Mayflies

If there is one aquatic insect that is always associated with the art of Fly Fishing, then the May Fly is that insect. This insect has been referred to as the very foundation of the sport. Since the year 1496, the Mayfly has been known to have a great influence for the angler. Dame Julianna Burners of England described the dressings for a dozen imitations that are known to catch fish. The journal that contained this information was called Treatys of Fyshing with an Angle. In the 1600s both Issac Walton and Charles Cotton wrote on the subject and started a splurge of writings promoting the use of Mayfly imitations and this insect became the symbol associated with the art of fly-fishing. Whether you are watching a film, video, movie or reading a book, magazine, or article on Fly Fishing you will be told that the May Fly is the Holy Grail insect. There are 16 Families, 47 different Genera and over 500 North American species of this important insect but only a very small portion is of importance to the fly angler. In Maine there are over 142 species.

All aquatic insects are under a constant attack from insect predators such as; their own kind, diving beetles, salamanders, frogs, back swimmers, birds and of course the fish.

These insects have a technical name, (Ephemeridae), which translates into the phase, "lives but a day." These insects emerge from their underwater world without mouthparts and therefore can't eat. Now, you know why they live only but a day.

Another common name is Ephemeroptera, which translates to mean upturned wing.

The crawlers are variable in size and generally inhabit areas of medium and slower currents; they consist of the prolific Ephemerellidae family, the weak-legged Leptophlebiidae family and the very small insects of the Tricorythidae and Caenidae families.

The clingers are of the fast-water Heptageniidae family and the very large Baetidae family is made up of fast swimmers, while the burrowing types are of the families Ephemeridae, Potamanthidae and Polymitarcyidae.

The eggs of the insect are deposited on or in water differently depending on the species. In some species the female will skim across the surface of the water in order to dislodge the eggs from her abdomen. Another species will fly across the waters surface and drop yellow or orange egg masses onto the waters surface. Some female mayflies will even use a protruding stem, leaf or other organic structure to crawl into the water in order to safely deposit her eggs at the bottom of the water column and others will actually dive into the waters surface in order to break the surface tension, then release the eggs underwater. Once the egg lying has taken place the exhausted insect will often times fall onto the surface of the water only to be taken by fish that have observed it from below the waters surface.

After time, which in some species can be as little as a few hours and in others the time can be several months, these eggs will hatch and an immature nymph will then crawl under the stones of a riffle or the medium to large rocks or boulder of a run, burrow into the silt or muddy area of the slower currents of pools or the nymph may cling to the under sides of submerged vegetation or the branches of a fallen tree along the banks or shoreline. There are even some species that will be free-swimming aquatic insects that will swim around areas of aquatic vegetation and/or any structure that has been created by fallen shoreline or banking debris. Most of the Mayfly Species have three tails but there are some that only have two. These tails are visible throughout most of the developmental stages. All will have six legs with one sharp claw on each foot. In the adult the tail can be as long as the insect itself. There are generally 10 abdominal segments with moving gills along the sides of the insect.

The Mayfly goes through an incomplete metamorphosis, which simply means that the insect misses one of the underwater insect stages common to most other aquatic insects. This Mayfly Life Cycle starts with adult female depositing eggs in or on the water. The eggs then fall slowly onto the lake or stream bottom and in time will develop into an aquatic creature called an immature nymph. These nymphs are classified into four basic groups: Burrowing, free-swimming, crawling and clinging. The Burrowing nymphs like areas that have a either slow or very calm current with a soft bottom made up of rich silt, fine sand, decayed organic debris and marl bottoms of pools, eddies and quiet stretches of river and streams, as well as, the firm bottom-muck of cool lakes and ponds. The free-swimming nymphs will inhabit areas where there is plenty of natural structure such as, aquatic vegetation and heavy aggregate bottom areas. Some fast swimming nymphs will also inhabit a riffled area. The Crawling nymphs will inhabit areas of moderate to fast current. Most species have weak legs and are very poor swimmers. They will inhabit the moderate currents among vegetation, gravel and the rubbled bottoms of the water column. Some will even exist in the riffled waters and also the faster current of runs.

Clinging

The Clinging nymphs love the faster and highly oxygenated waters of the riffles. This nymph has a classic flattened appearance with their heads and bodies designed for the faster currents. Nymphal life cycles can range from between 3-4 weeks to 2.5 years depending on the species of the insect. This process skips the common Larval Stage that most other aquatic insects go through, thus the incomplete life cycle that I mentioned earlier.

These Mayfly Nymphs can spend as little as six (6) months or as much as the next two years (give or take a month or two) Borrowing, Crawling, Clinging, and Swimming around the bottom of the water column. The period of time spent as a Nymph will depend on the specific species of the Mayfly. For instance the Baetis Mayfly can complete up to three life cycles in a years time. However, the Hexigenia limbata mayfly will require slightly more than two years completing its life cycle.

Swimming

Nymphs will feed on algae, diatoms, plankton, vegetable or organic matter and microscopic organisms. As the aquatic insect grows, the outer skin, which serves as a skeleton, limits the ability of the nymph to enlarge. In order to continue to grow this insect must from time to time, shed or molt the hard exoskeleton.

Once the hard shell has been removed the insect will secrete a fluid from its epidermal cuticular membrane, which will harden into another exoskeleton in which the nymph can grow.

The period of time between these molts is called an "instar" and many species will molt some 20 to 30 times before emerging into the air-breathing world above. Between the molts and during the instars the nymph is very vulnerable to its principal animal, bird, fish, amphibian and insect predators such as: dragon fly nymphs and adults, diving beetles, frogs, back-swimmers, salamanders, swifts, swallows and phoebes. The mayfly nymph will spend nearly 95% of its entire lifespan below the waters surface.

Burrowing

When the Nymph reaches maturity it will transform into a 'sub-imago'. The sub-imago is what we see emerge or hatch from the Nymphs. They are not an adult but are fully winged. This insect is called a Dun and must go through one more molt before becoming a sexually mature, "imago."

