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Henry’s Fork Drake Trifecta

Jun 9, 2017 | Mike Lawson Brown_with_Gray_Drake.jpg

It’s that time of year again. The questions have turned from the salmon fly hatch to “When do you expect the Green Drakes?” Last night I took a walk along the Henry’s Fork below my home in St. Anthony and saw a few Gray Drake Spinners hovering over the water. It’s time.

The Henry’s Fork is blessed with three species of large mayflies commonly known as Drakes. I doubt there is another trout stream in America or throughout the world for that matter, which features significant hatches of three completely different kinds of these great mayflies.

Green Drake


Green Drakes receive the most attention. They are hefty mayflies that emerge throughout the entire reach of the Henry’s Fork. They are also common on several tributaries of the Henry’s Fork as well as the surrounding waters including the Teton River and the South Fork of the Snake.

Most anglers are wise not to get too caught up in the Latin names of aquatic insects but it is very important to understand their taxonomy at least down through genus. The last I checked Green Drakes of the Henry’s Fork are of the genus Drunella and the specie common to the Henry’s Fork is grandis. Other Drunella mayflies common to the region include doddsi and coloradensis as well as the flavilinea, a smaller cousin which emerges at the tail end of our Green Drake hatch on the Henry’s Fork. My measurements for the Green Drake average about 11 mm (wriggling mayflies aren’t easy to measure) which translates to a 10 or 12 hook, depending on the brand of hook you are using.

Like their smaller Pale Morning Dun cousins, Green Drake nymphs are crawlers. They prefer clean gravel where they can hide in the interstitial spaces between and under the rocks and come out to feed. They are always available to trout and it is likely that the early nymph patterns like the Pheasant Tail imitated crawler type nymphs. Prior to emergence these hefty nymphs get very active. Their body cavity begins to fill with gas which eventually buoys them to the surface. They really don’t swim to the surface but rather swim to fight the process which eventually will pinion them to the surface film where they emerge. These nymphs are best matched with a hefty imitation. My personal favorite is the olive Anato May Nymph in size 12 originated by Ken Morrish.

Some of the most effective patterns to imitate Green Drakes are emergers and cripples. After arriving at the surface the transition from nymph to dun is an active process. They wiggle, squirm and fight to escape the nymph shuck as quickly as possible. They can’t wait to get airborne. Many of them end up stuck in one way or another where they drift helplessly in the surface film providing a lavish opportunity for trout. In many cases a Green Drake Cripple fished in the film will outperform a dun imitation.

It’s hard to beat the explosive rise of a large trout on a Green Drake dun. In the old days my favorite pattern was the Green Drake Paradrake first described by Doug Swisher and Carl Richards in their excellent book, Selective Trout. Unfortunately I had a problem with hook ups with Paradrakes. Over time I morphed the Paradrake into an extended body pattern that doesn’t impede hooking called the Lawson’s Drake.

The timing for Green Drakes depends on the weather and water year. In the past we rarely saw Green Drakes before the opening of the Ranch on June 15. Our early spring weather coupled with low flows in the past few years has resulted in an emergence in early June. While again we experienced early spring weather, our snowpack was above normal with unusually cool, wet weather in late April and early May. This should move our hatches of Drakes back to the traditional emergence in the middle of June. They usually start showing up on the Buffalo River a few days earlier than on the Henry’s Fork. If you stop in at Pond’s Lodge for lunch, take a look at the Buffalo. Look for these big mayflies around midday but on cloudy cool days they might not show up until late afternoon. Green Drakes are also common on the South Fork of the Snake and the lower Teton River near St. Anthony. They usually emerge on these rivers a week or so later than on the Henry’s Fork.

Gray Drake


If you haven’t experienced a good Gray Drake spinner fall on the Lower Henry’s Fork, you’ve missed one of the great wonders of fly fishing. For reasons not fully understood, these big mayflies are most prolific on the Henry’s Fork on big water years. The last big year was 2011. We are hopeful 2017 will be another good one.

Gray Drakes belong to the genus Siphlonurus. While there are several western species that are thought to inhabit the Henry’s Fork, the most important is occidentalis. They are easily recognizable by two tails, a large secondary wing, and “U” shaped markings on the underside of the abdomen. They usually rest with their large primary wings sloped back more than other mayfly species. The body is slightly longer than but not as robust as the Green Drake.

