Mayflies (Ephemeroptera)

Mayflies are arguably the most elegant insect of the fly fishing world. They vary in size (16) and color and are a staple in the trout’s diet. As fly fisherman, we imitate this order with patterns like the parachute adams, adams dry fly, pheasant tail, comparadun, and the mercury baetis.

How to identify a Mayfly Dry/Adult:Easy answer is if the fly has wings that post straight up like a sailboat, it’s likely a mayfly. They emerge/hatch during the morning and evening hours most of the time and you will see trout slowly and methodically eating something on the surface. Good chance it’s a mayfly.

Mayflies have 2 wings that sit vertical, and have transparency to them and often detailed designs. The nymphs have long legs, short antennae, and have 2 or 3 tails.

Flies of the Mayfly cycle: Nymph, Emerger, Dun, Spinner

Eggs are laid in water and either settle to the bottom or adhere to some submerged object. They often hatch in about two weeks but may, under certain circumstances, undergo a period of varying duration in which no growth occurs. This cessation of growth, known as diapause, is a highly effective adaptation that enables the insects to avoid environmental conditions hostile to developing nymphs or to emerging winged stages.

Nymphal life may be as short as two weeks or as long as two years, although an annual cycle is most common. As many as 50 molts (periodic shedding of skin) may occur, depending on the species and the environment. When growth is complete, the nymphal skin splits down the back and a winged form, called the dun, emerges. The dun flies from the surface of the water to some sheltered resting place nearby. After an interval lasting a few minutes to several days, but usually overnight, the skin is shed for the last time, and theadult stage (sometimes called a spinner), emerges. Mayflies are the only insects that molt after developing functional wings. The dun resembles the spinner in overall appearance, although it is softer and duller in colour than the adult. The wings of the dun, generally rather opaque, are tinted with gray, blue, yellow, or olive. Heavy pigmentation along the veins may give the wings of the dun a mottled appearance that rarely persists in the spinner. Legs and tails of the dun are shorter than are those of the spinner.

Nymph

Mayfly nymphs are broken down into 4 groups: Swimmers, Clingers, Crawlers, and Burrowers. Most mayfly nymphs are imitated with the same patterns, but fished at different depths and different styles. Swimmer nymphs for example can be stripped like a streamer to get a strike, burrowers, are often drifted along the bottom

Swimmers: Pheasant-tail nymph,Hare's Ear. (10-22)

Good imitations include standard versions of the Pheasant Tail and Hare’s Ear nymphs (right). Use beadhead flashback versions for deep, fast, or off-color water.

How to FishMayfly Patterns

There are a few instances in mayfly life cycle when they are most vulnerable to the trout, and these are all great opportunities for a fisherman to imitate with flies, each with its specific patterns.

Subsurface, when the mayfly nymphs start their journey to the surface, they are an easy target to the trout.
On the surface (or subsurface) during their emerging from their exoskeleton.
While they are floating on the surface as duns, getting ready to fly off.
During egg drops – trout find them the most deliciouswhile still containing eggs as their body consists of eggs mostly at this phase, plus they are super nutritious.
When they fall to the water, known asspent.

Each of the above mayfly life cycle phases should be looked at separately, matched with different fly patterns and different presentations.

Fishing Mayfly Nymphs

Mayfly’s underwater life is fairly long compared to its dry stage. Typical mayfly nymph lives anywhere from few months to few years in the water, living in the protective gravel, protected by their camouflage coloring. Nymphs live under rocks or in sediments.

Swimmers

Swimmershave weak legs but lean bodies that is streamlined for moving fast through water. They can swim very fast, even upstream, and can be found in both, very fast currents as well as slow waters, even lakes and ponds. However, their favorite habitat aremoderate to slow currents with weed beds and lots of aquatic vegetation – like spring creeks.They breathe through gills located along the sides of their bodies. Their tails are fringed to enable them to swim faster. Swimmers tend to be on a smaller size, #10 down to #20.Gray drakeandblue-winged oliveare swimmers. One of the effective patterns to use for swimmers is Pheasant Tail. On slower currents, the best presentation with swimmers would be a delicate long cast, drag-free drifts, but an occasional light twitch to give it a short darting motion would also work. In faster waters, no action is needed.