Now, the year has gone by and the Mayfly Nymph along with tens of thousands of other Mayfly Nymphs begin to instinctively desire to leave their aquatic environments and rise to the air breathing world above. What really triggers this event can be debated by those much wiser that I. There seem to be two schools of thought allowing us to consider two options. These options are that the processes are either biological or environmental. The biological explanation is that during the last few weeks of the mature Nymphs life stage, gasses will form between the Nymphal Shuck (outer shell) and the immature Mayfly. Over time the gas will greatly affect the insect's ability to remain below surface and the gas will create positive buoyancy sending the insect to the surface whether it likes it or not. The other real factor is the water temperature. When an area of water reaches a temperature of 50 degrees and maintains that temperature range for three consecutive days, there will be a Mayfly hatch. You could even include the two by allowing the gases to expand as the water temperature increases. In any event, we all know that in the spring, the fly angler will eagerly await this ritual.

The four stages of a Mayflies life cycle are; egg (Ovum, 1 to 3 weeks), Nymph (Nymphal 11 months to 24 months with 20-30 Moults), Dun (Sub-imago 1 to 4 days) and Spinner (Imago about 1 day).

This process of aquatic insects rising towards the surface is called an Emergence. Yes, I know that everyone refers to this event as a Hatch but you know the truth and that is that nymphs hatch from eggs and emerge from the water as duns. Every species has its' own emerging characteristics and time table. As the insects rise toward the surface, they become very vulnerable and fish will feed readily on them. During this emergence, fish will become very selective to the physical size, color, shape and actions of the emerging species.

Once on the surface the newly emerged Mayflies will either remain in the waters current or attach itself to a partially submerged limb or rock in order to then separate themselves from their skins or shucks - or more appropriately called exoskeleton, spread their wings, pump fluid into the veins causing the wing to strengthen in order to support flight. The Mayfly will float on the surface of the water, like little sailboats, with its newly inflated wings acting as sails being dried and blown around by the wind. This surface activity can last for only a few seconds to only a few minutes. Once the wings are dry enough and strong enough the insect will take flight. After taking flight, the sub-imago usually rests on the shoreline vegetation for 1 or 2 hours or 1 or 2 days depending on the species, while gradually going through the last molt and transforming from sub-imago into adult (imago or spinner).

This adult Mayfly has no functioning mouth and therefore can't eat, and now you know why they, "live but a day." These Mayflies can emerge like this by the thousands and is an experience that will be remembered by any angler encountering it for the first time. These mass emergent patterns are the Mayflies main defense against its natural predators, among them being fish and birds. They will hatch in such great numbers, condensed in both time and location, that the before mentioned predators are unable to rally their troops for a mass consumption.

This hatching process is natures why of a guaranteed survival rates that will allow the species to thrive. After this transformation, the adult will still take one day to three weeks to become sexually mature. The sexually mature adult male spinner will mass in swarms over the waters surface. The characteristics and timing of the nuptial flight or mating swarm will vary from species to species. Once the selection and the mating activities have occurred the male will shortly die and the female will wait for low light conditions before depositing her eggs, then she too will die and fall to the surface of the water only to be consumed by a waiting fish. The dead or dying adults will then lie on the waters surface with wings spread and, at that point, is referred to as 'spent' spinners.

Most Mayflies have one or two generations per year but can range from a couple to weeks to a few years. This whole process completes the lifecycle of egg (ovum), nymphal (larval), dun (sub-imago) and finally the sexually mature adult spinner (imago).

In order to identify this aquatic insect, you start at the upright wings. If you look closely the wing will resemble a stained glass window. Among other characteristics, the wings veins or venations are used to classify these insects. The other real important characteristic of the wing is its appearance. Are the wings clear and shiny or slightly discolored or opaque? The shiny wings will indicate that the insect is getting ready to lay its eggs and the slightly discolored or opaque wings will indicate that the insect has just hatched. This insect will usually lay its eggs during the low light conditions of dusk or a dark overcast day.

Since our quarry will consume nearly 85% of its nutritional needs below the waters surface, then it only seems proper that we should have a working knowledge of this all important food source.

Now, let's assume that you have decided to dive head first into the more technical aspects of the sport. This subject is called Entomology and to be more specific, Aquatic Entomology. You will quickly find that there is no shortage of reading material or videos covering this subject matter. The study of aquatic insects can drive a person into buying a can of worms.

Imitations, When, What and Where

The basic problem is the trout is a master of survival in an otherwise cool, shallow, fast moving and ultimately hostile environment. The fish's basic survival is directly attributed to its' ability to find an area that provides the four necessities of life; comfort, food, proper habitat and shelter. When the fish start to feed on aquatic insects, they will almost always become selective to the most prevalent species. They will intentionally ignore anything that doesn't imitate the same size, shape, color and action of the most prevalent emerging species. The angler's observations will dictate the required pattern. During the various emergences, the need for different imitations to duplicate the size, shape, color and required action is demanded in order to be consistently successful.

The advanced or expert angler will also react to the fish's feeding behaviors that may shift from the sub-surface nymph to the surfaced, struggling dun or to the egg laying or spent spinner. This is the key to the entire problem of what to use and when to use it.

Let's look at the source of all these imitations that are required for our fly box. Almost all of the Entomology books that I've read or seen, concentrate their efforts on insects found in the West and Mid-Western rivers plus the more famous Eastern streams. In fact, they are known for including European species that are not even in this country. There is some mention of Northern New England aquatic mayflies but sadly I found them all too short and many times all too inaccurate. That is not to say that all these mayflies weren't important, because they certainly are but only to those that frequent those particular waters. I was eager to learn all about the aquatics of my home waters here in Maine.

I started quite some time ago attempting to solve the riddle of what should the average fly angler carry in his/her fly box that would help during any circumstance occurring on any body of water in our home state. Yes, I know it's a tall order but like most problems, the answer was considerably easier that the question. If you've heard any of my lectures or attended any of my classes then you know that I like to keep things real simple and easy to understand.

I started the process just like everyone else and that was to read everything that I could on the subject, watched endless videos and talked to those who were much wiser than I and wanted to share their precious knowledge. I also utilized information received from professional entomologists, numerous authors, university entomology department heads, professional associations, Iowa State Entomology Index, University of Maine Entomology Department, The Smithsonian Entomology Department, The Federation Of Fly Fishers, University of Illinois Department of Entomology, Trout Unlimited and every angler I ever met on any body of water.

At first glance, the problem seemed rather formidable. Just go to the L.L. Bean, the Kittery Trading Post and any local Tackle Shop and check out all the fly cases and see the hundreds and hundreds of patterns that have been tied to imitate your favorite natural. Then take a look at the variety of books dedicated to your favorite aquatic insect and you will find hundreds and hundreds of imitations there too. In fact, the largest percentage of imitations sold and listed in pattern books are actually imitations of insects not even found in our northern New England area let alone our state waters.

