The caddis pupa is one of those flies that just about guarantees you some hot action pretty much all season – somewhere!

It is the stage in the life cycle of the caddis fly when the caddis larva changes into the pupa and begins its ascent through the water column to the surface.

Once the pupa has left the stream bed it is at the mercy of the currents, and pupae can be carried along for vast distances in their thousands during an intense hatch. It is at this time they become very vulnerable to the trout.

As they drift along, gases build up inside their casing, enabling them to rise closer to the surface where, eventually, the build-up of gases assist in the breaking of the shuck for the adult caddis to emerge.

I have written in the past about trigger points on flies; something that catches the trout’s attention and causes a reaction. With the caddis pupa there are several aspects which alert the trout.

The first is the fine trail of air bubbles left behind as the pupa rises in the current. The second is the prismatic effect the trapped gases in the pupal shuck give off as the pupa nears the surface and catches the sunlight.

You can imitate this in a number of ways as you tie the pupal fly.

First is to tie in a couple of strands of pearl sparkle flash at the tail of the fly to imitate the escaping air bubbles. The second is to add a pearl craft bead to the shank of the hook, which will catch the sunlight as it breaks through the surface film.

Fishing the pupa is the fun part as the action can be fast and furious and the takes quite savage.

I prefer to fish this particular pattern leading up to and through the evening rise and then after, into the dark.

The best method is to fish it across and down, starting with the rod held quite high. As you fish the fly across the current, lower the rod slowly until your line is directly downstream from where you are standing.

I have often spent an entire evening moving no more than 10m from where I started, with hits, hook-ups, nips and bumps at the fly happening almost non-stop.

I am often amazed at the number of fish that seem to all of a sudden appear when the caddis is on the move. Water that seemed dead all of a sudden bursts into life, with fish slashing everywhere.

The other bonus of using this fly, especially in low light, is that you do not have to go cross-eyed trying to see it on the surface as you would fishing dries for the evening rise – it’s all in the touch.

TYING INSTRUCTIONS and MATERIALS