There are said to be upwards of ten quintillion insects alive and breathing at any one time, but I have only six patterns in my fly box. When it comes to matching the hatch, I just can’t get into the swing of things.
Insects make up more than half of all life forms on earth, but I have been known to fish all day with just a size 16 Gold Ribbed Hare’s Ear.
Up to a million species of insects have been classified worldwide, and our best guess is that there may be up to 10 million more unclassified species extant. So I was surprised to learn that there are only a little more than three thousand known species of mayflies worldwide, six hundred or so in the United States, and a mere 51 known mayfly species in Great Britain, where modern fly fishing originated. When I read this, I thought it couldn’t possibly be true. Surely the number of patterns dreamed up by fly tyers far exceeds that. Leave it to fly fishers to make life even more complicated than it already is. Most insects are disgustingly ugly and seem designed by nature to give humankind a fright. Only mayflies, butterflies, and fireflies are genuinely beautiful. So naturally, these are the insects most at risk from our behavior. These flights of angels are not what they once were. Caddisflies, far less pretty and more resistant to pollution, now outnumber mayflies in many trout streams. And as milkweed gives way to monoculture, businessmen are gathering the souls of butterflies and using them to light their cigars.
Mayf lies are aquatic insects of the order Ephemeroptera, part of a larger group known as Palaeoptera, which includes dragonflies and damselflies. They are related to earth’s oldest flying insects — yet they are “ephemera,” reminders of the brevity of life. They are the embodiment of mono no aware, as the Japanese say. Literally, this means “the pathos of things.” They live only briefly, and we glimpse in them our own impermanence and the transient nature of all life. (The Japanese allusion is also apt, because on tricky spring creeks, even our best casts can fall one syllable short of a haiku.)
An adult mayfly lives but a day — give or take a few hours. (The adult form of one species, Dolania americana, lives less than five minutes!) As mayflies swarm above the water to mate, we are witness to a mass spectacle of life simultaneously entering and departing this world. Make of that what you will. Many have and do. A 1495 engraving called The Holy Family and the Mayfly, by the Northern Renaissance master engraver Albrecht Dürer, depicts Joseph, Mary, and the Christ Child in the company of the Holy Trinity. In the lower right-hand corner of this engraving, rendered in clear naturalistic detail, is what appears to be a common European mayfly (Ephemera vulgate). Art critics have suggested that it symbolizes a link between heaven and earth, the sacred and profane, and the microcosm and macrocosm.
Mayflies have three basic life stages that fly fishers have divided into four stages for purposes of their own art: nymph, emerging adult, dun, and spinner. Anglers have tied flies and developed fishing methods to imitate all four stages. Trout subsist on aquatic and terrestrial insects, along with worms, leeches, and other fish, but aquatic insects are the mainstay of their diet: mayflies, caddisflies (Trichoptera), stoneflies (Plecoptera), and midges and other “true flies” (Diptera). All are aquatic in their immature form, living in streams and still waters, before emerging and transforming into flying, air-breathing insects.
In their immature or underwater stage, mayflies are classified as nymphs or naiads. (In Greek mythology, a naiad is a spirit that inhabits a river, spring, or waterfall.) They spend most of their lives growing to maturity underwater, living for about a year, sometimes two or more years, or only for a few months, depending on the species. In the nymph stage, they swim, burrow, or cling to rocks and molt several times underwater as they grow in size.
Ninety percent of a trout’s diet is said to consist of aquatic insects in the nymph stage. Ergo, the most successful fly fishers spend a lot of time fishing with nymph imitations on or near the bottom of the stream. Do you prefer to fish with dry flies or wets, on the surface or below, visually or intuitively? Nymph fishing takes more imagination. Nymph specialists remind me of the kid in the adage who said he preferred radio over television because “the pictures are better.”
In its final underwater stage, the nymph will split its shuck and swim upward to the surface to emerge as a dun, a sexually immature adult mayfly that is technically called a subimago. This emergence, which occurs en masse, triggers a rise of visibly feeding trout. These trout are usually focused only on the hatching mayflies. We fly fishers choose patterns that imitate the emerging insects in size, shape, and color. We fish these flies either as emergers inside the surface film or just below it or as dry flies riding high on the water. Although they are called mayflies, these insects don’t just come out in May, but emerge all throughout the warmer months, from spring through fall, and even winter. Some species release two broods, one in the spring and another in the autumn. The duns at this stage have opaque or cloudy wings and soft, rather drab bodies that are various shades of brown, tan, cream, or olive. As they are borne downstream by the current, the insects must wait for their wings to dry before taking off. At rest on the water, these wings stand upright like a butterfly’s, and the helpless insects are easy pickings for trout.
Poor fliers at first, mayflies flutter off the water to land on streamside vegetation, where they undergo their next remarkable transformation. The mayfly molts a second time — the only insect to do this after acquiring working wings. The mayfly has now become an imago — a sexually mature insect. Now it is at its most beautiful and delicate stage. The membranous wings are now transparent, the tails have grown longer and more elegant, and their body colors have brightened to attract mates. Most have only a few more hours to live and only one more thing to do.
In their final day on earth, the mayfly imagoes rise up and gather in a swarm. This occurs usually at dusk or early in the morning, when light is low. The nuptial dance begins at treetop level and gradually descends to within a few meters directly over the water. The mayflies seem to dance around each other in midair. They act like swirling atoms in the fading light. Each insect has a characteristic up-and-down movement. Strong wing beats propel the insects upward and forward, tails tilted downward. When the beating of the wings stops, the insects fall passively, tails tilted upward. Closer examination shows the males grouping together and females flying into these swarms, where they mate in midair. The males fall spent upon the water with flattened wings. Females either drop their eggs onto the water from above or dip their abdomens momentarily onto the surface. Each lays between four hundred to three thousand eggs. As all this is going on, the surface of the river is covered with the rings of rising trout. They feed on the ovipositing females and spent insects, and we catch them either on traditional dry flies or on artificial imitations called “spinners” that are tied to resemble the exhausted and dying insects.
This is all very exciting and beautiful, and when we are caught up in the ongoing drama of the fishing, maybe it is time to take a moment to remember that we also live in synchrony with the big flow, in the larger story of biological and evolutionary change, and that we are a part of the regal and unrelenting process of the cosmos.
And as we match our artificial flies to the tiny insects on the stream, we might want to keep in mind that the river we wade flows by the grace of gravity as our planet revolves around a yellow dwarf star that is three-quarters of the way up one of the shorter arms of a spiral galaxy that has a hundred billion stars and maybe as many planets. And that we are not even at the center of an observable universe that contains a hundred billion or more of these galaxies. And that nothing we do on earth has any significance whatsoever in the big picture. Now, which fly to choose?
