Early season trout fly fishing in Northern Michigan is typically centered on the Hendrickson (ephemerella subvaria #14) hatch. This three-tailed mayfly was given it’s common name by Theodore Gordon who tied flies to imitate the hatch for Albert Everett Hendrickson. The Hendricksons are sometimes referred to as the “Gentleman’s” hatch because of its late morning emergences and late afternoon and early evening spinnerfalls. Theoretically, one could play cards all night, sleep in after a night of great intemperance, get to the stream in time to catch the emergence, return to lunch, a nap, and then catch the spinner fall in time to return for the cocktail hour. Now that’s a full day of hatch fishing. At least that’s the story my late-rising, intemperant, ol’ timers told me.
There are two important factors for good Hendrickson fishing. First, correct habitat is necessary for good numbers of Hendricksons who love faster moving water and gravel. So, don’t expect to find them where your favorite silt bed, Hex waters are located. Next, correct water temperature is crucial
for the emergence to occur and temperate air temperatures are needed for the spinner fall.
My mentors were careful not to go to the river during Hendrickson time without their thermometers. As the morning sun warmed the water, they carefully dangled their gauges in the water and checked regularly to see the temperature rise from the upper 40’s into the low 50’s. Most expected the hatch to commence at 53 degrees. The ol’ pros nymphed Hare’s Ear nymphs below Hendrickson emerger patterns as they waited patiently for the water to warm. Sure enough, as the temp reached 52 or 53 degrees, they popped. (Usually late morning or early afternoon.) The tiny dun-winged flies could be seen floating and leaving the water during a hatch that lasted about an hour and then sporadically throughout the afternoon.
Once leaving the water, the newly hatched insects would wing their way to a nearby tree or bush sporting freshly budded leaves. Over a period of two or three days, they would molt one last time and become sexually mature adults ready to mate. No longer a pinkish shade of gray and tan, they now are a rich brown color with clear wings instead of the cloudy gray. Warm late afternoon air temperatures and calm winds would entice the spinners to gather in the air over the stream. Clouds of the tiny bugs would gather as the late afternoon and early evening sun fell low in the sky. In the clouds of male adults, females would fly through, mate, and fall to the water to lay their eggs. Tiny yellow egg sacs would be visible to both angler and fish as the female spinners fell to the water, deposited their precious package, and then died. Males Hendricksons, now spent and weak, would also fall to the water and die. It wouldn’t take long for the eager trout to take advantage of this and start to feed on their remains.
There would be one more important element to consider for good fishing though. In Early May, trout are just coming out of a Winter-long nap. For them to aggressively feed, their metabolism kick into gear. Trout need several days of upper 40’s and 50’s to get their motors going. Warm daytime temperatures are common to encourage emergences. However, so are cold 35 degree nights that will once again cool the water slowing the trout’s appetite. Many an early season angler has been frustrated with clouds of Hendricksons without a feeder in sight. No worries, the fish will feed tomorrow.
The tricky part of the Hendrickson hatch is that after a week of emergences, we will typically start to see tiny black caddis flies emerging all day long. Initially, trout will turn their noses up at the caddis, preferring to eat the Hendrickson. But, once the black caddis are around for a few days, the trout begin to eat them and look for them. In fact, trout will often avoid the Hendricksons choosing instead to look for telltale bright green egg sacs on the back of the egg-laying black caddis. So, look carefully and be ready for some selective fish.