Do trout eat caddis?
Cased-caddis larvae often become dislodged in the currents of swift riffles. When trout find them, they eat them -- case and all. Imitating a cased-caddis larva is very simple, and a Zug Bug or Prince Nymph can pass as one.
What color fly do trout like?
Chartreuse and white or red and white produce the most contrast and are the best combinations under any light. Black, due to its contrast is the most visible color under most conditions and best at night. Use darker colors like black, blue and violet under low light or when fishing deep.