DF22. The Pale Morning Dun Dry Fly

THE PALE MORNING DUN FLY PATTERN (PMD)
The PMD is a small mayfly found in most western North American trout streams and other locations throughout the world. On most days during the emergence period you can practically set your watch by the start and stop times of the hatch. On some rivers the hatch lasts for months. This gives the trout time to tune into this abundant food source at all the different stages; nymph, emerger, dun and spinner. There body size ranges from 6mm to 9mm in length which corresponds to size 14 to 18. Like other mayflies they get smaller as the season progresses. This phenomena lead to confusion in identification of species by the early angling entomologists, along with the even more confusing different body shades of the females and males which did not help classification. Body colours range from pale yellow olive, pale chartreuse to rusty orange.

'Pale Morning Dun' is a common term for different species of the insect family group called Ephemerella. It is hard to tell them apart without the help of a microscope. For the fly fisher it does not matter what sub species is hatching. In appearance, behavior and habitat they are so much alike. The PMD nymphs are crawlers. They live among rocks and debris feeding on vegetation. They have well developed legs that enable them to crawl along the bottom of the river without getting swept away. They stay hidden among the rocks and debris and are seldom available to the trout. They are not very good swimmers. If they do lose contact with the river bottom they can drift for long distances before sinking to the bottom again. They are very vulnerable if this happens. They have square shaped head and rectangular body. A Gold Ribbed Hairs Ear Nymph or Pheasant Tail Nymph is ideal as a PMD nymph imitation.

On rivers where the water surface is broken or there is a lot of fishing pressure, you may find the trout more cautious and feed exclusively on drifting nymphs ignoring anything on the surface. If you see drifting and  flying duns but no rises this is what the fish are doing and you will need to change tactics from surface dry flies to nymph fishing. The best way to choose your nymph imitation is to collect a few samples of the natural insect from the river or stream bed and match the size and color. Remember to look at them up to the light to see their true color as seen by the fish. Trout normally attack their prey from below and will look at them against the light of the bright sky. Nymphs that look black in the hand turn out to be brown or olive when the light is behind them. When the nymph is mature it rises to the surface, where the nymphal shucks split open and the duns emerge and fly off onto nearby vegetation. Soft hackle wet flies are ideal for imitating the nymph moving up the column of water to the surface. Emerger flies like Klinkhammers, Shipman's buzzer or Suspender buzzers make good choices for PMD nymphs hatching. 

The Pale Morning Dun sits on the water surface for a few seconds after hatching to enable the blood to pump up it's wings and for them to dry. The colder the weather the longer this takes. On windy days, gusts can topple over the drifting duns and drown them. If you cannot see any rises for surface floating duns during a hatch on windy days the fish are feasting sub surface on the unlucky sinking drowned duns as well as the emerging nymphs. Try using a partridge and Yellow Soft hackled spider wet fly, Gold Ribbed Hares Ear Wet fly, Blue Dun or Light Cahill wet fly to imitate drowned PMD's, depending on the local insects body color that can range from pale yellow, olive to tan. Wing color also varies throughout the world from pale gray to pale yellow. I often fish these wet flies on a dropper about 18 inches behind a PMD dry fly. The soft hackle or wet fly imitating the drowned dun often catches the fish when nothing else works.

If the drifting newly emerged PMDs have not been eaten by a fish during this vulnerable time, they fly off and hide on the surrounding vegetation. Within 24 hours the duns molt into spinners and and are ready to mate. Mating swarms are formed by the males to attract females. When a female flies into the swarm she mates with a male. The males fall onto the water spent and drown. The females return to the riverside vegetation for a short period whilst the eggs mature. When the eggs are ready the females fly out over the water, dip into the water, lay their eggs and then fall into the water spent. Try and scoop up a natural spinner floating dead in the water surface and match the body color with a parachute dry fly like a Greenwells, Tup's Indispensable or Gold Ribbed Hares Ear Parachute.

The Pale Watery Dun (Baetis fuscatus) likes streams and rivers. The spinner is seldom seen in large swarms and often falls to the water earlier in the evening than others. But if the trout are being picky about what they take they often prefer a Pale Watery rather than other spinners. This fly can be used to represent of the light colored mayfly duns and spinners. Treat with floatant and fish on the surface. Leave the fly to drift with the current. Every now and then tug it over a short distance to mimic take-off or give it a twitch to represent the fly being caught in the surface film just before death.

