RAMBLINGS OF A CATSKILL FLY FISHER

Dance of the mayflies

BY TONY BONAVIST
Posted 12/31/69

Some years ago, my friend Roger and I found a good hatch of mayflies on one of our favorite rivers. It was Hendrickson time in the Catskills, with a good number of duns that were beginning to hatch, and right around 2 p.m. We had good sport that afternoon, deciding to call it a day right around dinner time. As we were getting ready to leave, I happened to look up at the late afternoon sky, just as the sun was sinking behind the mountains to the west. The angle was just right, and the fading light cast its last rays on thousands of glinting wings, as the Hendrickson and red quill spinners began their mating dance. 

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RAMBLINGS OF A CATSKILL FLY FISHER

Dance of the mayflies

Posted

Some years ago, my friend Roger and I found a good hatch of mayflies on one of our favorite rivers. It was Hendrickson time in the Catskills, with a good number of duns that were beginning to hatch, and right around 2 p.m. We had good sport that afternoon, deciding to call it a day right around dinner time. As we were getting ready to leave, I happened to look up at the late afternoon sky, just as the sun was sinking behind the mountains to the west. The angle was just right, and the fading light cast its last rays on thousands of glinting wings, as the Hendrickson and red quill spinners began their mating dance. 

It would end all too soon with the spent flies falling to the river. A generation to end; a new generation to begin. 

The events that anglers call spinner falls bring to a conclusion each spring and early summer one of the most unique and interesting reproductive life cycles in all the insect world, if not the entire animal kingdom. 

Unlike most insects, aquatic insects included, mayflies are the only order I’m aware of that go through four distinct life stages before reaching maturity: egg, nymph, subimago (dun) and imago (spinner). Mayflies are also one of the few orders of insects that emerge directly from the larval (nymph) stage directly to the winged form, without a resting, or pupation, period. 

The only other orders that I’m aware of with a similar, but not the exact same, life cycle are stoneflies and dragonflies. There may be others. Neither of those groups of insects have subimago or imago stages. Instead, the stoneflies and dragonflies change directly from the larval (nymph) stage to the winged adult. Since mayflies, stoneflies and dragonflies do not go through a pupation period, metamorphosis is deemed incomplete. Emergence is direct, from the immature stage to the adult.

Mayflies have been documented in the fossil record as far back as the Paleozoic and perhaps the Carboniferous periods, both of which were hundreds of millions of years ago. According to the research, these delicate, short-lived creatures are considered to be some of the earliest of all insects. As most of you who fly-fish know, mayflies are classified in the order Ephemeroptera, which from the Greek translates to “living a day,” because the insects have such a short life after emergence. 

Mayflies are part of the major group of animals classified in the phylum Arthropoda (arthropods). Several classes are included, for example Insecta (insects), which is where the order Ephemeroptera is classified. Because all members of the arthropod community have no ridged internal structure, the animals are considered invertebrates. Invertebrates have an exoskeleton instead of an internal support structure; that is, they have no bones. 

After the eggs are deposited and hatch, the tiny nymphs feed on algae and organic detritus, such as decaying leaves. In order for the nymphs to grow, they must shed their exoskeleton. The nymphs are called instars during this period of growth and development.

Most mayflies complete a one-year life cycle.

During the many years that I taught fly fishing and lectured about the various species of aquatic insects that were important to anglers, emphasis was always placed upon the mayflies and how important that order was in fly fishing. I can clearly recall standing in front of a new class, explaining how the river gods must have had fly-fishers in mind when the life cycle of the mayflies was created. 

It’s all part of the great theme of the aquatic insects that trout feed upon. What could be more perfect than a group of river insects that live along the bottom, move through the water column to emerge, and then float along the surface for the trout to rise to? The absolutely perfect life cycle for anglers casting their dry flies.

As the evening progressed, Roger and I watched, somewhat in awe,  as the spectacle, this mating dance of thousands of mayflies, unfolded above the river. Once fertilization was complete, the spent males, with their big reddish-brown eyes, fell to the river. Their role in the reproductive process was complete. The females, with their bright-yellow egg sacs, rose and fell over the water’s surface, dipping to oviposit their eggs. Then they too fell to the river’s surface, their mission also complete. Lifeless, spent bodies at the mercy of the river currents.

As dusk approached, soft rings appeared on the quiet water below, as hungry trout fed on the dead and dying spinners. Another life cycle complete, another dance over. We left the river humbled with nature’s ways and that we had the privilege to cast our flies, because the river gods created the mayflies.

mayflies, insects, outdoors, species

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