Looking back in the archives of the River Reporter, I found that I first wrote about the Hendrickson mayfly in the May 3, 2017 edition. I believe that was my first column for the paper. That, my fellow anglers, was seven years ago.

So what has transpired with the Hendrickson/red quill hatch since that time? What I can say is that Hendrickson and red quill hatches have—as is the case with a lot of Catskill mayfly hatches—dwindled. 

Although we don’t refer to this hatch as the Hendrickson/red quill hatch, that is exactly what it is. The red quill is the male, and smaller. Ephemerella subvaria is the scientific name of the species, and only mayfly that I’m aware of where the male and female are distinctly different in color.

Last year toward the end of April, a friend and I found a Hendrickson hatch along the upper East Branch of the Delaware River around 3:30 p.m. I don’t know if this was the beginning of the hatch or a few days in, but there were not very many flies. Which in some ways is a good thing, because too many flies can often be just as much of a problem as too few. There were enough flies, however, to get a few trout rising. 

Sadly, a few days later the rains came, and that was the end of Hendrickson fishing in 2023.

Every year, anglers throughout the Northeast and the Catskills in particular eagerly wait for the Hendrickson mayfly hatch. Although Hendricksons are preceded by quill Gordons, which appear up to two weeks earlier and often overlap, anglers look to Hendrickson for the best fishing. 

First of all, in their heyday, Hendrickson hatches were huge, emerging when the water and weather had warmed considerably, making for better and more comfortable fishing. I can recall fishing the lower East Branch with my friends Willie and Heidi one late afternoon in the 1990s. There were hundreds of Hendricksons and red quills on the water, with trout rising freely. I think we caught a few fish that day. 

By the time this piece goes to press, the Hendrickson hatch should be about a week away, if the emergence takes place as it did in the past—the third to fourth week in April. There are a lot of variables, which of course can impact the hatch itself and certainly the fishing. If water temperatures remain too chilly, and fail to reach 50 degrees Fahrenheit for a few days, Hendricksons will be repressed until temperatures rise accordingly. 

Then of course there are all the issues associated with stream flow. Right now, and immediately after checking the U.S. Geological Survey streamflow site (see waterwatch.usgs.gov/?id=pa07d), all West Catskill reservoirs are spilling, with additional water being released by the DEP. Flows range from 810 cubic feet per second (cfs) for the Neversink at Bridgeville; 1,130 cfs for the East Branch at Downsville; and 2,660 cfs for the West Branch at Hale Eddy. 

Of all Catskill rivers, the Willowemoc remains in decent shape at 245 cfs near Livingston Manor. The Beaver Kill is at  1,000 cfs at Cook’s Falls. If the rain stays away, the freestone streams should be in decent fishing condition by the time Hendricksons begin to hatch. 

Since all Catskill reservoirs are spilling, it’s not very likely that those rivers will be fishable, at least not by wading anglers. Unfortunately, almost every spring anglers are confronted with very high flows at the beginning of or during the Hendrickson hatch. So it’s a rare year when the weather cooperates, stream flows remain normal, and we have a decent opportunity to fish the Hendrickson/red quill hatch. Right now, looking at current conditions, other than the freestone rivers, conditions are not looking very good for Hendrickson. Hopefully by the time the emergence of the species begins, conditions will have normalized. 

Fly fishers need to keep in mind too that regardless of the flow, Hendricksons and red quills will hatch once the water temperature reaches 50 degrees.

If all goes well, anglers should plan to be on the river no later than 1 p.m. A hatch of little blue quills—Paraleptophlebia adoptivia—almost always precedes Hendrickson/red quill hatches. I’ve observed blue quills on the water as early as 12 noon. Later they mixed with Hendricksons and red quills as the day progressed. 

It’s been my experience that Hendricksons begin to hatch right around 2 p.m., depending on the day. Yet I’ve seen duns on the water as late as 4 p.m.

Fly fishers should also keep in mind that just because they find a good hatch of flies, that does not always mean there will be rising fish. I recall too many occasions where I watched hundreds of Hendrickson and red quill duns float along unmolested for several hours, without seeing a rise. Sometimes the water is warm enough for those flies to hatch, but not warm enough for trout to feed extensively at the surface. All too frequently, most of the feeding during early-season hatches, including that of Hendrickson, is done subsurface, frustrating the dry-fly man completely.

Many times, after a few hours fishing a Hendrickson hatch, I’ve stayed around for the spinner fall. That can occur as early as 6 p.m. and will usually bring trout to the surface. I’ve had some of my best dry-fly fishing during these spinner falls. So anglers should keep this in mind before leaving the river too soon.

Tony Bonavist has a degree in aquatic biology from the University of  Montana, and was a fisheries biologist with the New York State DEC for over 25 years. He has been an instructor at the Wulff School of Fly Fishing, and at the Frost Valley YMCA. Tony resides in Hurley with his boxer, Marley.