The Pale Evening Dun (Proclueon Pseudorufulum) is recorded all over Britain, but seems commonest in Ireland. It is also found in other parts of the world. It resembles the Pale Watery Dun with the exception that it does not have the Pale Watery Dun's additional hind legs. The nymph seems to like slow moving streams and rivers. A hook size 14 is ideal for this fly. A Gold Ribbed Hares Ear Shipman's Buzzer is a good emerger paten for this insect

DRY FLIES
The dry fly is designed to float on the surface of the water. To prevent it sinking, water repellent hackles are wound around the hook to distribute the weight over the surface of the water. The hackles also simulate the legs and splash of an aquatic or terrestrial insect trapped on the water surface. Most Dry flies are deceivers designed to imitate a specific natural fly like the crane fly, ant and hopper series of flies. Other flies like the Adams are more general designs that are just intended to produce an edible looking fly. Dry fly fishing has always been regarded as the supreme art in fly fishing circles. Accurate presentation of the fly can be essential. Trout will rise to a variety of natural flies but as far as the dry fly fisherman is concerned the mayfly hatch has to be the favored time. In almost all instances where trout feed on drowning insects the rule is not to move the fly. An imitation is far more likely to succeed if it is cast out and then left. So long as it is cast in the right spot.

The color of the fly is always important when matching the hatch, then size is the next important decision. The artificial fly does not have to be a precise imitation of the natural insect, but what is important is how and where it is presented in relation to the depth of water. This includes the height at which the fly floats above the surface of the water. Some fish will greedily take flies that are floating in the surface but ignore flies that are floating above it and visa versa depending on the conditions that day. Use your eyes to see which natural insects the fish are taking. A high-floating dry fly will have more chance of being taken on a bright day because of its visibility, but if it does not dent the surface film on a dull day it will be less effective. A fly floating in the surface on a sunless day leaves a much more visible halo of outlining light which surrounds it.

Always try and get the leader immediately in front of the fly to sink under the water as this makes it harder for the fish to spot. This can make the difference between a blank day or one with lots of action. When putting on floatant make sure you keep it off the leader. This is a common mistake that can affect your fish catching chances. Degrease the front 10 inches. Do not try and fish this pattern downstream as it will drown. Fish it upstream and look in front of you for where the fish are rising for the natural insect. Be observant. If the trout start to dine on spent spinners rather then duns consider changing fly patterns.

MAYFLIES
Some adult mayflies hatch throughout the year but other species hatch only during certain months of the year. The term Mayfly applies to all members of the order of insects not just those that emerge in May. There are hundreds of fly patterns tied to imitate the many different mayflies and stages of their development. The natural insect belongs to the group of insects called Ephemeroptera. Ephemeros means 'lasting a day' and peteron means 'a wing'. Mayflies have cylindrical bodies, slender legs and two pairs of veined wings which are held vertical when at rest. They are found all over the world and are commonly called up-winged flies in some areas. The adults do not feed and live for only a very short time: most less than a day and some only for a few minutes. 

The aquatic Mayfly nymphs moult anything from 12 to 50 times and take up to two years to reach adulthood. The fully grown nymph swallows air and floats to the surface where it emerges into the subimaginal stage. The mayfly is very vunerable to attack at this time from under the water surface and from dragon flies from above the surface. The dull winged subimaginal winged insect flies to rest on nearby plants if it survives. Mass swarms of emerging mayflies occur at dawn or dusk to reduce the chances of single insects being taken. The final molt to the hairless adult with shiny wings can take place in anything from a few minutes to a few days depending on the species. Adults are known as 'spinners' and when they die and fall onto the water they are known as 'spent spinners'. The prime motivation for spinners is to mate before they die. After mating female spinners drop their eggs into the water. Some females species swim down to attach their eggs to submerged vegetation or objects. Others just land on the water surface making tempting targets for hungry trout. In any square yard or meter of a stream there may be a few hundred to many thousand mayfly nymphs. They are an important part of any predator fish's diet.