Fly in Focus &Tying Guide!

Monday, 13 December 2021  |  Sarah

Fly in Focus: Dirty Bug Cased Caddis

Whilst caseless (free swimming) caddis like hydropsyche and rhyacophila constitute part of the Grayling’s diet during winter the various types of cased caddis are perhaps more common.  However, caddis larvae cases constructed of small pebbles provide adequate ballast so they remain safely tucked away for much of the time.  That said, any appreciable lift in water is bound to flush these juicy morsels out from under larger stones.  Tumbling down the river now, they become easy pickings for Grayling holding on the stream bed.
This simple tying has all the hallmarks of such hapless cased caddis and can be tied in a range of sizes to cover caddis larvae of over an inch long, or those that are much smaller. A black tungsten bead not only provides the required weight to get this fly down deep, but appears as part of the case too. 
Dirty Bug Yarn is an extremely versatile and durable material.  Although only one shade has been used here, it’s worth incorporating one strand of two differing colours (2 strands in total) for a more textured finish.
 
Tying Guide

Hook: Barbless Grub #10-14
Thread: Classic Waxed Thread 6/0 Dark Mocha Brown
Weight: Turrall Tungsten Off bead Large 3.3mm Black
Body (case): Dirty Bug Yarn Mottled Dark Green
Grub: Green Wool (burnt with lighter)
Legs: Brown Partridge Back Hackles

 
1: Having secured the bead at the eye, take a layer of thread down to the hook bend and catch in the pre form wool/yarn caddis grub

2: Next, arrange the loose partridge hackle fibres on both sides of the hook shank.  Don’t worry if these rotate around the shank a little, as this looks more appealing.

3: Catch in a length (or two) of dirty bug yarn and take the thread back to the hook eye, so it comes to rest immediately behind the tungsten bead.
 
4: Using touching turns that slightly overlap, form a neat, compact body (case) be winding the yarn to the hook eye.

5: Once you reach the point tie off the yarn and cut away any surplus. Complete the fly with a 5-turn whip finish at this junction.
 
Fishing Tips
Like all the other heavy bugs used for nymphing in winter, the dirty bug cased caddis is best presented on a short fixed line, typically known as ‘Czech nymphing’.  Discussed in previous newsletters this short line method allows flies to sink extremely and is very sensitive when it comes to take detection. 
To achieve optimum depth it’s best three flies are position all of 18 inches apart. Be mindful that you must keep on the move by gently wading, so your flies are constantly covering unexplored water.
 
Deeper water that prevents us from wading is best tackled using the ‘high sticking’ method of nymphing.  This involves 2-3 rod lengths of fly line outside the rod tip, when casts are directed upstream at 45 degree angle. Once sunk, the flies are then left to drift downstream some 45 degrees below you, before being lifted out to re-cast.  In its purest sense, watching the end of the fly line where it enters the water is used for take detection.  However, many nymph fishers prefer to use some sort of indicator that’s positioned at the fly line/leader junction.
 
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