Cased Caddis
  |  First Published: May 2005


The magic and mystique that surrounds flyfishing for trout stems from the sight of trout leaping and rising to the many insects that inhabit and hover above our streams and lakes. The excitement this creates is increased ten fold when that leap or rise results in your delicate imitation being taken in place of a real insect.

Having said that, it is important to remember that only about 10% of a trout’s food comes from terrestrial or airborne insects; the other 90% resides on the lake or streambed. Various nymphs and larva are possibly the most prolific sub-aquatic organisms targeted by trout, and one of the most common of these is the caddis.


Caddis larvae are a slow moving food item so trout can grub around stream and lake beds to seek them out at leisure. Therefore, they have many different forms of accommodation such as reed stems, hollowed out pieces of dead grass, sticks, bark, sand and stone. Other caddis larvae weave webs to live in and occasionally, really daring larvae choose to live as free swimmers.

The famous American flyfisher and flytyer Gary Lafontaine dedicated much of his angling life to the study of caddis flies and conducted long, in-depth studies of the larval and pupal stages as well as the adult caddis. He wrote ‘Caddis Flies’ – a flyfisher’s classic, which I encourage all budding flytyers, flyfishers and amateur entomologists to read.


Caddis larvae seem to be most active in the early morning and evening in low light conditions. I have had most success with this fly while fishing it in the faster runs and riffles close to the bottom under an indicator. In these runs and riffles, caddis are more likely to be dislodged from the stream bed by the current, cattle walking across the stream or even wading anglers. The dislodged larva are readily accepted by trout!

The larva drift freely in the current and are always going to be close to the streambed so this is where your imitation needs to be. Assess the depth of the water and adjust the length of tippet between your indicator and nymph – you know you are at the right depth if you occasionally hook the bottom.

I always use a rather large, bushy dry fly as an indicator, such as a Royal Wulff or Humpy, as I have occasionally taken fish on these as well. I remember fishing a nice pool on the upper Mitta Mitta River when the indicator was taken in a bash-and-crash style of rise. The fish was obviously hungry! On landing the fish, I found both the indicator and nymph firmly embedded in its jaw about 1cm apart.


This fly pattern is tied to represent the cased caddis often found in many Victorian alpine streams. The real thing has a case constructed of fine grains of sand, and the larva living within the case is bright green with a jet-black head and legs. Caddis larvae move about the streambed by dragging themselves with their strong pro-legs. About one third of the larva is exposed from the case while they are on the move, and that is the trigger for the fish as they go for the exposed larva. Although this fly looks difficult to tie, it is really quite easy, and the materials help to closely match the natural larva. The clipped pheasant tail is the actual colour of the natural casing and gives the fly the fine taper of the case. The thinly dubbed hairs allow the green underbody to show through, giving a translucent effect, which a number of cased caddis have. Finally, the green glass bead replicates the larval segment extending from the case and the black midge dubbing gives a nice buggy imitation of the larval head and legs. You can vary the colour of the underbody and glass bead depending on the colour of caddis larvae in your particular area.


A 4 to 5 weight outfit is ample for this type of fishing, especially on the smaller alpine streams and rivers. You can use a 6 weight outfit on the larger streams if you like and a double taper line is fine, as long as it matches the rod. I use a leader of about 12ft in length, tapered to around 2kg. However, you can lengthen and shorten your tippet depending on the depth of the water you are going to fish.

I tie all my leaders but you can purchase packaged leaders in varying lengths and breaking strains from most tackle stores. These commercial ones are mostly knotless and tapered, which is ideal if you are a beginner. If you tie your own and are sick of endless blood knots, try using a surgeon’s knot to connect your sections of leader and a surgeon’s loop at the butt end to attach to your fly line.

For beginners who want to know more, there will be a small section on leaders in a coming issue.


HOOK: Mustad R50 #10-16

THREAD: Black and fluoro green

THORAX: Glass bead and midge dubbing

BODY: Hairs mask

UNDERBODY: Fluoro green spanflex

RIB: Spanflex

TAIL: Clipped Pheasant tail


Slide the glass bead onto the hook then place the hook in the vice. Using fluoro green thread, build a small bed for the glass bead to sit on, apply a drop of superglue to the thread, then slide the bead onto the thread and let it set.


Attach the black thread behind the bead and at the same time secure in a section of spanflex. Take the tying thread to the bend of the hook and tie in the clipped Pheasant tail. Wind the spanflex to the hook, bend to form the underbody, and secure in place with the tying thread. The tag of spanflex is left to use as the rib. Now apply some hairs mask dubbing to the thread.


Wind the dubbing on sparsely so that the underbody shows through right up to behind the bead. Wind the spanflex on as a rib and tie off behind the glass bead and whip finish. Re-attach the thread in front of the bead and apply black midge dubbing to the thread.


Take two turns in front of the bead then form a small head with the thread tie-off and whip finish.

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