Wednesday, 16 August 2017 12:28

Leave No Stone Unturned

GAIA instructor and angling guide John Boon visits the gin-clear rivers of Slovenia, where he comes across the stonefly, a fly he’d previously ignored…

Plecoptera, more commonly known as stoneflies, are a group of flies found throughout the world. They are a staple part of the trout and grayling diet, and while the Europeans and Americans recognise this, here in the UK they seem to be largely forgotten or ignored. I too guiltily ignored them up until a couple of years ago, but that changed when I paid my first visit to the towering mountains and gin-clear rivers of Slovenia.

Francis KIng Smith John Guiding on Lepena

The rocky River Lepena, typical stonefly habitat.


Flies From The Horror Show

Many different species of stonefly appear in abundance throughout Slovenia’s turbulent and rocky rivers. My guide for the week, and now good friend Kevin Smith of Sloveniaflyfishing.com, introduced me to fishing stonefly imitations.

As we tackled up Kevin pulled out a large foam creation with legs. It looked like it belonged in a horror show, rather than drifting on the currents of a clear blue river. “A Chernobyl Ant!” he exclaimed with a wry smile, in response to my puzzled look.

Chernobyl Ant Fly

He told me the fly represented many things, from stoneflies to grasshoppers, when tied in different colours and sizes. With much trepidation but also a little hint of curiosity, I tied it onto my tippet and headed out to the river.

Over the course of the day I was amazed how fish would come up from deep and take the fly with unbelievable confidence. Even fish that weren’t feeding would shamelessly come and have a look at it.

Needless to say the pattern proved very effective throughout my holiday in Slovenia; so much so that I began to wonder how it would fish back home on my local rivers. I knew there were good populations of large stoneflies as I had seen them in the past, but up until now had always neglected them.

When arriving back home, my ‘experiment’ began.

It quickly became apparent that the pattern worked phenomenally well, from large rivers to small streams. That week in Slovenia proved a real eye opener, and never again will I ignore the stonefly.

Flat Wings

In the UK there are 34 different species, which include the large stonefly (which hatches from April to June), the Yellow Sally (hatching April to August) and needle and willow flies that hatch throughout the year.

Stoneflies are easily recognisable; they have flat wings over their backs and often have two tails. When airborne you can distinctly see two pairs of wings, one behind the other. You find them frequently in the UK on rocky streams, and very occasionally in some rocky-bottomed lakes.

They have an incomplete metamorphous life cycle, meaning that there is no pupal stage. The nymphs hatch from eggs anytime from two weeks to two months after being laid.

As nymphs, stoneflies feed on a diet of weed and vegetation on the riverbed, with some species becoming omnivores, feeding on shrimps, and other aquatic insects. As the stonefly nymphs grow they split their outer shell several times, before emerging by crawling out of the water onto rocks or plants where they split their skin one last time and become adults, living from anywhere between a few days to a couple of weeks, depending on the species. They will then mate and after a couple of days of the eggs maturing, the female will deposit the eggs into the water.

A Fly With Few Patterns

The good news is that you don’t need many flies in order to effectively cover the stonefly life cycle. For nymphs, you could do worse than using Pheasant Tails tied on long-shank hooks in sizes ranging from 8 to 14. If you want to get a little more creative with fly choice, good patterns include Copper John, the Prince Nymph, and Kaufmann’s Stonefly nymph, again in sizes 8 to 14.

stonefly x3

The stonefly nymph…

…imitated with nymphs tied on long-shank hooks…

… with the addition of tungsten putty to get the fly down.


For the large stonefly nymph my personal favourite by far is Steve Thornton’s semi-realistic stonefly nymph. Although it may look complicated, it’s actually relatively easy to tie. I carry this in sizes 4 to 10, in brown and golden yellow. I like this nymph because it fishes very naturally due to the very small amount of weight used in the dressing. In order to fish it in deeper water, I add a couple of pieces of tungsten putty about three inches from the fly, which allows it to ride just off the bottom. Handily, this also means I lose fewer flies over the course of a season.

