11 Best Blue Wing Olive Fly Patterns for Successful Trout Fishing

The Blue Winged Olive Mayfly (BWO) is a remarkable insect tied to fly fishing. Its unique hatch generates a special response from fish, standing out among other species.

The BWO, a member of the Baetis genus and Baetidae family, has its hatch during the warmer months and forms a substantial part of a trout’s diet. This provides anglers an opportunity to make the most of these hatches.

Like all mayflies, the BWO has four life stages which anglers can imitate with their fly patterns: nymph, emerger, dun, and spinner (including spent spinner). Each stage offers an array of possible patterns, and while some prove more effective, it ultimately depends on personal preference.

We’ll discuss our favorite imitations in the following sections, but remember, your choice of pattern is ultimately flexible and subjective.

Understanding the BWO Life Cycle

As mentioned earlier, the BWO mayfly forms part of the genus Baetis family, which has many different species in it. In most instances, only a closer look under a microscope will allow you to see the actual differences between the flies. But what all of these species have in common is the beautifully ‘up-winged ‘wings and distinct tail filaments.

All these species go through a four-stage life cycle, with various species remaining in certain stages for longer than others.

The nymph, emerger, dun, and spinner are the basic stages of the life cycle. We can fish these imitations in various ways and at various times to ensure the best results.

In the BWO case, they have a lengthy dun stage of the cycle. Now this is great for the angler as we get to tie and drift those dun imitations for longer, with more chance of hooking that big one. The fish see the dun stage as a free meal, as the insect is on the surface drying its wings before it begins to fly.

Understanding the life cycle and when to fish what correctly will drastically improve your catch rate and allow you to become a better angler. If you are new to the world of fly fishing, there is no doubt you will have heard of this dry fly hatch and dry fly purist side of things, and I would strongly suggest remaining open-minded to the other stages of the insect and what they have to bring to the fishing arena.

Yes, catching the trout on a drifted dry fly is amazing, but we have three other stages to fish, of which two of them will be sub-surface. These methods are just as exciting and productive as the others.

Nymph Stage BWO Patterns

The nymph stage of any insect is an important one to recognize. Most of the trout’s diet is made up of this stage of the insect, and we as anglers need to make a mental note of this and use it to the best of our advantage. The BWO nymph stage is no different from most other species.

They tend to flick their tails to swim and sometimes drift motionless with the current. This motionless drift is a good sign that the hatch will start soon, and they will start the swim to the surface to emerge. They are usually found in most gravelly, freestone streams and have a beautifully characteristically long slender body ranging from a light brown body all the way to a deep dark olive.

1. Pheasant Tail Nymph

I don’t think there is a more celebrated nymph pattern than the PTN. Its slim profile and use of a singular material make this fly a very deadly pattern to have in the fly box. In all honesty, I could probably write a whole piece just on this pattern and its hybrids. Frank Sawyer was one of the early anglers that realized the need to fish more of the water column and not just the top section.

This pattern was tied to be fished on the River Avon, Wiltshire, United Kingdom. Everything about the pattern sings mayfly, and one of its key factors for me is the slenderness of the body. This thin body is key to success. A small variant that I like to fish is a gold beaded version as well for the deeper water and runs.

One of my favorite things is to fish the patterns in a dry dropper. I like to drift this through any run and will also fish this style of setup when searching the water and waiting for a hatch to start.

Fish the nymph in sizes #14 to #18 and keep to the natural colors of the pheasant tail. A black version is also a great color to have for the more stained water or post-rain wash-off.

2. BWO Juju Baetis

The Juju Baetis is said to be the one and only baetis BWO nymph you will ever need to fish. Now, while it is a brilliant pattern to have, there are a few patterns that could trump its success. Again, this is all subjective; you need to fish what works for you and what you are confident in. Let’s not take away from the Juju. There are numerous reasons why this pattern works so well.

Its simplistic design is not only easy to tie but has the ability to attract trout in almost all conditions and waters. This is the one thing about this fly that I like, you can fish it in all waters and conditions, the weight needs to be changed accordingly, and away you go.

The UV resin abdomen gives this pattern a fast sink rate, getting it down to the bottom where the fish are feeding. This also makes the fly a little harder, and it will generally last a little longer.

I like to fish this in size #16 in brown, black, and a touch of red.

3. Copper John Barr

John Barr designed this pattern, and boy, what a pattern it is! With the inspiration taken from the Brassie for the body and a more fly-like-looking thorax on the front, this is a killer pattern. It’s not uncommon to see a whole fly box dedicated to this fly with many different colors and weights.

