Large, prolific, exciting, and fabled, Western Green Drakes are one of the most anticipated hatches of the year. Yet, as stimulating as this hatch can be, it can also be frustrating.

One of my early encounters with this large mayfly was a crushing failure. During a solid Green Drake hatch on Montana's Bitterroot River, I correctly identified the insect, located regularly feeding trout, and made many adequate casts with the "hot fly" suggested by a local fly shop. But I had little success. (Actually, I had no success.)

Despite doing everything I knew to fool the foraging fish, trout kept feeding and ignoring my offerings. What transpired on that day initiated a long study of Green Drakes--how to imitate them, and how to fish the imitations.

I collected a number of adults and partially emerged duns that day and loaded them into an empty film canister. Then I retired to camp to salve my wounded pride and study the insects.

Carefully comparing my collection of bugs to the unproductive fly quickly highlighted its inability to imitate the living insect. Some common fly patterns simply do not work when trout feed selectively. Green Drakes and their standby imitations are an outstanding example of this. Through close examination of the insect, from rock-crawling nymph, through levels of emergence, winged dun, and drowned adult, I discovered how to design effective imitations for each life phase.

Family Ties
The Ephemerellidae mayfly family includes Hendricksons, Sulphurs, PMDs, and BWOs, and is notorious for prolific hatches which cause trout to feed selectively on the most available and vulnerable stages of emergence.

Green Drake hatches are often unpredictable. Many variables affect the timing and density of the hatch. Drought, unseasonably warm weather, and low water may accelerate emergence by as much as two or three weeks. Hatch schedules vary dramatically based on local weather conditions and latitude.

The largest Ephemerellidae, Green Drakes provide superb dry-fly action--often the best of the season. But the life stages below the surface more often excite the largest trout.

Before we delve further into matching the hatch, let's identify exactly what bugs we are studying. For clarity in this article, Green Drake refers to Western Green Drakes

(E. grandis and E. dodsi). It also includes Ephemerella flavinea (the small Western Green Drake), understanding that it appears much the same as its larger cousins--only one hook size smaller--and hatches during and after the end of the larger Green Drake emergences.

Deep Green Drake
Green Drakes frequent most coldwater streams and rivers from New Mexico to Alaska, and Colorado to California. Flat and wide, mature nymphs reach lengths of close to an inch. The immature insect, a crawler, frequents the strong flows of rocky riffles and runs, and remains available to trout year-round.

Emergences typically start in late June or early July on most Western streams, with the smaller flavinea hatching in July and August. My Deep Green Drake fly, when fished bouncing the bottom, produces good action through the hatch but is especially effective the hour or so prior to the midday (1 P.M. to 4 P.M.) emergence, when the nymphs become active. On hot sunny days, Green Drakes may not emerge, but nymphs still catch fish. Since Green Drake nymphs live in rough, fast water with vegetation, rocks, and snags, bring lots of flies. If your fly does not hang up occasionally, you're not fishing deep enough.

Green Drake nymphs have three thin brown tails, segmented olive-brown abdomens with distinct olive gills, and six chunky legs. A wide olive-brown thorax and hard dark wingcase--turning to black on the edges at maturity--combine with large dark eyes on the head to complete the immature insect.

To imitate this phase, I combine a bead head with wireweight on the hook shank to keep my Deep Green Drake on or near the bottom. Three tails of ostrich herl give a thin and lifelike appearance.

I build a dark olive underbody of Antron as a base for the segmented abdomen and rib it with amber or yellow vinyl rib. I use Antron to imitate the Green Drake's short puffy gills and finish the body with a dubbed olive-brown thorax covered by a dark brown and black wingcase, coated with epoxy for a hard, shiny appearance.

The addition of thick goose biot legs pulled to the rear, and small black eyes, puts the finishing touches on the realistic imitation of the nymph.

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John R. Gantner has been fly fishing for more than 40 years. He lives in Redding, California, where he teaches fly-tying classes. Contact him at jrgantner@charter.net.
This article originally appeared in the July 2008 issue of Fly Fisherman.

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