When most of us think about fishing the Baetis hatch or for most of us, referred to as the BWO hatch, we usually think about the small mayfly duns rafting down the river. This is the portion of the life cycle that we are probably most enamored by. We must not forget the emergent and crippled BWO's that are often caught in or under the surface film or the spinners that often go unnoticed.
I'll never forget the first time I encountered a blanket BWO hatch which was on the Henry's Fork in Idaho. I was fishing in late September or maybe it was early October. I was fishing the box canyon with Pete Stahl. The weather had turned cold and we were fishing in a cold drizzle and intermittent snow. The run we were fishing had rafts of Baetis duns. I remember there were probably 100's of duns per square foot. They were size 20's and maybe even 22's. I looked in my box and the best imitation I had was some BWO parachutes in a size 18 and I gave it a go. My size 18 looked like an air craft carrier compared to the naturals. At least it let me tell my imitation from the naturals. Luck was with me that day, I guess there were a number of trout that were looking for a bigger meal. I also remember my hands being so frozen that I could hardly get the hook out of the fishes mouth to release it. It was what I remember as a glorious but miserable day. A time that I remember vividly to this day.
Well, on to the Fishing Discussion.
Fishing a Nymph Just Under the Surface
When the duns first appear, you may want to continue fishing a nymph rigg, with a long leader and present the fly with upstream casts, just as you would a dry fly to a rising fish. Let the small imitations sink a few inches below the surface film. It may be necessary to treat all but the last few inches of your fly line with floatant. This will keep the fly up in the water column and help you to detect strikes. You may want to add a tiny yarn indicator into the leader five or six feet up from the fly. Set the hook to any movement of the indicator or to any visible rise anywhere near it.
Dry and Dropper
You can also fish the Baetis complex hatch with a dry dropper setup. You can tie one or two un-weighted nymph droppers about 2 to 3 feet behind the dry. The dropper can be tied to the hook bend of a dry fly chosen to imitate the dun. You might even want to try a cripple as the fly in the surface film if the currents are smooth enough to see it.
Presenting Drys and Emergers
When presenting dry flies and emergers to a Baetis Complex hatch on smooth currents, you will be required to fish with delicate precision. The trout are almost never more careful in their feeding lanes, nor will they move far out of range to take a natural or its imitation. The fish are typically feeding in the smoothest of currents so stealth is a must.
Before making a cast, take up a position as near to the rising trout as you can without alerting them to your presence. Look for a position that will put as many conflicting currents behind you rather than leaving them between you and the trout. This is the water your line will land on. When encountering a pod of rising fish target a single fish, time its rhythms, and cast to it carefully and deliberately. This is the best tactic as opposed to casting at random to the pod of lifting and subsiding noses.
There are two prime positions to present your imitations. Try to position yourself either directly across stream from the trout, where you will use a reach cast. Or, place yourself upstream and slightly off to the side of the trout, in position for a downstream wiggle cast. Both of these casts allow you to show your fly to the trout instead of your line and leader. Be as accurate and gentle with each cast as you can. It may take a long time and many casts before all the stars align and the trout takes your fly in rhythm, in its feeding lane.
If you find it necessary to make an upstream presentation and the fish are feeding on the surface, place the fly just a foot or two upstream from the position of the fish. That way a very little amount of the leader and no line are allowed to fly through the air and over the head of the fish. It doesn’t take much to get a feeding fish to head for cover.
Baetis complex nymphs are so small and hatch so often on smooth currents, they are susceptible to getting stuck in the film, Hogan Brown has created a pattern BWO SIM which is for (stuck in the middle). The dun often finds itself half in and half out of the nymphal shuck. They are helpless in this position, and trout often feed selectively on them.
The emerger imitations should float flush in the film and should represent both the emerging dun, or at least its wings, and the trailing shuck. Many anglers and guides often fish the emergers during the Baetis complex hatches.
When fishing the Baetis complex hatch you should use your finest presentation outfit. Many anglers use a 3 or 4 weight set-up. This hatch requires short and accurate casts with the most delicate presentations.