The copper wire abdomen is what gives the pattern the weight and ability to cut through the water column. Fished as a singular nymph or on a dropper rig, it gets the job done.

Fish the pattern in A size #14 for single nymphs and in a #16 for a dry dropper rig. You could go one size up on the dropper rig if you choose. Just make sure your dry will float ok, though. A chubby Chernobyl is a great dry to drift with the larger Copper Johns on the drop.

I like to fish them in natural copper, greens, and reds.

Emerger Stage BWO Patterns

Fishing an emerger pattern can prove tricky but very successful. It is generally a subsurface pattern that you won’t be able to see all that well and thus may miss a few eats at times. It is a very important part of the life cycle, and trout, at times, hone in on the emerging Mays and have a feeding frenzy.

It is at this time that you need to be ready with the pattern that you are confident in and that you can see. A tip I like to use is if I’m fishing an emerger that I can’t see, I will fish it behind a sigher dry. They are not far apart, but the sighter will help me spot the emerger when it lands and pick up on any eats.

4. BWO Barr’s Emerger

John Barr is no stranger to the fly-fishing world, and his contributions to the sport have paved many a way for new things. John’s BWO emerger is a great pattern to have and use. It can be fished as an emerger or a cripple, whichever you choose.

The dry-style version will sit a little higher in the subsurface and give more of a cripple appearance, while the beaded version will cover the emerging insect better. One of the best attributes this pattern has is the fact that it can be fished repeatedly. The trout seem to love it. Tied in olive and white, lighter browns are ideal, and a size #16 scud hook is best.

5. BWO Klinkhammer

The Klinky is just one of those patterns you must have! It is my go-to fly on the first change if I have had a few rejections. I tend to always tie on a size #16 black klinky to fish after I have had a few solid refusals. I’m not too sure why, but this always works and gets the trout to rise and eat.

The Klinkhammer was originally designed and tied by Hans Van Klinken, who was trying to imitate an emerging caddis pattern. What he didn’t realize at the time was the effectiveness of the pattern in imitating many other emerging fly patterns. The BWO is one of these, and the klinky is a great emerging representation of this.

It is also a great pattern to fish as a dry dropper pattern, and if you tie the halo hackle rather densely with the added CDC under, they float all day and can hold a fair bit of weight under it.

What is also a great attribute of the Klinkhammer is that the quilled abdomen tends to sit in the water film and thus looks very much like an emerging mayfly.

Blacks and browns are the first choices here, with the sighter post in a hotspot orange or white for the larger size #14 and upwards.

Dun Stage BWO Patterns

The Dun stage of the mayfly is a very exciting one for me. It is where we get to tie all these lovely visual patterns and test them on the waiting trout. The dun stage of the mayfly is when the emerging nymph has successfully swum to the surface and is now breaking out of its shuck or casing.

Once out, the fully formed adult mayfly needs to sit on the surface to allow its wings to dry in order to start flying. Now, the BWO dun is known for its lengthy dun stage, and the trout love this. As anglers, so should we. There are many patterns and styles of flies that have been tied for this stage, and one can get quite lost in the world of duns, cripples, and stillborns.

6. BWO Sparkle Dun

The sparkle dun is no stranger to the dry fly scene. This dun stage pattern has been around for a few seasons and is no doubt one of the firm favorites when it comes to fishing the dun or cripple.

The low riding body profile, in combination with the upwinged presentation, makes it the perfect imitation. Fished in olives and browns in sizes #14 to #18 will do the trick.

7. BWO Comparadun

The Comparadun is one of those fly patterns that I’m never sure what I enjoy more about, fishing it or tying it. I remember going through a stage when all I did was tie Comparaduns, and I was obsessed with getting the splay of the deer hair at the perfect 180 degrees and super flat on the underside.

These are great patterns to fish when the duns are on the surface. I like to tie mine with a red tag under the splayed tail fibers. It’s a great trigger, and the trout love it. I keep the pattern in natural colors, no bigger than size #12. The bigger ones are easier to tie, but the smaller ones are better targets.

8. May Day Dun

This scraggly-looking fly is great. The messier it looks, the better it works. What is also great is that this pattern, like many other dun imitations, covers a few of the mayfly species BWO, PMD, and march browns, to name a few. It’s a low rider with a little extra help to float from the halo of hackle.

A super light fly, so I wouldn’t drift it with a dropper, but in most cases, you don’t need to. Keep to the colors of the hatch you are covering and fish them in sizes #14 to #18.

Spinner Stage BWO Patterns

The spinner stage of the mayfly is an interesting stage to fish. It can be a free for all type scenario, or it can be a painstaking event when nothing is being eaten, and you can see the fish cursing and inspecting your flies. The spinner fall is when the adult is dipping low on the water surface to lay the eggs; it is at this time the trout feed on these insects.

