Estimated reading time: 12 minutes
As it is nearly May, I thought it was time for a little info on the famed Ephemera danica – The Mayfly.
This first part (of a two-part series) focuses on the culture and traditions of the Mayfly, and then continues to explore the life cycle. Part 2 is all about the techniques used to fish the various lifecycle stages – in both Rivers & Stillwaters.
This period of the year (mid-May Through to the end of June) is where virtually any angler can cast a fly and experience the magic.
It’s colloquially known as “Duffers Fortnight”.
What is Duffers Fortnight?
There are moments in the fly fishing calendar that transcend mere opportunity and become something closer to ritual. In the UK, none is more celebrated, more anticipated, or more deeply woven into our angling heritage than the so-called “Duffers Fortnight” – that magical window when the Mayfly hatch transforms our chalk streams and rivers into theatres of natural wonder and exceptional fishing – which any “duffer” can enjoy!
For those new to fly fishing traditions, Duffers Fortnight refers to the approximately two-week period, typically occurring from mid-May to early June, when Mayflies (Ephemera danica) emerge in their greatest numbers. These large, elegant insects with their distinctive sail-like wings create such abundant feeding opportunities that the trout abandon their usual caution and feed with reckless abandon.
The name itself reveals much about this cherished time. “Duffers” – a charming if slightly pejorative term for inexperienced anglers – suddenly find themselves capable of success that eludes them the rest of the season. Even those new to the art of fly presentation can often tempt trout during this remarkable window when fish focus so intently on the surface.
The Natural Drama Unfolding
To understand why this period holds such significance, you must appreciate the biological spectacle it represents. The Mayfly has one of the most fascinating lifecycles in nature – spending up to two years as a nymph burrowed in river sediment before emerging to live as a winged adult for just 24 hours or so.
This ephemeral existence creates an evolutionary imperative: mate quickly before time runs out. The result is a synchronised mass emergence that transforms riverbanks into clouds of dancing insects. For trout, this represents the feast of the year – large, protein-rich meals delivered en masse to the water’s surface.
The sight of a river during a heavy Mayfly hatch is unforgettable: the surface dimpled with rising fish, air thick with fluttering wings, and the distinctive “plop” as spent females (referred to as “spinners”) return to lay their eggs before dying.
A Cultural Institution
Beyond the natural phenomenon, this period has also evolved into something approaching religious observance within the fly fishing community. Anglers book their holiday time months in advance. Fishing clubs hold special events. Time-honoured traditions are maintained and passed to new generations.
On the famed chalk streams of Hampshire, Wiltshire and Berkshire – the spiritual home of this tradition – riverbanks that sit quiet most of the year suddenly buzz with activity as anglers gather to witness and participate in this seasonal pageant.
The River Test, Itchen and Avon see their bankside pubs filled with fishermen swapping tales of the day’s catch over a few pints. Gamekeepers who maintain strict limits the rest of the season might relax slightly, knowing the trout are so focused on Mayflies that they’ll recover quickly from the increased angling pressure.
What makes this period so culturally significant is how it connects modern anglers to centuries of tradition. When you cast a Mayfly pattern during Duffers Fortnight, you’re participating in a ritual that generations before you have experienced in nearly identical fashion. The same excitement, the same rises, the same satisfaction when a brown trout breaks the surface to take your fly – these experiences create a thread through time connecting today’s anglers with those who fished these same waters centuries ago.
Personal Reflections from the Bankside
I’ve witnessed countless “Mayfly” moments that remain etched in my memory. My most treasured memory comes from a quiet stretch of the River Avon. The Mayfly hatch was peaking as the sun began its descent, casting dappled light across the water. For two hours, I watched a pod of large trout – fish that had refused everything I’d offered on previous visits – rise methodically to naturals. When I finally made my imperfect cast with a loopwinged pattern, the largest fish rose in slow motion and confidently sipped in my fly. The resulting battle produced my personal best river brown trout at just over 5 pounds.
This is the magic of this period – it delivers those perfect, timeless moments that remind us why we fell in love with fly fishing in the first place.
Practical Advice for Your Duffers Fortnight Adventure
For those looking to experience this unique period, preparation is key:
Timing is everything: The exact timing varies each year depending on temperature and conditions. Generally, southern chalk streams see hatches start earlier than northern rivers. Keep in touch with local tackle shops or fishing reports to pinpoint the peak.
Technique: During heavy hatches, accuracy becomes more important than delicate presentation. Trout often focus on a specific feeding lane – getting your fly into this zone is crucial.
Etiquette matters: Popular waters get crowded during this period. Respect other anglers by rotating through pools rather than claiming a spot all day. Share information about where fish are rising and which flies seem to be working well, and maintain the gentlemanly traditions that make our sport so special.
A Tradition Worth Preserving
As climate change and environmental pressures affect our waterways, the predictability and abundance of Mayfly hatches face increasing threats. Many anglers report shorter hatches or reduced numbers in recent years. This makes our appreciation and protection of Duffers Fortnight all the more important.
By practising catch-and-release, supporting river conservation organisations, and introducing newcomers to the tradition with an emphasis on environmental stewardship, we can help ensure this angling celebration continues for generations to come.
