Blue Wing Olive Nymphs

Mayfly life cycle


The madness of Spring is enticing. It melts the snow and creating spring water where the rested garden of winter comes to life. The sunshine and spring drizzling rains aid in the growth of leaves to garnish the trees and youngling blades of grass to sprout along the river banks. Spring is in the air and so are the Blue Winged Olive hatches.

The Blue Winged Olive Mayfly is one of the most prolific mayfly families across the country. These attractive mayflies can be found on many rivers, creeks, and stream habitats. They dwell in crawling, to moderate, and fast currents in the gravel of freestone riffles, in gentle spring creeks, and tail waters. They thrive in aquatic plants in the river beds. The BWO mayfly will often have two to three generations per year happening in the spring and fall with some early hatches in between seasons. Hatches may vary in different parts of the country, and they can materialize nearly any time of the year. The completion of their lifecycle is relatively short of around four months from egg, to larva, as an emerger, to a dun, and as a spinner.

The majority of their lives are in the larval stage spending life in the cobbles and aquatic vegetation of rivers, creeks, and streams. Once the nymph matures, it will drift and swim through the water column before breaking the surface film into a dun. The newly emerged adults whisk like sailboats along the surface as their wings dry. The duns will blanket the water banks vegetation and molt into spinners. The spinners will mate, and the females may return down to structures in the water to deposit eggs within hours or days as a dun.

The BWO nymphs provide food for the trout of its entirety of their lives. Nymphs in general, are poor swimmers tumbling about as they whirl up to break the waters surface making them a susceptible meal for the trout. They can be imitated by a wide variety of nymph patterns. While I love to rock the BWO dry flies to rising fish, I also like to prolong my fishing days by tossing some favorite BWO nymphs before and after hatches. These nymphs are just some of the many that mimic the Blue Winged Olive Mayfly.

Zebra Midge

The Zebra Midge is a nymph that mimics the midge pupa ascending to the surface to emerge. It is most effective to fish with when trout are observed feeding up high in the water column. You may observe rises which are actually trout taking the pupa just under the surface as the midge drift upwards. Midge patterns often with a beadhead will imitate a pupa because the flash of the bead imitates the air bubble. The darker colors like black are particularly effective with a tungsten bead.

Cats black zebra
Cats Black Zebra, Image by Cat Toy, Togens Pro Staff

Juju Baetis

I have grown fond of the Juju Baetis. It is one of the most effective patterns you can fish to copy the baetis BWO to match. With the tungsten bead and slender design, the BWO nymph sinks quickly. With an opal mirage tinsel on the back of the fly and the UV resin finish front to back, this fly makes the worthy trout do the big tail dance. Have this fly stocked in your fly box!

Ducs Juju, Image by Duc Nguyen
Ducs Juju, Image by Duc Nguyen

Pheasant Tail

The Pheasant Tail impersonates a wide variety of mayflies in their nymph stage like a small BWO nymph. These small crawler nymphs prefer slow to moderate currents and are well-adjusted most often where riffle is modest and where some vegetation are able to take root on the bottom. They mimic a diverse of crawlers and clinging mayfly nymphs the trout seek in many rivers. The Pheasant tail is certainly one of fly fishing’s most proficient and all-around productive subsurface attractor fly pattern.

Pheasant Tail, Image by Rick Beck, Togens Pro Staff
Pheasant Tail, Image by Rick Beck, Togens Pro Staff


The RS2, or “Rim Semblance 2” is a very effective pattern that is a replica of a midge or mayfly. It makes for a winning pattern of an emerger, and it can be fished as a nymph or a mayfly. With the right color of the body, some showy wings, and the tantilizing tail of microfibetts, this eye-catching fly will bring plenty of trout to the net!

It is one of my favorites to cast out to the persnickety trout targeting a helpless nymph without an escape. Black and grey RS2 seem to be most effective in tailwaters as well as small creeks. Consider a tandem nymph rig of a dry fly and a trailing RS2 in a size 20 trolling below.

Cats Black RS2, Image by Cat Toy, Togens Pro Staff
Cats Black RS2, Image by Cat Toy, Togens Pro Staff
Yellow RS2, Image by Chuck Loftis, Togens Pro Staff
Yellow RS2, Image by Chuck Loftis, Togens Pro Staff

Barr's emerger

The Barr’s Emerger is one of the very best replications of a BWO or baetis nymph. You can fish with the bead head variation to get down deep, or fish the benchmark Barr Emerger with no weight. This fly can be fished in the higher part of the water column when the hatch is near.

Barr's emerger, Image by Duc Nguyen
Barr's emerger, Image by Duc Nguyen

Sparkle Dunn

The Sparkle Dun is an amazing knockoff emerger pattern that is best fished as a dry fly. A trailing brilliant shuck tied at the end of a Comparadun, this fly pattern mimics a mayfly breaking out from its exoskeleton during emergence. This pattern emulates the precise life process of the mayfly as tiny sailboats on the surface trying to dry their wings. It is best tied with a sparse wing which allows the fly to ride lower in the water adhered to the surface film.

If the trout are feeding during a BWO hatch, it is important to observe whether their feasting below or above the water surface. If observed just a few duns are slurped, the trout are most likely taking more nymphs than duns. Fish with a nymph pattern below your dry fly. This could be a deadly, winning set up! Be ready as the Blue Winged Olive mayflies are hatching! See you at the river!

BWO, or Sparkle Dun. Image by Des O'Rourke, Togens Pro Staff

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