Clingers

Clingerslive in fast rivers and streams and are mostly found under stones. They are rarely found in still water. Clingers are found mostly under the rocks and are only available as food at the times of a hatch. You can start fishing them about one to two weeks prior to the hatch.March brownis a one of the clinger nymphs. Clingers are medium sized nymphs, from #12 to #16. A good pattern for clingers is Hare’s Ear, but a wet fly pattern would also be very effective as these nymphs emerge subsurface. As for presentation when fishing these nymphs, dead drift works the best, casting it slightly off from straight across (either up or down) and letting it drift drag-free. Letting your fly drift towards the edge of the riffle into the slower waters would be most effective.

Burrowers

Burrowerslive in calm, slow waters and have long bodies and short, but very strong legs with large claws which enable them to dig protective burrows in the gravel of the river bottom. They have pale, yellowish bodies and are mostly nocturnal.Fish can find burrowers only when they come out of their hiding – at night to eat or in times of a hatch, which also happens when it’s dark – starting at late evenings. To fish burrowers, drifting along the bottom would be your best bet. Due to their size – they are a tasty meal for the trout that rarely get passed. In size, they range from #4 to #10, most common being #8 and #10.

Crawlers

Crawlersare found in medium to fast waters, their habitat beingbrisk waters with rocky bottom with lots of small crevices and nooks. Theyare not great swimmers. They range in size quite a bit, from #8 to #24, but most important ones being in the range #12 to #16. Popular crawlers aregreen drakesandpale morning duns. An effective pattern would be Hare’s Ear. An upstream cast with a light tumbling along the bottom would be a good presentation for this fly. An indicator would be a useful tool here.

Mayfly Emergers(10-22)

Molting (moulting)oremergingof nymphs happens when the water is warmer (inspring and fall), or during mornings or evenings in the summer time. When mayfly nymphs start molting, air and gases start collecting under their protective shell (exoskeleton), increasing their buoyancy, which pushes them up to the surface. They start fighting the upper pull forces and large percentage dies in the process, not having enough energy for the transformation.Mayfly emergers are likely one of the most important stages for trout fisherman to know and identify. Emergers will have a shuck behind their bodies and will be fresh on the water or just below the surface. Often, fish will rise, you will see their tails but never their mouths or heads pop out of the water. This is because trout are feeding just below the surface and feeding on emergers.

Emerging Para Dun.This CDC fly is terrific on flat water when the fish are really picky.

RS2. Possibly the best emerger imitation for tiny mayflies, especially small olives.

Sparkle Dun. This one floats high and combines a shuck with an upright wing of deer hair.

Klinkhammer. A European fly that has become very popular in the States. It’s a combination of an attractor fly and an emerger, and seems to work best when you are not quite sure what the fish are eating.

Parachute-style dry flies, tied in a couple colors—olive, yellow, gray—in sizes 10 to 22, do a good job of imitating most mayfly duns. Parachutes work very well when fishing to rising trout in flatwater pools. And those same flies tied with a dark brown material for their tails imitate emergers.

You can also use Catskill- or Wulff-style flies in the same colors for fishing rough water and riffles. These styles stand high on their hackles (chicken feather fibers) on the surface, keeping their bodies dry.

Fishing Mayfly Emerger

When in theemergerphase, mayflies easily become trout’s pray. Furthermore, an emerger is always a better meal choice for a trout than a dry fly. Least effort, most calories. If you see dry flies on the surface and trout rising but not taking them in, most probably a trout is grabbing those emergers subsurface. You can tell if trout is feeding on emerger by the way they rise and what you see showing above water. If you do not see the head, and only see the dorsal fin, then a tail with a splash, it is most likely the emerger in trout’s mouth. Great mayfly emerger patterns are Soft Hackle Mayfly Emerger and CDC Mayfly Emerger. As for presentation, dry fly drag-free drifting is most effective. An occasional slight drag could produce a strike as it brings the fly close to the surface, but keep it as short as possible.