Remember that we have over 500 species of Mayfly and that's impressive, but we only need to know about the ones that exist in our home waters and would be the predominate species at any given time. Thanks to a lot of work done by a lot of other people; I feel very strongly that this number can be safely reduced to a little more than a dozen imitations. How this occurred is by the process of elimination.

The key to understanding which fly to use, is solved by your own observations to figure out which food source interests the fish at any given time or place. This can be accomplished in any of four different ways. First, the angler can catch a fish and determine the fish's diet from the stomach contents, the most prevalent food source just prior to the catch. The second technique would be to catch the very same thing that the fish was catching and try to match that food item with an imitation from your fly box. Third, you could take a seine net and obtain an accurate sample of all the biological drift and determine the most prevalent food source from the samples in the net.

Last but certainly not least, is the ability of the angler to use nature as the guide to understanding the environment and obtain the various clues to determining the best possible choice. This done by careful observations made as you approach the water. Be alert to any insect activity at or high above the water. Check for bird activity that may be a sign of prominent insect activity. Check the streamside vegetation and the rocks on the edge of the water. Take the water temperature and use a seine net or pull some smaller rocks and boulders to see what's crawling or clinging to there undersides.

Our task is to reduce the numbers of imitations in our fly box but without affecting our ability to match the hatch. In Maine there are really only six out of the 16 Families that are of any real importance to the fly fisher. Yes, I know that all the other mayfly families can catch fish. But you have heard me more than once admitting that I play the odds and like to keep things simple. Remember the 142 species of mayfly in northern New England, well I know how to get rid of 128 of them, and here is how it's done. Many mayfly families simply don't do well this far north and therefore emerge sparsely and infrequently, resulting in a hatch that seldom becomes the prominent species, so I didn't consider them at all. A large number of early and mid-season species were not considered because they are simply outclassed by more significant mayfly and caddisfly hatches. Others were not considered simply because they don't emerge until after dark and most anglers don't or won't fish after dusk. I then eliminated several species that emerge only sporadically throughout the day. Some May Flies only emerge for a few days then just disappear. Now, although for those very few days they may be the dominant species, you would have to be very lucky to be there when the hatch occurred, so their importance is very questionable. Another fact that helped reduce the numbers were imitations that can quite easily imitate more than one family, genus and species of mayfly. The last groups to be eliminated were those whose differences were so minimal that only a trained entomologist could tell the difference and even though fish can be very selective during an actual emergence, even the smartest wouldn't be able to tell the difference.

Now, I know that every fly eliminated will catch fish on any given day with the right circumstances but we still have within our box an imitation that will be just as effective. Always remember that a few minutes spent searching for the most prominent insect emergence will eliminate countless hours of pure angling misery.

So, I concentrated my efforts on the selection of flies that will cover the most prominent hatches and yet still be able to imitate other species the same time. By doing this, the angler can have the ability to reflect the characteristics of several different species and can cover a multitude of selection errors, at the same time.

The end result is a list of 14 flies that should provide a very close match for almost any circumstance that the Maine angler might encounter. These 14 Mayflies are also numbered based on their probable emergence dates and periods of prominence.

These crawling mayfly nymphs hang out in medium fast riffles that have a gravel, pebble or medium-sized rocky bottom. They are 3-tailed flat-bodied nymphs that are colored yellowish-green or almost chartreuse. Emergence will take place downstream from the riffled areas, in the slower sections and side-currants that separate the riffled area from the run. The emerging nymphs will make several attempts to reach the surface, creating an inviting scene of hundreds of wiggly nymphs rising toward the surface causing nearby fish to take advantage of this activity.

Once the nymphal shuck is split several inches below the surface, the newly emerged dun will break the surface tension and sit on the waters surface.

While on the surface, the dun will spread its wing and allow them to dry in order to support flight. During this period, the dun will float freely in the wind like a small sailboat. The mayfly's color will quickly change from a yellowish-green to a medium olive. By the time the new Blue Winged Olive flies to the nearest shrubbery and completes the last molt, the color will once again change to a dirty, dark olive.

Like other early-season species, the attenuata nymph splits its shuck while still on the bottom and rises to the waters surface as a dun. Hatching usually will take place around 9 A.M. until early afternoon. Both the slightly larger cornuta and attenuata hatches will overlap one another but the cornuta species are usually more prominent, so plan accordingly. Check for the signals that will reveal the fish's preference for either sub-surface or surface takes. The glassy-winged adult (imago) spinner will return to the riffles within a 24-hour period. After mating in-flight over the riffles, the female will deposit her fertilized eggs by dropping the egg sacs onto the fast waters surface before falling back to earth as a spent-spinner along with the male.

Tactics

Check the water for rises which will indicate the fish's preference. If you see bulging or the flash of white color from the fishes open mouth, your best bet is to fish below surface. Use a wet or nymphal pattern and cast up and across. Then let the imitation sink and allow for a drag-free drift to the point where the line will force the fly up to the surface. Place your cast so that the ascending nymph or wet will rise just in front of a suspected lie.

If you want to allow the imitation to drift just below the surface, then grease the tippet from the butt section to within 6 inches of the fly. Now you can cast either up or down for a drag-free drift to the area you suspect a feeding fish will take the offering.

If the fish seem to be concentrating on the surface duns, then the same cast up and across will allow the offering to glide drag-free across the lie. If no takes, let the fly drift beyond the lie before recasting upstream. That way you will not spook the fish and give yourself another chance.

• Don't forget to mend your line for that drag-free drift or use a Serpentine cast for your downstream presentations.

These nymphs have a special identifiable feature in that the middle of the 3 tails is half the length of the two outer tails. Look for these nymphs to be around aquatic vegetation and under submerged gravel, rocks and boulders at the tail end of pools. Because these little darting swimmers can negotiate in the faster currents, they can also be found in fast gravel runs and riffles.

These nymphs feed on the detritus and debris that accumulates between rocks or around dead falls within the riffles and medium fast runs. When emerging, the nymph will crawl up to the surface by using aquatic plants, partially submerged streamside vegetation rocks and boulders.

