Tying the Corixa pattern

We take a look at tying that essential stillwater fly pattern, the Corixa, which imitates trout favourite the Lesser water boatman.

Tying the Corixa pattern
Picture copyright © Piet Spaans, Creative Commons
Tying the Corixa pattern
Picture copyright © Piet Spaans, Creative Commons
Tying the Corixa pattern
Estimated reading time 6 - 9 minutes

George had great success last month with a lovely little Corixa fly expertly tied by angling coach Paul Ainsworth. Surprisingly, this stillwater essential was absent from our fly boxes (especially surprising given the number we have littered around the house.)

Paul told us all about this little bug and how he'd tied his imitation and we rushed home to have a go and to see what other patterns we could find for this versatile little fly to try out on our next stillwater trip.

What is a Corixa?

Corixa punctata, or the Lesser water boatman, is an aquatic bug found in stillwaters, from reservoirs to small ponds, and also in slow running water.

There are many different Corixa species in UK waters but they all tend to grow to around 1cm in length and have dark striped boat shaped bodies, hence the common name. They have three pairs of legs; a short front pair used for collecting food, a longer mid pair, and a long oar like hind pair which they use to paddle through the water.

Corixa spend most of their time at the bottom, in the weedy margins of ponds and lakes. As they are aquatic insects, they need to come to the surface regularly to breathe. To allow them to stay under water for longer, the Corixa collects air which it stores as a bubble on its body.

This bubble is a prominent mark on the little bug and makes it look like it has a silver bead attached, a great feature for the fly tier to imitate.

And, most importantly for the fly fisher, trout love them!

Where and when should I use a Corixa pattern fly?

Corixa are found mainly in the margins of stillwaters. They naturally prefer water depths up to about two metres, and congregate around weeds and reed beds, where they feed on the bottom on algae and other vegetation.

Picture copyright © Fly and Lure. Corixa pattern flies are ideal for targeting trout lurking in the weedy margins.

These flies are good for casting parallel to the bank, which allows you to fish the margins for a longer distance, targeting those trout feeding in the shallower waters.

On smaller stillwaters many anglers will cast out into the middle of the water, something a beginner to fly fishing may find challenging. However, fishing with a Corixa fly means those beginners whose casting distance is still quite small can target trout lurking closer in to the margins. This is especially useful if it's a windy day and you are struggling to get your line out.

It's a pattern that will work all year round, but is at its best in late spring and summer when the Corixa are naturally at their most plentiful.

How do I fish a Corixa fly?

There are both weighted and buoyant variants of the Corixa fly pattern.

The Corixa naturally lives at the bottom of stillwaters. Once its air supply has been used up it will rush to the surface, collect more air, then rush back down again, so using a weighted fly will help you to imitate the bug's natural movement more easily, and get your fly back to the bottom more quickly.

They are easily retrieved with a jerky, figure of eight to mimic the bug's rowing movement back to the surface to replenish their air supply.

Tying a Corixa pattern fly

The two most distinctive features of the Corixa are probably its silver air bubble and its long hind legs. Some fly tyers use hackle to give the impression of the insects leg, but as the legs are quite prominent, others, like Paul's pattern, use rubber to create a more defined look.

The silver bubble can be imitated by various means; a body made from metallic litebrite creates a good impression or a strip of flash is equally effective.

The red headed Corixa

Starting with Peter Gathercole tying a red headed Corixa. The Corixa has prominent red eyes (these darken as it matures) and Peter's fly pattern highlights this feature.

This is a weighted variant so Peter starts by tying on fine leaded wire. He creates the body from pearl litebrite, presumably to imitate the Corixa's air bubble, but tones down the effect by blending it with tan hare's fur.

To increase the fly's durability, and make it more like the hard shell, as a finishing touch he varnishes the head and back.

The floating Corixa

Now Steve Cullen tying England International Ben Bangham's Floating Corixa. The fly's buoyancy is achieved by the addition of craft foam to create the body and, like Peter, Steve also uses litebrite to represent the bug's air bubble.

The wire woven Corixa

Here Lawrence Finney, from Finney's Flies, ties his version of a Corixa fly. He adds wire to his pattern to enable it to sink quickly into the reed beds when cast out.

Unlike Peter Gathercole, Lawrence adds his wire over a bed of black thread which he uses to build up the humped body shape of the Corixa.

He then cleverly uses a shuffle weave of two wires, black and silver 0.2mm wire, to create a black top and a silver underside (representing the Corixa's distinctive air bubble.)

He creates the legs from black pheasant tail and then builds up the head with the black thread. He finishes the fly with varnish not only on the head but also on the pheasant tail legs, using it to bunch up the feather fibres to create more pronounced looking legs.

Corixa Cruncher

And finishing with something a bit different, here is Davie McPhail tying a cruncher in the colours of a Corixa.

Davie uses crinkle and pearl flash to create the impression of the Corixa's air bubble and a natural cock pheasant tail feather to create the dark brown back.

This fly will also sink quickly as he ribs it with fine silver wire.

Davie uses a white Uni thread 8/0 as the tying in thread and has a neat trick to save you tying in another thread to create the Corixa's black head; he colours a section of the thread with a black permanent marker and then uses it to create the Corixa's pronounced head.

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