I trudged up to the top of the bench above the seeps and springs along one of my favorite spots on the Madison River. I wanted to check the osprey nest atop a snag in a dead aspen tree to see if the pair that nest there every spring had returned. I knew from past late April days struggling through the rocks and boulders to inspect the eyrie, that if the birds had arrived so would Baetis (BWO) mayflies be found emerging on the river below. Their emergences herald the arrival of a new dry-fly fishing season on most of Montana’s rivers.

An adult Mayfly dun floats without breaking the surface tension of the water.

As I gripped the sage brush branches to pull myself up to the top of the bench to view the birds’ nest I heard familiar calls of chirps and whistles as one bird communicated with its mate warning of my approach. I smiled to myself with a sense of relief knowing the birds had made it through the winter, not to mention I too had survived another long Montana winter. Out of breath from the climb I said to myself, “well, the fish hawks are back to their nesting site, so I’m betting the Baetis mayflies are going to hatch today too…and trout will rise to them”. I smiled and waved at the birds as they flew around their spot talking back and forth to each other, and me. I patted the side pocket of my waders making sure I had remembered the box of new Baetis fly patterns I had tied to try on the trout in the river below.

A box of baetis patterns geared toward surface feeding trout.

The April Montana weather was perfect to bring on an early season Baetis emergence. Mid 40’s with low clouds, spitting rain and snow as I hustled down to the river and sat on a familiar rock along the shoreline to check for rising fish. Just upstream, a short cast away, I noted mating midges clustered along the downstream side of a huge boulder where I often encounter fish rising. I checked my watch that read 1:30. Pulling a fresh 3foot length of 6x tippet from its spool I triple surgeon knotted it to my leader. Then I sat watching the pool for any rising fish. I did not have to wait long before a rainbow showed with a slow, head and tail rise. Since I’d seen midges I assumed the fish rose to an emerging midge. I knotted a size #22 imitation on and presented a perfect cast followed by another, and another while the fish rose again, and again. After several unsuccessful presentations I reeled in and watched hoping to see what the fish rose to. Alongside of the boulder another fish came up barely breaking the surface. I could see a tiny emerging dun escape the rise form. The trout had risen to it, and missed as it escaped its nymphal shuck and skittered along on the surface arriving at my spot now clinging to my waders. There I saw my first Baetis mayfly of the season. I did what the river told me to do. I knotted on one of my new fly patterns, a #20 CDC Baetis Sparkle Dun.

Craig’s fly choice: #20 CDC Baetis Sparkle Dun.

The north wind took my first presentation into the main current a yard off the big boulder and was taken by the rainbow I’d first saw rise. After a run and jump I brought the brightly colored 15” male to hand and released it. While drying off the fly I glanced back at the boulder and saw the large trout rise nearly touching the rock not 12feet from where I was perched. I roll cast just my leader and tippet and this time the wind brought my fly 2feet above the trout. I could watch it float down to the fish that took it barely disturbing the surface of the water. I did not have to set the hook, the big trout bolted when it felt steel, jumping twice then making a long run downstream. A short while later I landed the lovely hooked jaw male brown trout just over 18”.

Returning to my rock I could not help think of how lucky I am to be able to fish small BWO, blue-winged olive mayfly dry flies to wild rising trout in Montana’s early season.

Craig waits on the hatch next to a favorite rock and a view of the Madison River.

Baetis inhabits every trout stream in Montana and is often the most abundant mayfly in any given stream. Their emergences can occur during any month but typically there are two peaks:  April-June, and September into early November. And while the mayflies are tiny, their hatches are most often so concentrated even large trout can feed efficiently on them.

Depending on the river, there is variation in the size and appearance of the tiny duns. They can run from sizes #16-26 with body color from cream, to gray, to olive and brown. The nymphs are streamlined with three tails and are strong swimmers moving in quick short bursts. Duns have two tails, slender bodies and very small rear wings. Baetis spinners are rarely seen and seldom important to anglers.

Elegance in form: the Winston PURE 2 and a baetis dry fly.

Emergences of duns takes place in the afternoon from 1-4pm. Weather plays an important role in determining the intensity of the hatch. The longest and heaviest emergences always occur on overcast, cool conditions. Sunny-warm days produce short-sporadic hatches while light rain or snow guarantee a strong hatch.

Baetis duns emerge from their nymphal shucks at the surface where it is common to find fish taking nymphs and impaired-crippled emergers in the surface film.

An adult baetis struggles in the film. A perfect meal for any trout looking up at dry flies.