Whether you’re a seasoned chalk stream veteran or a complete newcomer to fly fishing, Duffers Fortnight offers a window into what makes British angling culture so special – the perfect harmony of natural wonder, sporting tradition, and community.
When the Mayflies dance and the trout rise, time seems to slow, connecting us to the river, to each other, and to those who cast before us. It remains, for many of us, the most anticipated and cherished few weeks of the year – a period when the ordinary transforms into the extraordinary, and even duffers can dream.
We’ll come right out and say it, Mayfly season is one of the highlights of the fly fishing calendar for us all. As soon as the first mayfly hatches in your local river, you know that for the next couple of weeks the fish will be as active as they will all year.
Trout especially go nuts for mayflies, with some of the most aggressive and violent takes you will see all year. You will frequently see even the most learned and wary fish doing their best bird impression and aggressively flying out of the water to take a stranded mayfly.
The Mayfly
Mayflies belong to one of the oldest orders of insects, the Ephemeroptera. They have an evolutionary history dating back over 300 million years. ‘Mayfly’ itself is a general term for all insects in this class and the origin of the name is from the time of year that they hatch for most of the UK.
There are some common misconceptions about mayflies however, with the most prevalent being that they only live for a day. While it is true that the adults only live for a day while flying around, there is the nymphal stage to take into account also. Mayfly nymphs live buried in the bottom of the river for up to 2 years, during which time they grow up to an inch in length.
Once the mayfly nymph gets to its desired size, it swims up to the surface and sits there as it hatches. This is commonly known as the emerger stage, where the fly hatches out of the nymphal shuck and sits on the surface of the water drying its wings so it can fly away.
Another common misconception is that once the mayfly has hatched it becomes a true adult, this is not true as they turn into duns on the surface of the water and spinners later in the bankside vegetation. This almost half adult stage is a survival mechanism for the mayfly as the dun is duller in colour to be more camouflaged from any watching trout.
The spinner is the final stage of evolution in the mayflies lifecycle and they significantly glossier and longer tailed than the dun. One of the sights of the fishing season is to see the huge clouds of mayfly spinners form as they mate in the early evening.
Male mayflies tend to go back into the trees to die once they have finished mating, whereas the females head back to the water. They head back to the water to lay their eggs in a similar place to where they were born. Trout are looking up and waiting patiently for the spinners to land on the water however, so the mayflies perform a series of swooping actions to be in contact with the surface of the water for as little a time as possible.
Once the female has completed these diving motions and laid all her eggs, they will fall onto the surface of the water, paralysed with exhaustion. Making one of the easiest and most delicious meals for any waiting trout all season.
The Mayfly – Lifecycle
The lifecycle of the Mayfly is outlined below. The Mayfly is one of the up-winged flies where all of the stages can be imitated by the fly angler.
Lifecycle Stage – Nymph
Mayfly nymphs are quite large and are found in the silt of a river/lake bed. The nymphal stage usually lasts either one or two years where they are buried in the silt. When the nymphs emerge the best imitation for these is a fat, long nymph (beaded when used in heavier flows). When imitating the Mayfly nymph, please take note of the body thickness, the body should be thick and long. Mayfly nymphs can be up to 25mm long and 5 to 7mm wide (just about the same as a size 10 or 12 hook):
Once the nymph decides the time is right to hatch (this can be anytime between 1pm and 6pm) the nymph swims through the water column to the surface.
Lifecycle Stage – Emerger & Dun (subimago)
The nymph then transforms into the dun in open water and takes a few moments for its wings to unfold and dry out (it is at this point where it is able to fly). From the time the nymph arrives at the surface to when its wings dry out is the point that trout usually take them (either just below the surface or as they emerge), so don’t be too quick to retrieve your fly if it should start to sink!
You will also notice that when the trout takes the fly, it will be a very splashy take. They know that the mayfly is one of the best meals of the year and need to make sure that they do not escape. I have even seen trout slash at hatching Mayflies just to disable them and then turn around to take it, knowing it cannot escape.
Mayflies famously only live for one day. From the time they hatch, they will fly off to some local vegetation (the underside of tree leaves is a favourite spot, where they will rest (which can be for up to 24 hours) then transform again into a spinner (the sexually mature adult).
Lifecycle Stage – Spinner (imago)
Once the adult mayfly is ready to mate, they will form together in clouds above the river and dance. This is a stunning sight – when you are on a river in the early evening, just look up and watch them.
Here the adults mate and the female will return to the water to lay her eggs (she can lay up to 10,000 eggs in one evening).
Lifecycle Stage – Spent
Once the female has laid all her eggs, she will die and float away (this is called a spent mayfly):
Once the female Mayfly has laid her eggs, she dies, these flies float down the river with their wings outstretched, and are easy for the trout to intercept. Due to the large number of Mayflies which hatch, there are usually lots which are malformed when they hatch, these are easy pickings for trout.
From a fly fishing perspective the stages which we must try to imitate are:
- Nymph – mornings until 1pm
- Emerger – from noon to 3pm
- Dun – from noon to 4pm
- Spinner – from mid-afternoon until dusk
- Spent – from mid-afternoon until dusk
The Mayfly hatch usually starts in the south of the UK in mid- May and lasts for two weeks. The hatch progresses north around 100 miles every week (weather dependent) so Scotland will usually see a Mayfly hatch starting in early June.
The Mayfly – An Infographic
