Fly Fishing – Using the Sawyer Killer Bug

Frank Sawyer’s Killer Bug is deadly on chalk streams. Although designed for catching large numbers of grayling, it can also be effective against trout. The Killer Bug technique is unique, but can be learnt quickly by anyone who is willing to learn.

As far as I am aware, no one is really sure why the Killer Bug is so effective. My grandfather, the late Frank Sawyer, originally designed it to imitate the freshwater shrimp Gammarus Pulex, but it is just as effective in water without the crustacean, or when tied several times larger than is natural. The Killer Bug is usually taken when it is made to ‘swim’. More often than not this will be in the ‘shrimp zone’ but it can sometimes be taken above this area while apparently ‘swimming’ to the surface. As shrimp only inhabit the bottom part of a chalk stream it is difficult to see why the fish would take an artificial shrimp in the wrong place. Pigs may fly, but who would eat a bacon sandwich if it was floating several inches above the table? My grandfather suggested in ‘Nymphs and the Trout’ that the swimming bug resembled a hatching sedge making its way to the surface. Some quite well known fishermen claim the Killer Bug looks like a maggot or a grub that has fallen into the water, others say it looks like a food pellet to stocked fish. I have even seen small pike follow a Killer Bug through the water (although never take) so perhaps it resembles a small fish under some conditions.

The widely reported chalk stream malaise and decline in fly abundance is a definite cause for concern, but we sometimes forget that perhaps up to 80% of a trout’s food is taken sub-surface. Unless we are lucky enough to be fishing during a hatch, the trout may not be that interested in dry fly. This presents a problem. Like most fishermen, I fish when I can find the time, hatch or no hatch. Fortunately fish have to eat. If there is no surface fly, or they seem to be ignoring any fly and hatching nymph that are present, then they must be eating something else. It is often the freshwater shrimp.

It is always amazing how often fishermen fail to spot the huge number of clearly discernible fish in a stretch of water. The first step in Killer Bug fishing is to try and operate where the fish are visible. It is not essential, but it makes the technique easier and much more fun.

The Upper Avon, where I enjoy most of my fishing, has a grayling population that far exceeds that of trout. It is very tempting to ignore the grayling and keep moving upstream on the hunt for trout. My grandfather had a phrase for this: “Giving up gold to fish for tinsel.” Grayling are a true wild fish and a joy to catch. Not only do they provide worthy sport, but they taste good and are more plentiful than trout. On many occasions I have been fishing for grayling and a previously hidden trout has darted out of cover to take my Killer Bug. For the out-of-practice fisherman, or those of us who fish infrequently, grayling are an ideal way to start the day and polish up those Killer Bug skills before tackling the big trout a few hundred metres upstream. My father and I sometimes make a day out of grayling fishing with a Killer Bug. The goal is to catch every single grayling in a shoal before moving on. It is not unusual for us to land well over 50 grayling in 3 or 4 hours of fishing.

The most important part of the Killer Bug technique is making the bug swim in the correct manner at the right place. To achieve this, the bug must be allowed to sink to the bottom part of the river and then made to swim up to the surface in a smooth, natural manner. Where to start the swimming motion will depend on the location of the fish and the current flow. The point at which the swimming motion commences is known as the activation point. The cast has to be made far enough up stream of the activation point so the bug can sink to the right depth before the swimming motion is started. This point is known as the cast area. Here’s the good bit. As long as there are no weeds or obstructions, the bug can bounce along the bottom for some distance before commencing the swimming motion. This reduces the requirement for accurate and delicate casting as anywhere upstream of the cast area will be satisfactory. All the fisherman has to do is allow the bug to bounce along the river bed until it reaches the activation point and then start the swimming motion by slowly lifting the rod tip and maintaining a tight line. The peculiarities of weed, obstructions and currents can occasionally prevent the fisherman from carrying out this technique, and fish have a habit of feeding in awkward places, but there will be many locations on the chalk stream where this technique can be used. Trout can sometimes be startled by a bug rolling along the river bed but grayling are hardly ever troubled.

