Scuds are crustaceans and are a favorite food source for trout in many lakes and streams. They range in size from about an 8 down to ridiculously small. Although the naturals are often associated with weed beds, I've found trout will take their imitations just about anywhere, particularly on overcast days.
For this simple scud, I'm going to use a Dai-Riki #125 size 16 emerger hook, and for thread, UTC 70 Denier in light olive. Start your thread about 1/3 of the way down the hook and then take wraps well down the bend before returning to about halfway between the hook point and the barb.
Many different types of dubbing can be used on this pattern, but I really like an Antron Australian Possum blend like the ones shown here. It works not only for the body of the fly, but for legs and antennae as well. For the antennae, pull just a thin wisp of dubbing, I'm using a color called smoky olive, and then snip one end off close to your fingertips. With a pinch wrap, secure the small bundle to the hook and take wraps of tying thread to direct it down the bend. You can then snip the fibers off to represent the antennae.
For the rib, which helps to create segmentation, gold Ultra wire in the small size works very well. An 8 inch piece will make several flies. Attach one end of the wire to the top of the hook shank and then take wraps of thread to secure it down the bend.
For the back of the fly, Thin Skin from Wapsi works great. Here I'm using something called Tan & Black Fly Speck, which I've cut into 1/8th inch strips with a paper cutter but scissors will also work. Although Thin Skin has no adhesive, you still must separate it from it's paper backing. Secure one end of the strip to the hook shank, leaving about 1/16th of an inch behind the eye. Carefully wind your tying thread rearward, all the while keeping the Thin Skin centered on the hook shank. Once again take your wraps fairly far down the bend.
To form the body and legs, I'm going to use the same smoky olive dubbing as I used for the antennae. Form a dubbing noodle about 3 inches in length. I like to add just a hint of orange to the middle of the noodle to liven the pattern up but this is definitely optional. Starting at the tail, wrap the dubbing noodle forward to form a plump little body that's tapered at both ends. Now pull the Thin Skin forward, once again keeping it in line with the hook shank. Take 2 or 3 wraps over the Thin Skin to secure it and then 2 or 3 jam wraps in front of it. Snip the Thin Skin off as close as you can without cutting the thread wraps.
With the Thin Skin secure, begin making open spiral wraps with the Ultra Wire. The more pressure you use, the more well defined the segments will be.
At the head of the fly, secure the wire with some nice tight wraps of tying thread. You can then helicopter the wire to break it off clean. Finally, whip finish a small head and snip or cut your tying thread free.
A drop of head cement helps to insure nothing will come unraveled. This high tech dubbing brush made with the hooked side of a piece of Velcro and an emory board works just great for teasing out the possum and Antron fibers to form the legs of the scud. Snip the fibers off so they're about a hook gap in length.
Try this simple scud not only in olive, but tan and gray as well.