Mayfly Adults (10-24)

The adults are most often fished and easily identifiable. They will have their wings intact and will be floating well on the water. The adults rarely spend much time on the water however, which makes this less important of a stage. Even though most of our fly patterns we use as fly fishermen are tied as an adult, I believe they imitate the spinner form as well and the fish are rarely too selective to only eat spinners vs the adults that are on the water or just recently emerged.

Black Mayfly Dun

Fishing Mayfly Dun

Mayfly dunhas usually three long tails (some have two). Their forewings are large, lightly-colored and transparent, covered with veins and standing upright (similar to those of a butterfly). Some species have hindwings, however, these are small in size and have no function (they are vestigial). Their bodies are long and tapered with long, slim legs. Their size ranges from #4 to #24, with most common size between #12 and #18.

Majority of mayfly species molt in the spring and early summer, while others do it at different times of the year. You could have sporadic hatches of certain species even in the late fall and early spring. These sporadic times could be even more interesting and productive for trout (and for a fisherman). During early spring and the fall, mayflies hatch in the warm hours of the day – usually midday. In the summertime, this event moves more towards the morning and late afternoon or early evenings. Usually, the warmer the weather, the shorter the hatch is – an hour or two. With cooler weather this can last a couple of hours. As mayfly duns float on the surface like little sailboats, this behavior dictates the method of presentation of the fly that is imitating it. When presenting a dun imitation to the trout, it has to be drag-free and from upstream, not giving a fish much opportunity to see the line or leader. This can be done by cross current reach cast. This way your fly will drift towards the trout before the line and the leader arrive. Hendrickson and Blue-Winged Olive are some of the patterns for mayfly duns.

Mayfly Spinners

Likely one of the most important stages to pay attention to and the easiest to identify. These are mayflies that are falling back to the water after mating. They don’t really move on the water as most are dead or close to dead and they are easy prey for trout. The key to identifying these is simple. You’ll see them on the water with wings fallen to the sides

For spinners, rusty and cream colored imitations in sizes 10 to 22 are all you really need. Have some tied with a buoyant material like Antron for their wings to help you see them during low-light conditions and some with hackle fiber wings to look more realistic to the fish during daylight hours.

You can recognize a spinner "fall" (because they are falling, not hatching) in a number of ways:

If the fish suddenly begin rising in a confident, regular manner.
Looking over a riffle into the sun, you see insects hovering over the water, dipping up and down as if suspended on a yo-yo.
You see insects high above a pool, moving upstream quickly and anywhere from head level to 100 feet above the water
You see bright orange, yellow, or green egg sacks hanging on the abdomen of flying insects.
You see mayflies with clear wings on the surface. Sometimes early in a spinner fall the wings are upright, but often the wings lie prone in the surface film, nearly invisible.

Fishing to spinner falls is often easier than fishing to hatches. Spinner falls are more common in the evening, when light is low and fish are less spooky. The flies come from above and land on the water (like ours) instead of hatching from beneath the water (difficult to imitate). And trout feed on spinners with a regular, predictable rhythm so it's easier to pitch your fly in front of a feeding fish at the right time. Here are some tips for fishing spinner falls:

Your fly must float absolutely, positively dead drift. Spinners don't skitter across the water or even hop. Once they hit the water all movement stop. Light tippets, slack line casts, and careful mends are critical.
The fly should lie with its body in the surface film, so standard hackled flies are out. Either use a spent spinner pattern or trim the hackle from the bottom of a standard fly.
Toward dark, when it's hard to see, you can often get away with a parachute or thorax fly with upright wings. But on flat water, or when there is still strong light on the water, fish may refuse a fly with upright wings if all the spinners on the water are in the prone position. Then you'll have to use a spent (and thus difficult to see) spinner pattern.
Some species of spinners fall with their wings upright, so you have to observe both what flies the fish are taking and what is on the water.
Spinners fall in riffles and it may be easier to catch fish in broken water, but the biggest fish often slide back to the tail of the pool, where it's easier for them to see and capture the helpless insects.
Sometimes it pays to fish a drowned spinner as you would a nymph during, or just after, a spinner fall; especially if the spinners fall during the day.