Proven Baetis Emergers and Dry Fly Patterns
Hook: Standard dry fly, 1x fine, size 16-24
Thread: Olive 8/0
Tails: Blue Dun hackle fibers, split
Abdomen: Pale Olive to olive-brown fur or synthetic dubbing
Wings: Ball of gray synthetic dubbing, as knot
Thorax: Slightly darker dubbing than abdomen
Legs: Blue dun hackle fibers
Pattern Notes: When fishing this fly, you can either treat just the ball or knot with floatant, and fish the fly suspended from the surface film or you can also dress the entire fly and fish it flush in the film.
Krystal Flash Baetis Emerger (Originator: Rick Hafele)
Hook: Tiemco 2457, 1x short, size 16-22
Thread: Olive 8/0
Tail: Olive or tan CDC fibers as long as the hook shank
Body: 4 to 6 strands of tan, olive, or mix of olive and tan or olive and brown Krystal Flash tied in at the hook bend, twisted into a fine rope and wrapped up the hook shank.
Wings: Gray CDC fibers
Thorax: tan to dark brown dubbing with guard hairs picked out.
This pattern is similar to the Krystal Flash nymph, but with the addition of CDC it floats perfectly in the surface film and represents the key elements of the emerger stuck there with the trailing shuck and unfolding wings. You can vary the colors to match most any BWO hatch.
Olive Sparkle Dun (Source: Juracek and Mathews)
Hook: Standard dry fly, 1x fine, size 16-24
Thread: Gray 8/0
Wing: Natural deer hair, tied Compara-dun style
Tail: Olive brown Z-lon
Body: Gray-olive fur or synthetic dubbing
This pattern is a standard emerger pattern and represents the emerging process as it nears completion, the dun is fully formed, but the nymphal shuck is still attached. This fly is actually representing the emerger and the dun with a single pattern.
Barrs Emerger (Originator - John Barr)
Hook: TMC 2487 or 2488 #16-24
Thread: 8/0 Iron Dun
Tail: Brown Spade Hackle Fibers
Abdomen: Olive Brown SuperFine Dubbing Wingcase: Dark Dun Spade Hackle Fibers Thorax: Grey Muskrat or Beaver Dubbing Legs: Leftover tips of wingcase fibers
The Barr Emerger is "Go To" pattern. The idea behind this pattern, according to John Barr, was to imitate the adult insect creeping out of the nymphal shuck. This pattern is meant to be fished below the surface, anywhere from streambottom to an inch under the surface. Fish the Barr Emerger down along the bottom with a split-shot on the leader and an indicator above, or as a point fly in the Hopper/Copper/Dropper system.
Hook: Tiemco 2487 #18,20
Thread: Gray, Olive, Olive Brown 8/0
Body: Muskrat under fur
Tail: Microfibetts gray
Wing: White Foam
Quigley's Olive Marabou Cripple (Originator - Bob Quigley)
Hook: Daiichi 1180 #12-#20
Thread:Light olive 6/0 or 8/0
Tail: Olive marabou.
Rib: Gold wire
Abdomen: Olive marabou
Hackle: Tinted yellow/olive grizzly or light blue dun grizzly
Thorax: Light olive or yellow spun hair
CDC Baetis Baetis
HOOK: TMC 100, sizes 16-20
TAIL:Betts' Tailing Fibers
BODY: Olive Dazl-Tron
WING: CDC, natural dun color
HOOK: 900BL, sizes 16-20
WING: Mallard flank, tied parachute style
TAIL: Two blue dun Micro Fibbets, split
BODY: Olive Haretron or Superfine
HACKLE: Natural or olive-dyed grizzly
DIVING BAETIS SPINNER: Pattern from Planet Trout
HOOK: TMC 100, #16-#22 or Daiichi 1100, #16-#22
THREAD: Gordon Griffith 14/0 sheer, olive or dark Brown
TAILS: Dun Micro Fibetts
EGG SAC: Olive-Yellow or Rusty Brown dubbing
ABDOMEN: Olive or Rusty Brown Goose or Turkey Biot, to match the naturals color
THORAX: Pearl Bead
WING: Z-wing or Tan or Gray raffia ( Swiss Straw)
This particular rendition is from Allen McGee …it may also be viewed here at WESTFLY- where the egg sac seems to be missing…this pattern is best presented on a tight line and dead drifted…the spinners are washed away after completing their mission and won’t be returning to the surface, unless pushed there by the current…
You can pick up Dave Hughes book, "Western Mayfly Hatches" at Amazon books by going to the following link. It is where most of this information came from.