These are highly specialized aquatic insects that can dart minnow-like in the warm water, when not perched on the shaft of aquatic vegetation or the slowly undulating filamentous foliage of sub-aquatic growth. They are very similar to the B. baetis, but can be quickly segregated by their three tails of equal length and generally larger size. These nymphs will (wiggle and squirm) to the surface of the water during the hatch. The hatch will often occur around mid-morning when the sun has warmed the water to a sufficient temperature. These insects are available to the fish all during the fishing season because these nymphs will continue to hatch from the third week of May until early in September.

After the hatch, you will see these newly emerged Mayfly adults (Duns) floating on the surface of the water. This nymph will lose its middle tail, during the transition from nymph to dun. The insect will spread its wings out to prepare for flight and often times during a slight wind these insects will be blown across the surface of the water and appear to be little sail boats. This is the time that these insects are most available to the fish and you will see the fish actively feeding on these Mayflies before the opportunity is lost when the insect takes flight. Of the 28 some species, only three are considered very important to the eastern fly fisher.

I should mention that because these insects will hatch during daylight hours instead of the traditional low light conditions of dawn and dusk, sometimes a strange event takes place, which confuses some anglers.

Here you are, sitting in your canoe and there are Mayflies all over the place in an obvious hatch but you can't see any feeding activity. This doesn't mean that the fish aren't aware of the hatch; they are just not comfortable with the bright sunlight and will prefer to concentrate on the nymphs as they rise towards the surface or that inhabit the more comfortable protection of the deeper water.

The majority of fly anglers in Maine rely on small wet fly patterns instead of Nymphs, primarily because they are easier to use, yet still produce the end result, catching fish. As the season progresses, the dry fly gradually replaces the wet fly, and the Nymph is generally ignored by the vast segment of our Fly Fishing Community. For those who know how to utilize the Nymph in its natural settings, will find far more productivity and under more circumstances than with any other fly design.

This will be true in the spring before adult naturals have emerged, throughout the season when hatches are sporadic, and at the tail end of the season when the large hatches have all but disappeared.

Look for these hatches to be in the quiet waters of eddies, pools and the side currants that have plenty of aquatic vegetation in the moving waters and alone the edges of ponds and lakes with shoreline aquatic vegetation.

Finding Nymphs can be as easy as walking along a stream and reaching into the water and removing a small rock. Turn the rock over and see who is crawling on or clinging to the underside of it. It is not unusual to see more than one species of aquatic insects living in the same area. Note the general color, shape and size of the most prominent mature species because that's your ticket to success. Take a close look at the end of the insect's legs and check for how many claws are present. If there is only one claw, then you are dealing with a Mayfly Nymph.

Check also the hump just behind the insect's head. This is called a wing case and you need to know if the case has started to split open. A split wing case will indicate that this particular species will hatch during the next low light conditioned event. If the case is not split then the hatch may occur within the next day or so. Based on your acute observations, your next task is to choose the right imitation to match what nature has shown you. Believe me when I tell you that there is no better thrill than to have guessed right, based on your newly learned skills and more especially if you are the one that tied the very fly that caught the fish.

The nymphs are dart minnow-like in the calm water when not perched on the shafts of aquatic vegetation. They are quite similar to baetis (BWO), but can be separated from them because of their three tails of equal length and their larger size.

The B. callibaetis mayflies are multi-brooded and it's not uncommon for three generations of these insects to hatch during one season. This means that on some waters, these insects are important from the middle of April until well into the month of October.

I will use the mature nymph heavily two weeks prior to the usual emergence date and when I notice the emergence occurring or the sudden rises, which are sipping in nature, I will then switch to an emerging pattern and work the imitation in the surface film.

Tactics

These nymphs are real quick and their movements are in short fast darting motions in amongst the aquatic vegetation. Use a full-sink or sinking tip line to get these nymphs down to the fish and use a short jerking retrieval motion.

These nymph patterns should be fished with a darting, twitching motion near weed beds, roots, boulders and undercut banks. These nymph patterns should be fished with a darting, twitching motion near weed beds, roots, boulders and undercut banks.

These are highly specialized nymphs that can dart minnow-like in the calmer waters when not perched on the shafts of aquatic vegetation or on the slowly undulating soft foliage of aquatic growth. Most of the important species range from 7 to 12mm in body length, while those of the Baetis, who prefer riffles and faster water, average between 5 and 8mm.

They are also dissimilar to the B. baetis by their three tails of equal length. Also, remember that these nymphs prefer the slower water then their cousins the B. baetis that, like the faster flows of riffles and runs.

This nymph will lose its middle tail during the transformation from nymph to dun. Look for the hatches to be in the quiet waters of eddies, pools and the side currents of runs.

The Callibaetis mayflies are multi-brooded and up to three generations may hatch during a single season where the environment is favorable. The hatching activity will vary from species to species and the timeliness of emergence will also vary according to whether the conditions are harsh or favorable in each geographical area. This means that on some waters, these insects are important from the middle of April until well into the month of September.

Their uniquely speckled or mottled wings quickly identify the duns of this genus. Of the 28 some species, only three are considered very important to the northeastern fly fisher.

Tactics

The nymph patterns should be fished with a darting, twitching motion near weed beds, roots, boulders and the underside areas of the bankings.

The 2-tailed epeorus nymphs require fast, pure water with very little or no pollution. The nymph needs vast amounts of highly oxygenated water, which is supplied by rapids, riffles and swift, gravelly runs. They cling to the bottoms of large gravel, rocks and boulders. Their flat heads, bodies and disc-like gill plates enable them to retain their tough existence in this turbulent environment. A unique activity of these nymphs is that they will migrate to the downstream sides of rocks and boulders where they will congregate a day or so before their emerging activity.

At nature's signal, which is a water temperature of 50 degrees or more for a few consecutives days, they will escape their nymphal shucks on the streambed and rise to the surface. Once started, this nymph will hatch daily even if the springs unpredictable weather and temperatures can drop back to the forties rather quickly.

Once emergence takes place and the adult spinners will return to hover over the riffles. These mating swarms will usually occur during the warmest part of the day, between noon and 2 P.M. and during the warmest days of late spring heat of 75 to 80 degrees, these spinners will return in the late afternoon or early evening.

You should remember that these imagoes mate, oviposit and fall as spent spinners in the white pocket-water or heavy runs.

