The following is reprinted from Philip Rowley,s website: Fly Craft Angling with his permission.

Scuds or freshwater shrimp are one of the premier food sources for trout in many of British Columbia's stillwaters. Next to chironomids scuds are the most important food source in our interior lakes. Christened the meat and potato food source these armadillo like crustaceans are rich in protein. The pink colored flesh of the Kamloops Trout is a result of the carotene absorbed from digested scuds. Any body of water containing a vibrant population of scuds signifies, fat healthy trout. Like aquatic rabbits scuds are incredibly fertile. One pair of shrimp can produce over 20,000 offspring within a single season. This kind of productivity offers phenomenal growth rates of over 1 pound per season.

There are two main families of scuds in British Columbia, Gammarus and Hyallela. Size is the main distinguishing factor. Gammarus can reach over 5/8ths of an inch while the diminutive Hyallela seldom exceed 1/8th of an inch. Of the two families Hyallela are the most widespread. Gammarus are limited to waters rich in calcium to maintain their citenous exoskeleton. Scuds have an almost chameleon quality enabling them to blend in with their surroundings. In stained or algae type lakes scuds are often a medium to dark olive color, while in the clearer marl lakes light olive to tan predominate. As with all food sources local observation can't be beat.Turning over rocks and logs or sifting through near shore weeds are great places for some quick detective work.

Scuds move in an erratic and random manner. Using their underslung legs scuds prowl about the bottom debris in search of food. These omnivorous feeders eat just about anything. When choosing a pattern stick to those tied on slightly curved or straight shank hooks to imitate cruising scuds. Curved scuds are either resting, falling or dead. A size 12 is a good basis point.

Their active habits make scuds a common sight to foraging trout. Slow handtwist or strip retrieves coupled with the odd quick strip or pause seem to work best. Use a set up that keeps your offering in the productive bottom zone of the lake. As scuds are common inhabitants of the shoals and margins knowledgeable fly fishers prefer floating lines coupled with long 18 to 20 foot leaders or slower sinking lines such as the intermediate to present their flies horizontally. Slower sinking lines make it possible to retrieve your pattern at a slow natural pace without the risk of a hang-up.

In the absence of an appreciable hatch trout dine on scuds anytime especially during the late fall just prior to ice up. Scuds favor low light conditions favor scuds as well. Naturally wary of bright light, scuds are most active on dull overcast days, and during the early morning and evening. Probing a promising shoal or sunken island with a scud pattern first thing is a always a good bet.