Scuds vary in size. Size twelve through sixteen are the usual that are bought commercially but scuds can get up to size eight. Rocky Ford has fairly large scuds, so I tie my own and fish size 8 and 10 at the Ford. I believe I catch as many fish as anyone else. I have caught them on size 16 at Rocky Ford but the larger sizes seem to work better for me. Though I had friend that out fished me using a size 14 once. But do remember that with scuds, matching the size is important.