Tactics

Fish will lurk in the small eddies and the smaller pools to opportunistically feed of this free lunch. These areas are just downstream from the riffled area where the insect have completed their mating activities and when they fall onto the waters surface where the currents will carry the spent spinners to waiting fish.

Now having said the above, even though these sub imagoes usually emerge in the riffles and pocket-water, pay special attention needs to be given to the downstream heads of pools where the helpless duns are swept along to the quieter waters below.

Tactics

Imitations should be fished in a way that will effectively simulate the emerging duns. Cast across and downstream and allow the imitation to drift across the feeding lanes and various lies. When the current starts to straighten the tippet, the imitation should be forced from the bottom to simulate the rising (emerging) dun.

When duns are being intercepted near or in the surface film, fly fishers need to cast upstream and allow the fly to float drag free to the feeding fish.

Don't forget to twitch or skitter the imitation to simulate the insects struggle to free itself from its watery environment.

The Stenonema vicarium nymph is the largest and first of these species to emerge in northeast waters. These nymphs are easily identified by their wide angled 3-tails. Each tail is almost 90 degrees to the others. They are one of the most popular mayflies in Maine waters, because these naturals usually emerge sporadically throughout the day, providing an easy day on the stream. Like the other clingers, they have the flattened head and body, including the femoral potion of the legs. This profile allows them to withstand the fast currents of riffles and runs.

These nymphs will usually migrate to downstream to the pools, quiet eddies and side currents of runs. The nymphs will often drift along the currents for long distances and thereby offering numerous opportunities to waiting fish. Like the other clingers and some crawlers, they can be found on the downstream side or rocks and boulders, as well as underneath the same.

During the emergence, these clumsy nymphs have a hard time getting off the water. They will flutter and bounce across the surface in their various attempts to achieve flight, creating such a disturbance, which often incites a feeding frenzy.

The spinner flights will usually occur just before dusk. Once the mating activity is complete, the female will dip her egg laden posterior into the water time after time to deposit the fertilized eggs. This is another activity that drives fish crazy. Oviposting done, the female will fall spent to the waters surface, joining the male who has preceded her.

Tactics

A weighted nymph fished on the bottom to imitate the swimming and crawling motions of the active nymphs is deadly. During emergence, nymphs labor strenuously in or just below the surface film to escape their shucks, causing such a commotion that fish find it irresistible. The duns have great difficulty in getting off the water, so wade to the middle of the stream, and then you can be in position to cast your offering to the deep side of pools while you rest the shallow edges. The shallow will often out-produce the more often fished deeper water. These emerging duns are a large sized treat for any opportunistically feeding fish.

These feeble legged crawling nymphs usually prefer the quieter water such as slow runs, side-currents and pools. They can also be found in eddies that have the faster water and moderate, gravelly runs. They can be found anywhere that detritus has accumulated which serves as an excellent hiding place with a built in food source.

During emergence, the nymphs will attempt to swim towards the surface in a real awkward and clumsy way.

Once they leave their bottom hiding places, they are at the complete mercy of both currents and fish. Once on the waters surface, these duns are quick to get air-borne.

A few days after the start of hatches, around midday, the spinners will begin their nuptial flights. The males will hover high above the riffles in swarms and the females will fly into the swarm and select a mate. After copulation, the females will repeatedly dip their posteriors into the water time and time again until the eggs have been deposited into the water. Having completed their duties, the male and females will fall as spent spinners onto the waters from whence they came.

Although the sub imagoes usually emerge for a one-week period, the spinners will be busy for a couple of weeks. Spinner flights will occur progressively later in the day as the hatches peak until the best flights will occur during early evening.

Tactics

Trout will gorge themselves on these emerging insects, so a nymph pattern can be deadly. Fish this pattern drag free through medium runs, the slower pocket water and side eddies for quick results.

You can also fish the emerger pattern drag free in the surface film to entice the fish that are feeding just below the surface.

When the duns are on the water's surface and trying desperately to get airborne, switch to a hackled imitation and fish with occasional twitches, to simulate this emerging activity.

Of the 27 species, only the above three are important to the northeast angler. These mayflies can exist in a variety of habitats. The subvaria species is the first to emerge, followed by the invaria and rotunda hatches about a month later. You should be aware that the subvaria species prefers slower currents, whereas the invaria and rotunda species will be found in the faster currents. Look for the subvaria in the gravel and aquatic vegetation of the slower waters. On the faster waters, the invaria and rotunda species can be found in the graveled riffles, slick runs and of course the eddies and side-currents of pocket water. As far as size is concerned the largest species is the subvaria (Hendrickson & Red Quill), followed by the rotunda species (Hendrickson & Red Quill) and last but not least the invaria species (Sulphur & Pale Evening Dun). These 3-tailed nymphs have a migrating instinct, which causes them to seek out convenient emergence sites adjacent to or within the fast-water currents. This mayfly hatch is one of the most exciting of the early season. This emergence is the most prolific and reliable hatch of the season. They wiggle enticingly during their ascent and like others of this genus; usually take several attempts to break through the surface tension. These nymphs are dark brown (almost black) in color, with some highlights of dark amber or dark olive. The dun will return to the riffled areas within a 24-hour period and the pre-nuptial mating swarm will develop high above the rough water. After the in-flight mating, the female will drop her egg sacs on to the fast water then both the male and female will fall to the water as spent spinners.

Tactics

In order to simulate the erratic swimming actions of this nymph, in the slower water, you should twitch the imitation with very short and rapid motion. In the faster waters, a drag-free drift is required with no nymphal movement.

Even though the Hatch Schedule indicates an emergence of late May to late June and the basic time frame should be from midday until 6 P.M. with a peak between 2 and 4 P.M., you need to consider the following conditions that will affect this schedule. The exceptions are during the unusual cold, rain or heat waves that frequent our northern New England weather. Hot weather will delay a hatch until later in the day or in some cases, early evening. During any unusually cooler weather, the emerging activity will be sometime during the warmest part of the day. Also during these cooler hatches, the duns will float along with the currents for extended periods of time, thus making themselves more available to feeding fish. Remember that inclement weather often provides the best fishing of the season. Accurate, drag free drifts are critical to success.

Tactics

If you see a fish rising to take offerings in the same area time after time, you can assume that the fish is holding in a lie and will continue to stay there until driven out by a larger fish or spooked by an impatient angler. You can now determine your choice casting position and the proper imitation to lure the fish to your leader.