After the spinner has laid her eggs, they die off and drift down the river as spent spinners. As mentioned, this is a very exciting time to fish a spinner dry fly. It is a very visual affair and can be quick and aggressive or slow and sippy. Either way, it is a very exciting event to experience and fish.

9. BWO Parachute Spinner

The parachute spinner is a great pattern to have. I am a massive fan of the parachute patterns for the main reason of being able to see the fly further away. They obviously have other attributes; being able to float better and ride the water film easier is another. I like to tie my posts in white or a hotspot orange.

The white is handy to dab with a strike indicator when you need to change the color quickly. The hotspot orange is great for the low light days and for the runs where there are a lot of white bubbles where the white sighter tends to get a little lost.

Pattern design is simple. A plain Adams-style fly is what works best, just adjusted to a parachute style. A Catskill-style pattern with the halo would also work just fine. An important note is to keep the body profile with the right ratios and not overcrowd the hook eye.

Light greys, browns, and olives are the best options for colors, but please match them to your colors as you see fit. As a singular dry, the size can be anything from a size #10 down to a size #18. It all depends on whether you want to fish a dropper underneath it. If you choose to, then bigger sizes are recommended.

10. Floating Wet

Though classically a wet fly by design, a larger wing tied using CDC is what gives the pattern its buoyancy. Tied by Jeff White, who mentions the great hare’s ears wet flies, is where this pattern first came to mind. This is an ideal pattern for those super picky fish who refuse to eat anything else.

The spent spinner stage can be a very tricky and intricate stage to imitate, and the floating wet does well here to get the eat.

The size really depends on what size the hatches are that come off your waters, but a safe size will always be a #14, but you can go as small as a #20 if you like.

Versatile BWO Patterns

11. BWO Quigley’s Cripple

Cripples are a stage of the mayfly that I personally never gave enough time to. But I can confidently say that I carry at least one cripple pattern these days, and they have come in very handy at times.

A cripple is when the mayfly is trapped in the water film and or casing. Basically, it’s a half-in, half-out type of pattern. Not quite an emerger and not quite a dun mayfly yet. It is at these stages that the insect is very valuable and usually picked off the surface.

This pattern has been around for a while and is one of the most innovative patterns of its time. It was originally designed by Bob Quigley for those northern Californian Fall River trout. Those fish are known to be very picky, and due to the clear flat runs, they have ages to examine the fly before they eat it, so it needs to be very convincing.

Sizes range from #14 to #18. Most times, the more important thing is to make sure it is treated before you fish it. Given that half of the pattern is submerged, it tends to sink easier, so make sure you treat it well with floatant.

Fly Fishing Tips and Techniques

To strategize a day on the water when fishing dries and the BWO can mean anything from sitting and waiting for the hatch to start or at least signs of a hatch to covering miles of riverbank looking for feeding fish.

What I like to do is to arrive at the beat early and give it a walk-through. Now, some beats are longer than others, and you may not be able to do so, but the general idea is to get a basic layout of your section’s pools, glides, and areas to focus on. Mentally mark deeper pools and tail outs where you think a few fish will rise. Keep an eye on the bank and how accessible the sections are. Once all this is done, get back the car, and kit up to start your day.

The peak of the day is going to be your best time for most hatches. While the sunshine isn’t always ideal for the Mays, the warmer temps do help bring on the hatch. Keep the time noon until threeish open, and keep an eye on the water for the hatch.

Be ready to change as you need to, and be as flexible as you can. I’m happy to change a pattern as often as I need to get the eat. That said, as I mentioned earlier, I tend to change the size of the same pattern a few times before I opt for the change in the entire pattern. If the fly needs to change from an emerger/ dun style to a spent spinner, then this is obviously a must. Matching the hatch is key.

When it comes to gear to use for fishing the BWO, or any single dry fly for that matter, things can be as complicated as you choose to make them. I, for one, like to keep my day on the water super simple and fish the following.

One More Cast with a BWO

So, there they are 11 of the best BWO fly patterns. Covering all the life stages, these are tried and tested patterns that not only catch fish but are great fun to tie as well. You don’t have to be a pro to fish or tie these patterns; the best place to start is at the beginning. Whether that means buying your first fly rod and reel or testing out one of the above cripple patterns, whatever it may be, be sure to have fun doing it and always be open to learning something.

Tight Lines!

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Sources and Thanks

• Thanks to Umpqua Fly Merchants – Worlds Best Flies – UMPQUA
• Thanks to Fulling Mill – Raising the Game – Fulling Mill