The activation point is easy to calculate. To be most effective the Bug should be made to start swimming 1 to 2 feet in front of the target fish. This makes the activation point 2 feet in front of the target fish if it is located at the bottom of the river, or further upstream if it is feeding nearer the surface. The cast area will depend completely on water depth and current speed. Unless it is a particularly deep pool or a very fast current, 4 feet is a good starting point, but trial and error will ultimately be the deciding factor. If it is clear that the bug has not sunk to the bottom before the activation point, move the cast area further upstream.

Knowing when to strike is without doubt the hardest part of Killer Bug fishing. I have seen fisherman draw in their line and cast again blissfully unaware that several fish have taken, and then spat out, the Killer Bug. The strike is easiest when the fisherman can see the bug and fish clearly, but can also be made when just the fish is visible. It is even possible to use the line at the point where it enters the water as a strike indicator and the very best Killer Bug fishermen can be successful by striking on instinct alone.

With good light conditions and clear water it is very easy to see bugs in the water and even easier to see the fish. What could be simpler than watching the Killer Bug enter the fish’s mouth and then striking? Unfortunately fish spit out bugs very quickly and the act of striking can take a long time in comparison, particularly if the fish is a long way off or there is a lot of slack in the line. That is why Killer Bug fishing is more successful close in; it removes the need to anticipate the fish’s action. If the fish is more than 15 -20 feet away, the strike will have to start before the fish has taken the bug due to the time lag between striking and the hook being set. Fish very rarely hook themselves on a Killer Bug.

It is also relatively easy to judge when a bug has been taken by watching the fish. This is the more common technique as it is very difficult to keep watching a tiny Killer Bug as it sinks several feet away. Although you may be unable to see your bug, you should have a reasonable idea of where it is located in the river. Any fish that runs towards that rough location and then stops may well have taken. This is the time to strike. If your cast has been very accurate the fish may not have to move that far to take your bug. In this case look for a flick of the tail, a sudden move of the head or a slight upward tilt. Ironically, inaccurate casting, that causes a fish to move to your bug, is sometimes more successful as it can be easier to identify the take.

Occasionally it is not possible to see either the fish or the Killer Bug. Perhaps the river is too dirty or the light is wrong. In these conditions it pays to watch the line at the point where it enters the water. When the bug is swimming, watch for tiny, almost imperceptible checks or movement at the point where the line dips beneath the surface. If you see such an indication, strike. Occasionally the fish will take with a thump and there will be no mistaking the act, but this is rare.

Fishing on instinct alone is the most difficult of the techniques, but really it is just common sense and experience. Common sense dictates that the Killer Bug is most likely to be taken in the first few seconds of the swimming action while in the ‘shrimp zone’. Experience tells us that grayling and trout are predictable; most fishermen know the places where they are likey to feed. Combining common sense and experience leads to an instinct for where and, more importantly, when a fish is most likely to take. Striking at this point may result in success. It is certainly worth a try if it is not possible to use any of the other techniques.

No matter how you caught the first fish it is important to ‘slime’ the bug, nylon cast and leader. Fish slime has several properties which are extremely useful to the Killer Bug fisherman. Firstly the slime makes the bug taste more natural. This causes the fish to take more time in spitting out the artificial, giving valuable extra milliseconds in which to strike. Slime on the cast ‘wets’ the nylon and allows it to slip through the water more easily. This makes the bug sink quickly and force is imparted along the line with less water resistance. Finally, slime masks the distinctly human smells, such as soap or tobacco, which are left in minute traces on everything we touch.

There are no promises in fly fishing but a competent Killer Bug technique on the chalk stream is as close as one can get to a guarantee while still adhering to club rules. The technique is simple, effective, great fun and, once mastered, it is never forgotten. The Killer Bug’s biggest attraction is arguably its versatility. In today’s hectic lifestyle, with the associated pressures on valuable fishing time, and the notable decline in fly life and surface feeding, it is perhaps more relevant to modern fishermen than ever before. After more than 50 years of distinguished service the Killer Bug remains a deadly enigma, and long may it remain so.

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