Now, what happens when the fish seems to be rising in different locations? The problem is that by the time your ready to cast, this same fish may be out of range or your casting position is all wrong for the situation facing you. Fear not, there are things that you can do to counteract this situation. For one thing, stay clear of the wide, flat areas of the slower water. Instead, pay particular attention to the heads of these same areas or locate yourself in the tail of a pool where these duns and emerging insects are naturally funneled into a more concentrated mass. The big fish will almost always protect these optimum feeding lies and force out the smaller or weaker fish.

Another tactic is to fish the faster pocket water where fish will hold behind rocks, boulders and deadfalls within the white, rough faster waters. For surface feeding fish, use a dun pattern such as a subvaria Compara-dun drag free to the feeding lies or through the feeding lanes of opposing currents.

If you get repeated refusals, switch to a Hackled pattern that will imitate an emerging insect. Also, remember to through in the intermittent twitching and skittering motions of the dun trying to break through the surface film. These above tactics are also very true of the Hendrickson and Red Quill imitations.

This is the second major Stenonema hatch to emerge and usually follows the S. vicarium by a week or so. The name Grey Fox is usually associated with this species. While the name, Ginger Quill, is associated with the spinner of this same species. Although these hatches tend to be early evening activities, remember that in cooler overcast or rainy days, these hatches will be in the afternoon or in the rain.

These are fast water clingers, so you know that they will be found in riffles and runs. The Grey Fox is a little smaller then the S. vicarium. Both species have the same migratory and emergent habits. During this emergence, the nymphs will abandon their bottom hiding places between the heavy gravel, rock and deadfall areas and crawl or clumsily in a swimming attempt, struggle towards the surface. Once on the underside of the surface film, the newly hatched dun will make several vain attempts to break through the surface tension. Trout will feed eagerly on these drifting duns and a properly presented imitation is deadly.

Tactics

When you locate a feeding fish, cast upstream and allow a drag free drift to the fish's location. If the fish ignores your offering but takes another insect instead, change your presentation. Try the same cast but add a little motion to you imitation by twitching and skittering the fly. Chances are that the fish will now want your offering rather than taking a motionless natural. Keep in mind that the shallow, quiet waters below you can also provide excellent fishing.

Just like the S. vicarium, most of your beginning hatches will be in the shallows of both eddies and pools. Remember that the weak, dead and crippled naturals will drift downstream to funnel towards waiting fish. The fuscum spinner activities and falls will occur over the rough waters of riffles and white pocket-water.

Before the females arrive, the males will congregate high above the stream in mating swarms. Once this activity is sighted, you should take the time to tie on the appropriate spinner pattern and wade into the stream for a proper casting position. The casting position should give the casting angler the ability to cast from the rough, white water into the calmer pockets and side eddies on the streams edge.

This very impressive sight is your signal to prepare yourself for the soon to come, spinner falls. Usually within 30 minutes or so, the females will arrive; the mating rituals take place above the rough waters. Now, the fun begins because the female will fly to the waters surface and repeatedly dips her posterior into the waters surface to release the newly fertilized eggs. Their instinctive responsibilities complete, both the male and female mayflies will fall to the waters surface and waiting fish.

These nymphs are typical of their subgenera group, having the same robust features but supported by feeble legs. Because of the weaker legs this nymph prefers less turbulent waters that are located downstream from the riffles or in the various side-current of both rough and calmer waters. Their hatch is almost always incorrectly classified as a "Sulphur Hatch." This also explains the often-used common name of a "Sulphur Dun." The "Sulphur" activity usually occurs after the first week of May. This activity is caused by the invaria and rotunda species and not by dorothea. The E. dorothea hatches are usually later, when the invaria and rotunda activity has diminished to the point of completion.

The easily recognized differences between E.dorothea and other members of this subgeneric group are both in size and color. The E. dorothea species are smaller (by 2 hook sizes) and much lighter in color. There are several other differences such as, thoracic markings, dorsal spines and the adult dun size of at least a hook size smaller than either the invaria or the rotunda species. Another important difference is that the hatches in the afternoon are without doubt, those of the invaria and rotunda species whereas the dorothea will hatch much later, just before dusk and of course later on in the season then those of its cousins. The last and real major difference is that the dorothea species prefer the quieter and calmer waters while their cousins the invaria and rotunda species are predominantly fast-water dwellers. I should also remind you that the fast-water cousins can be flushed or drift into the quieter dorothea waters of the heads of pools and side-currents, adding to the "Sulphur Myth."

These small, yellowish mayflies will make their appearance when the early warm days of spring turn into the much warmer temperatures of late spring.

Shortly after the first series of hatches, the spinners will make their appearance above the riffles and mate in the usual generic fashion. The female will either jettison a single egg sac above the fast water or like others of her genera; dip her posterior into the water to release the egg sac.

After the mating rituals and subsequent egg-laying, the spent-spinners will fall exhausted to the waters surface. These spinners will normally be active at dusk and as the season advances the spinner falls will take place just before dark.

Tactics

Like the other Crawlers, dorothea emergers can't swim so there efforts are very clumsy because they will wiggle enticingly in an effort to reach the surface and emerge as a dun. Bottom bump your nymph pattern along the bottom or fish your emerger pattern on the surface and don't forget to add some action.

Because it is possible for the early dorothea species to hatch overlap the late invaria and rotunda hatches, you must take care and observe whether the fish are taking dorothea or the larger invaria and rotunda species. Trout are normally very selective to the size, shape and color of the dorothea imitations as these mayflies emerge in the slow waters and pools. The angler should take up the best casting position just prior to the expected fall. During the start of the fall, pick up a natural and carefully match the size, shape and color.

This mayfly is one of the largest and quite possibly most spectacular in the northeast. Its size is only surpassed by the mighty Hexagenia limbata. The hatch is considered to be one of the most thrilling of the season and many believe it to be the climax hatch of the northeast fly-fishing. Large fish that would usually be sitting on the streams bottom until dusk will often willingly rise with reckless abandon in the bright of day to grab these large tasty treats.

Like most burrowing nymphs, these nymphs avoid sun-light by being burrowed into the slower sections of soft-bottomed pools, mud banks, or pond and lake bottoms that are primarily mud or silt covered. The nymph will only leave the protection of the burrow to moult. In the faster currents of streams, these nymphs can be found in the silt, fine rich gravel and debris that accumulate between boulders and other obstructions.

