You really can't go wrong with a blue winged olive wet fly on those drizzly, overcast days when the trout seem to be active but aren't quite breaking the surface. It's one of those patterns that every fly box needs, yet it's often overshadowed by its more famous dry fly cousin. We've all been there—standing mid-river, watching tiny little olives pop off the water, frantically swapping dry flies while the fish keep bulging just under the film, completely ignoring our high-floating offerings. That's usually the moment you realize the fish aren't looking up; they're looking at what's happening just a few inches down.
Why the Wet Fly Version Often Wins
Most anglers reach for a dry fly the second they see a BWO hatch. It's a reflex. But the reality is that for every insect that successfully makes it to the surface and flies away, there are dozens more that get stuck, drown, or struggle in the surface tension. The blue winged olive wet fly mimics these vulnerable stages perfectly. Whether it's an emerger that didn't quite make it or a spent adult that's been pulled under by the current, it looks like an easy meal.
Trout are essentially lazy—or maybe "efficient" is a nicer way to put it. They want the most calories for the least amount of effort. Chasing a flying insect requires a lot of energy and leaves them exposed to birds. Sucking in a drowned olive as it tumbles past in the current? That's just a free lunch. When you switch to a wet fly, you're playing into that instinct. You aren't asking the fish to come to you; you're putting the food right where they're already looking.
Reading the Day for BWOs
If the sun is shining and the sky is a bright, piercing blue, you might struggle with a BWO hatch. These bugs absolutely love "nasty" weather. I'm talking about that light, misty rain, heavy cloud cover, and cool temperatures. On those days, the humidity makes it harder for their wings to dry, which means they spend more time on the water or just under it.
That's the prime time to tie on a blue winged olive wet fly. When the light is low, the fish feel braver. They move out of the deep holes and into the riffles. If you see "soft" rises—those little swirls or humps in the water rather than a splashy take—that's a dead giveaway that they're feeding on emergers or drowned adults. A wet fly swung through those riffles is almost like cheating at that point. It just looks too natural for them to pass up.
The Art of the Wet Fly Swing
There's something incredibly relaxing about fishing a wet fly. You don't have to worry about the perfect, delicate dry fly presentation where a single micro-drag ruins the whole drift. With the blue winged olive wet fly, you're often using the "swing" technique. You cast across and slightly downstream, let the line tighten, and allow the current to pull the fly in an arc across the river.
As the fly reaches the end of the arc, it starts to "rise" in the water column because of the tension on the line. This is often when the strike happens. To a trout, that rising motion looks exactly like a nymph or emerger heading for the surface to hatch. It's a trigger. You'll feel a sharp tugging sensation—don't jerk the rod back too hard, or you'll snap the light tippet. Usually, the fish hooks itself against the tension of the line.
Adding the Leisenring Lift
If the standard swing isn't producing, you can try the Leisenring Lift. It's a classic move that works wonders with a blue winged olive wet fly. You basically sight a spot where you think a fish is sitting, cast upstream of it, and let the fly sink. As the fly gets close to the fish's "den," you gently stop the rod's movement. The current will catch the fly and lift it toward the surface right in front of the trout's nose. It's a very persuasive way to convince a stubborn fish that its dinner is trying to escape.
Tying and Choosing Your Patterns
When it comes to the actual fly, you don't need anything overly complicated. A traditional blue winged olive wet fly usually features a slim olive body—either dubbed fur or even just thread—and a soft hackle or a small slip of gray bird feather for the wings.
The "soft hackle" version is my personal favorite. Using a feather from a partridge or a hen allows the fibers to pulse and move in the water. Even when the fly is just sitting there, those feathers are twitching, making it look alive. Color-wise, you want to match the specific BWOs in your local water. Some are a bright, vibrant olive, while others are almost a dull, grayish-brown. It's always a good idea to have a few variations in your box, ranging from size 16 down to a tiny size 22.
Pro tip: If you're tying your own, don't over-bulk the body. Natural BWOs are very thin and delicate. A fly that's too "fat" won't sink as well and won't look right to a picky trout. Keep it skinny, keep it simple.
Gear Considerations for Wet Flies
You don't need a specialized setup to fish a blue winged olive wet fly, but a few tweaks can help. A longer rod—say a 9-foot or even a 10-foot 4-weight—gives you better control over the line during the swing. It helps you keep more line off the water, which reduces drag and lets you guide the fly into those little pockets behind rocks.
For your leader, you'll generally want a bit of length. A 9-foot leader tapered down to 5X or 6X is standard. Since you're fishing under the water, you don't have to worry quite as much about the fish seeing the line on the surface, but BWOs are usually found in clearer water, so staying subtle is still a good call. If you need the fly to get down a bit deeper in faster water, you can use a tiny bit of split shot, but usually, the weight of the hook and the wetness of the materials are enough to get it where it needs to be.
Why This Fly Still Matters
In a world full of flashy new streamers and hyper-realistic nymph patterns, the blue winged olive wet fly feels like a bit of a throwback. It's an old-school way of fishing that's been around for centuries. But there's a reason it hasn't disappeared: it works. It captures the essence of the insect without needing thirty different synthetic materials.
There's also a certain satisfaction in fishing this way. It's tactile. You feel the river more when you're swinging a fly through the current. You feel that sudden, electric "thump" when a trout grabs it. It connects you to the water in a way that staring at a tiny speck of foam on the surface sometimes doesn't.
Next time you find yourself on the water and the clouds start rolling in, don't just reach for your dry fly box. Take a second to look at what's happening just below the ripples. If you see those little olives starting to emerge, tie on a blue winged olive wet fly. Trust me, once you see how effective it is during a tricky hatch, you'll wonder why you ever bothered with anything else. It might just turn a frustrating day of "near misses" into one of the best days you've had on the stream all season. Tight lines, and don't be afraid to let that fly sink a bit!