Gammarus, or freshwater shrimp (a.k.a. "scud") patterns abound, and for good reason as these little crustaceans live just about everywhere there is calcium and vegetation! Most prolific in spring creeks and in lakes, freshwater shrimp will comprise a healthy portion of a trout's diet when available so it is important to know how to mimic them.

Trying to improve upon established shrimp pattern is akin to improving the wheel or mousetrap. A typical effective pattern needs to exhibit the slender profile, proper color, and feeble attributes of the real thing. Most patterns achieve the end product using a spiky dubbing. That is fine if the tier can apply the dubbing in a way that will both keep the profile slim, yet imitate the tiny filamentous "legs" that protrude from the underside of the shrimp-a very important feature to imitate.

One common myth about shrimp is that they are ever-present in a curved form. This is actually a defensive/resting position. Shrimp are naturally very mobile, and when not clung to a piece of vegetation, they will be swimming quite adeptly. When swimming, scuds are rather straight in orientation. They will swim for a few inches, then stop to rest where they will sink in a curled position before taking another burst of locomotion. For this reason it is hardly inappropriate to add movement to your scud patterns when fishing them.

Gammarus are semi-transparent with visible digestive tracts. Their exoskeleton is largely clear, with the contents of their recent diet giving them their color. For this reason, a shrimp is usually near the color of the predominant bottom color of the water it lives.

It is also important to realize that since a shrimp is a crustacean it does not have a lifecycle like an insect. Immature shrimp look just like adult shrimp, only smaller. Thus, waters will have a wide variation in sizes available to the fish. I tend to start larger than life, and work smaller until the fish approve. I carry these in sizes #10 through #16.

As mentioned, shrimp need a source of dissolved calcium to build their shells. For this reason, alpine lakes, lakes with strong populations of lily pads, and acidic/tannic rivers will to have dense populations.

MATERIALS

Hook: Partridge CZ or CZF

Weight: Lead Wire

Thread: Lt. Olive

Tail: Lt. Olive marabou strands

Shellback: Lt. Olive Scud Back

Rib: Monofilament Thread

Body: Ostrich

Place the hook in your vise and coat the shank with a layer of lead wire. I adjust the lead diameter to suit the sink rate I want since I use these heavily in lakes.

Start your thread among the wraps of wire.

Coat the wire wraps and taper the ends.

Select a few strands of marabou, emphasis on few!

Measure the tips to be about equal to the gap of the hook.

Tie the tips in at the rear to imitate the posterior legs (shrimp do not really have tails).

Get some 1/8" scud back, or split some 1/4" scud back in half.

Tie the scud back in at the front, atop the hook.

Bind it back to the rear, stopping at the tail.

Advance your thread forward.

Secure the monofilament rib on the far side of the hook, again binding it to the rear.

From an ostrich feather, select 4-6 barbs.

Align the tips.

Tie them it, by the tips, at the front and bind them back to the rear.

Advance your thread forward again.

Wrap the ostrich barbs forward forming a dense, fuzzy underbody.

Secure at the front and clip the excess.

Fold the scud back forward to form the shell. Although the product stretches, resist the temptation to pull it taught or it will simply slide to the underside of the hook. Instead, pinch it in place with your thumb and forefinger as shown.

Catch it with a few wraps of thread. Let go and reposition as needed.

Fold the material back and secure with about 5 very tight wraps. This technique will ensure that the back does not slide out later on.

Make a half-hitch with your thread. If you do not, you may touch your bobbin as you wrap the rib and the thread wraps may slide off, undoing your previous work.

Counter-rib with the mono (wrap in the opposite direction as your body material) to secure the shell and give it segmentation. Be sure that you relax the tension on the mono as you come over the shell so that you do not torque it to the side. All the tension should be directed downward. If the shell slides during a wrap, reposition it before proceeding.

Build a neat head and whip-finish.

A completed LW's DL Scud!

The ostrich will slim down when wet creating a very accurate profile and well-represent the abdominal legs. If your local species have a different color, I find it best to alter the thread, marabou and scud back - keeping the ostrich natural.