Gray Drake nymphs are swimmers. They thrive in the margins of the stream. When mature you can see them swimming about like small minnows. I have a strong feeling that one of the reasons they are more prolific on big water years is that when the river is high it creates lots of soft water, back eddies, back waters and sloughs which creates more habitat for the mature nymphs.

One peculiarity of these mayflies is the duns crawl out of the water rather than emerge at the surface like other mayflies. Because the nymphs are swimmers they can be distributed over vast areas. They go wherever the water goes. Many are flushed throughout the extensive irrigation systems of the valley.

After molting into spinners, they seek out moving water to mate and deposit their eggs. It is a wonder to behold to see how many spinners can be so concentrated while the emergence of the duns is usually quite sporadic. The spinners usually begin their mating flights by hovering over the water in the mid-morning hours. The flights become more concentrated as the day goes on until by late afternoon they start to hit the water in a flurry. It is not uncommon to see males and females copulated together drifting on the surface.

Because of the nature of emergence, the duns are not as important as the spinners. I have witnessed trout feeding on duns, especially when the water is slow and shallow with lots of exposed vegetation. It’s hard to beat a size 10 Parachute Adams when the trout are looking for the duns. An Adams Split Flag or Sparkle Flag, originated by the late Bob Quigley is even better.

The main source of the action is almost always with the spinners. The trout can get a bit selective when the spinner fall is heavy. Our Drake Spinner, first developed by John Hudgens, is a deadly fly when the trout get selective. It works equally well for Green Drake and Brown Drake Spinners.

The greatest concentration of Gray Drakes occurs on the Lower Henry’s Fork from Ashton downstream to the confluence from mid to late June. They are also common on Lower Fall River and the Lower Teton. I have also witnessed good Gray Drake activity on the Yellowstone River in the Park. Some of the best Gray Drake action occurs in late September and early October on the Upper Teton River. It is likely that these are a different specie than the June Gray Drakes but I have no reason to care. Individual specie identification can only be done under high magnification by a trained entomologist. All I care about is that when there are big Gray Drakes on the water the fishing is very good.

Brown Drake


The third member of the Henry’s Fork Drake Trifecta is the Brown Drake. This is the largest of the drakes reaching up to 20 mm in length. The nymphs are burrowers preferring soft sediment laden areas like that found in the lower reaches of the Ranch downstream through Pinehaven. The nymphs dig “U” shaped burrows where they get their food from water that filters through their burrows. Even though they spend almost their entire aquatic lives living in their burrows they are very agile swimmers.

Emergence usually takes place at dusk. Mating flights also occur at dusk. This phenomena presents a dilemma whether to fish a dun or a spinner. Trout can be very selective. My personal experience fosters a strong conviction that individual trout focus on different stages. One trout might be picking off emerging nymphs, another might be quietly sipping duns while yet another is eating spinners. It pays to be patient and observant. The challenge is magnified as darkness settles in.

I usually use a two fly system. My favorite pattern is my Extended Body Drake with a Brown Drake Emerger or Cripple as a dropper. Our Drake Spinner, described earlier is also a great pattern.

Brown Drakes are not as widely distributed as our other two drakes. They produce exciting action on Silver Creek. The hatch on Silver Creek is almost always about 10 days to 2 weeks earlier than the Henry’s Fork. I’ve also had some good Brown Drake action on the Gibbon River in the meadow section of Yellowstone Park when the river wasn’t too high and off-color. The Buffalo River and the Upper Henry’s Fork above Coffee Pot Rapids also produce great Brown Drake hatches.


To sum things up, Green Drakes and Brown Drakes have 3 tails while Gray Drakes have two. All three have a tall primary wing and a good sized secondary wing. Green Drakes are important in the Ranch as well as the lower river from Warm River to Ashton and below the Ashton Dam to St. Anthony. Gray Drakes are most important below Ashton and their numbers intensify further downstream below Chester. Brown Drakes only emerge from the middle of the Ranch downstream to the fast water at the Henry’s Fork Lodge. For more detailed information about these and other important hatches, refer to the hatch chart on our website. I can promise you won’t find a better, more detailed hatch chart.

Check our online store for specials on fly selections to match the drake hatches.

It’s On, It’s Drake Time!