CDC Olive fly: How to tie this highly effective dry fly pattern

This CDC olive fly is based on the pattern devised by Gwilym Hughes that won him honours at the 1998 River International on the River Tweed.

It was designed to match a hatch of blue-winged olives, but it also works as a general imitation of various olive flies.

I’ve been using this pattern for several years and found it’s a great dry fly for catching brown trout and grayling throughout the season and is now…

One of my Go-To fly patterns.

So, lets take a look at…

How to tie the CDC Olive fly

Tying material list:

• Hook:        Kamasan B100 #14 & 16
• Thread:      Olive-brown 8/0
• Body: Wax olive-brown thread
• Rib: Fine gold wire
• Hot spot: Pearl Mylar
• Underwing: 6-8 deer hair fibre
• Wing: 3 Cul de Canard feathers
• Legs: Thread dubbed with Fox Squirrel

Step-by-step fly tying instructions:

Step 1. Place the hook firmly in the vice and start the thread 1mm behind the eye. Wind the thread in touching turns down the hook shank and catch in a length of fine gold wire.

Step 2. Take the thread back up the hook shank stopping 4mm from the eye. Wind the gold wire up the hook in 4 – 5 open turns to form the rib. Tie off and remove the excess wire.

Step 3. Wax the silk thread and catch in a length of Mylar tinsel and form a 2 mm hot spot.

Step 4. To form the underwing, prepare a small bunch of deer hair and tie in with the waxed thread.

Step 5. Take 3 Cul de Canard feathers and match-up their tips. Align the bunch of feathers on the hook with their tips protruding over the bend of the hook. Once in position, secure the feathers in with the tying thread.

Step 6. Dub the tying thread with a small pinch of fox squirrel dubbing. In front of the CDC-wing make two turns of the dubbed thread. Finally, form the head with the thread, whip finish, and apply a drop of varnish to the head.

The step of tying the deer hair under-wing is worth the effort because supports the Cul de Canard wing and aids the buoyancy of the fly.

I tie variations of this fly using a range of coloured tying threads from is light olive to dark-brown. These variations are useful when the standard pattern is refused.

Fishing the CDC olive fly

On wild rain-fed rivers and streams, dry fly fishing with this fly tied on the end of your leader is often the best approach for trout feeding on olives as they emerge.

It was originally designed to imitate blue-winged olives. However, I use this fly throughout the trout season and into the autumn grayling fishing season.

In March on the Welsh Dee, a size 12 fly is great for trout are feeding on emerging Large Dark Olives. As the year progress, hatching olive flies become smaller and therefore, it is best to use a smaller fly (#16).

I usually fish this fly in the slower sections of pools and riffles where trout and grayling are being selective.

Equipment-wise, I use a 9ft 5# rod for dry fly fishing. Attached to the floating line is a 9ft 5X copolymer leader tipped with a 3 to 4 ft length of 3lb fluorocarbon.

It is important to apply fullers mud to the fluorocarbon tippet to remove its shine and make it sink. Whereas, Mucilin grease is applied to the remainder of the leader.

I don’t use floatant on CDC dry flies. Instead, when the fly becomes waterlogged, I dry it using a microfibre household cleaning cloth, make a couple of false casts, and it returns to riding high.

However, there are floatants available for CDC flies. For example, Loon Blue Ribbon that is pure floatant powder with nothing extra.  Drop the fly with tippet attached into the jar, close the lid and shake it a few times.  The fly comes out with a powder coating that does a good job, and doesn’t change the structure of the CDC feather.

Finally, I hope this article stimulates you to tie this CDC olive fly pattern and test it on your local river or take a trip to fish the Welsh Dee at Llangollen, where it catches plenty of spring brown trout.