Ephemera varia, a closely related species, can occupy the same areas as the guttulata and in the nymphal stage are very similar to the Green Drake. Some Ephemera nymphs can take more than one season to mature. These guttulata nymphs will go through some thirty moults before emergence takes place.

Around three days after the first emergent activity is observed, the spinners will make their appearance. Emergence usually takes place sporadically all day with a peak around 7 to 8 P.M. Fish will take the easy offerings of the awkward, struggling duns and spinners. An hour or so before dusk, the male imagoes can be observed high above the waters. They will descend lower and lower, with the sky so thick with them, it will look like a snowstorm in July.

Just before the arrival of the females, the males will be seen hovering erratically just above the waters surface, awaiting the arrival of the females.

Every now and then, some of the males will land on the waters surface to rest, causing the premature rise of smaller, unknowing fish.

At this point, I would like to mention a most peculiar trait of this mayfly. On the cloudy or overcast and sometimes rainy days, you already know that the emergence activities are different in that the activity will be much earlier in the day. This will result in the male making his appearance a few hours early. The resultant premature mating flight will exhaust the impatient male forcing him to fall the surface of the water frequently to rest. While somewhat rested, the male will attempt to get airborne but still somewhat weak will struggle to get off the water. These impatient male will even attack newly hatched females in their frustration to instinctively mate. It is not unusual to observe two or three males clumsily clasp to an uncooperative female dun. This impatience just causes the group to fall onto the waters surface providing yet another opportunity to waiting fish not to mention the anxious angler.

Once the females finally show, the nuptial flights commence, followed by the males falling to the waters surface as spent-spinners. Eggs fertilized, the female will begin to make their final descent. They will land on the surface of the water; the eggs are extruded, as the female lies semi-spent. This oviposting act is almost irresistible to waiting fish as a feeding frenzy ensues.

Tactics

Trout are very critical of the imitations offered. These are large mayflies so the imitation is also large enough for the fish to have a good look at the offering before deciding to act on its observations. Another disadvantage is that the peak spinner activity is in a short period of time and often just before darkness descents. This doesn't leave much room for error in either the cast or imitation. Remember that the female is almost twice the size of the male and fish will prefer the larger female to the smaller male. The use and tactics for both the nymph and emerger are the same as all other mayfly species. Remember that the reason the spinner is called a Coffin Fly is because the duns color changes to a Black and White after the final moult and prior to the nuptial flights take place.

Northeastern anglers praise this species because their arrival is one of the last predominant mayflies to hatch. This species will emerge from the middle of June through the second week of July, well past the peak hatches of mayflies in the east. For many years the ithaca species were mistaken for their cousins the S. fuscum and S. vicarium. This mistake is common and completely understandable. Most anglers do not really want to become too advanced in the technical aspects or their sport. The ithaca emergence takes place after the peak hatches of its cousin, S. fuscum by about a week or two. The two also share the same color but S. ithaca is slightly smaller in size. These clingers live most of their lives in the fast wasters of riffles and runs.

Some will migrate to the calmer waters of eddies and side-currents a few days prior to emergence. The duns are the same color as the S. fuscum but are actually larger. These nymphs will quickly rise to the surface film where they will split their nymphal shucks, then drift along with the current for a reasonably long period of time.

During the dog days of summer, you should look for any cooler, overcast or rainy days. This type of weather will promote active hatching of this species during both the mornings and early afternoons. The duns of the ithaca species have the same color as their cousins but are slightly larger in size and the same color, is pale in comparison. The real good news is that if you carry dark brown patterns in three sizes, you can imitate all three species.

Once the emergence starts and the emerging duns free themselves of their nymphal shucks, they will, like their cousins, drift along with the current for an extended period of time.

The delicate cream-colored duns will return to the riffles at dusk. These mating swarms will hover high above the rough water. Mating completed, the female will fly over the riffles and jettison the eggs onto the water, followed by both the males and females falling to the surface as spent-spinners. Once the spinner activity begins, it will only last for 30 to 45 minutes.

Tactic

Remember that during low water conditions, the fish are quickly spooked. Your attention should switch to the deeper runs and pools. Your leader will also change because the imitations are smaller and may require a smaller diameter tippet and a more accurate presentation. After a catch, always rest the water or go elsewhere. Prior to emergence, fish these nymphs on the bottom with occasional twitches to imitate the crawling motions of the nymph as it instinctively migrates to the quieter waters to await the urge to reach for the air-breathing world above. During the actual emergence, your patterns should be fished in the surface film and allowed to drift along drag free with the currents. Use fine-wired hooks for the surface work and the heavy-wired hooks for the sub-surface work.

These varia nymphs have plumage-like gills arranged dorsally in two rows on their abdomen and their heads are adorned with fearsome tusks. They are also long and slender, looking more like a swimmer than a burrower. Remember that these large insects take more than one season to mature to the point of emergence. Although they burrow into silt beds and mud bankings as do those of E. guttulata and E. simulans, but they can also be equally abundant in the faster runs and riffles where sand, silt and organic debris is collected between the rocks and boulders.

The cream-colored duns are erroneously referred to as the Yellow Drake and Yellow Dun. Oddly enough, the yellowish P. distinctus mayflies are commonly called Cream Duns and Cream Variants. This is why advanced anglers always use the less confusing scientific names to promote better and much more accurate communication.

During emergence, the varia nymphs wiggle temptingly towards the surface. Once there, the newly emerged dun will struggle to get air-borne. At this time, you should utilize as much imagination as possible when manipulating your imitation. The best emergence takes place on days that have both low humidity and a water temperature of less than 70 degrees.

Unlike the E. guttulata spinners that appear high at treetop level in swarms prior to ovipositing, the E. varia imagoes appear sporadically and are first sighted at shoulder height. The males will often appear prematurely and therefore must rest from time to time on the waters surface. During a good spinner-fall, many male spinners will rest intermittently on the surface film.

Once the females arrive and the mating activities are in full swing, the wise angler will select the best casting positions prior to the resultant spinner-fall. The first activity is when the female flies to the waters surface and rests on the surface trying to extrude her eggs. This in combination with the males falling spent on the waters surface plus the spent females is a real natures picnic for any fish around.