On pocket water rivers like the Madison approaching rising fish from directly below is best. Wading, walking on your knees, or scooching along the shoreline on your butt to get within 15feet is best as it eliminates as many currents as possible between you and the fish, reduces drag, and improves casting accuracy. Trout lock into tight feeding lanes so getting close to rising fish helps cast flies into these narrow lanes and helps defeat the effect of wind on casts.

On pocket water rivers like the Madison approaching rising fish from directly below is best.

On smooth water rivers like the Missouri, Firehole and Henry’s Fork it is best to approach the fish from the side and slightly upstream. These rivers do not allow an angler to get as close to rising fish as the Madison. This along with a myriad of surface currents can make drag a major problem best handled by casting across and downstream of the rising fish.

I like fishing dry flies such BWO Sparkle Duns during Baetis times. It is much easier to see by keeping casts short especially to trout rising in current seams. Short upstream casts help manage inevitable drag that quickly takes over in so many pockets. Sometimes big trout will barely sip in a dry fly or unweighted nymph imitation making it even more challenging. Yesterday, fishing with noted photographer Forest Mankins and Patagonia’s head of field testing, Kyle Toyama, in tow we found large brown trout would take our CDC Sparkle Duns and hook themselves not requiring a quick hook set when the trout took the fly. The trout would take and hook itself, and continue feeding as long as no pressure was put on it while we watched it feed as it nothing had happened.

Choices, choices, choices.

Baetis emergences can be so heavy at times that it is difficult to compete with the naturals. You can do everything right and still not take as many fish as you would like because of competition your fly faces. It is important not to flock shoot. Single out one fish and concentrate on it. Make short-quick presentations. Put the fly a foot above the rising trout, and let it drift only a foot or two beyond it if it does not take then recast. Quick, short-accurate drifts increase the chance your fly will be taken.

Patience, accurate casts, and great fly selection are all key to catching baetis eating trout.

The preferred fly patterns reflect the trout’s preference for emerging nymphs and impaired duns fished on the surface. Floating Baetis Nymphs, Sparkle Duns and Baetis Emergers are favorite patterns. As noted earlier, Baetis exhibit considerable variation in size, and much of this is seasonal. Early season Baetis emergences, those occurring in April, May and early June contain mayflies as large as #16 with most #18-20. Fall Baetis can run from size #20 to #26, a size #22 usually works fine in the fall season. And, even though the coloration of naturals varies I find a grayish-olive dubbing is representative of most Baetis mayflies.

Catching fish is great, but the process of fishing baetis dries is the best reward.

It’s the last week of April as I finish this piece. At 11am the weather is unsettled with heavy overcast and a threat of rain. I tied several Baetis Sparkle Duns and floating nymphs last night, now safely stowed in fly boxes in my fishing vest. Earlier I cleaned my fly line, and put on a long pull of fresh 6x tippet to my 10 foot leader. I’ll pack a lunch and head to the upper Madison River knowing I will meet a Baetis emergence around 1-2pm, one of my favorite dry fly hatches to fish during Montana’s long fishing season. I am lucky to live here. I hope to see you someday soon on the river.

Craig’s Baetis Hatch Rod: PURE 2 8’3″ 4 weight

The rod of choice for picky baetis eaters: The PURE 2 8’3″ 4wt.

I enjoy fishing dry flies on spring creeks and smooth flowing western waters. I demand a medium flex rod that easily loads for short distance casts, 15-30 feet, and can still be counted on to punch out longer distance casts if needed.  The rod must be light and smooth, with enough power and flex throughout, and yet protect light tippets fished with small dry flies to big trout.  Winston’s Pure 2 Rod fits all of my requirements and allows me to fish with confidence under the most challenging dry fly situations. Plus, Winston’s quality is unmatched, it never varies!

About Craig Mathews

In 1979 Craig with his wife Jackie founded Blue Ribbon Flies a retail fly fishing store with outfitting based in West Yellowstone, Montana. Craig enjoys designing dry flies to fool trout on his home waters like the Madison River and nearby Henry’s Fork, Yellowstone, and Firehole. He is an Umpqua Signature Fly Designer. He has authored and co-authored 9 important books on western US and Yellowstone National Park waters. His latest book, Pheasant Tail Simplicity, co-authored with Yvon Chouinard and Maruo Mazzo, will be released September 2025. Craig was selected as “Fly Rod and Reels” 2005 Angler of the Year. He continues to be involved in land and water conservation projects. He and Chouinard co-founded of 1% for the Planet that has contributed over $700 million to conservation and environmental programs.