Francis King Smith Rainbow Arctic Silver

Both trout and grayling will make the most of the stonefly either in its nymph stage or as adult fished dry.


I fish my nymphs with a 9ft, 5-wt rod and micro-diameter line from Arctic Silver, on a short line of two rod lengths. I attach a 7ft leader of 6lb level Maxima to a tippet ring, where I add a 5lb tippet of two or three feet. I fish either a single nymph or a Copper John on the dropper, and a large fly on the point. I use a New Zealand-style indicator on the leader to detect takes, but it’s just as effective fishing the nymphs using a French leader setup.

Once I’m set up, I look to fish the faster runs, and pocket water, by casting upstream and following the line down, raising the rod as I go to stay in contact. Unlike most of my nymphing, though, I allow the line to drift past me and let it start to swing, sometimes employing a slow figure-of-eight retrieve. I find this method to be very successful, often with the takes coming just as it starts to swing. I see it like an induced take, but perhaps it could look like a real nymph that is crawling along on the bottom of the river.

Big Dries

Although I enjoy fishing the nymph, and have been successful with it, my most memorable days have been with the dry fly. For imitating the needle flies, I use Oliver Edwards’ Spent Needle fly in sizes 16 or 18, and F Flies in sizes 12 to 16 in yellow to imitate the Yellow Sally. I fish these much like any other dry fly on a 12 to 16ft leader and 3 to 4lb tippet. If you are fishing smaller rivers then drop your leader size down to suit.

I like to fish these flies on the smoother glides to rising trout, especially towards evening time. Often the adults will scurry across the water when egg laying, so a good tactic can be to lift the rod and shake the tip, which will impart movement on the fly.

In my experience, the best fun is when the large stoneflies are about, and when the fish switch on to them, you can enjoy fantastic sport.

Despite saying this, even when the fish don’t seem to be feeding on them, one presented over their window will often see it snaffled up. For the large stoneflies, the flies I use are Chernobyl Ant, Stimulators and my own detached bodied Stonefly, in sizes 6 to 10. Again I use a 9-ft, 5-wt rod, but with a short, heavily tapered leader of seven feet, to help aid turnover. A short stiff tippet of 6lb is also helpful, which I find also helps stop leader twist.

Splash And Crash

Although I have taken fish on smooth pools with these flies, I tend to concentrate on the broken water. Look to put the fly in pockets, and creases where faster and slower water meet. This is where the fish will lie, as it provides good cover and comfort from the faster flow.

Don’t be afraid to try slapping the flies down in this sort of situation either – the naturals are poor fliers and tend to land with a bit of a crash.

Be prepared for the take at all times, as fish in fast water don’t have much time to think, with the take usually happening instantaneously. If the fish doesn’t take straightaway, don’t be afraid of letting the fly skate. Many times I have seen fish chase a skating fly across a pool before taking it.

Kevin Smith John with rainbow

The big dry imitations should see most fish make it to the net.


Of course, the stonefly can also be fished ‘klink and dink’ style. I would recommend that you stick to short leaders, and lighter nymphs for this technique. The distance between the flies is of course dependent on the depth of water in which you are fishing. I like to have the nymph slightly overdepth to ensure I am fishing close to the bottom. Also I prefer not to use a large foam fly as the indicator fly, but a Stimulator instead. The reason being that foam patterns tend to be too buoyant, taking a lot to submerge them. This resistance can cause the fish to spit the nymph out of its mouth before the take has been registered.

Hopefully this article has given you a good insight in to the stonefly’s life cycle. I also hope it will have inspired you to give fishing stonefly imitations a try, and I trust that it will bring you success. On its day the sport can be exhilarating, with the fish literally hammering the fly as they take it. All that remains to be said is HOLD ON TIGHT!

Angler Profile:

John Boon is a full-time fly fishing guide and part of the pro team for Arctic Silver. He is an instructor with the Game Angling Instructors Association and International Federation of Fly Fishers to master and two-handed levels.



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