Other Common Names: Freshwater shrimp
Scientific Names: genera Gammarus and Hyalella

Scuds are shrimp-like, freshwater crustaceans. They can occur in huge numbers in lakes and in slackwater sections of rivers. When present, they offer trout a delicious morsel that's hard to resist.

Scuds favor weedy areas, but can be found other places as well. Because they are sensitive to light, the best times to fish an imitation are on overcast days and near dawn and dusk. A healthy scud population results in large trout with deep bellies.

Scuds swim in spurts. Each spurt is 6-12 inches, and there is a pause between each. So on a lake or slackwater, use a sinking or intermediate line and retrieve the fly with short strips, pausing between each strip.

On rivers, scuds may be found either drifting or swimming. Drifting a pattern just over the top of a weed bed can be very productive. A swimming scud will straighten its body, whereas a drifting scud will curve itself; choose a pattern that matches your presentation.

Gammarus scuds are typically 10-25 mm long, while the Hyalella scuds are a tiny 3-5 mm. Don't automatically assume trout only want the big ones! There may be a preference.


How to Match a Scud

Hatches are matched from Westfly's database of "standard" fly patterns.

Size 6-16 Scud. Olive, tan, olive-pink, olive-orange


COLOR: Olive, tan, gray; may have orange spot

OTHER CHARACTERISTICS: Shell-like, curved back; many legs on underside.