The large mayflies of the P. distinctus species, along with the cream colored duns of the E. varia, constitute some of the best evening fly-fishing of the season for every angler in the northeast.

The nymphs are very distinct and easy to identify from the other mayfly genera. Their most notable feature is the obvious gills, which extend laterally from the body in pairs on abdominal segments 2 through 7. Another easily recognized feature is the large pincer-like tusks. The obvious amber body is mottled with brown body markings that are arranged dorsally along its entire length.

An interesting fact is that over the years this Potamanthus species was mistakenly classified as a burrower. It was probably due to this species originally classified as a member of the Ephemeridae family. They have been since placed in their own family, Potamanthidae. The reason being that these nymphs are not burrowers at all, they are most definitely crawlers and slower swimming types of the Polymitarcidae family which inhabit the quiet stretches and medium runs as well as the eddies of faster pocket water. These nymphs are quite similar to the E. varia species in size, color, so many tiers will tie imitations that are a compromise between the two species. This nymph shares the same habitat as the Hexagenia and Ephemera genera.

Hatching is usually best on pleasant summer evenings of low humidity and a water temperature of less than 70 degrees. Prior to emergence, the nymphs will move about nervously on the bottom. The emergence starts off rather sporadically a few hours before dusk. The much heavier emergence will take place at dusk. Just about dusk, they will make a quick ascent to the surface, lingering momentarily as they transform into the delicate duns and struggle to get air-borne. If the weather is hot and humid these same hatches won't take place until after dusk. These duns will emerge in slow-to-medium currents.

Like the E. varia species, the mating activity begins at or just before twilight and is at shoulder height rather than, like most other mayfly species, high above the waters surface. Oviposting occurs around dusk and into the dark evenings. Like the E. varia, the P. distinctus females will fly to the waters surface to extrude her eggs into the water. Then both the males and females will fall spent to the waiting fish.

Tactic

One of the best imitations that you can use is the Light Cahill pattern. This is a time-tested design that has not been improved upon since William Chandler tweaked Theodore Gordon's original pattern. The reason for its success is not too surprising because the barred Wood-duck wing and light gingerish hackle blended over the creamish body of the classic pattern is very impressionistic of the S. ithaca, E. guttulata, E. varia and P. distinctus nymphs. All you do is add some motion to create a deadly combination. If your fishing the surface or just below it with your distinctus Deerhair Emerger, be sure to manipulate to simulate the various movements of the dun.

The nymph of the genus Hexagenia and Litobrancha recurvata are the largest mayflies in North America. These burrowing nymphs thrive on marl-rich, siltaceous bottoms laden with detritus. In these slow moving waters, the nymph gets its oxygen by undulating its body and plumage-like gills.

These areas can exist in lakes and ponds as well as areas between rocks, boulders, deadfalls and other submerged structures in rivers and streams.

These large nymphs can take as much as two years to mature enough to emerge as duns. They will moult every 24 days or so and can go through some 30 moults before their emergence.

During the emergence, the nymphs evacuate their burrows and ascend towards the surface reasonably fast considering their rather poor swimming capabilities. Once in the surface film, the newly hatched duns have great difficulty shedding their nymphal shucks. This problem will require them to remain on the waters surface for up to 10 or 15 minutes. You can imagine the commotion made and how it would create easy opportunities for the fish, let alone a number of birds eager to participate in natures banquet.

The mating swarms, nuptial flights and resultant spinner-falls all occur sometime after 9 P.M. Most anglers don't bother because of the lateness but to those of you that feel adventurous, here's the schedule. In some rivers and streams, the hatch and or spinner fall happens usually between 10 PM and 4 AM. This can be as little as a 20 - 30 minute event. This large nymph spends some eighteen months burrowed in the mud and silt, so as it ascends toward the surface, fast and agile, wiggling, sometimes taking over two minutes to get airborne. The final moult will take place usually within 72 hours after emergence. The male imagos are then ready to create the cloud-like mating swarm. When the females arrive and enter the swarm, nuptial flights are developed and mating takes place. The female will then usually fly to a riffled area and land on the water, where she attempts to extrude twin egg sacs containing some 8000 eggs. Having completed their duties the male and female spinners will fall to the waters surface as spent-spinners.

These mays are a yellowish olive to golden olive in sizes 6 - 8.

Tactic

Artificials should be cast and allowed to drift drag-free over the feeding fish. In the case where the fish seem to be taking only the duns that are struggling, imitations must be twitched and moved to look like the natural.

Because these duns appear at night, one casting tip is to pick your casting position during the late dusk and make your various casts. Once you've determined the correct distance, place a piece of tape at the point just beyond the reel. This way during the late night when visibility is very restricted, you can feel the tape and know that you haven't cast beyond the safety zone so you won't cast into problems after dark.

Fish the nymph with a lot of movement, and the dry, across, dead drift and then back up with short twitches.

Maine's Mayflies in Order of Emergence Without all the Fluff

Here are your best Imitations (Flies)

Pheasant Tail Nymph

This pattern will imitate the dark Ephemerella (Hendrickson, Red Quill, Pale Evening Dun, Cream Variant and Green Drake), Isonychia (Mahogany Dun), Paraleptophlebia (Blue Quill) and Epeorus (Quill Gordon) nymphs and of course the first important early spring mayfly, the Ephemerella cornuta,attenuata & Baetis vegans (Blue Winged Olive). Use this style for your emerging and sub-surface applications.

Bead Head Pheasant Tail Nymph

When you need to be down and quick, this is the trick. Use this fly for all your bottom presentations.

Gold Ribbed Hare's Ear Nymph

These flies will imitate the light Ephemerella (Hendrickson, Red Quill, Pale Evening Dun, Cream Variant and Green Drake), Baetis (Dark Blue Winged Olive) and Stenonema (March Brown, Grey Fox and Light Cahill) nymphs. Fish these patterns in the surface tension or just below the surface.

Bead Head Hare's Ear Nymph

Use your bead heads when you absolutely need to be deep and bouncing across the bottom.

Zug Bug

This pattern will imitate the Isonychia (Mahogany Dun) nymphs.

Bead Head Zug Bug

I'll let you figure it out for yourself.

Wooly Bugger

Black and Olive patterns will imitate baitfish, leeches and stonefly nymphs.

White Marabou

Add this to any pattern and the very fine barbules will give the imitation a much more lively action which can result in consistent strikes.