ecosystem. When they emerge, they provide a valuable source of nutrients for other organisms, both in the water and on land.
The Blue Wing Olive fly is a small insect with a big impact on the ecosystem. Its unique life cycle is certainly astonishing. If you have never had the opportunity to fish during a BWO hatch. I highly recommend fishing the Blue Wing Olive hatch along Missouri River in Craig Montana
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