The scud or freshwater shrimp

Start with threading the bead on the hook. If you have never seen a flytying bead before: notice that the hole through the bead is not a simple hole. On one side the hole is small on the other it is much larger. The idea is that the funnel shape of the hole will allow the bend of the hook to pass more easily. This only works if you start threading from the small hole's side. There is another reason to start from the small hole's side: the hook eye will disappear in the larger hole but will rest on the rim of the small hole. Sticking the bead on the wrong way round will make the fly useless because it will be impossible to attach the leader point to the eye.

Mount the copper wire directly behind the goldbead and tie in, in touching turns to a point halfway through the hook bend. Note that this is far further than you would normally go.

Bring the tyingthread slightly back with a few turns and create a dubbing loop by doubling the tying thread over about 10 cm. Tie the dubbing loop in by wrapping the tyingthread towards the end of the fly. Keep tension on the loop while you are wrapping, end with three tight turns.
What will happen is that the wraps close the loop on the hook side. There must be no gap between both sides of the loop close to the hook (If you see a gap it means that you will have to tie the loop in again and this time keep it under tension.)A gap will cause the dubbing material to fall out when you try to use the loop.
Bring the tyingthread in open turns to just behind the goldbead and hook in the dubbing twister. The springarms of the twister will keep the dubbing loop open.
I have included a picture of a dubbing twister. There are many models; this is a version without weight. You can see that the spring-arms are crossed, which means that when the twister is pulled the arms move towards each other closing the loop.

The dubbing I use comes from a rabbit's mask (Hare works too). You might have noticed that there are different kinds of hair in different spots on the mask. Some are spiky some are downy etc. and in all kinds of colours. We want a mix of these hairs. The way to achieve this is by cutting the hair as close to the skin as possible, don't forget the ears, collecting the cuttings in a container that is not too small and mix with your fingers. Simply stirring won't do it. What you need to do is take a clump of hair between thumb and forefinger. Pluck half away with the other hand, re-join and pluck again. Keep on doing this until all colours blend. Tedious, I know, but one mask will last many, many flies.
Back to the fly. Take a small clump of hair and stick it in the dubbing loop. The size of the clump is easy: take a clump you think will work and divide it in half, that should be about right.
The next step is very important for the result. Divide the dubbing over one side of the dubbing loop (see photo). We want a nice taper. The smallest amount of hair should be close to the hook. Take your time and keep your cool. Strive for a nice taper with no pills. The more even the taper the nicer the result. The dubbing can be controlled by putting tension on the dubbing twister. So don't try to imitate the photo: keep tension on the dubbing twister.
If you are happy with the taper you can start twisting the dubbing. Keep tension on the dubbing twister while you twist. A nice little brush will be formed. Keep twisting until you feel that the loop wants to double itself. Be careful it is possible to break the thread by twisting it too much. Do not pull too hard on the loop; allow it to shorten while twisting.

Wrap, using the dubbing twister, the dubbing brush in touching turns towards the hook eye. The last one third of the fly is the thorax. This part of the fly should be slightly thicker. If you feel that one pass of the dubbing leaves it a little bit thin just wrap over it again until it looks good.

The next step: ribbing.
The purpose of ribbing is to strengthen the fly and to add a little bit of sparkle to the fly, a bit of life. On this fly it also adds some weight.
To optimise the strengthening of the fly the ribbing is counter-wound. This means that if you wrap far side down you should wrap the ribbing far side up and vice versa.
So, counter-wind the ribbing in open turns to just behind the goldbead. It should take about 5 wraps (see photo).
At this point we are going to add some weight by making three more turns of ribbing just behind the bead. Tie the ribbing off with three turns of tyingthread and snip off the waste.

The fly is almost ready; all we have to do is secure the tyingthread. You have two options: half-hitches or a whipfinish. Half-hitches are easy but not 100% reliable. A whipfinish is better.
Making a whipfinish is not difficult it is just hard to explain. I tried on the page: How to make a whipfinish.

List of materials: